Is there any benefit to speed in large ships?

Admiral Fisher would say, "Speed is armor". Without thinking about it, the natural reaction would be to say that the more speed the better. John Paul Jones didn't say "Give me a slow ship for I intend to go in harm's way". The lessons of World War II in the Pacific showed that there was still a need for ships that could make 34 to 35 knots. The requirement was caused by the need for escorts to "run" with the fast carriers. The Japanese had retained the requirement for 35 knots through the 1920's and 1930's. Their first examples were the 5,500 ton light cruisers. All of the 8in gun cruisers also aspired to 35 knots, although as the ships became heavier, they lost the ability to make that sort of speed. The United States had made a conscious decision in the 1920's to abandon high speed, after heading that direction in the 1916 to 1921 time frame. The only ships from that period to complete were the Omaha class light cruisers and the Lexington and Saratoga. They ultimately were not as fast as originally planned. They originally were all 35 knot ships. The change in direction was because of the idea that aviation obviated the need for fast ships. If anything, in the modern era, the situation has gotten even "worse" in the sense that the new ships we building and planning are slow by early 20th Century standards.

More about the light cruiser design

One merit of the light cruiser design I just described is that it has substantial freeboard. The bow has a substantial rake with the bow suitably flared. A more balanced design might scale the speed back to 35 knots and add a fourth twin turret. I actually happen to prefer triple turrets, although from a purely gunnery perspective, four twin turrets is preferable. With the barrels in separate sleeves, you can alternatively fire four gun salvos. This can produce much smaller spread at long range than triple turrets, especially of the guns are in a single sleeve.

My second Italian-looking light cruiser

I had glanced at the drawing, last night, and though that this design must be like the Muzio Attendolo, or Raimondo di Monteccucoli, but I was wrong. The dimensions are: 575ft x 52ft x 17.4ft (designed). The normal designed displacement was intended to be 6,000 tons with a 7,500 ton full load displacement. The armament surprised me, as it was only 6-6in/50 guns. There are some small patches of 1in armor, with a 1/2in deck. There was room to give the design more power, so I did. The original intent was to make 37 knots. The only thing was, is that it takes more like 104,000 SHP to reach that, rather than the original 67,400 SHP.

I can report my light cruiser could reach 39 knots

I just did a quick data entry job and ran my program for my fast light cruiser (5,000 tons). The displacement was a good estimate. At 5,093 tons the ship could reach 39 knots. The deep load speed is 36 knots. The actual Washington Naval treaty Standard Displacement was 4,452 tons. The deep load displacement was 6,680 tons. The normal range was 3,351 nm. The maximum cruising range at 15 knots was 10,054 nm. The max fuel capacity was 1,200 tons. The normal fuel load was just 400 tons.

My attempt at a Bartolomeo Colleoni-style light cruiser

My attempt at an Italian-style light cruiser caught my eye, tonight. I am guessing that my design dates from about 1973. The standard displacement was to be 5,000 tons with a 6,500 ton full load displacement. The dimensions were 555ft x 50ft x 16.3ft, with a 30ft hull depth. The coefficients were Cp=0.56 and Cm=0.90. The hull structure is rather light, the factor being 2.85 x 10^-3. That produced a hull weight of 2,370 tons. The power was 90,000 SHP normal and 108,000 SHP on overload. The machinery weight was 1,800 tons. That means that the overload SHP was 60 SHP/ton of machinery. The armament was 8-6in/50 and 4-4in/50 QF. There was only 55 tons of protection, so that ship was essentially unarmored. The design speed was 42 knots. I suspect that the actual speed would be much less than that.

My friend's GB/DL/1905 design

My friend Cliff conceived of a family of destroyer-type ships that would fill the role of both light cruisers and destroyers. The 1905 DL type was 1,200 tons with a speed of 35 knots. The armament was strange, in that the guns he specified were 4-88mm/50 QF. He also specified 2-21in torpedo tubes, although I don't believe that anyone had a 21in torpedo in service at that date. The coefficients were Cp=0.56 and Cm=0.85. The dimensions were 326ft x 30ft x 9ft. The design incorporated superfiring guns, fore and aft. There were three funnels, with two low and the first funnel raised. There was the usual raised forecastle. When I try to run my program, I am having a problem with the design being overweight. I will need to look at what could be done to solve the problem.

Narrower beam producing a better ship seems counterintuitive to me

When I narrow the beam for the Ger/BB/1907 down to 90ft, I seem to produce a better ship. The speed is somewhat higher and the metacentric height is reasonable: 3.27ft at normal load and 4.68ft at deep load. The displacement comes down to 24,948 tons for the normal displacement. The design goal was 25,000 tons, so this works very nicely. The thing is, why shouldn't a 105ft beam work? Isn't more, better, even for beam?

The problem seems to be "excessive beam"

I experimented with a 95ft beam for the Ger/BB/1907 design, and the metacentric height dropped to something closer to an acceptable number. That tells me that the problem is related to a beam being greater than needed, given the other design parameters.

My Ger/BB/1907 design

I'm experimenting with my Ger/BB/1907 design. The basic concept was a 25,000 ton ship with 8-12in/50 guns and 12-4in QF. The lower belt was 13in as was the turret face thickness. The barbettes were 10in. The decks are 3in + 1in. The designed speed was 24 knots. The dimensions were: 620ft x 105ft x 26ft, with coefficients of Cp=0.56 and Cm=0.95. The main problem I am seeing is a metacentric height that is too high. The ship would be excessively stiff, which I would think would mean that it would have a tendency to roll. The speed isn't a problem. Because of the combination of length and displacement, 46,591 SHP is sufficient to reach 24 knots. What seems to have been my originally designed power, 54,000 SHP, would actually give a speed of 25 knots. I can't tell if the stability issue is a "bug" in the specification or the actual design.

There is not as much weight information for WWI destroyers as I would like to see

The definitive book on British Destroyers (March) is sorely lacking in the sort of data that we need to be able to design WWI-era destroyers. That is not to say that there is none, for there is a bit. There is just not the breadth of data that would need to design a range of destroyers (large and small, from 1905 to 1921). D. K. Brown generally doesn't have that sort of data, either. He is more concerned with what I would call "structures".

An 870 ton 1905 destroyer

My German 1905 destroyer (admittedly, a "super ship") was 870 tons designed displacement. I seem not to be able to make that work with my program. The "Standard Displacement" is 865 tons, but the "normal displacement" is 1,103 tons. The machinery produces 27,000 SHP and a speed of 32 knots at the normal displacement. The dimensions are 270ft x 28ft x 10.46ft, with coefficients of Cp=0.66 and Cm=0.74. The armament is 2-4in/50 QF and 2-18in TT (actually 17.7in). All 18in torpedoes of this era were actually 45cm in diameter, even the British "18in".

Nathan Okun on the Bismarck, compared to contemporaries

Nathan Okun is the foremost expert on armor and penetration of our time. He has an instructive article about the Bismarck's protection system compared to contemporary ships. By the time he wrote this article, the wreck of the Bismarch had been found and explored.

D. K. Brown's book A Century of Naval Construction

The book is dated, but has a good deal of information about what happened with British warship design and shipbuilding from 1919 to 1945 (he covers the earlier periods as well). D. K. Brown writes that Stanley Goodall was the greatest naval architect of all time. He certainly was a giant in his field. His first ship design was for the Arethusa class light cruisers of 1912. They set the pattern for modern cruiser design. He had his hand in submarines, destroyers, and aircraft carriers, as well. His best ships were never built: the 1921 battlecruisers cancelled because of the Washington Naval Treaty.

You couldn't build a balanced cruiser within the 10,000 ton limit

Norman Friedman's reflection of considered opinion up until WWII was that you couldn't really build an 8-in gun cruiser that would be a balanced design within a standard displacement of 10,000 tons. The Japanese approach was to try to build 10,000 ton ships but do whatever was needed to build a successful ship. That mean that their ships exceeded 10,000 tons by a good amount. That was true for the Italians, as well. I have written previously about the Trento and Trieste. The Americans, who wanted the treaty regime to "work" tried hard to stay within the 10,000 ton limit. The result was that they produced ships that were seriously compromised. Some of their best ships were "taken apart" at Savo Island. Those were ships that they sorely needed, as well, such as the Astoria, Quincy, and Vincennes. Of the 18 pre-war heavy cruisers, they lost the Chicago, Houston, Northampton, Indianapolis, Astoria, Quincy, and Vincennes. The Indianapolis had almost survived the war, before being torpedoed.

The North Carolina Class Battleships

I was amazed at how Garzke and Dulin blow off any criticism of the North Carolina and Washington. Norman Friedman makes clear how close they came to failing. My estimate as to the cause of the disease was the extreme measures taken to keep the design within the 35,000 tons standard displacement. They failed, but in doing so, they severely compromised the design. The worst feature was the severe longitudinal vibration. That problem was "bandaided" by trying various combinations of propellors, which partially helped. Almost as bad was the lack of hull strength. The symptoms showed up when the North Carolina was torpedoed, and flooding was much more extensive than should have been for a new ship. Another example was the collapse of the Washington's bow after a collision with the Indiana. A battleship should have been able to shrug off such a collision, but that was not the case with the Washington. The ships were also too wet, as the hull depth had been drastically reduced as another weight-saving measure. There is a picture showing whitewater breaking over the bow, almost continuously, and a huge wake, while escorting a carrier in wartime. The basic concept for the class was sound. They just had a poor implementation.

The Japanese heavy cruiser Takao

Janusz Skulski's book about the Takao gives some of the coefficients and other numbers, which I found very instructive. Left to my own devices, I have typically thought that cruisers would have a prismatic coefficient (Cp) less than 0.6 and the midship coefficient around 0.9. I seem to be pretty much wrong, at least for fast cruisers. The coefficients for the Takao were Cp=0.627, Cm=0.822, waterplane coefficient=0.721, B/H=2.776. The weight basis for machinery seems to have been 51.42 SHP/ton of machinery.

American triple turrets with guns all in the same sleave

I consider that the American practice of having triple turrets with three guns in the same sleeve was a bad practice. The opposite extreme was the British triple 4in gun mounts on the Renown and Repulse, as originally built, which added unneeded complexity for rapid fire guns. The American triple 14in gun turrets on battleships were the first appearance of three guns in a single sleeve, as far as I can tell. I suppose that it was an attempt to simplify the design. Apparently, saving weight was also a factor. The real reason that the single sleeve happened is that the Americans lacked experience with long range firing with triple turrets. To get smaller spreads, individual sleeves were critical. There needed to be a way to make small corrections in elevation for individual guns. Apparently, the American system didn't allow for this feature. If the guns got out of alignment from firing, there was no way to realign them. The same bad practice was continued for the "Treaty Cruisers", apparently up through the New Orleans class.

DL-1 Norfolk: another Atlanta class variant

The DL-1 Norfolk was based on the Atlanta class light cruiser hull. The post-war goofiness had set in by the time she was designed. She was armed with only 8-3in/70 rapid fire guns and 4-twin 20mm AA mounts. She also had 8-ASW torpedoes in single mounts and 4 of the "Weapon Alpha" devices. He speed was 33 knots, showing how the navy had backed off from higher speeds after the end of the war. Since 1949, armaments and speeds have decreased. Much of the weight and volume now goes to electronics. The navy decided that the Norfolk type was too little capability for the cost: a self-inflicted wound, typical of the Cold War era.

The fast AA cruiser devolved to the Mitscher class DL design

When the fast anti-aircraft cruiser armed with twin 5in/54 guns seemed to grow too large, the navy ended up building a very large destroyer in place of that design. The ships were originally classified as destroyers (DD), but ended up as destroyer leaders (DL). These were the Mitscher class ships. They had several of the twin 5in/54 gun mounts. They had a very similar look, as they had the twin cruiser funnels, similar to the Atlanta class ships.

US Navy thinking about speed in cruisers

Before 1921, the US Navy still believed in fast cruisers. In the 1920's, that thinking changed. The idea was that aviation made speed in cruisers irrelevant. Given that, 32 knots was more than adequate. What they didn't realize was the impact that aircraft carriers would have on tactics. By 1944-1945, American thinking had changed. Now, they wanted 35 knot cruisers, if they could get them, to run with the aircraft carriers. There was a replacement for the Atlanta class cruisers that would have been armed with with twin 5in/54 guns in power mounts. The Atlanta class turned out to be too slow, although they had a good anti-aircraft armament. The idea was to build a faster ship that would still be a good anti-aircraft platform. Again, this was needed for the fast carrier task forces. A good source on the subject is Norman Friedman's book U. S. Cruisers.