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Thursday, September 30, 2004

Rick Robinson's program is useless for designing small ships

Well, Rick Robinson said as much: his program is intended for designing larger ships, not destroyers. I was trying to design my 1905 scout cruiser, and finally had to give it up as a lost cause.

Wednesday, September 29, 2004

I struggled to get a stable version of the "Super-Fast Light Battlecruiser"

One of the ships that I kepted working and reworking (with Rick Robinson's "Spring Style" ship design program) was the "Super-Fast Light Battlecruiser". What I finally ended up with was not so "Super-Fast", although 35 knots is pretty fast. This is what was produced, although it is not pretty:

fastcbl, laid down 1920

     Length, 804 ft x Beam, 87.0 ft x Depth, 29.5 ft
          34312 tons normal displacement (31571 tons standard)

     Main battery:       4 x 17.0-inch (2 x 2)
     Secondary battery: 16 x  4.0-inch

          Weight of broadside: 10338 lbs

     Main belt, 4.0 inches; ends unarmored
     Upper belt, 4.0 inches
     Torpedo bulkhead, 1.0 inches
     Armor deck, average 2.0 inches
     C.T., 4.0 inches

     Battery armor:
          Main, 4.0"

     Maximum speed for 225027 shp = 34.43 knots
          Approximate cruising radius, 14500 nm / 12 kts

     Typical complement: 1261-1639

                    Estimated cost, $30.612 million (£7.653 million)


     Relative extent of belt armor, 55 percent of 'typical' coverage.

     Main belt does not fully protect magazines and
     engineering spaces.

     Magazines and engineering spaces are cramped, with poor
     watertight subdivision.

     Roomy upper decks; superior accommodation and working space.

          Distribution of weights:

          Armament .........................   1292 tons =   4 pct
          Armor, total .....................   4014 tons =  12 pct

               Belt                             912 tons =   3 pct
               Torpedo bulkhead                 570 tons =   2 pct
               Deck                            1801 tons =   5 pct
               C.T.                              91 tons =   0 pct
               Armament                         640 tons =   2 pct

          Machinery ........................   7868 tons =  23 pct
          Hull and fittings; equipment .....  14289 tons =  42 pct
          Fuel, ammunition, stores .........   4289 tons =  13 pct
          Miscellaneous weights ............   2560 tons =   7 pct
                                              34312 tons = 100 pct

          Estimated metacentric height, 5.6 ft

     Displacement summary:

          Light ship:             30023 tons
          Standard displacement:  31571 tons
          Normal service:         34312 tons
          Full load:              36368 tons

          Loading submergence 1391 tons/foot


     Estimated overall survivability and seakeeping ability:

          Relative margin of stability: 1.19

          Shellfire needed to sink: 18353 lbs = 7.5 x 17.0-inch shells
               (Approximates weight of penetrating
               shell hits needed to sink ship,
               not counting critical hits)

          Torpedoes needed to sink: 2.1
               (Approximates number of 'typical'
               torpedo hits needed to sink ship)

          Relative steadiness as gun platform, 48 percent
               (50 percent is 'average')

          Relative rocking effect from firing to beam, 0.65

          Relative quality as a seaboat: 1.02


     Hull form characteristics:

          Block coefficient: 0.58
          Sharpness coefficient: 0.37
          Hull speed coefficient 'M' = 7.57
          'Natural speed' for length = 28.4 knots
          Power going to wave formation
               at top speed: 56 percent

     Estimated hull characteristics and strength:

          Relative underwater volume absorbed by
               magazines and engineering spaces: 145 percent

          Relative accommodation and working space: 191 percent

          Displacement factor: 106 percent
               (Displacement relative to loading factors)

          Relative cross-sectional hull strength: 1.08
               (Structure weight per square
               foot of hull surface: 187 lbs)

          Relative longitudinal hull strength: 1.45
               (for 26.0 ft average freeboard;
               freeboard adjustment +6.6 ft)

          Relative composite hull strength: 1.11

I find that the "Spring Style" program is addictive

I have been experimenting with the "Spring Style" program, and find it hard to stop. I have been trying some "over-the-top" designs that we did in the early 1970's. I find that I have had to modify the designs so that they "work" in many cases. I just did the GB/BB/1914 design conceived by my friend Cliff for the British navy. It was intended to 'bust loose" from the usual constraints. Here are the specs:
  • laid down 1914
  • length: 800 ft
  • beam: 120ft
  • draft: 33.1ft
  • normal displacement: 48,489 tons
  • "standard" displacement: 45,446 tons
  • main battery: 9-18in/45 (3x3)
  • secondary battery: 20-5in (10x2)
  • broadside weight: 24578 lbs
  • main belt: 15in, ends unarmored
  • upper belt: 10in
  • torpedo bulkhead: 2in
  • armor deck average 5.0 inches
  • conning tower: 12in
  • battery armor: main 15in, secondary 2in
  • maximum speed for 97,017 SHP 26.16 knots
  • approximate cruising radius: 15,200 nm at 10 knots
  • typical complement: 1634 to 2124 men
  • estimated cost; $23.361 million (£ 5.840 million)

There are more details generated by the program, but this is a start. I would like to try generating a power curve with my own program to see how it compares. Anyway, I like Rick Robinson's program. I want to study it to see what he is doing.

Another interesting piece of software from Rick Robinson: "Spring Style" (warship design)

Rick Robinson has another DOS program written in C that you can download. It is doing general design of warships. You can download the source in C, so that you can actually see what he is doing (just like the Big Gun program). I experimented with it, and he is doing "quite a bit" (in some ways). He is going "easy" on armor weight calculations, but he is doing strength and stability calculations, so this is not some lightweight thing.

Gun performance: 9.2in/45

I have been looking around at what software exists for guns and ships. I have been experimenting with Rick Robinson's "Big Gun" program. I just ran the simulator to generate data for a 9.2in/45 guns with a 380 pound AP shot. Here is an example. The data is the gun elevation, the range that the shot would travel, and the belt and armor penetration. You get two tables. One has output that shows the gun elevation, the range, the time of travel, the terminal velocity, and the fall angle in degrees. The other has the gun elevation, the range, the belt and deck penetration, based on parameters that you supply to the program. Rick includes his C source code with the download.
  • 1.1 deg 2600 yards 18in belt
  • 1.8 deg 4200 yards 16in belt
  • 2.8 deg 5900 yards 14in belt
  • 4.2 deg 8000 yards 12in belt
  • 5.3 deg 9500 yards 1in deck
  • 6.1 deg 10500 yards 10in belt
  • 9.1 deg 13500 yards 8in belt
  • 12.6 deg 16400 yards 2in deck
  • 14.4 deg 17600 yards 6in belt
  • 19.8 deg 20700 yards 3in deck
  • 25.9 deg 23400 yards 4in belt
  • 26.7 deg 23600 yards 4in deck
  • 34.2 deg 25800 yards 5in deck
  • 42.9 deg 27000 yards 6in deck

Tuesday, September 28, 2004

I'm tweaking my residual resistance tables and testing

I've been testing my program with real ships from different countries in the WWI timeframe. The main ships that aren't good enough are the Queen Elizabeth class and the Bayern class battleships. They both show too little SHP required to meet their designed speeds. I have been tweaking values in the tables to correct the results. I probably need to go back and reanalyze the tables to clean them up, as they are probably pretty rough, as they stand now.

Monday, September 27, 2004

Sanity checking power calculations: Lion class battlecruisers

As an experiment, I estimated values for the Lion class battlecruisers to see what sort of power that would be calculated for 27 knots. The answer is that my program came up with the following results for the parameters that I used:
  • displacement: 26,779 tons
  • dimensions: 700ft x 88.5ft x 28.6ft
  • Cp: 0.575
  • Cm: 0.92
  • propulsive efficiency: 0.49
  • speed: 27 knots
  • SHP: 69,184.4
  • residual EHP: 12,831.7
  • frictional EHP: 21,068.7
  • speed-length ratio: 1.0205

I thought that this was reasonable result, given the inherent sloppiness of the program vis-a-vis hand calculations where I looked up exact Cr values from The Speed and Power of Ships.

My 48,000 ton 1921-style battlecruiser

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


  • 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


  • 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


  • 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


  • 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


  • 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


  • 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.)


  • 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.

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