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Tuesday, November 30, 2004

I would be willing to run ship designs through my program

If anyone besides me would be interested, I would be willing to supply a specification template and run your warship design through my program. The output file is not neat or pretty, but is packed with information. You will find that you cannot specify your ship as closely as you would like, as the input to my program is a compromise. Admittedly, I have made the specification increasingly exact, as I became dissatisfied with the results. You can email me with your request, and I will respond with a specification attachment that is an example. You will probably need me to answer questions.

Sunday, November 28, 2004

Danger Spaces and Immune Zones

I first saw a danger space mentioned in old Jane's Fighting Ships. The 1914 Jane's mentions the danger space. This is the space where the trajectory of the shell carries below the height of the ship, while not striking the water. This ignores the issue of whether a shell can penetrate the ship's armor. An immune zone is the distance from the firing gun where the target ship's armor defeats the arriving shot. The shot may hit either deck or side armor, depending on the range. The immune zone concept is what drove the "all or nothing" armor design philosophy. There had been a recognition, from testing, that thin armor could still detonate a shot. The thin armor will allow an armor-piercing shot to easily penetrate and activate the fuse, so that after a delay, a charge will explode. If a shot hits an unarmored area, the fuse will likely not be activated, and the shot will not explode. Therefore, only protect the most important parts of a ship, and do that with the thickest possible belt armor. The belt needs to be backed by a splinter deck, below the belt, and for protection against plunging fire, there needs to be an upper deck, placed at the top of the belt. The upper deck will activate the fuse, causing the shot to explode, hopefully above the splinter deck.

Saturday, November 27, 2004

B/H as a factor in propulsion

I believe that the smaller the B/H ratio the lower the residual resistance. That means that a ship like the Trento, with a B/H of about 3.0, could be faster if she had a narrower beam. I experimented with decreasing the beam to 65.6ft and then to 62.6ft, and the speed increased for the same power.

Friday, November 26, 2004

More about the Trento

I really am interested in why the Trento design is so fast. My estimate for the standard displacement is 11,213 tons. The real normal displacement is 12,328.9 tons. The nominal normal displacement is more: 13,114 tons. That may be part of the answer: what I am using is lighter than the real ship. If I use my "optimal Cp" of 0.61, the Trento can make 36.1 knots. That is with 150,000 SHP. I may be giving the Italians more credit than they deserve, as I am using a machinery weight of 54 SHP/ton. Another explanation is that the B/H is pretty high. The designed B/H is about 3.0.

The Italian Trento class works like it should

Since I have long been interested in fast ships, I naturally took an interest in the Italian cruisers from 1925 to 1943. I just ran the Trento class heavy cruiser design through my program, and "it works". It works in the sense that for 150,000 SHP, the speed is 35 knots. That's at the normal displacement of 13,114 tons given on the Italian navy website. My deep load speed is 33.6 knots. I was never that sure that the nominal speed (35 knots) was actually a good number, but I can see that it is feasible. Admittedly, that is with a propulsion efficiency of 0.53. The coefficients that I used are Cp=0.536 and Cm=0.88. If the Cp were 0.61, it could make 36 knots. That is actually the speed they were said to have in the Conway's book, All the World's Fighting Ships 1922-1946.

I find myself very gullible with respect to ship speeds

I find that I can be very enthusiastic about the prospect of high speeds, especially as reported in Jane's Fighting Ships and the Warship periodical. A long time ago, and not being very knowledgable about the issues, I had believed that the Atlanta could have reached 40 knots no trials. I now know that she was lucky to reach 32 knots. Other high speeds that we shouldn't have believed were for the destroyer leader Swift (1905) and the Renown and Repulse in 1918. The Renown and Repulse, when light could reach 32 knots, but something like 40 knots was a ridiculous claim. As I have written in the past, I was taken in by the 43 knots claim for a Capitani Romani-class light cruiser in 1943. Frank Fox had warned me against the idea, but I had to actually do the calculations for myself. Quite quickly, I saw that at a normal displacement, in service, even 41 knots would probably have been beyond reach.

Wednesday, November 24, 2004

Some in the British navy were ready to adopt superfiring guns in 1905

You wouldn't realize that there were progressive influences in the British navy in the period from 1905-1914, but they were there. For example, Admiral Fisher wanted to be a progressive, although he often didn't actually know what would be the best thing to do. He was someone who "could make things happen", and he would embrace anything which held some promise to be an improvement. He like big guns ("Hit first, hit hard, and keep hitting"), many of them, and speed ("Speed is armour"). He accepted the need to fit adequate armor ("Armour is vision"). His armored cruiser design still had a mixed caliber armament. It was Captain Bacon who suggested that the new fast armored cruiser carry 12in guns. At one point, Fisher was in favor of a 12-12in gun armament with two levels of superfiring guns, all on the centerline. That was quashed due to the size limitations imposed.

Retrograde influences on British warship design from 1903 to 1927

The period specified is non-intuitive, but the retrograde influences on British warship design were present at least as early as 1903. The first casualty was the semi-Dreadnought design (4-12in/45 and 12-9.2in/50) that was proposed. Building was delayed until 1904 and then the size was reduced to produce the extremely cramped and reduced Lord Nelson and Agamemnon. There were many culprits. Budgetary pressures were a constant issue, early in this period. There was also the issue of Liberal governments not liking building armaments. The greatest individual negative influence was John Jellicoe. He seems to have had a misplaced sense of proportion. For him, being able to conveniently handle boats was more important than providing a smoke-free foretop (for example, the Orion class). Successive, conservative chief engineers also contributed. The British navy could have adopted small tube boilers much earlier, but instead, their designs were saddled with machinery that weighed too much and took too much volume than their German counterparts. After 1914, resources were an issue. I suspect that the top priority was providing armaments to the army in France. The navy's priority received a boost only from the need to deal with German submarine warfare. That allowed the navy build more destroyers and smaller ships. They were also forced to deal with German mine warfare, and to build suitable minesweepers (better than the the torpedo gunboats in use in 1914). Some light cruisers could be built, but larger ship construction languished. The only thing that kept the construction of the Hood going was the fear of what the Germans might be doing. As it was, she was only finished postwar and her sisters cancelled. The planned "1921" battleships and battlecruisers were kept smaller and less capable due to a combination of budgetary and docking issues. They were stillborne, due to the Washington naval treaty, but desire to build the best ships in the available displacement had lead to the extreme armament layouts. Like Captains Hiraga and Fujimori, in Japan, Stanley Goodall seemed to relish squeezing everything that he could from the available displacement, even if the result was extremely odd. Of course, his chiefs, Sir Eustace Tennyson-d'Eyncourt (DNC) and Edward L. Attwood were complicit in the atrocity. That influence lead to the unfortunate Nelson and Rodney, completed ini 1927.

Monday, November 22, 2004

Tony DeGiulian at NavWeaps had some suggestions for sources

Tony DeGiulian, from, had a suggestion for the source that would have weights for gun directors and included some example weights. He says that the source for director weights is John Campbell's book Naval Weapons of World War II. I never had any interest in this book until I found that I needed weights for fire control directors so that I could better calculate metacentric heights for WWII ships. I may need to consider that for WWI ships, as well, but hadn't seemed to need that information.

Sunday, November 21, 2004

Fire Control Directors

In analyzing American cruiser designs from the 1930's, I find that to correctly model them, I need to allow for Fire Control Directors, their weight and their position, so that they affect stability correctly. For the Radar era, that needs to be included, as well. My approach would be to have a Fire Control Director database and a Radar database. A ship specification would have room to list directors, by type and height to their base from the keel. The stability calculations would need to factor them in, when appropriate.

Cruiser guns

In the Southwest Pacific in 1942 and 1943, the Americans found that he 8in/55 gun had too slow a rate of fire while the 6in/47 gun was outranged by the "Long Lance" torpedo. The 6in/47 gun could fire 10 rounds per minute, and the Brooklyn class had 15 of them. They could fire so rapidly that you could see a stream of shells heading for the target.The US might well have benefitted from a 175mm gun with a 176 lb. shot. The US was building 175mm guns for the Army, so it was a known caliber, although not in the Navy. Concievably, they could have built a new gun with a 16cm or 16.5cm caliber.

Saturday, November 20, 2004

The Atlanta class cruisers (CL-51)

I have been experimenting with testing designs based on real ships to see how they compare with what is computed. Earlier today, I tried the Atlanta class cruiser, and found the phenomenon that Frank Fox had told me about. For the Atlanta class to reach their measured speed at a given SHP, their propulsion efficiency would need to be adjusted. Thanks to Friedman's book about American cruisers, I have the real coefficients (Cp and Cm), as well as accurate dimensions. There are also figures about speeds, displacements, and power. I found that to reach the correct speed, that the propulsion efficiency needed to be adjusted to 0.53. For those who are interested, the coefficients are: Cp=0.603 and Cm=0.832. Those are destroyer-like figures, from my experience.

Motor ships

The Admiral Graf Spee had machinery that generated 54,000 HP with a weight of 1,648 tons. That is a HP/weight of machinery ratio of about 32.77 HP/ton. The machinery space volume seems to have been something like 171,000 cubic feet. That would mean 3.167 cubic feet per HP. I've tried an example ship based on this type ship. The gun I will use is a 11in/50 gun firing a 718 lbs. shot. The muzzle velocity is 2,764 ft/sec. I'm having some trouble getting the metacentric height low enough. For better or worse, this is a typical problem. The good thing about this design is that the ship with this gun would be much stronger than any conventional cruiser. The standard displacement is 11,460.9 tons. The maximum range is 14n438.1 nm. That is with an armament of 6-11in/50, 8-6in/50, and 6-4in/50 guns. The belt is 3.3in. That is thicker than a real panzerschiffe, but not by much. The speed is 27.6 knots at normal load and 26.9 knots at deep load.

Friday, November 19, 2004


After William Hovgaard described the "Battleship-Cruiser" as a type in the early 20th Century, that prompted people to think in new ways about ship types. The Italians and Japanese were actually early adopters. At the time of the Russo-Japanese War, the Japanese designed armored cruisers with 4-12in guns. The Japanese had also hoped to build a ship like Colonel Cuniberti's "Ideal Battleship for the British Navy" (1903), but they didn't have enough 12in guns. They had to settle for a "semi-Dreadnought" with a mix of 12in and 10in guns. The Colonel Cuniberti designed the Roma class fast battleships that had 2-12in guns and a fairly high speed (21.5 knots). The 1921-type British battlecruisers could have been classed as fast battleships, as the Hood almost was. The late 1930's fast battleships were exactly what William Hovgaard envisioned.

Wednesday, November 17, 2004

The reality is that ship sizes were limited by a number of factors

Often, the size of ships was limited by budgetary factors. There was also a strong British navy prejudice, at least in some quarters, against really large ships. In the "1921" design process, for example, they had to back off from 18in-armed battlecruisers and accept 16in guns. The battleships were still to be armed with 9-18in guns, but the battlecruisers had to have smaller. The battlecruisers were really fast battleships, but were only limited in armament, not armor or speed. They were really much better ships than the so-called fast battleships built in the late 1930's and early 1940's. The American ships were especially underwhelming. The worst were the North Carolina class. Their problems were partially corrected in the South Dakota class. At least, the South Dakota's were structually sounder and better protected.

Tuesday, November 16, 2004

The website

Tony Lovell pointed out this website to me, recently. The site is called The Dreadnought Project, and has some really impressive 3D models, as well as scans of German plans from the 1890's up until 1918 or so. He is using a 3D modeling tool called Rhino 3D (or Rhinocerous) that does NURB modeling. It gives really impressive results. I just downloaded an evaluation copy.

A Question: how much should ship characteristics be constrained by date?

I ask the question about whether a high-level ship design program should restrict characteristics by date. I think that political considerations could reasonably be waived, if in an alternate world situation where you were designing your own ships and building program, you could possibly specify a ship in 1905 that had 8-20in guns and 15in armor. Reasonably, the guns could be 20in/35 or 40 caliber, and the size would be less. The look would be transitional between pre-dreadnought and dreadnought. The size would still be large, but there could be restrictions against using triple turrets. I'm choosing an extreme case. More normally, you might restrict ships to being under 20,000 tons and to 12in/45 guns at the upper end. You could also restrict SHP/ton of machinery to 10.0, as was the case for British battleships up until 1912. Battlecruisers had better powerplants than that, but only marginally. So, that is the question: by year, what should be premitted with respect to ship characteristics?

Monday, November 15, 2004

Japanese Cruisers: SHP/ton of machinery weight

Since I am interested in ship design, I thought that computing the SHP/ton of machinery for some representative Japanese cruisers. For better or worse, I am generally using trial data for SHP.
  • Tenryu 59,844 SHP 1042.9 tons 57.38 SHP/ton 1919
  • Kuma 91,229 SHP 1588.1 tons 57.445 SHP/ton 1920
  • Nagara 92,670 SHP 1630.3 tons 56.84 SHP/ton 1922
  • Yubari 61,336 SHP 1056.5 tons 58.056 SHP/ton 1923
  • Aoba 103,003 SHP 2173.7 tons 47.386 SHP/ton 1927
  • Haguro 132,568 SHP 2689.5 tons 49.29 SHP/ton 1929
  • Mogami 154,266 SHP 2477.3 tons 62.27 SHP/ton 1935
  • Kumano 153,698 SHP 2358.1 tons 65.18 SHP/ton 1937

Sunday, November 14, 2004

Now, let's design the cruiser analog to the "moderate dimensions" battleship

I have been experimenting with a battlecruiser analog to my "moderate dimensions" (for 1921) battleship. The battlecruiser has the same armament (9-15in/45 and 16-5.5in/50 guns) and can make 31 knots at normal load. The normal displacement is 30,237 tons (at the present), and has dimensions of 814ft x 95ft x 29.8ft. The coefficients are: Cp=0.53 and Cm=0.90. The armor basis is 9in. This is only a preliminary cut, as I haven't made a drawing, yet. Without a drawing, you can't be sure that everything will work.

The "Moderate Dimensions" trap

Lord Brassey, and many others got caught up by the "Moderate Dimensions" trap. The argument stems from the knowledge that in sailing naval warfare, you didn't build a fleet of 100 gun ships, you built a fleet with a few 100 gun ships and many 74 gun and 64 gun ships. Logically, they thought the same idea should hold true in navies of ships built of steel and powered by steam. The counter argument is that you will end up with small ships, simply by the passage of time, as your latest ships will dwarf those built 5 years earlier. The biggest ships are the best armed and best protected, and nothing else can stand up to them. So don't build small, more lightly armed ships, as they are a waste, and will be defeated.

I've fallen into the moderate dimensions trap, myself, in that I'm interested in a smaller battleship, built to 1921 standards, with 9-15in/45 guns and 16-5.5in/50 guns. The speed would be 24 or 25 knots with a 32,500 ton displacement. The ship would be suitable for convoy escort and operations in secondary theaters. They could still put up a credible fight against stronger ships, although they would be unable to fight the really big ships with 18in or larger guns.

Saturday, November 13, 2004

The obvious thing to do now would be to try and make a Capitani Romani-style ship

What would a "Capitani Romani" style ultra-fast cruiser look like? It would be small. With a standard displacement of about 3750 tons, the normal displacement should be about 425o tons. The design would be moderately larger than my GB/CL/1921e ship. I think that dimensions should be 462ft x 45ft x 16ft with coefficients of Cp=0.66 and Cm=0.86. The power plant should be very lightweight but high power. I need to experiment to see what can be done. For my design, I would have 6-5.5in/50 guns (510 lbs broadside). It probably should have 8 guns, or should have 8-5.1in/50 guns. I'll have to see how this works in my program. The answer is that I was able to make the design work, but with a very high power-weight ratio. The revised dimensions are 462ft x 43ft x 13.6ft. The hull depth is 30.5ft and the normal displacement is 4,184 tons. The ship can reach 41 knots at normal displacement and only 36.8 knots at a deep load displacement of 5569 tons. The stability is adequate, as the metacentric height at normal load is 2.2ft and 3.96ft at deep load.

I'm working on a small cruiser design

Given that I have a 5.1in/50 gun design, the next idea was to create a small cruiser design for use as a convoy escort and cruising ship. I want to have 8-5.1in/50, as that has a broadside weight in excess of 500 lbs (568 lbs). I correctly guessed that 29 knots was possible at normal load. That is with a designed power of 40,000 SHP. The challenge is stability. My current compromise is to reduce the range, and raise the metacentric height, slightly, to get the normal displacement down under 3,800 tons. That still gives a metacentric height of 2.014ft at normal load. That is sufficient for such a small ship. The range of stability would still be great enough to be safe. The crusing range at normal load would be 2,780 nm and at deep load would be 7,078 nm. The dimensions are 439ft x 43ft x 13ft with coefficients of Cp=0.61 and Cm=0.88. The secondary battery is 8-3in/50 in twin mounts for AA use. The 5.1in/50 gun is also capable of 45 degrees elevation and AA fire. The ship has a 1in deck and 2in side armor.

Friday, November 12, 2004

The 5.1in/50 gun

The British came very close to adopting a 5.1in gun similar to that used by the Germans and French. The actual caliber was 13cm, but the gun was typically referred to as a 5.1in gun. With a heavy shot, this gun is also quite potent for its size. The piece would weigh 5 tons and has a 71 lbs shot. The muzzle velocity is 2774 ft/sec. The gun performance looks like this:
               Maximum penetration: 13.33 inches

     Elevation          Range            Belt       Deck

       1.9 deg        4100 yards          8 in
       3.6 deg        6400 yards          6 in
       7.1 deg        9800 yards          4 in
      12.8 deg       13300 yards          ...        1 in
      18.6 deg       15600 yards          2 in
      27.1 deg       17900 yards          ...        2 in
      47.7 deg       19300 yards          ...        3 in

     Maximum range = 19500 yards at 42.5 deg elevation

The 7.5in/50 gun performance

There is a striking difference between the 7.5in/50 gun firing a light projectile at high velocity and a heavy projectile at a lower velocity. This is what the performance looks like for the 200 lbs AP Shot at 2948 ft/sec:

     Elevation          Range            Belt       Deck

       1.3 deg        3500 yards         14 in
       2.1 deg        5100 yards         12 in
       3.2 deg        7100 yards         10 in
       4.9 deg        9400 yards          8 in
       6.6 deg       11300 yards          ...        1 in
       8.0 deg       12600 yards          6 in
      14.5 deg       17200 yards          4 in
      16.7 deg       18400 yards          ...        2 in
      25.9 deg       22100 yards          ...        3 in
      35.4 deg       24400 yards          2 in
      36.6 deg       24600 yards          ...        4 in

     Maximum range = 25200 yards at 44.5 deg elevation

This is the gun with a velocity of 2691 ft/sec and a shot weight of 240 lbs:

     Elevation          Range            Belt       Deck

       1.1 deg        2500 yards         16 in
       1.9 deg        4200 yards         14 in
       3.0 deg        6200 yards         12 in
       4.7 deg        8500 yards         10 in
       6.0 deg       10100 yards          ...        1 in
       7.2 deg       11400 yards          8 in
      11.6 deg       15200 yards          6 in
      15.0 deg       17400 yards          ...        2 in
      21.2 deg       20700 yards          4 in
      22.4 deg       21200 yards          ...        3 in
      30.7 deg       24000 yards          ...        4 in
      40.1 deg       25700 yards          ...        5 in
      48.1 deg       25800 yards          2 in

     Maximum range = 26000 yards at 44.7 deg elevation
I find it pretty amazing how more potent the gun is with the heavier shot.

The 7.5in/50 gun

The 7.5in gun seems like a very "pre-Dreadnought" caliber. I just designed a gun that is a 7.5in/50 gun weighing 18.75 tons. That would be the weight without the breech. I've gone ahead and used the standard shot weight of 200 lbs. The muzzle velocity is 2,948 ft/sec. That is sufficient to do a good bit of damage at relatively close range. The shot would rapidly lose velocity, as the shot is only 0.474 of the cube of the shot diameter in inches (a useful empirical relationship). A better shot weight would be at least 210 lbs or greater. 210 lbs is about 0.5 of the cube of the gun caliber. A really heavy shot would be 240 lbs (similar to the 15in/42 shot).

Thursday, November 11, 2004

A moderate-sized heavy cruiser design with 9-7.5in/50 guns

I don't know how viable the design is, but I thought last night that I would like to try an Exeter-type heavy cruiser (moderate dimensions) with 9-7.5in/50 guns. That gives a heavier broadside than 6-8in/50 guns and probably is superior from a gunnery perspective. I know that the British didn't like the 9-gun layout, but the ship would be able to fire alternate 4 and 5 gun salvos. That should be superior to 3-gun salvos from an Exeter. The normal displacement is 9,070 tons with dimensions of 590ft x 60ft x 16.7ft. The designed speed at the normal displacement is 32 knots and not quite 31 knots at deep load. The maximum range, at 15 knots, is 10,090 nm. The belt is 3in and 16ft wide and the decks are 1.5in + 1in. The range at the normal load is only 4,030 nm at 15 knots. The normal fuel carried is 685 tons and the additional fuel carried at deep load is another 1,030 tons. I've designated the design as the GB/CA/1921d.

Wednesday, November 10, 2004

Details about the GB/CL/1921d type

Tonight, I fleshed out the British 1921-style commerce protection light cruiser. It came out with a Washington Naval Treaty Standard Displacement of 7,160 tons. The dimensions are 555ft x 57ft x 16.6ft, with a normal displacement of 8,060 tons. The belt is 3in and is 16ft wide and 350ft long. The barbettes and turrets are also 3in. The decks are 1in + 1in, amidships. The metacentric height at normal displacement is 5.27ft. The normal range at 15 knots is 4,451 nm. The maximum range is 10,175 nm. The speed at normal displacement is 32 knots and at deep load is 30.75 knots. The armament is 9-6in/50 and 6-4.7in/50 guns. The machinery is arranged using the unit system and is 48 SHP/ton of machinery.

A light cruiser for trade protection (1921-style)

Major navies had a definite need for a light cruiser for trade protection (in the period from 1903-1945). For 1912, an 8,000 ton ship is a very reasonable size. My initial estimate for dimensions would be 555ft x 57ft x 18ft, with coefficients Cp=0.56 and Cm=0.88. This is only very slightly more than 8,000 tons. I would like to see a speed of 32 knots, as that seems to be the minimum acceptable speed at normal displacement. I would go with a 9-6in/50 gun armament with a secondary armament of 4.7in/50 guns.

Tuesday, November 09, 2004

The GB/CA/1921c1 armored cruiser design

It turns out that the GB/CA/1921c1 design can reach 32 knots after all. This is my compact armored cruiser design with 9-9.2in/50 and 6-4.7in/50 guns. The belt is 6in and 16ft wide. The citadel is 372ft long. The deck armor isn't even too bad. I reduced the upper deck to 2in while lower deck and slopes stayed at 2in as well. While the designed displacement is 14,700 tons, the Washington Naval Treaty standard displacement is just 13,426 tons. The speed at deep load is 31 knots. The range at normal fuel load of 950 tons is 4,142 nm. The maximum range is 12,209 nm. Both are at a cruising speed of 15 knots. The design has a 6in CT and a 4in comm tube. There are two stacks with funnel caps.

My revised 9.2in gunned armored cruiser

I did some more work towards revising my 1921-style armored cruiser with 9-9.2in/50 guns. I rolled back to a much smaller ship: 14,700 tons, dimensions of 635ft x 70ft x 23ft, Cp=0.56, and Cm=0.90. I need to run the revised design through my program to see how the design is fleshed out by my program. I am looking at a 6in belt, hopefully 16ft wide. I am into the "all or nothing" philosophy, so the citadel will be fairly short on a 635ft ship.

Monday, November 08, 2004

This is too big a ship for the armament

My impression is that this design is too large for the armament. I've started an inboard profile drawing, and the turrets look very small in relation to the ship size for a 721ft long ship.

A triple 9.2in/50 turret

I am probably the only person in the world interested in this, but I calculate the barbette diameter give the caliber of the gun and the number of barrels per turret. For the triple 9.2in/50 turret, the barbette diameter would be 26.6ft (rounded). I always figure that 60% of the barrel protrudes from the turret face, so in this case, the guns would protrude 23ft.

A 1921 "armored cruiser"

I've started the design process for a 1921-style "armored cruiser". I am experimenting with an armament of 9-9.2in/50 and 6-4.7in/50 guns. The side armor, initially is 6in. I'm not sure what power or anything else would be appropriate. I still like 32 knots but could live with 31 knots. I must not have a 9.2in/50 gun defined, as I got the usual "not-a-number" result for metacentric height. That is a sure sign of an undefined gun. I ran the gun program to calculate the muzzle velocity for a 50 caliber 9.2in gun (I'm going with 2,900 ft/sec). The preliminary dimensions are 721ft x 84ft x 48ft depth. The draft at normal load is 26.4ft. Design is an iterative process, and I don't have an inboard profile, yet, so this is very preliminary. My belt, amidships, is 7.5in KC, 16ft wide (two decks high). My designed speed is 32 knots at normal load and 31 knots at deep load. I'm hoping for a maximum cruising range of 10,000 nm.

Sunday, November 07, 2004

The slower heavy cruiser design

The rationale for a slower heavy cruiser design would be to have greater protection. Even if slower, the minimum speed should be 32 knots. My designs are generally low, so they tend to have too much stability, before I take measures to raise the center of gravity. By shortening the hull and lowering the power, a 16-foot wide belt, 3 inches thick can be carried. There is almost excessive deck armor: 3in + 2in amidships. That's with my favorite armament for a heavy cruiser: 9-8in guns. I like the 9.2in/50 gun, as well, but it takes a larger ship.

Saturday, November 06, 2004

A fast, 1921-style heavy cruiser

After having finished my first cut at a faster 1921-style light cruiser (37 knots), I decided to do a fast heavy cruiser design with 9-8in/50 guns. I used Rick Robinson's "Big Gun" program to aid my gun design effort. It would have been nice if his program would estimate the weight of the piece, but it doesn't. I use a formula: D^3 x Length in Calibers / Constant to determine the weight in tons. The only reasonable thing to do is to look at example guns to determine the constant. I used 1365.33 as the constant. I derived that from the 7.5in/50 gun (for better or worse). The idea is to have a heavy cruiser that is capable of more than 35 knots at normal load, carries 9-8in/50 guns, and has a 10,000 mile maximum cruising range at 15 knots. The speed at deep load is about 34.4 knots (at 15, 337 tons).

Friday, November 05, 2004

Tweaking the GB/CL/1921 Design

I am interested in further modifying the GB/CL/1921 design. One thing I want to experiment with is to move the forward guns further towards the bow. I also want to do away with the semi-superfiring 4.7in/50 guns, at the forward and after parts of the superstructure. I would put all the 4.7in/50 guns on the broadside (3 per side). I want to move the funnels forward, as well. I might even try to increase the machinery power, if there is volume to expand further.

Thursday, November 04, 2004

My rationale for high-speed ships is for strategic mobility

I'm all but convinced that the Italian Captani Romani class scout cruisers would not be able to reach 43 knots in service. If they had, they would be the ideal ships for operations in the Mediterranean Sea. Their range-speed combination gave them ability to stage mining operations at night at a considerable distance. The British Abdiel class were an attempt to perform a similar mission, but with a less-capable ship. I have to agree with the American view that speed for tactical purposes is less important, once we got past the point of fighting Jutland-style battles. The ability to move ships a considerable distance in a short time is still a needed capability, even in modern times. In WWII that ability was needed even more than now.

Wednesday, November 03, 2004

Warship Speed in the early 20th Century

I have mixed feelings about the utility of speed in warships during the period from 1903 to 1945. For one thing, the period is not uniform. From the 1920's on, airpower had become a major factor. Prior to 1914, airpower was essentially a non-factor in operations.

During that time, the tactical value of speed was clear. The more speed, the greater the tactical advantage. After 1918, not all navies agreed on the importance of speed. In Britain, they were about ready to only build fast battleships (called battlecruisers, but heavily armored and gunned). In the U.S., the authorities dismissed the value of speed and were ready to build 32 knot cruisers rather than emulate the Japanese. The Japanese retained their mania for speed. The Nagara class were intended to be 36-knot ships. The original intent for the "10,000 ton cruisers" was for them to be 35-knot ships. They retained that desire right up until 1941. Having fast cruisers gave them ideal companions for fast aircraft carriers.

Monday, November 01, 2004

Specs for my 1921 super destroyer

Continuing my obsession with radical ship designs is my GB/DL/1921 super destroyer. The idea is that construction would have commenced in 1921.

  • Year: 1921
  • Length: 376.0 ft
  • beam: 40.0 ft
  • Hull depth: 26.0 ft
  • Design displacement: 2840.0 tons
  • Cp: 0.66
  • Cm: 0.82
  • Machinery Wt. Basis: 66.0 SHP/ton
  • Hull Wt. Basis: 3.00 x 10^-3
  • FreeboardForward: 25.0 ft
  • FreeboardAmid: 13.0 ft
  • FreeboardAft: 15.0 ft
  • Designed SHP: 75000.0
  • Designed Speed: 36.0 knots
  • Board Margin: 50.0 tons
  • Electrical Power KW: 300.0
  • Main Batt Gun Type: 4.7in/50
  • Main Batt guns: 5.0
  • Main Batt Mount Type: shield
  • Normal Fuel: 200 tons
  • Extra Fuel for Deep Load: 250 tons

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