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Monday, September 27, 2004

My 48,000 ton 1921-style battlecruiser

This is what my 1921-style 48,000 ton battlecruiser looked like:

Specs:

  • displacement: 48.054.2 tons
  • dimensions: 855ft x 105ft x 33.3ft
  • armament: 9-16in/45 (105 tons) and 20-5in (5 tons)
  • Cp: 0.58
  • Cm: 0.97
  • propulsive efficiency: 0.51
  • designed power: 143,500 SHP

Power curve:

  • 25 knots 66,274.9 SHP (SLR=0.854982)
  • 26 knots 77,441.9 SHP (SLR=0.889181)
  • 27 knots 89,452.3 SHP (SLR=0.92338)
  • 28 knots 102,271.0 SHP (SLR=0.95758)
  • 29 knots 115,953.0 SHP (SLR=0.991779)
  • 30 knots 135,782.0 SHP (SLR=1.02598)
  • 31 knots 160,286.0 SHP (SLR=1.06018)

The German L20eα battleship design

As WWI progressed, the Germans kept working on designs for new battleship and battlecruiser construction. The war situation kept anything from being started, but that didn't keep the designers from continuing to refine their designs. One ship that has been prominently mentioned was the L20eα. Her dimensions were: 780ft-10in x 109.9ft x 29.53ft. Her displacement was something like 43,797 tons. Her armament was intended to be 8-16.5in/45, 12-5.9in/45, and 8-88mm or 4.1in AA guns. Her protection was on a 350mm scale (13.78in). That was the thickness of the lower belt, the barbettes, and flat turret faces. Her power plant was designed to achieve 26 knots at 100,000 SHP.

I just ran my propulsion calculation program for this ship. This is part of that output:

  • 24 knots 72,850.0 SHP (SLR=0.858881)
  • 25 knots 87,950.6 SHP (SLR=0.894668)
  • 26 knots 104,169.0 SHP (SLR=0.930454)
  • 27 knots 121,494.0 SHP (SLR=0.966241)

My reference for WWI-era German capital ships is:

Friedrich Forstmeier, Siegfried Breyer, Deutsche Grosskampschiffe 1915-1918 (1970)

Sunday, September 26, 2004

Linienschiffe/Schlachtschiffe (45,000 tons)

This was a design study that I did for a German battleship. The specs were:
  • displacement: 45,000 tons
  • dimensions: 755ft x 110ft x 32ft
  • Cp: 0.61
  • Cm: 0.97
  • armament: 9-16.5in/45 (130 tons) and 10-6in/50 (6 tons)
  • power: 120,000 SHP
  • speed: 25 knots

The 16.5in/45 gun had the following specs:

  • caliber: 16.5in
  • weight of piece: 130 tons
  • length: 45 calibers
  • AP shot: 2,480 lbs.
  • muzzle velocity: 2,800 ft/sec
  • muzzle energy: 134,741 ft-tons

Here are the propulsion calculation details:

  • displacement: 44,928.6 tons
  • DLR=104.396
  • wetted surface: 93,186.9 sq. ft.
  • B/H=3.4375

It is unclear how useful the powercurve is, yet, as I need to do more testing. Here is what I just generated. Note the advantages of length, as the SLR stays below 1.0 up through 27 knots.

  • 10 knots: 3,907.12 SHP (SLR=0.363937)
  • 11 knots: 5,138.67 SHP (SLR=0.400331)
  • 12 knots: 6,587.29 SHP (SLR=0.436725)
  • 13 knots: 8,268.46 SHP (SLR=0.473118)
  • 14 knots: 10,174.50 SHP (SLR=0.509512)
  • 15 knots: 12,382.70 SHP (SLR=0.545906)
  • 16 knots: 15,039.30 SHP (SLR=0.5823)
  • 17 knots: 18,017.20 SHP (SLR=0.618693)
  • 18 knots: 21,324.20 SHP (SLR=0.655087)
  • 19 knots: 24,973.40 SHP (SLR=0.691481)
  • 20 knots: 29,017.10 SHP (SLR=0.727875)
  • 21 knots: 35,536.80 SHP (SLR=0.764268)
  • 22 knots: 46,076.70 SHP (SLR=0.800662)
  • 23 knots: 57,531.00 SHP (SLR=0.837056)
  • 24 knots: 69,935.00 SHP (SLR=0.873449)
  • 25 knots: 83,283.90 SHP (SLR=0.909843)
  • 26 knots: 97,791.80 SHP (SLR=0.946237)
  • 27 knots: 113,667.00 SHP (SLR=0.982631)
  • 28 knots: 135,716.00 SHP (SLR=1.01902)

Saturday, September 25, 2004

I find that I need to add more residual resistance data

I find that I am getting some inaccuracies in my power calculation program, seemingly caused by needing data for intermediate speed-length ratios (such as 0.25, 0.75, 1.25, 1.75, 2.25, and 2.75). Without out these points, I am getting results at higher displacement-length ratios that are to large. Even the Dreadnought comes in about 27,000 SHP to reach 21 knots instead of 23,000 SHP. At higher speeds, the difference is more pronounced. The Invincible class battlecruisers have a jump up in power to reach 25 knots that is unrealistic, but which I believe is caused by the fact the the DLR is about 97.5 (higher than anything that I had tested, to date). On the other hand, a Chatham class light cruiser came in about right: 25,000 SHP to reach 25 knots.

Power calculations for the "Super Fast Battlecruiser"

I just did power calculations for my "super fast light battlecruiser". As I previously mentioned, the specs were: light displacement: 32,000 tons normal displacement: 33,500 tons dimensions: 800ft x 85ft x 29.7ft (45ft hull depth)Cp: 0.60 Cm: 0.97 I had hoped that 510,000 SHP could be generated and delivered (somehow). The ship is probably too short for what was attempted, as a longer ship that was less full would reach higher speeds for less power (up to a point). This is some of the power curve data:
  • 25 knots: 60,404.6 SHP
  • 26 knots: 67,869.1 SHP
  • 27 knots: 75,832.5 SHP
  • 28 knots: 84,305.9 SHP
  • 29 knots: 106,515.0 SHP
  • 30 knots: 135,587.0 SHP
  • 31 knots: 166,478.0 SHP
  • 32 knots: 199,153.0 SHP
  • 33 knots: 233,762.0 SHP
  • 34 knots: 270,231.0 SHP
  • 35 knots: 308,512 SHP
  • 36 knots: 348,665 SHP
  • 37 knots: 390,772.0 SHP
  • 38 knots: 434,861.0 SHP
  • 39 knots: 480,793.0 SHP
  • 40 knots: 528,651.0 SHP

I just calculated the power curve for my "Compact Large Battleship"

Now that I am confident that my power calculation program is working, I tried it out on the "Compact Large Battleship". The specs are:
  • displacement: 85,484.2 tons
  • dimensions: 900ft x 150ft x 35.7ft
  • Cp: 0.64
  • Cm: 0.97

I ran a curve from 10 knots to 23 knots:

  • 10 knots: 6,124.24 SHP
  • 11 knots: 7,904.5 SHP
  • 12 knots: 9,995.1 SHP
  • 13 knots: 12,408.4 SHP
  • 14 knots: 15,182.8 SHP
  • 15 knots: (found a bug at this point: SLR 0.5)
  • 16 knots: 27,082.1 SHP
  • 17 knots: 36,911.9 SHP
  • 18 knots: 47,839.7 SHP
  • 19 knots: 60,018.2 SHP
  • 20 knots: 73,454.9 SHP
  • 21 knots: 88,066.5 SHP
  • 22 knots: 103,897.0 SHP
  • 23 knots: 120,946.0 SHP

Obviously, I have a bug that happens Speed-Length Ratios that are exact multiples of 0.5.

Actually, the designed speed for the Japanese 5,500 ton light cruisers was 36 knots

I remembered that the designed speed for the Nagara and similar ships was 36 knots. My program calculated that to make 36 knots, 90,256.7 SHP was required. That was at a displacement of 5,492.13 tons and a draft of 15.875 feet.

I just duplicated what I have in my spreadsheet for power calculations for the Japanese light cruiser Nagara

Needless to say, I want to do more testing, but I just confirmed that my power calculation program produced output that closely matched my Excel spreadsheet calculations for the same ship (the Japanese light cruiser Nagara). I will be doing some runs for some of my ship designs and publishing the results. I may be doing other historical ships, as well.

Friday, September 24, 2004

I found the bug in my propulsion calculation program

I just found the bug that was in my propulsion calculation program. I had not been sure if it was a residual resistance table problem or a program bug. It turned out to be caused by a bug. I had the columns in the residual resistance table switched between where it was initialized and where it was used. I may still have table issues, but I will first have to reenter my residual resistance data, so that I can test.

I have found the book Japanese Cruisers of the Pacific War to be extremely useful. It is perhaps the best ship book, ever. The book gives the data necessary to to do propulsion calculations. I am using the data for the light cruiser Nagara for debugging purposes. I should see something like 90,000 SHP to achieve a speed of 35 knots, at a normal displacement. The Nagara was nominally 5,500 tons. This is the data I am using:

  • displacement: 5,492.13 tons
  • length on the waterline: 520ft
  • beam: 46.5ft
  • mean draft: 15.875ft
  • Cp: 0.619
  • Cm: 0.809
  • Displacement-Length Ratio: 39.0599
  • Beam/Height ratio: 2.92913

The 5,500 ton light cruisers were very destroyer-like. Their stern was wide and round, similar to a destroyer, and the machinery was that of two destroyers, as a high-output plant with light weight was needed to achieve 90,000 SHP in such a small ship.

Thursday, September 23, 2004

Japanese guns

I was to look at Japanese gun data in Japanese Cruisers of the Pacific War:

20in/45 (510mm)

  • length of barrel: 77.3ft
  • weight with breach: 227 tons
  • AP shot: 4,299 lbs
  • charge: 1,058 lbs
  • twin turret weight: 2,780 tons
  • date: 1940

18.1in/45 (460mm)

  • length of barrel: 69.3ft
  • weight with breach: 165.76 tons
  • AP shot: 3218.75 lbs
  • charge: 793.66 lbs
  • triple turret weight: 2,565 tons
  • date: 1934-1939

18.9in/45

  • length of barrel: unknown
  • weight with breach: 167 tons
  • AP shot: 3,417.17 lbs
  • charge: 751.78 lbs
  • twin turret weight: 2,500 tons
  • date: 1916

Wednesday, September 22, 2004

I have gotten my program for calculating power curves working

I found the bug that had been keeping my program for calculating power curves for ships from working. Typically, it was a typographical error (a misspelling). Now, the primary issue remaining is to get good residual resistance tables for higher values of speed-length ratio, prismatic coefficient, and displacement-length ratio. Even simplified as much as I have, the values for more moderate speed-length ratios gives reasonable answers. As I had suspected, by residual resistance values for larger coefficients seem to be too high. What Frank Fox had suggested to me is that the main obstacle to very high speed is frictional resistance, not residual resistance (wavemaking).

Tuesday, September 21, 2004

Edward Attwood and Stanley Goodall

Edward L Attwood was head of battleship design during the critical period up of the First World War, and beyond. He had a young, rising star under his supervision: Stanley Goodall, a future DNC. Stanley Goodall had first come to prominence with his design for the Arethusa class light cruisers. Edward Attwood lead the design of the 1915 battlecruisers, of which one, the Hood, was completed. D.K. Brown notes that by the time the Hood was completed, her designers had lost faith in her. To solve the problem, they had the design approach up their sleave that would have resulted in the 1921 battlecruisers. That was eventually adapted for the battleships Rodney and Nelson. Too often, during this period, requirements given to the design staff resulted in flawed ships being produced. In the flailing around after the Battle of Jutland, the Hood design was altered, in many ways, for the worse. One feature of the Hood and the 1921 ships was a huge conning tower. We know, from the work done examining the wreck of the Hood, that when she capsized, the conning tower fell out. An alternate view is that the conning tower was ejected by the force of the explosion. I am somewhat skeptical about that, given that the conning tower weighed over 200 tons. The Hood would have been a better ship if they had used a lighter conning tower. This was a problem of "design by committee" (or specifications by committee). In any case, I very much like the direction taken in the 1921 designs. There was a flush deck, with a bow that flared and rose to give a good freeboard forward. There was the small transom stern that saved weight and gave a small increase to the effective length, slightly lowering the propulsion cost. These ships also finally included triple turrets for the main armament and twin turrets for the secondary armament. They also employed the "all-or-nothing" armoring scheme. I think that placing the three turrets forward was overkill. They would have been better ships with a conventional layout. At this point, Stanley Goodall was into some of these radical features, so the designs had them.

Monday, September 20, 2004

Compact very large battleship

This may seem a contradiction in terms, but the reason is that he displacement for this design is quite low for the armament. The designed standard displacement (I was into Washington Naval Treaty design standards at the time) was ONLY 80.000 tons. That was low, because the designed armament was 10-21in/45 guns. These guns would have fired a 5,000 lb. AP shot. Each 21in-piece would have weighed about 300 tons. By my current design standards, I would make a 21in/45 gun of 320 tons. The main armament was to be in 2-triple turrets and 2-superfiring twin turrets. The secondary armament was to be in twin gun mounts. This ship's specifications were:
  • standard displacement: 80,000 tons
  • full load displacement: 85,650 tons
  • dimensions: 900ft x 150ft x 35.7ft (hull depth: 65ft)
  • armament: 10-21in/45 and 24-5in/50
  • Cp: 0.64
  • Cm: 0.97
  • designed speed: 20 knots
  • machinery: 85,000 SHP
  • machinery: 2,840 tons
  • auxiliary machinery: 3,000 tons
  • hull: 24,000 tons
  • armament: 6,876 tons
  • protection: 36,884 tons
  • miscellaneous: 6,400 tons
  • max. oil fuel: 5,000 tons
  • feed water: 650 tons

Sunday, September 19, 2004

My ship power curve calculation computer program

I just did some testing, and found that I have a bug in the residual resistance calculation code. The frictional resistance EHP looks to be correct. I just tested with my "super-fast" light battlecruiser design. At 40 knots, the Reynolds number is 4.2169e+009. The Schoenherr table value read is 1.291, which must be multiplied times 10^-3. The frictional EHP is 78,264.6. I will fix the residual resistance table reading code and retest tomorrow.

Saturday, September 18, 2004

A "straight" German battlecruiser design

My concept for a straight-forward battlecruiser design for circa 1915 was a vessel of 45,000 tons armed with 9-16.5in/45 (130 ton) and 10-6in (6 ton) guns. This were the specs:
  • standard displacement: 45,000 tons
  • dimensions: 850ft x 110ft x 30.3ft
  • hull depth: 48 ft
  • Cp: 0.57
  • Cm: 0.97
  • armament: 9-16.5in/45 and 10-6in/50
  • power: 200,000 SHP
  • speed: 33 knots
  • machinery weight basis: 30 SHP/ton of plant
  • hull weight: 15,250 tons
  • hull weight factor c: 0.34 x 10^-2
  • armament: 2,830 tons
  • protection: 16,650 tons
  • machinery: 6,670 tons
  • miscellaneous: 3,600 tons
  • fuel: 8,000 tons max.
  • feed water: 900 tons

The ship had a long forecastle with a step aft, just forward of the after turret. The main armament was mounted in three triple turrets, while the secondary armament just had shields, and were mounted singly.

Friday, September 17, 2004

The battlecruiser version of my alternate world design pattern

This is is the battlecruiser analog to my battleship built to the German Nassau class Dreadnoughts. This is approximately built to the dimensions of the Von der Tann.

Therefore, this ship would have four twin 11in/45 turrets and 12-5.9in/45 guns. The pencil drawing that I worked from was not as clean as that for the battleship, so I don't like the look of this version as well as the battleship of this design pattern. The pattern is a Derfflinger-style hull and secondary armament with a British-looking superstructure and masts. This is slightly enhanced version of the drawing.

An "alternate world" version of the German Nassau type battleships

This drawing follows a design pattern that I have used at various times over the past 30 years. This is a battleship built to the dimensions of the German Nassau class Dreadnoughts, but with a flush deck and my version of a British upperworks.

Therefore, this ship would have four triple 11in/45 turrets and 12-5.9in/45 guns. There is a battlecruiser analog to this design that is approximately to the dimensions of the Von Der Tann, but with this sort of "look". When I finish cleaning up that drawing, I will post it as well.

I've simplified the residual resistance tables so that I can make progress

I reduced the amount of data that I need to generate for residual resistance tables, so that the work is more manageable. The drawback is that calculation accuracy is diminished, but could be improved by adding in data for more Speed-Length Ratios. I am using my handdrawn graphs from late 2002 to help with the data generation. The need filled is to extrapolate for values beyond those listed in The Speed and Power of Ships. The data most often used will be reasonably accurate, as some of the extrapolation is pretty low-risk. Where the values may never be used, as they are so extreme, the data is less reliable.

Thursday, September 16, 2004

Picture of the "Super-Fast Battlecruiser"

This is my drawing of the "super-fast battlecruiser". I took the 30-some year old pencil drawing and did some digital editing to enhance it.

As I previously noted, this was intended to be a 32,000 ton ship (actually, 33,500 tons normal) with 4-17in/45 and 16-4in QF guns. The armor was to be thin, as in the preceding light battlecruiser designs.

Wednesday, September 15, 2004

My 1905 building program for Germany (from 1971)

For our naval wargame that centered on designing building programs, we used a figure of £90 per ton of ship. In reality, that figure would vary according to ship type, but that was simplification we used. This is what was originally conceived, before any subsequent tweaking took place. Note that we were not so concerned about being unrealistic about what was possible at the time, although I would like to think that we were just thinking about doing things that had not been seriously considered "in real life", rather than being too technologically advanced. My 1905 German building program consisted of:
  • 3 battleships
  • 1 light battlecruiser
  • 6 scout cruisers
  • 12 destroyers

Ger/BB/1905

  • displacement: 22,000 tons
  • dimensions: 580ft x 90ft x 26.6ft
  • Cp: 0.57
  • Cm: 0.97
  • armament: 8-12in/45, 12-4in QF
  • armor belt: 10in
  • speed: 24 knots

Ger/CB/1905

  • displacement: 19,000 tons
  • dimensions: 700ft x 80ft x 24.4ft
  • Cp: 0.54
  • Cm: 0.90
  • armament: 4-12in/45, 12-4in QF
  • armor belt: 4in
  • speed: 31 knots

Ger/CS/1905

  • displacement: 2,480 tons
  • dimensions: 370ft x 38ft x 13ft
  • Cp: 0.56
  • Cm: 0.85
  • armament: 5-4in QF, 2-18in TT
  • armor: 2in H/T steel over machinery
  • speed: 36 knots

Ger/DD/1905

  • displacement: 870 tons
  • dimensions: 270ft x 28ft x 9ft
  • Cp: 0.56
  • Cm: 0.80
  • armament: 2-4in QF, 2-18in TT
  • speed: 32 knots

Tuesday, September 14, 2004

I used to be very big on deck armor for capital ships

This is an example of what I used to think was the right way to protect a battlecruiser:

Ger/CB/1912 midsection

The design had 5in + 4in deck armor, and tapered side armor, tapering from a4in at the top to 8in at the bottom. The belt was backed by 3in armor on the slopes. the anti-torpedo bulkhead, which continued the belt to the bottom, was 2in thick. Between the decks, the funnel protection was 2in, and above the decks was 4in.

Monday, September 13, 2004

More machinery weights

In D.K. Brown's book, The Grand Fleet, he provides a little more data about machinery weights. He says that a typical 1912 British cruiser design might have had machinery weighing 1050 tons and producing 30,000 SHP. That is about 28.6 SHP/ton of machinery. For the 1912 Arethusa class they wanted 40,000 SHP from a plant weighing 850 tons. That is 47 SHP/ton of machinery. In Brown's book Warrior to Dreadnought, there are a few other nuggets:
  • destroyer Arab: 41.3 IHP/ton of machinery (1896)
  • destroyer Express: 44.5 IHP/ton of machinery (1896)
  • destroyer Albatross: 39.5 IHP/ton of machinery (1896)
  • large cruiser reciprocating 41,000 IHP plant: 11 IHP/ton of machinery (1905)
  • large cruiser turbine 41,000 SHP plant: 13.7 SHP/ton of machinery (1905)
  • flotilla leader Swift: 32.7 SHP/ton of machinery (1905)

The lack of better weight data for British ships from 1890 to 1921 is particularly bothersome.

There is much better data for USN ships. For example, the Omaha class cruisers had a plant that produced 52.3 SHP/ton of machinery, and this was in a plant designed circa 1918. The Lexington class battlecruisers were designed with a plant that produced something like 31.4 SHP/ton of machinery. This was a 1919 design.

A little perpective on SHP per ton of machinery weight

I was looking at D.K. Brown's book Nelson to Vanguard, where I was looking for data about machinery weight. In one table, he lists pounds per SHP. I prefer to turn that around to SHP per ton of machinery weight. The Queen Elizabeth class battleships were originally 26 SHP/ton of machinery. The WWII-era King George V class were 60 SHP/ton of machinery. The former used large tube boilers, and was designed about 1912. Using D.K. Brown's figures, the battlecruiser Hood, with small tube boilers achieved 34 SHP/ton of machinery. This was a 1916 design. The modernized Queen Elizabeth class ships had a plant that was 51 SHP per ton of machinery. Cruisers had long had lighter-weight machinery. Again, using D.K. Brown's figures:
  • Kent: 43.7 SHP/ton
  • Exeter: 45.7 SHP/ton
  • Leander: 47.8 SHP/ton
  • Amphion: 55 SHP/ton
  • Arethusa: 52.4 SHP/ton

These are all 1920's-early 1930's ships.

Destroyer machinery weight bases seem harder to find. The WWI Admiralty R-class had machinery weighing 395 tons. The power output was 27,000 SHP designed. This gives us 68.35 SHP/ton for a ship designed in 1915. For comparison, the WWII Hunt class machinery was 285 tons. The power output was 19,000 SHP. That gives a machinery weight basis of 66.67 SHP/ton. That was for a plant designed in 1938-1939. There was no improvement in output.

Strategic Mobility

Speed is not so important in tactical situations, but for strategic mobility. The best example of a high-speed ship type is the Italian Capitani Romani class. These were ships like the Attilio Regolo, the Pompeo Magno, and Scipione Africano. Their dimensions were: 469ft x 47.25ft x 16ft. Their initial armament was 8-5.3in (135mm)45, 8-37mm/54 AA, and 8-20mm AA. They had a 110,000 SHP power plant. Their normal displacement was 5,035 tons. Their nominal speed was 40 knots, but in service they were able to sustain as much as 43 knots! They carried 1,400 tons of fuel and had a nominal range of 4,352 miles at 18 knots. The only ships even close to these in their speed-range combination were the British Abdiel class minelayers. They were much smaller ships, with a standard displacement of 2,600 tons. They only had 6-4in guns, and had a nominal speed of 40 knots. They were very overweight (about 3,450 tons), so that 35 knots was a more realistic speed with 73,000 SHP. Even that speed, with their ample internal volume allowed them to be fast supply carriers to Malta. The Italian vessels were much superior ships. They were really the precursors of the large destroyers built postwar, especially by the USN. They were flush-decked and had a flared bow, and were decent seaboats. Their guns were rather unsatisfactory, as 13cm (5.1in) would have been a better choice, but if their opponents had been the French contre-torpilleurs, they might well have had need for a gun as big as 135mm.

Sunday, September 12, 2004

My variant of the light battlecruiser

I'm not the creator, but I did help develop the idea for a light battlecruiser that sacrificed gunpower for speed. Armor was secondary to speed, and then gunpower. My friend Cliff's original concept was for a 32 knot ship with 4-12in/45 and 9-6in guns. He thought that we could economize and use 9-6in/50 instead of 10-6in/50, so that one was on the centerline, superfiring the aft 12inch turret. The next refinement was to add 12in/50 guns for the next pair. Finally, after a hiatus, there were to be four with 4-13.5in/45 guns. My superfast version designed about 1973 with 17in/45 guns was an attempt to take the concept to the extreme. I wanted more weight to devote to power, so I reduced the hull depth, thinking that I would be able to then reduce hull weight. That ignores the loss in strength, but there was little increase in length, so it didn't seem that much of an issue. As soon as I can run my power calculation program, I want to generate a power curve for the "super fast" ship, as well as the other light battlecruiser classes. How they do is greatly dependent on the weight basis for the power plant (SHP per ton of machinery).

Saturday, September 11, 2004

Superfast light battlecruiser

I did a design for what was intended to be a "super fast" light battlecruiser with 4-17in/45 (138.6 tons) and 16-4in/50 QF (2.2 tons) guns. I did somethings to drastically reduce hull weight, but using a low hull depth design. The specs were:
  • light displacement: 32,000 tons
  • normal displacement: 33,500 tons
  • dimensions: 800ft x 85ft x 29.7ft (45ft hull depth)
  • armament: 4-17in/45 and 16-4in/50 QF
  • Cp: 0.60
  • Cm: 0.97
  • hull weight: 8,890 tons
  • machinery: 12,750 tons
  • auxiliary machinery: 1,232 tons
  • armament: 2,088 tons
  • protection: 4,480 tons
  • miscellaneous: 2,560 tons
  • machinery weight basis: 40 SHP/ton of machinery (too high)
  • machinery: 510,000 SHP (probably wildly overoptimistic)

The fundamental problem with this ship is now to deliver that much power. Frank Fox has spoken to me about a fundamental limit of about 70,000 SHP per shaft, before the shaft would give way. It might actually be slightly higher, but not with 1921 technology.

Another factor is the shallow draft, which also complicates shafting, along with the narrow beam.

The specs for the Ger/CB/1906

I may not have mentioned this recently, but the specs for the Ger/CB/1906 battlecruiser were:
  • legend displacement: 25,000 tons
  • dimensions: 800ft x 85ft x 25.6ft
  • Cp: 0.53
  • Cm: 0.95
  • armament: 8-12/45 (50 tons), 8-6in/50 (6 ton)
  • machinery: 120,000 SHP
  • speed: 32 knots
  • armor belt: 4in, angled outwards

I have some weights calculated, but I am sceptical of them, so I will not list them until I can do a new calculation.

My Ger/CB/1906 design (picture from 2002)

This is my attempt to produce an updated drawing for my Ger/CB/1906 design from the early 1970's. I did the pencil drawing for this attempt two years ago. I just scanned it and darkened the lines using Paint.

German battlecruiser Ger/CB/1906

Ger/CB/1906 design. Drawing from August 2002. If you have seen any of the other drawings, you can see that it "looks like it came from my main shipyard".

Friday, September 10, 2004

Residual resistance tables

I finished my first cut at my power generation program and am now in the process of generating residual resistance tables. This is the most time-consuming process. That is because of the need to extend the graphs in The Speed and Power of Ships to cover the ranges of speed-length ratios and displacement length ratios. This program, at a minimum, make an appearance by producing power curves. It also could appear in game programs.

Thursday, September 09, 2004

Port Arthur map

In responce to a message on the NavWarGames Yahoo group, I looked in various Jane's, including the 1914 and 1919. They have the same map, on a 2000yd grid, with elevations in feet. I thought it would be worth looking in my 1903 All the World's Fighting Ships (Fred T. Jane) to see was there. I don't expect there are too many copies of this work "running around". The Russian section has a small map of Kronstadt that shows the harbor layout and water depths. There is also a nice map of Vladivostok. It only has a rudimentary map of Port Arthur, although it does point out the forts. I would thing that this small snippet is pretty accurate. The map that appears in the 1914 and 1919 Jane's replaces this one, although it might be instructive to compare the two.

The Midship Coefficient (Cm)

One issue that had never occurred to me, until Frank Fox pointed it out to me, is that using his system, a midship coefficient can be greater than 1.0. I had always assumed that the box used to compute the Cm would be drawn to touch the widest part of the hull, for the width. The height is the mean draft, and that remains undisputed. This becomes important for ships that are bulged. Frank Fox (probably correctly) draws the box, using the waterline beam as the width of the box. Thus, the bulges could protrude outside of this box. Frank Fox gives the Cp as 0.661 and the Cm as 1.021, while Garzke and Dulin give the Cp as 0.612 and the Cm as 1.121. The bulges don't seem to protrude enough to give a Cm as high as 1.121, so I am sure that 1.021 is accurate.

Wednesday, September 08, 2004

Calculating electrical and auxiliary power usage

Again, this method is due to Frank Fox. Any errors are in my interpretation of what he wrote. The idea is that we will use an arbitrary 37% of the horsepower needed to generate the maximum Ship's Service Turbo Generator (SSTG) output (this is the American term), at 0.746 HP per KW. American WWII-era turbogenerators "have a power factor of 0.8". This is the calculation: HP = (0.37 x max KW) / (0.746 x 0.8) So, taking some liberties, my earlier-era ship that has a 1KW electrical plant would give the following: SHP = (o.37 x 1000) / (0.746 x 0.8) = 619.97 HP

Computing range, considering electrical power generation

This is my attempt to implement what Frank Fox wrote to me about considering electrical power generation in range calculations. It is as close to what he described as I could make it, at my level of understanding.
  • The starting point is to know the "sea speed" and the SHP required to make that speed.
  • Add 10% to that power to allow for "sea state"
  • Then, add to that SHP the "SHP" needed to generate the electric power (I will discuss that separately)
  • Add 10% for deterioration of the plant
  • Multiply the SHP by 1.045 to allow for split plant operation, where applicable
  • Compute the burnable fuel rate: (SHP x 0.9 lbs/SHP/hour)/2240 lbs per ton
  • Compute normal range: sea speed x normal fuel load x 0.97895/(burnable fuel rate) (the factor accounts for unusable fuel, among other things)
  • Compute max. range: sea speed x max. fuel load x 0.978595/(burnable fuel rate)

There are issues caused by the variable displacement and the power required to reach the sea speed under different loading. I'm pretty sure that the calculations described here are just designed to give the average performance. I suppose that you could integrate over time to get a more accurate figure, as the required power decreased, as fuel is burned.

I rediscovered how to compute a ship's range, using Frank Fox's system

I had a spreadsheet design that I had built, with help from Frank Fox, to do range computations, taking into account turbine generator fuel usage. In the fall of 2002, I had a hard disk crash which wiped out all electronic versions of the spreadsheet. As I am getting back into the design process, I wanted to include range calculations. I had put down my program to do power calculations using David Taylor's The Speed and Power of Ships approach that I learned from Frank Fox. I am ready to pick up where I had left off, and push towards making it usable. The program is an important component, as it will be a critical timesaver in the design process. Essentially "one button" spped and power calculations are then possible. I had done a lot of the work, when I converted graphical data into Excel spreadsheets, extrapolating from what is in The Speed and Power of Ships.

Tuesday, September 07, 2004

My "Project Ger/BB/1915" battleship design

The original concept, at least to be published, was for a 60,000 ton battleship of 20 knot speed. Either a redesign, or the stealth design, was for a ship of 72,000 tons with 9-18in/45 guns (180ton) and 24-5in QF (5 ton). The specs were:
  • legend displacement: 72,000 tons
  • armament: 9-18in/45 (180 ton) and 24-5in QF (5 ton)
  • speed: 20 knots
  • power: 120,000 SHP (original concept was 60,000 SHP)
  • Cp: 0.66
  • Cm: 0.98
  • dimensions: 750ft x 130ft x 40ft (65ft hull depth)
  • machinery weight basis: 40SHP/ton of machinery
  • hull weight basis c: 0.29 (x 10^-4)
  • machinery weight: 3,000 tons
  • hull: 18,400 tons
  • auxiliary machinery: 2,770 tons
  • armament: 4,000 tons
  • protection: 38,070 tons
  • miscellaneous: 5,760 tons

I believe that the armor basis was intended to be 16in (belt, barbettes, CT, etc.)

Monday, September 06, 2004

My concept of a good German light cruiser for 1914

My Ger/CL/1914 design seems to have been inspired by the British Arethusa class, but has a very German "look". I believe that the original concept was to have 7-5in QF guns, but that I apparently decided that it needed more guns, so I added a 5in gun on either side of the bridge. Speed continued to be important to me, so I specified 32 knots. The specs are:
  • legend displacement: 3,500 tons
  • armament: 9-5in QF, 4-21in TT, 40 mines
  • dimensions: 430ft x 40ft x 15.9ft
  • speed: 32 nots
  • power: 60,000 SHP
  • machinery weight basis: 45 SHP/ton of machinery
  • Cp: 0.56
  • Cm: 0.80
  • hull weight basis (c): 0.30 (x 10^-4)

I had to rediscover my notation, as I did not remember how my "c" factor was scaled. The way this is used is:

hull weight in tons = length in feet x beam in feet x hull depth in feet x c x 10^-4

  • protection: 1in deck, amidships
  • oil fuel: 700 tons
  • feed water: 100 tons
  • machinery weight: 1,335 tons
  • hull weight: 1,500 tons
  • armament: 103.5 tons + 6 tons of mines
  • full load displacement: 4,305 tons

Sunday, September 05, 2004

Above water torpedo tubes on large ships

Frank Fox has told me that he is very opposed to having above water torpedo tubes on cruisers and capital ships. It had been thought that an exploding torpedo could have broken the Hood's back, although I am not sure what the current assessment is. One or more Japanese cruisers were lost from damage sustained when torpedo tubes were hit by bombs from the air. I believe that was what really decided things for Frank Fox. While Frank Fox's primary interest is in 17th Century English ships and naval history, he is also interested in WWII era ships. He is another person who likes to design his own warships, although he does it more infrequently. He is the one who taught me a system for calculating power for ships, using The Speed and Power of Ships for residual resistance and Gertler's book for frictional resistance.

Saturday, September 04, 2004

I used to like tapered armor

I am looking at the cross section for the Ger/BB/1905 design I did way back, and one of the things that is readily noticable is that the armor belt (lower and upper) is tapered. The lower belt, at the waterline, is 8ft tall and the greatest thickness is at the top. That was 11in and the lower edge was 9in, for an average of 10in. That was backed with wood, and had a 3in slope that angled to touch the lower edge of the belt. The upper belt was thicker at the lower edge, having 6in thickness at the top edge and 8in at the lower edge, for an average of 7in. The upper belt, and side, above that have a normal plating W/T bulkhead that is parallel, with a 3ft space behind, to limit flooding, if the outer skin or armor is pierced. The deck was unusual for me, in that there are only patches of thicker armor. The forecastle deck has 3in high tensil-strength steel (H.T.S) at the deck edge, about 8ft wide. At the main deck level, the deck is 1in H.T. steel, with a pacth of 3in H.T.S., about 10ft wide, set back about 7ft. The main deck is 1in H.T.S., with a 3in patch across the middle of the deck, about 45ft wide. The anti-torpedo protection is about 10ft deep, with layered bulkheads. There is a 2in H.T.S. bulkhead, inboard, with another layer to try to limit flooding, if that is breached. The boiler rooms are unbroken by bulkheads, to limit any tendency to listing.

Friday, September 03, 2004

Cliff's "BBX" design

My friend Cliff had this concept for what seemed like a breakthrough battleship design. For whatever reason, he had switched from high speed to moderate speed and heavy armor and guns. The ship was built around the 20in/45 gun (202 ton). The APC shot was 4,370lbs with a muzzle velocity of 2,700 ft/sec. The specs for the ship were:
  • dimensions: 800ft x 135ft x 36.5ft (light displacement)
  • legend displacement: 70,000 tons
  • armament: 9-20in/45 (202 ton) and 24-5in QF (5 ton)
  • speed: 20 knots
  • power: 89,300 SHP
  • machinery basis: 30SHP/ton of machinery

The weight breakdown:

  • hull: 18,800 tons
  • aux. machinery: 2,450 tons
  • machinery: 2,980 tons
  • armament: 4,461 tons
  • protection: 35,709 tons
  • miscellaneous: 5,600 tons

Thursday, September 02, 2004

The Super-Swift

Winston Churchill described the super-Swift (as he wrote the name) as having 6-4in guns, 600 tons of oil fuel, and able to make 37 knots. The cost was to be £250,000. The question is how large the type was to be. The super-Swift type would have been built under the 1912 estimates, so we could use the Laforey class destroyers as a guide. The Hotspur cost the most, being £107,800. The Laforey class were designed to be 1112.5 tons. That is a cost of £96.9 per ton of displacement. If the super-Swift cost £250,000, that would be displacement of about 2,580 tons. I had previously guessed a much lower displacement: about 2,250 tons.

I found the more detailed specs for the "Super Lion"

It turns out that I have the more detailed specs for my version of the "Super Lion" battlecruiser. I will just lay out the specs as a list:

  • light displacement: 27,000 t0ns
  • normal displacement: 28,500 tons
  • full load displacement: 31,500 tons
  • Dimensions: 800ft x 90ft x 26.5ft (normal)
  • hull depth: 48ft
  • Cp=0.55
  • Cm=0.95
  • hull weight basis: 2.9 x 10^-3
  • Armament: 10-15in/45 (97 tons), 16-5in/50 (5 tons)
  • Protection: 6in belt, 9in turrets, 9in barbettes
  • Speed: 32 knots
  • Power: 114,000 SHP normal, 136,600 SHP max.
  • V/sqrt(L) (normal): 1.175
  • V/sqrt(L) (max.): 1.26
  • machinery basis: 30 SHP/ton machinery
  • power/wt: 4 SHP/ton of displacement (normal), 4.8 SHP/ton (max.)

Weights:

  • Hull: 10,050 tons
  • Aux. Mach.: 1,060 tons
  • Machinery: 3,800 tons
  • Armament: 2,410 tons
  • Protection: 7,520 tons
  • Miscellaneous: 2,160 tons

Wednesday, September 01, 2004

Admiral Fisher's Super Lion battlecruiser (my drawing)

This is my drawing from thirty-some years ago of my concept of what Admiral Fisher's Super Lion class battlecruiser would look like. As you can see, I was really into drawing ships so that they looked like the drawing should be in Jane's Fighting Ships. Admiral Fisher's Super Lion class battlecruiser
(I've been struggling to get an image type and size that will fit the blog format)

My "Super Lion" design

Admiral Fisher had proposed a "Super Lion" battlecruiser to Winston Churchill in January 1912. The class would have "restricted armour", "all oil", 10-"improved" (15in/42) guns, "cost £1,995,000", and "speed over 30 knots" .
In response to that idea, I designed my "Super-Lion": 27,000 tons standard, 28,500 legend displacement, 31,500 tons deep load.
I wanted 32 nots, 10-15in/45 (97 tons), and 16-5in/50 (5 tons).
My projected cost was £2,430,000. For that size ship, and my cost basis, this was the best that I could do. I need to post the picture, as it is worth seeing.

Tuesday, August 31, 2004

I had this concept for a 1915 heavy coast defense ship

I had an idea that I could have a heavily-gunned coast defense battleship to be built in 1915. The profile is very anachronistic, in that it looks like a German armored ship (pocket battleship). The hull was flush-decked, and had a rather low freeboard. Admiral Fisher's Super Lion class battlecruiser These are the specs:
  • legend displacement: 28,000 tons
  • dimensions: 585ft x 100ft x 29.1ft (50ft hull depth)
  • armament: 4-18in/45 (180 ton), 20-5in (5 ton) QF (twin gun mounts)
  • speed: 20 knots
  • power: 25,000 SHP
  • Cp: 0.62
  • Cm: 0.97
  • V/sqrt(L): 0.827
  • machinery weight basis: 30SHP/ton of machinery
  • oil fuel: 1000 tons
  • feed water: 150 tons
  • hull weight basis: 2.4 x 10^-3

Weights:

  • hull: 7,000 tons
  • machinery: 834 tons
  • aux. machinery: 1,070 tons
  • armament: 1886 tons
  • protection: 14,970 tons
  • miscellaneous: 2,240 tons
This was an attempt to achieve the "moderate proportions" battleship for which people like Sir Charles Beresford and Lord Brassey were always lobbying.

Monday, August 30, 2004

Large destroyers and scout cruisers

I have gone through phases where I was sure that large destroyers and small scout cruisers should be equipped with 6in guns. I had this concept to modify my Ger/CS/1905 scout cruiser design to carry 3-6in/50 on the centerline. I would have upgraded the torpedo armament to 4-21in torpedoes in twin tube mounts. These are the detailed specs:
  • legend displacement: 2,500 tons
  • dimensions: 370ft x 38ft x 13ft
  • Cp: 0.56
  • Cm: 0.85
  • protection: 2in HT steel over machinery
  • speed: 35 knots
  • fuel: 500 tons
  • machinery: 50,000 SHP

The problem with this design is that 6in guns are really too large for small ships. 5.5in guns are about as large as are suitable and about 5in is ideal. The shot weight is what really matters. Manhandling 100lb shot in a seaway is problemmatic. 5.5in shot weighing 85lbs is not much better. 50 or 60lb shot is about the largest that is reasonable. A 13cm (5.1in) gun with 68lb or 72lb shot is probably too heavy to be reasonable, although it was still used.

Saturday, August 28, 2004

Ger/CB/1911 design

My German 1911 battlecruiser design evolved from a concept for a fast armored cruiser. the original concept was for a 14,000 ton ship with 8-9.4in (25 ton) guns and a 6in belt. The 9.4in (24cm) gun was intended to fire a 419lb APC shot. The next step in the evolution was a 20,000 ton battlecruiser with 6-12in/50 guns and a 6in belt. This design was filled out more, and the dimensions were 725ft x 80ft x 22.7ft. The Cp was 0.56 and the Cm was 0.95. The hoped for speed was 33 knots. The armor was restricted to a narrow patch amidships, with 3in+2in decks and a 1in A/T bulkhead. The final design was much larger: 35,000 tons legend displacement. The final dimensions were 750ft x 100ft x 30.1ft, with Cp=0.56 and Cm=0.97. The hull depth was 55ft. The armament was still 6-12in/50 (66 ton) and 8-6in (8 ton). The main armament was in two triple 12in turrets, superimposed forward. The power was 140,000 SHP. I was hoping for 30 knots. The weights broke down as follows:
  • oil fuel=6000 tons (full load)
  • feed water=750 tons
  • armament=1062 tons
  • protection=9128 tons
  • hull=12,300 tons
  • machinery=3,500 tons
  • miscellaneous=2,260 tons

The protection was an inclined belt (4in-8in), 5in upper deck and 3in lower deck, and 2in A/T bulkhead. The uptakes had 4in armor above the upper deck and 2in between the decks. The turrets and barbettes were 8in. The conning tower was 8in with a 4in comm tube. The bulkheads on the citadel were 6in, as was the steering protection.

Friday, August 27, 2004

The GB/CB/1910 design

My friend Cliff's concept for the 1910 and 1911 building programs was for a battlecruiser with 4-4-13.5in/45 guns, 8-4in QF, and 9in side armor. The type retained the three funnel look with the first funnel raised. In this case, the funnels were equally spaced. In my early 1970's redrawing, I gave the ships an anachronistic bridge and tripod mast (more like 1918 or the 1920's rebuilds of the R-class and Queen Elizabeths). The specs were:
  • legend displacement: 33,000 tons
  • dimensions: 775ft x 94ft x 30ft-11in
  • speed: 33 knots
  • armament: 4-13.5in/45, 8-4in/50 QF
  • protection: 9in belt, no conning tower

The basic concept was to sacrifice firepower to achieve higher speed, and providing moderate protection in battlecruisers ("Speed is armour"--Admiral Fisher).

Thursday, August 26, 2004

19.75in guns are 50cm

The reason that we would have 19.75in guns is that if we were metric-oriented, we would prefer 50cm guns over 20in guns. Let's do a few "back of the envelope calculations":
  • Weight of piece (19.75in/45): 210 tons
  • AP Shot weight: 4175 lbs
  • Muzzle velocity: 2640ft/sec
I need to run Nathan Okun's program to see what kind of performance it could achieve.

A "very large" battleship design

One of the largest battleships that I thought about 30-some years ago was 105,000 tons legend displacement. The armament was 9-19.75in/45 and 16-6in guns. The secondary armament was to be arranged in 8-twin turrets. The power was 280,000 SHP hoping to produce 31 knots speed.
The dimensions were 1,085ft x 140ft x 34ft (hull depth 66ft).
Let's see if we can add a little flesh to this outline:
  • displacement: calculated to be 84,448.588 tons, far less than 105,000!
  • L=1085 ft
  • B=140ft
  • d=34ft
  • Cp=0.59
  • Cm=0.97
To reach 105,000 tons, it would take dimensions like this:
  • displacement: 105,000 tons
  • L=1160ft
  • B=145ft
  • d=37ft
  • Cp=0.60565
  • Cm=0.975
The larger dimensions are necessary to keep the navigational draft from getting far out of hand (42ft). As it is, 37ft is deep, and would restrict access to harbors and docks.

Wednesday, August 25, 2004

Residual resistance tables

I have been working the issue of programmatically calculating power curves for ships for slightly more than two years. My previous approach had enough problems, that I set the problem down for about a year. I have picked it back up, and have taken a new tact. Instead of using sparse matrices, I am using complete matrices with all values populated. As The Speed and Power of Ships has graphs that do not cover the space for all ships, I have assumed that they can be extended. The underlying assumption is that residual resistance is a continuous function and has no discontinuities. Given that, it is possible to extend the graphs, by plotting resistance, given the prismatic coefficient and the speed-length ratio, in one direction. The other necessity is to extend the graphs for greater displacement-length ratios, so that we can calculate power for 1860's ironclads. That requires displacement length ratios up to 420. The higher speed-length ratios are needed for fast destroyers that are fairly short. I am only computing for speed-length ratios up to 2.5, but I expect to have to go above 3.0, eventually. I had done enough experiments that it seemed to be possible to get reasonable approximate figures, so I am going forward with the project. A useful aid has been the ability to look at data with line charts, using Excel spreadsheets. That speeds up the process, so I don't have to use paper and end up having to estimate numbers from pencil-drawn graphs.

Tuesday, August 24, 2004

My program for calculating power curves for ships

I decided that since data entry was a roadblock to finishing this program, I will reduce the amount of data to be entered. At least as an interim measure, I will use data for Speed-Length Ratios for whole tenths (0.3, 0.4, 0.5,...,2.5), Displacement Length Ratios in increments of 40 (20, 60, 100, ..., 420), and prismatic coefficients in increments of 0.04 (0.50, 0.54, 0.58, ..., 0.70).
That greatly reduces the data entry problem. I will still need to draw graphs to extend what is in The Speed and Power of Ships beyond what is found in graphs. For example, Speed Length Ratios only go to 2.0 and Displacement Length Ratios terminate anywhere from 60 to 250.
There are some ships which are on the margins (such as 1860's ironclads), but for which I would still like to be able to generate power curves, hence the need to extend the range of coverage.

Monday, August 23, 2004

My 2002 version of the Ger/CS/1905 design

I had this elaborate document (which I only have in hard copy, due to my hard disk loss in the fall of 2002) has a drawing and specs for the German scout cruiser that I had designed for 1905. This drawing is very spare, with three uncased funnels, pole masts, and a light bridge, still with a conning tower. There are no tubs for the guns and the torpedo tubes are shown on the centerline, although that wouldn't work, due to the beam being 38ft.
The basic specs were:
  • LWL=370ft
  • B=38ft
  • d=13ft
  • Cp=0.559
  • Cm=0.85
  • Cb (block coefficient)=0.475
  • Legend displacement=2,480tons
At deep load:
  • LWL=370ft
  • B=38ft
  • d=15ft-3in
  • Cp=0.562 (estimated)
  • Cm=0.86 (estimated)
  • Displacement=2,962 tons
The designed speed was 36 knots at 44,000 SHP (original intent) The maximum overload was 52,800 SHP. I had hoped for 37.4 knots, but I doubt that was possible. It remains for me to do the calculations to see what was actually possible at legend displacement.
The armament was 5-4in/50 QF and 2-21in torpedo tubes. Both are not good choices, as the 21in torpedo didn't come into service until later, and not in the German navy, but the British. The contemporary German torpedo size was 17.7in (which is what the British 18in actually were). The guns should have been 10.5cm (4.1in, but were not).
There was also a small 2in high tensel steel belt, over the machinery. 2in might have been enough to "flash off" 12pdrs.
This design was inspired, as I may have said before, by the "Super Swift" type proposed in 1912 in Britain.

Sunday, August 22, 2004

I have been an admirer of fast scout cruisers

When I first saw the Italian scouts that resembled large destroyers, I liked what I saw. In 1971, I needed to add faster scouts to my building program, I went with this sort of vessel. My design was for a 2,100 ton destroyer-like ship, with the following specs:
  • legend displacement: 2,100 tons
  • LWL=350ft
  • B=37ft
  • d=-12ft
  • Cp=0.5564
  • Cm=0.85
  • V=36 knots
  • SHP=45,000
  • Armament: 4-5in/50 and 2-21in TT
The would have been built as part of my 1909 program as S-1 to S-7, and would have had three funnels, with the first one raised. The forecastle was raised, and stepped just forward of the first funnel. The 5in guns were arranged on the center line with one on the forecastle, one between the second and third funnels, and two in line on the quarterdeck.
The cost would have been about £ 245,205 each. We used the British pound as our standard measure for cost, so that we could directly compare expenditures.

Saturday, August 21, 2004

Talk about extreme ships: GB/CB/1921d

I am looking at a version of a British 1921-style small battlecruiser that I designed in 2002. A feature of it is the extreme speed attained: 37 knots. To achieve it, the armament is just 9-10in/50, 12-5.5in/50, and 6-4.7in AA and the belt is 5in.
The specs are:
D=24, 500 tons
LWL=835ft
B=82ft
d=25ft
Cp=0.5445
Cm=0.92
V=37 knots
Belt=5in
SHP=215,000
The key to my abbreviations is:
Cp=prismatic coefficient
Cm=midship coefficient
LWL = length on the waterline
B=Beam
d=draft
D=displacement
V=speed
SHP = shaft horsepower

Friday, August 20, 2004

To give you an idea about what is possible

I have been looking at my designs for cruisers and cruiser killers from 2002. I have in front of me a prime example of what is possible. This version is 28,500 tons legend displacement. The hull is flush decked with high freeboard. The bow rises to about 35ft from the water, and has a considerable flare. The rest of the hull has a 25ft freeboard. The aft gun turret is 225ft from the stern while the forward gun turret is 200ft from the forward perpendicular. The stern has a narrow transom in same style as the cancelled British 1921 battlecruisers and the WWII Colony Class cruisers.
Here are the specs:
LWL=825ft
Lpp=789ft
B=85ft
d=28ft
Cp=0.53475
Cm=0.95
D=28,500 tons
SHP=225,000
V=36 knots
Belt=7in
Armament=9-11in/50, 12-5.5in/50, 6-4.7in AA
11in/50 AP shot=745lbs
5.5in/50 HE shot=85lbs

Thursday, August 19, 2004

Frank Fox really likes "cruiser killers"

The American Alaska Class battlecruisers are one of Frank Fox's favorite ship types. I had sent him a copy of my design for a 1921-style armored cruiser. One version had 9-10in/50 guns, and 8in side armor. In 2001 and 2002, I did a series of new ship designs that included power calculations. Alas, the Excel spreadsheets were all lost when I had a hard disk go out in October 2002, so that work is almost all lost. thankfully, I have the pencil drawings that include some of the specifications. I am looking at those, and still like the "look". I had even made some planview wargame pieces, at 1:2400 scale. I have some of those, but the softcopy is gone. I may post some of the drawings, as they still seem to be noteworthy.

The original concept for the Ger/BB/1907 ships

My original concept for German battleships to be built starting in 1907 was for a 25,000 ton ship that carried 8-12in/50 guns and had 12-4in QF guns as the torpedo defense battery. The belt and turret faces would be 13in and the deck armor would be 3in + 1in. The anti-torpedo bulkhead would be 1.5in.
The designed power would be 54,000 SHP, which I hoped would produce 24 knots, given dimensions of 620ft x 105ft x 26ft. The form was Cp=0.56 and Cm=0.95.
The weights were:
Armament: 800 tons
Machinery: 4,000 tons
Protection: 6,700 tons
Hull: 11,500 tons
Miscellaneous: 2,000 tons.
The appearance would have been like the British King George V class, except without the fifth, amidships turret. The absence of the amidships turret allowed the forecastle to extend to the X turret. There was a tripod foremast, with a topmast for long range signalling. There was no mainmast. There would have been a derrick and kingpost near the second funnel, with boats stored aft of the second funnel.
A feature of the design was the restricted length of the armored citadel and the unprotected ends, except for splinter protection to the steering gear.

Tuesday, August 17, 2004

I am making progress on the Propulsion Calculations program

I have a new design for a ship propulsion calculation program, and I am moving along with it. I have all the Schoenherr resistance values entered in a table, and am working on entering data for residual resistance calculations. The calculations are straight forward, once you have the tables. I will just take the calculations from my Excel spreadsheet as the basis. I know for sure that they are correct. Admittedly, this is all "obsolete technology", in that in industry, they use a system involving interpolation from a database of known ship performance. Still, for ordinary people (admittedly amateurs), this works. Frank Fox had shown me how to do the calculations, and I implemented that in an Excel spreadsheet. The spreadsheet still required me to look up values from Gertler's book, A Reanalysis of the Original Test Data for the Taylor Standard Series. For the residual resistance data, I use the 1943 edition of The Speed and Power of Ships. The data is in the form of graphs, from which it is necessary to estimate the values.

Calculating power curves

I have a Smalltalk "program" (actually, a group of Smalltalk classes) that calculates power curves for ships, given their characteristics. The only problem with it has been getting the residual resistance graphs from David W. Taylor's book, Speed and Power of Ships, into a usable form. I have done some of that work, and then put it down, as it seemed as if I didn't have the right representation for the graph in my program.
The idea is to bring up a simple user interface, enter the ship characteristics, and then generate a power curve (SHP needed to drive the ship to a range of speeds). It is necessary to use a sparse graph representation, as it seems to be the obvious approach.
I am seriously thinking of doing a rewrite in a different language. I really want a program to do this. It is so time consuming to do the work, even with an Excel spreadsheet.

Monday, August 16, 2004

The Naval Annual: 1894

I am very fortunate to have an original copy of Lord Brassey's book The Naval Annual for 1894. The only thing about it that is not original is that my copy has a new spine.
I purchased the book in somewhat better times so that I would have a resource for Chinese ships for the Sino-Japanese War. It has some really good drawings (as well as some really drawings are sort of diagrammatic, not to any scale).
The best drawings seem to be taken from original blueprints. The worst are childish sketches.
The cool thing about early copies of The Naval Annual is the text. While there is much good ship data, often beyond anything you might find in modern reference books, there is some that is unreliable, as well.
This was in a period when essentially ALL data was published. This lasted until the early 1900's when the navies became security conscious. In the British case, ship capabilities were exaggerated after 1905.

Frank Fox,in the past, has blamed the British battlecruiser losses on Cordite

I have been privy to an ongoing discussion about the British battlecruiser losses at Jutland. Frank Fox is definitely in the camp that blames the losses on Cordite being fundamentally unstable and poor handling procedures. I have put David K. Brown into this camp, as well, although I may be mistaken. In The Grand Fleet, he addresses this problem, as well.
There is an alternate theory, which wants to blame Lyddite shells for the losses.
There is an interesting case from Jutland, where the battlecruiser Tiger received a hit on Q turret, but not only did not explode, but the guns were back in action after "a short time". The X turret barbette 9in armor was also penetrated, but again, the Tiger did not explode.
The Lion was almost lost due to a Cordite fire, after the Q turret hit. DK Brown thought that the ship was only saved due to the magazine flooding.
The Invincible was lost due to the hit on Q turret.
The dangers were perceived to be threefold:
  1. poor quality in manufacture of Cordite
  2. old Cordite would become unstable, and it was retained for too long
  3. exposed igniter charges (but this may not really have been a factor)
The conventional wisdom, circa 1917, was that the deck and side armor was too thin. This really was not the issue. Instead, there was the inherent instability of Cordite and poor handling practices in the battlecruiser fleet (except where they were corrected on the Lion by Chief Gunner Grant).

Sunday, August 15, 2004

Ger/DL/1915

I very much liked the large German destroyers in WWI. My attempt at such a ship was the Ger/DL/1915 (or 15). The displacement was 1,800 tons and the dimensions were: 332ft x 32ft x 12ft-4in. The armament was 5-5in/50 QF and 4-23.6in torpedo tubes (no reloads).
The designed full load displacement was 2,250 tons. The designed fuel capacity was 450 tons. The propulsion plant was 45,000 SHP, giving 20SHP/ton of displacement.
The machinery basis was 50 SHP/ton of machinery. The machinery would have been 900 tons. Fule consumption would have been 12.1 tons/hour, good for 37.4 hours, at full speed.
I believe that the nominal designed maximum speed was about 35 knots, but it is not listed. I don't think that I ever seriously considered producing this design (in the planning game).

Friday, August 13, 2004

Talk about an ambitious design: Ger/CB/15

I was amazed to see what I had hoped to achieve with my 1915 German fast battlecruiser design. It looks tremendously over-optimistic about achievable speed: 40 knots.
The dimensions were: 900ft x 100ft x 29.7ft deep load. The displacement was 40,000 tons, full load. The form figures were: Cp=-0.54 and Cm=0.97. The hull depth was 58ft.
The armament was 6-=16.5in BLR and 12-6in QF.
The power plant was 216,000 SHP. That would provide 5.4 SHP/ton of displacement.
The weights were:
40,000 tons full load 3,620 tons fuel oil 543 tons feed water 35,837 tons standard
Hull: 12,528 tons Machinery: 7,200 tons Armament: 2,875 tons Protection: 8,974 tons Miscellaneous: 2,860 tons Auxiliary machinery: 1,400 tons
Hoped for range:
2,500 miles at 40 knots for 62.5 hours
0.616/SHP or 57.80 tons/hr.
30 SHP/ton of machinery

My big gun designs

I was looking at my papers from my ship building program/planning game from 30-some years ago. I noticed a page with gun data. My 15-inch gun was pretty standard: 42 calibers and a weight of 97 tons. My 18-inch gun was 45 calibers and had a weight of 179.5 tons. The muzzle velocity was 2,800 feet/second and the AP shot was 3,645 lbs. The muzzle energy was 198,027 ft-tons. I don't really know how to use muzzle energy, but old Jane's Fighting Ships would generally supply this figure.

Wednesday, August 11, 2004

I am working on a 3D model of the 29,000 ton battlecruiser

I am working on a 3D model, and finished the hull above the waterline, as well as the barbettes. I have to add the turrets, funnels, superstructure, and secondary armament. Once I do that, I will post a jpg of the model. I intend to use it in a 3D naval warfare simulator for the period of 1903 to 1927. Hopefully, it would the first of many. It is slow going, as "I am learning as I go."

Monday, August 09, 2004

There is a scarcity of weight information about destroyers prior to 1918

If you want to do a meaningful general design of a ship, you need a model to follow. The most important aspect of doing a general design, for me, has been doing the weights analysis. That is where the greatest tradeoffs occur. The weights interact with dimensions and power when trying to achieve a particular speed. Speed will drive the optimal length for a given displacement.
For example, my attempt at a light battlecruiser was too short. The wavemaking resistence was higher with the shorter length that I had chosen, so the top speed was thereby limited. The available weight for propulsion was insufficient to overcome the losses caused by insufficient length. The only alternative would have been to lower the displacement, to achieve a better balance.
The bible for British destroyers has been March's book. It is quite old, but there is really no alternative. It is comparable to Oscar Parke's book, British Battleships. March's book has some really good drawings in it. In some cases, they are either from original plans, or from tracings from them.
I don't understand why he omitted detailed weight information for each destroyer class. That level of detail would have been of incalculable value. Instead, the book is very uneven. That has greatly detracted from the books usefulness as a reference for doing general design.

Saturday, August 07, 2004

Cliff's "FG" design

My friend Cliff defined a new type of ship. He called it the "FG" (Frigate Gunboat). He already had a variety of destroyer types. This was yet another. The idea was to have a destroyer-type that was well-armed with guns, with a small torpedo capability. they had a modern look. They were to have superfiring guns, three funnels with the first raised and a 4in gun on a bandstand between the first and second funnels. The torpedo tubes were in a twin mount located between the third funnel and the aft superstructure.

The type was designated the "GB/FG/13": GB for Great Britain, FG for Frigate Gunboat, and 13 for 1913.

The specs were:

Displacement:1200 tons legend
Dimensions:315ft x 30ft x 10ft
Armament:5-4in/50 QF, 2-21in TT
SHP:25,000
speed:32 knots
Fuel:300 tons oil

We figured that war would break out in 1914, and that these vessels would become available by late 1914 or early 1915.

Friday, August 06, 2004

I'm looking for an "open" computer naval wargame

I want to be able to fight a campaign with the ships that we designed. It may not be easy to do, but I would like to be able to import user ship definitions and run battles with them. I really would like a game with a campaign map and with detailed regional and tactical maps. I want to be able to game with 30 or 40 ships on a side, and maneuver by divisions or squadrons. Doesn't that seem like something that we would want? What we really want is to be able to accommodate large numbers, so that we could refight the battle of Jutland with real numbers of ships. For sailing naval warfare, I can create my own ship definitions and scenarios, and fight battles with Privateers Bounty. Sadly, it can't accommodate really large numbers of ships, so we can't fight the large battles with the actual numbers of ships. Something like this is needed for the 1903-1927 period (this is my own time period of interest).

Thursday, August 05, 2004

My 1907 German battleship design

From my 30 year-old planning and shipbuilding game, my 1907 battleship design was for a 25, 847 ton 24 knot ship. The displacement is quite large, compared to real ships of the period. The armament is not inappropriate: 8-12in/50 and 12-4in QF. The belt was intended to be 8in-13in with 3in + 1in decks.

The specs:

dimensions: 620ft x 105ft x 26ft
Cp = 0.56
Cm = 0.95

Machinery: 54,000 SHP

Weights:

Armament: 800 tons
Machinery: 4,000 tons
Protection: 7,547 tons
Hull: 11,500 tons
Misc: 2,000 t0ns (about 8% is what I allowed)

I wouldn't be surprised if the original intent was for a 25,000 ton ship. That would give protection as 6,700 tons.

The appearance of my sketch design is similar to that of the King George V class of super dreadnoughts (pre-WWI). The main turrets are superfiring, and there is a long forecastle that breaks about 75% of the length.

Wednesday, August 04, 2004

Large, fast ships

I like very large fast ships, preferably battlecruisers. The reason is simple: strategic mobility. Strategic mobility requires the ability for sustained speed. Tactical speed is of less importance, although it is useful in pursuit or in escape. Large, fast ships often will outrun their escorts. That is why their escorts need to be large, for their type, and fast. Still, in increasingly rough seas, the large battlecruiser will be able to maintain speed longer than smaller ships. It could well be that the large battlecruiser will have to slow to allow their escorts to keep pace. In operations such as the Falklands in 1914, the battlecruisers were able to cross from Britain quickly to bring Von Spee's squadron to action. This was just the sort of employment envisioned by Admiral Fisher, when he conceived of the battlecruiser type.

Monday, August 02, 2004

the Renown and Repulse could have been superships

If the latest technology had been used, the Renown and Repulse could have been superships. that would have required small tube boilers and geared turbines. That combination could have given them higher speed and a little more weight to have been put into armor. The weight savings from small tube boilers would have been considerable. They could have been given a greater SHP and with geared turbines, the propellor efficiency could have been increased. The net result could have been a greater EHP and, presumably, a higher speed. The basic hull was perfect for speed. The length to beam ratio was about 8.8, which was quite extreme for a capital ship. So, the "what if" design would be the same dimensions, with a slighter greater draft, 8-15in/42 guns, 16-4in/50, perhaps a 7in belt, inclined outward, about 28,000 tons legend displacement, 125,000 SHP, with small tube boilers and geared turbines. We should easily have seen 32 knots and could hope for 33. It would be interesting to do the calculations to see what was possible. Even in their original form, they were capable of 32 knots, if only on trial, and pressing their boilers.

The Renown and Repulse really should have had 8 guns

The only reason that the Renown and Repulse ended up with 6 guns each was the number of guns and turrets that were readily available. The ships were large enough to have carried four turrets. They were almost 800 feet long, and had plenty of room. Their displacement was small, but quickly grew, as equipment and, eventually, armor was added. They represented Admiral Fisher's latest ideas as of late 1914. They had the Invincible armor basis, but with much greater speed. They also had the advantage of the latest anti-torpedo protection and outward-inclined armor. They were very leading edge. Admiral Fisher had hoped for 32 knots but they had to be pressed to almost 120,000 SHP to make that. They could more comfortably make 31 knots, which was still faster than any existing capital ship.

Saturday, July 31, 2004

Large cruisers

I have liked the concept of an updated armored cruiser that would have been viable in 1921 and beyond. I have a sketch design that I did in the early 1970's for a 14,000 ton cruiser. The hull had a long forecastle that extended for about 70% of the length. There was step aft, and the quarterdeck was empty, except for two triple torpedo tube mounts, one on each side. There was a single trunked funnel, mounted just aft of the midpoint of the length. The main armament was all forward. There were two quadruple turrets, each mounting 4-9.4in/50 guns (25 ton). The secondary armament was 8-4in QF, in twin mounts, facing aft, just forward of the step. The dimensions were 675ft x 75ft x 20ft. The hull depth was intended to be 45ft. The machinery was 150,000 SHP. The machinery basis was 30 SHP/ton of plant. The weights were: machinery: 5,000 tons hull: 6,844 tons The belt was intended to be 8 in thick, 340 ft long, and 8ft high. The deck armor was overoptimistically specified as 4in + 3in ( upper and lower decks). The loaded displacement was expected to be 17,000 tons. I have a sketch drawing that I may try to clean up before posting.

Thursday, July 29, 2004

This is my concept of what Colonel Cunibeti's "Ideal Battleship" would have looked like

I just drew a picture of what Colonel Cuniberti's battleship would have looked like. This is at least the current state of the drawing. Colonel Cunibert's battleship, at sea The drawing was made by graphically editing the pencil drawing that I had previously posted. I used PhotoPaint 8 and MS Paint for the drawing. In this case, it is a .bmp file, rather than a jpg. The .bmp file is useful for many purposes, and is a sharper drawing. The .jpg file tends to blur.

Wednesday, July 28, 2004

So how useful were large destroyers?

I have long been enamoured of large, fast destroyers. In 1905, 1200 tons would be considered "large", although the British Swift was much larger than that. My friend Cliff's flotilla leaders (DL's) were 12oo tons. His larger fast gunboats (PGL) (destroyers without torpedoes) were 1600 tons. The plan was to use these in place of light cruisers. The PGL type would have had 4-5in/50 QF guns, able to fire a four-gun broadside. That would have been sufficient to outgun many light cruisers prior to WWI.

Tuesday, July 27, 2004

My 1905 German battleship design (circa 1971)

Part of my building program for the "planning" wargame that I did with my friend Cliff in 1971 was a German battleship design for1905. My building program contemplated three ships for 1905. They were 22,000 tons legend displacement. The dimensions were: 580ft x 90ft x 26.6ft. The speed was rather high: 23 knots. The armament was 8-12in/45 and 12-4in/50 QF (anti-torpedo armament). The armor was planned to have a 10in belt. In 1906, I would have built a fourth vessel, to the identical design. The appearance was distinctive, and more closely resembled a later British ship than a German ship. There were three funnels, a long forecastle, superfiring turrets, a large conning tower with a small "torpedo" conning tower aft. Reviewing my notes, I see that I had revised the armor plan. The lower belt was 11in at the top and 9in on the lower side, so it was tapered. The upper deck side was 8in at the bottom and 6in at the top. The slopes, backing the lower belt, were 3in. There was a 2in anti-torpedo bulkhead. At the time, I was into heavy protection for the uptakes, so above the belt, it was 8in. Behind the upper deck side, it was reduced to 6in. The deck armor was pieced, so that at a particular level, there were varying thicknesses. The maximum was 3in HT steel. The boiler room was the width of the ship, to reduce the chance of capsizing, while accepting the increased flooding risk. The anti-torpedo battery were in casemates. There were three forward and three aft, on each side, at the forecastle level. That way, there was little risk of spray problems. I included a tripod foremast and a top, forward. The mainmast was just a post, with a crane for handling boats. There was a light topmast for signaling.

Monday, July 26, 2004

Conning towers

In the late 19th Century, battleship and armored cruiser design always included an armored conning tower. By the late 1930's, the British had eliminated this feature. Instead, they contented themselves with moderate armor on the conning station, in the bridgework. Admittedly, on the Hood and Nelson class, they had gone overboard with conning tower design. In typical government bureaucratic fashion, they overspecified what was needed, and so they got the $1000 toilet seat of conning towers. Reportedly, when the Hood exploded and sank, the conning tower fell out, as the ship capsized. The weight was over 200 t0ns. After the fact, the Americans discovered that having a strong conning tower was a good thing. In the battle against the Japanese battlecruiser Kirishima, the battleship South Dakota was hit on the bridgework, and many exposed crewmembers were killed or wounded. The captain was conning the ship from the conning tower, and he and the ship survived the battle. After the battle, the Americans abandoned the move towards eliminating the conning tower. Admittedly, the West Virginia, California, and Tennessee had their heavy, battleship conning towers removed and replaced with cruiser conning towers.

Wednesday, July 21, 2004

Inclined side armor

Inclined side armor for fast ships has always seemed like a sensible and effective measure. The primary argument against inclined side armor is that it compromises the anti-torpedo measures. The best anti-torpedo protection is to use the system used for the American battleships like the West Virginia. There are a series of longitudinal voids and bulkheads, with an armored bulkhead at some distance from the side. Beyond that might be another bulkhead, in case the armored bulkhead has been breached. I had a design for a fast battlecruiser that included inclined side armor. The displacement was to be 25,000 tons, the armament would be 8-12in/45 and 12-4in/50 QF guns. The side armor would be 4in, but inclined outward. I would have divided the hold into thirds, longitudinally. The A/T bulkhead would be 1-1/2in, and with 2in on the "slopes". That connected with a 2in deck. The 2in deck was 3 feet above the waterline. The 4in belt was two decks high, but was 18 feet wide, due to the inclination. The upper deck, on top of the belt was to be 3in. The originally planned speed was to be 32 knots, but I kept hoping for higher. Almost immediately, I hoped for 33 knots. The power was designed to be 120,000 SHP, but an overload of 144,000 SHP was wished for. Since the dimensions were length = 800ft, beam = 85ft, and draft = 25.6ft, I can believe that a good speed would have been possible. I see that my revised armament replaced the 4in guns with 8-6in/50. My original weight breakdown was: hull: 11,250 tons machinery: 8,580 tons armament: 955 tons miscellaneous: 2000 tons (8% for aux. mach., etc.) protection: 2,215 tons. I can see from the original sketch that the armor decks would be VERY short in length. The "citidal" would be 425 ft long in an 800ft long ship.

Tuesday, July 20, 2004

Naval Warfare Simulations is worth your look

I would commend the games from NWS for your consideration. I have tried the WWI game and think it worth learning. Obviously, a lot of work has gone into what they have, and I want to learn more about it.

Monday, July 19, 2004

Makeup of the battlefleet at Jutland

I think that the makeup of the British battlefleet at Jutland was close to the ideal, for the time. There was the main battlefleet of dreadnoughts and super-dreadnoughts (all designed for a speed of 21 knots or better). Then there was the battlecruiser force/fleet, whose core was 6 battlecruisers backed up by the four fast battleships. Both the main battlefleet and battlecruiser force had light cruisers and destroyers. The light cruisers were largely armed with 6inch guns. The 6inch shell was hard to manhandle on a small ship in any sort of seaway, but it was what was needed to be able to effectively fight their German counterparts. In addition, the main battlefleet had the one squadron of three Invincibles, which D.K. Brown says fulfilled Admiral Fisher's vision for the type. The came out of the fog and pounded the head of the German line, and reduced Hipper's Lützow to a sinking wreck which had to be scuttled. Sadly, the British had their Cordite problem. Otherwise, the Germans would have been more clearly defeated. The British also used their eight heavy (armored) cruisers as a strong scouting line, ahead of the fleet. The basic concept was reasonable. The only fault was that the ships that were available were unsuitable, as they were the pre-dreadnought armored cruisers with thin decks, a mixed armament, and Cordite. That was a bad mixture, and they lost three ships, because of it (Defence, Warrior, and Black Prince). The Black Prince situation was almost uncalled for. It was a lone ship, wandering around, out of touch, and ran afoul of the German battlefleet. They made short work of the Black Prince. What they really needed were "heavy cruisers", with adequate deck and side armor, and a uniform gun armament, augmented by an anti-torpedo boat and anti-aircraft secondary batteries. The British never really built anything adequate. They left it to the Americans and Japanese to build this type in numbers.

Friday, July 16, 2004

Booklet that gives an example design

I have a booklet that is still available from The Kentish Knock Company and from ABE Books. The title is The Battlecruisers Essex and Sussex, Hypothetical Ship Designs from 1971. This booklet provides more information about my design methods, although it is now three years old. The basics are still a valid description of how I proceed. I have refined my process for computing power vs. speed, however, in that I make more use of an Excel spreadsheet.

William Hovgaard and warship design books

My meager amount of knowledge of this subject, compared to someone like David Manley or David K. Brown, originated with the published works of William Hovgaard. He started his career as a Danish naval constructor, and finished his career as a professor at MIT. He had become an advisor to the U.S. Navy by the time of World War I.

William Hovgaard had three important books, in his series about warship design. The first that I had encountered was The Modern History of Warships (1920). The second was The General Design of Warships (1920). I had first seen these books at the University of Michigan, in the mid-t0-late 1960's. I never had expected to find the latter book, but the first had been reprinted, so I expected that I would eventually own a copy. To my surprise, in the fall of 2001, I was able to purchase a very fine copy, after I had bought a photocopy from the Library of Congress.

The third book was perhaps more influential, and went to multiple editions. It was The Structural Design of Warships. Given that I have not done the detailed design for a warship, this is the volume with which I have the least experience.

I have since supplemented my knowledge by study of D.K. Brown's books and the other books that do analysis of warship designs. At my level of understanding, we are reduced to needing to essentially interpolate from existing designs. What I have found really helpful are the published lists of weights for various battleships and battlecruises (primarily British). Perhaps I just need to expand my library, but there is much less information available about cruisers and destroyers weights distribution. For destroyers, I rely on Marsh's classic book, British Destroyers. It is good, but not as good as it would be if there were detailed weights for all the ships.

Thursday, July 15, 2004

The pictures

I finally was motivated to do quick freehand drawings, on quadrille paper of the 29,000 ton battlecruiser and battleship designs. As I looked at the battlecruiser, I saw the hand of my friend Cliff, as he was quick to discard a conning tower, while I am a traditionalist, and tend to include at least a forward conning tower, if not an after "torpedo" conning tower, as well.

The top picture is the fast battlecruiser while the lower is the fast battleship that I described

The top drawing is the fast battlecruiser, while the lower drawing is the battelship (my quick pencil sketches, done freehand).

The battleship analog to the fast 29,000 ton battlecruiser

The fast battleship that was intended to be built in parallel to the very fast battlecruiser was also 29,000 tons. The intended armament was 6-13.5in/45 guns. The idea was to restrict numbers of guns, so as to be able to carry less weight and devote more weight to armor and power.

The normal displacement was 29,000 tons, with dimensions: 620ft x 95ft x 30.2ft mean draft. The Cp was 0.59 and the Cm was 0.97 (Cp = prismatic coefficient and Cm = midship coefficient).

The weights would be allocated as follows:

Machinery 2,900 tons

protection 10,496 tons

Hull 12,180 tons

Armament 1,104 tons

Miscellaneous 2,320 tons

The ship looked like a Queen Elizabeth class battleship, as built, except with two turrets forward and one aft. There was still to be a conning tower and a tripod mast forward. The mainmast was a post, with a derrick for handling boats.

Wednesday, July 14, 2004

A fantasy light battlecruiser

In one of my periods of wishful thinking about what was possible for powering ships, I conceived of a 38-knot light battlecruiser. The designed displacement was 29,000 tons and the armament was 4-13.5in/45 guns. The powerplant would generate 180,000 SHP. The speed-length ratio (V/sqrt(L)) was 1.3034. The dimensions were 850ft x 95ft x some draft. Let us assume a Cp=0.54 and a Cm=0.92. That would mean that the mean draft was 25.3ft. Two years later, I estimated it would take 209,235 SHP to reach 38 knots. Right now, I would not believe that 38 knots would be reachable under any circumstances.

The look of the ship was not that dissimular to the Courageous, except that the bow was raked. I gave her two funnels, with the fore funnel raised. There was no conning tower. The bridgework just rose at the start of the deckhouse. There was a tripod mast with a lower director top and then the main top centered on the mast. There was a light pole topmast with yards. There was also a mainmast that was sufficent to have a derrick. There was the usual distinctive top, with the triangular web pieces and then the pole topmast with a yard. The forecastle was very long, with a step foreward of the after turret. I didn't include any secondary armament, but there should have been at least some 4in guns for anti-torpedo work.

I had the mistaken idea, thirty years ago, that you could extrapolate a speed-length curve, based on SHP/ton of displacement. The problem is that "kind of works" for the residuary resistent (wavemaking), but it ignores the frictional resistence.

Frank Fox had seen my fantasy ship that had hoped to reach 45 knots, and gently demonstrated that it couldn't be done. The fastest that was feasible was about 33 knots (as I recall). The problem was that the length was too short (770ft). If you want speed, you must have length with enough displacement to carry a large power plant.

Tuesday, July 13, 2004

Torpedo Gunboats

I was just rereading what D.K. Brown says about torpedo gunboats. By the early 1890's the Navy thought that they were too slow, and they turned to the early torpedo boat destroyers. D.K. Brown says, though, that in any sort of a seaway, the TGB's could outrun the early destroyers, which had too little freeboard. This was not corrected until the River class boats, which had a lower speed and a raised forecastle.

D.K. Brown says that the TGB's could have formed the basis for building, rather than the enlarged torpedo boat, which was in fact used. He says that they were better ships than they were given credit for at the time.

Saturday, July 10, 2004

I found some drawings that I did for ships that I drew in 2001

I will be scanning and writing about a group of ship designs that I did up to the spring of 2001. I have long had a design pattern for battlecruisers and fast battleships during the period of 1905 to 1914. Most or all of these designs have three round funnels, with a forward tripod mast with a top and director. I have liked the sort of tiered bridge structure with a pilot house that protrudes forward, as the highest level. Good examples of real ships that these are similar to are the Barham (8-15in) and Tiger (8-13.5in).

Friday, July 09, 2004

Colonel Cuniberti's battleship resembles an armored cruiser more than a battleship

Looking at my drawing, I realized that Colonel Cuniberti's battleship design looked more like an armored cruiser than a battleship. Perhaps it was the four funnels or it might have been the 24 knot speed. The gun layout also resembles a pre-dreadnought armored cruiser, with the wing turrets, with single and twin guns.

I probably need to play with the parameters, to see if I can make some compromises to make my rendering of the design closer to what Colomel Cuniberti intended. I would like to have thicker belt and barbette armor, in particular, while maintaining a good speed. I need to break out my copy of D.K. Brown's book, Warrior to Dreadnought, to get some additional data that might be of help.

Wednesday, July 07, 2004

Sketch of Colonel Cuniberti's battleship design

I thought it would be good to illustrate the sort of drawing I do as an aid to doing the general design of a warship. I generally do the drawing on quadrille paper. If I wanted to do a cleaner drawing, I would print it and trace on the back, with ink. I would then rescan that traced drawing.

Colonel Cuniberti's battleship design

Sketch of Colonel Cuniberti's battleship design.

I just made my spreadsheet available for download (Colonel Cuniberti's battleship)

I just tried to see what I could do with Colonel Cuniberti's battleship proposal from 1903. I must admit that D.K. Brown is correct that "it can't be done", as originally proposed. I have made some compromises to see how close I could come to the original design, and I have made the result available for download. This are only the weight calculations. I have not attempted the power calculations. The lowest displacement I could get was 18,014 tons normal. That is with very lightweight construction for the hull, pared down protection, and cruiser-style machinery. My designed SHP is 37,500 tons.

I have made a design document available for download

I found that I had a Word document, from three years ago, that sort of explains my methods for doing a general design. The example is rather extreme, a large battlecruiser with 20-inch guns. Actually, the displacement is rather light for the size of the ship, but this is the most accessible example that I have. I will make other documents available for download, over time.

I imagine that a professional, such as David Manley could do a better job

Obviously (I would think), a trained naval architect who is also a naval history enthusiast, such as David Manley, could probably do a better job of doing a general design. I suspect that the sort of data that is really needed to do a good job might not exist. I have some hope that "ship's covers" might be obtained that would provide much of what is needed to analyze classic Dreadnought designs, so that we might be able to do a better job in our design work. The "Anatomy of a Ship" books would seem to be another good source of data.

Ship calculations

I don't know if anyone else has been interested in designing their own 1905-1927 era warships, but I have been interested in doing that for a very long time. All that is really needed is to do the general design. That involves doing a layout, weights analysis, and power calculations. The last is the most time consuming of the design process (at least the way I do it). I am just going to outline the process, for this post.

The weights analysis can be done, with some work, using an Excel spreadsheet. I have been using an Excel spreadsheet for the power calculations as well. I mechanized a process for doing the calculations that I learned from Frank Fox (he is interested in more than just 17th Century ships).

I use the weights spreadsheet to do the displacement calculations, as well, so that I define the fundamental dimensions there. Then, I do a scale drawing. I have found that a 1-inch = 100 feet drawing is adequate. For greater accuracy, you can always do a larger scale drawing, but there are so many approximations involved, that I only do a larger scale drawing for smaller vessels.

I actually clone an existing spreadsheet, to start the process. However, the basic outline is that I have the dimensions and summary weights on the left. On the lower right, I do the hull armor calculations. On the upper right, I do the turret and gun weight calculations.

To do decent estimates of turret and gun shield weights, you need to do some larger scale drawings that you can measure. It is also helpful to refer to real ship data for which there are weight noted. I have use both R.A. Burt's book, British Battleships of World War One and John Roberts' Battlecruisers book. The book that got me started on doing general design was William Hovgaard's classic book, The General Design of Warships. I was amazed that I was actually able to buy a copy at a reasonable price. Another source is paying some fairly big bucks to get the Library of Congress to make a good photocopy for you. I did that first, before I knew that the book might be available.

The propulsion calculations require determining the wave-making resistance and the surface friction resistance. There are more modern methods available that seem to depend on interpolating from a database of ship characteristics. The classic method uses graphs from Speed and Power of Ships and Schoenherr coefficients from Morton Gertler's A Reanalysis of the Original Test Data For the Taylor Standard Series. This book occasionally comes on the market. I found a copy a few days after Frank Fox had recommended the book to me. Explaining the method will have to wait for later, as it is quite involved. Essentially, for a range of speeds, the residual resistance and frictional resistance are calculated and summed. From this "effective horsepower", then we can estimate the actual horsepower needed, given some assumed efficiency. I have some example spreadsheets that illustrate the method (sadly, I lost a lot of this sort of work in October 2002 when I had a hard disk failure that wasn't adequately backed up).

Tuesday, July 06, 2004

D.K. Brown on battlecruisers

Several years ago, I had some communication with David K. Brown, the retired naval constructor and author. My understanding is that he thinks that battlecruises with light side armor are acceptable (with "splinter protection") if the "vitals" are sufficiently protected. That is really the modern protection design pattern. I think that he would prefer at least 6inch side armor, if it could be had, for a battle cruiser. What really needs to be protected are the magazines. I would add that something besides Cordite should be used as your gun propellant, as well. Nitrocellulose would seem to be a good candidate. Cordite is BAD, and should be avoided at all costs. Four British battlecruisers, as well as other ships, were lost due to the use of Cordite. The problem was not the lack of armor, but the unstable propellant in use. As Admiral Fisher would say "armor is vision", so more armor is not that bad, if you can provide a good speed and a heavy armament. Ships like the Derfflinger were good, but needed something larger than 12inch guns.

Sunday, July 04, 2004

I really would like to own all the early "Jane's Fighting Ships"

Actually, they were called "Jane's All the World's Fighting Ships", but let's not be picky. I have the 1898 reprint and a REAL (former Brooklyn Navy Yard copy) 1903 volume. I was positioning myself to get 1899 and 1904 copies, when all that got swept away by the "economic downturn". I had seen the 1904 volume in 1966, but the University of Michigan library did not take care of it. It essentially ended up as dust (they didn't take care of the acid paper problem).

"An Ideal Battleship for the British Fleet"

I just unpacked the box that had my copy of All the World's Fighting Ships 1903. Of course, I wanted to be able to write about the article by Colonel Cuniberti. His "ideal battleship" has a raised forecastle, with a ram forefoot and a "cruiser spoon" stern. The rudder is balanced, and the deadwood is cutaway, quite radically. The bottom slopes up to the forefoot from the first funnel (the Moltke and Göben were like that. There are two pole masts and four funnels. There are conning towers, fore and aft, with a minimal amount of bridgework around them. The guns are arranged in lozenge fashion. On the raised forecastle is a twin 12inch turret. On the quarterdeck is another. At the forecastle deck level, there are twin 12inch turrets at the deck edge, on either side. They align between the second and third funnels. There are four single 12inch gun turrets. They are at the quarterdeck level and form a square. They are forward and aft of the amidships turrets. There is no "secondary armament", just an anti-torpedo battery of 12-12pounders and 6-"pom-poms" that can be dismounted.

The belt is complete. The thickness is 12-inches, at the waterline. The six amidships turrets are protected by a raised citidal that is 12-inches thick. Forward of the citidal, there is 6-inch armor to the bow.

Colonel Cuniberti's dimensions were:

Length: 521-1/2 feet

Beam: 82 feet

Mean draft: 27-1/2 feet

I have come around to the view that if the form and parameters are only moderately outrageous, it might be possible to have a ship that comes close to these parameters. I suspect that fuel capacity would be small, the hull would be rather light weight, and the machinery to a lighter weight than would be typical in British pre-dreadnought battleships. I did a spreadsheet to try the design, and I must admit it could be done, although it would be pretty radical.

Saturday, July 03, 2004

I highly recommend Friedrich Forstmeier's book, Deutsche Grosskamschiffe 1915-1918

Anyone who is interested in German warships during the period 1905-1918 needs to read Deutsche Grosskamschiffe 1915-1918. What I was interested in is the information about planned ships that were never built, and the evolution of ideas, during the war. The last drawings in the book look a lot like the panzerschiffe Deutschland/Lützow, built postwar. There may be something better, than this book, but this is the work that I know on this subject.

Thursday, July 01, 2004

One of my favorite photographs

Ever since I saw the photograph of the torpedo boat destroyer Viper making 36 knots on trials, I was attracted to the picture. The Viper is shown squatting at the stern, with the forefoot out of the water. It is amazing to me. It really was a hotrod, as built. It had direct drive turbines, and too much power for the size of the hull. I was inspired to paint the picture, and it can be seen at HMS Viper painting.

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