Naval History Forums

alecsandros wrote:

dunmunro wrote:
How did you calculate 34%? PoW ran trials at 11.6k shp at 28 knots @42.1k tons . The power curve will rise steeply as the speed increases, so another 22k shp to gain 1.1 knots is about right. The log entries confirm the data from G&D.

Bismarck's nominal power rating was 118K shp, but it achieved considerably more.

Well, I'm thinking about KGV class normal power output, which was 100.000hp. The maximum power was 110.000 hp (at least the design specs). So achieving 134000hp would be 34% above the normal, and 21.8% above the maximum. The Bismarck maximum output was 138000hp, with an overload of 9.2%, up to 150700hp...

I remember a KGV speed trial @41000t, at around 113000hp, and 28.5kts. I may be wrong though...

The original design called for 100,000 shp, but this was changed during building and the new rating was 110,000shp

PoW ran trials at 111,600 shp and made 28 knots.

The normal power was 110,000shp with a design overload of 125,000shp:

4-shaft single reduction geared turbines,
110,000shp = 27.5 knots (29.25 knots with 125,000
shp maximum); 8 Admiralty 3-drum boilers.
Maximum speed at full load = 28.25 knots
Maximum continuous sea speed = 27.8 knots
Raven, King George V class Battleships, (Ensign 1)
But as is common with warships, these figures were exceeded in service.

alecsandros wrote:The Bismarck maximum output was 138000hp, with an overload of 9.2%, up to 150700hp...

Alecsandros, the Tirpitz made 163,026 hp so I think Bismarck could do more 150,700 hp (even if maybe she was never pushed that far) since both ships had the same machinery.

Pandora wrote:
Alecsandros, the Tirpitz made 163,026 hp so I think Bismarck could do more 150,700 hp (even if maybe she was never pushed that far) since both ships had the same machinery.

I think the builders of the machineries were different... but the design specs were similar, AFAIK.

What was the fastest BB in the war anyways?

19kilo wrote:What was the fastest BB in the war anyways?

It was probably Iowa, but possibly Richelieu.

Gentlemen,
Many thanks for your replies, but as I stated in my opening post even the N3 was only going to be about half a knot quicker than the Nelsons and still slower than the QE's. It almost seems as if the British designers were still thinking of Nelsonion ways of fighting i.e. ships plodding along, staying in line and pounding hell out of each other - albeit at much longer range, but which they were still doing even at Jutland. It seems that they wanted to up the gun power but not the speed.

Not necessarely. Britain was in the formidable position to be able to play both games.
That of the slow Dreadnought line of the battle (kind of reminds me on dinosaurs, big claws, plenty of armour but not very responsive to environmental changes and equipped only with rudimentary means of situational awareness) for which the N3 class was to provide gun superiority
AND
that of the fast knives, able to maneuver at will and impunity, covering long distances, the G3 class was to be suppose to do battlecruiser type of actions.

Britain didn´t required a "unification" type like HMS HOOD, which eventually was buildt by Britain but merely in order to augment the existing battlecruiser force by another, but this time well protected fighting vessel.

The Royal Navy fully understood the benefits of speed and unlike other naval services (Germany already knocked out of the table) the Royal Navy not only had a sizable battlecruiser force but also had plenty of battle experiences with it´s fast wings. In within the political environment of naval limitations issued by the new treaties, power was more important than speed for Britain, that was because Britain already had battlecruisers at it´s dispoal, a type not to be found in navies like the french M.F., the italian R.M. or the USN.

Wasn't propulsion technology (i.e. engines, boilers etc.) a limiting factor in the 1910's and 1920's?

If it was, then in order to produce a ship with high speed it would have to be bigger to accomodate the machinery - hence the size and length of Hood compared to the QE's. Smaller battlecruisers sacrificed armour for the size and weight of machinery to generate the speed. The limitations imposed by the Washington Treaty would then make it very difficult at the time to build a fast battleship. So the 33,900 ton Nelson's ended up at 23 knots whereas their design predecessors, the 48,000 ton G3 BC's would have been 32 knot ships.

By the 1930's power plants had developed enough to power well armoured 35,000 ton ships at greater speed......

Does this make sense or am I out to lunch?

Makes sense to me Paul.

Hardly.
As noticed above by another poster, the pre-Jutland QUEEN ELIZABETH class, despite large tube boilers already showed an acceptable top speed, faster by design (but not in practice) than the NELSON´s.
After ww1 the small tube boilers and as important, reduction gears were generally adopted. That allowed
[a] lighter boilers
smaller and thus lighter turbines to be designed which operate at higher efficiency, causing a higher propulsive efficiency

All this reduced the machinery weight for any SHP generated over that of the previous classes of Dreadnoughts. The NELSON´s could have been larger a bit and still remain Treaty conform but power and protection were considered more important than speed. The UK already possessed the means to produce a fast battleship, of, say 26 to 28 kts or so, armed with 15in and protected adeaquately but did they really needed such a ship? The opinion was that enough of these fast ships were aviable but that the old "R"´s and "QE"´s may get outdated soon against more powerful opponents like the COLORADO-class, SOUTH-DAKOTA-class or the NAGATO´s, AMAGI´s or TOSA´s. The G3 armed with 9 x 16in would have displaced 48,500ts normal and about 44,000 ts standart and would have been very fast, ca. 32kts. It´s among the most efficient ship designs with regards to the balance of speed, gunpower and protection to emerge from the drawing boards.
One of the other proposals submitted at that time, replaced the 16in/45 by 15in triples, cut down the deck armour from 8in max to 4in max and woul have been conform to the Treaty rules. It could have been accepted but the RN choosed to prefer the slower, albeit better armoured and better armed Nelson type.

But Delcyros, what you're saying does generally fall in with what I suggested - the RN opting for a slower, better protected, more heavily armed Nelson over a faster, weaker design - sacrificing a few knots for gunpower and protection. So machinery still seemed to be a limiting factor then, though maybe less so than during WW1?

Machinery certainly is a limiting factor-rightfully so for ship design. But this is true also for a general assessment, weighting machinery versus other factors.
What maybe played more a role in the decision making process was that albeit Britain pioneered the "unification type" dreadnought, which later will be called a fast battleship with types like HMS DREADNOUGHT, HMS QUEEN ELIZABETH and HMS HOOD, it didn´t pressed for the idea in 1922.
Rather differently, G and -N series proposals were seperated from each other in 1920 to 1923, indicating a distinct differentiation between the slow dreadnought on the one hand and the fast battlecruiser on the other.
It appears to be odd on the first view, when You consider how much effort Japan and Italy invested in transforming their Dreadnoughts in fast battleships through intensive and lengthy rebuildts. But then again, the RN didn´t experienced a pressing need to do so for they were well established in the battlecruiser aspect. There was nothing comparable to that in France, Italy or the USN while Japan´s KONGO´s would have been at a severe disadvantage to HOOD, RENOWN, REPULSE and TIGER.

delcyros wrote:But then again, the RN didn´t experienced a pressing need to do so for they were well established in the battlecruiser aspect. There was nothing comparable to that in France, Italy or the USN while Japan´s KONGO´s would have been at a severe disadvantage to HOOD, RENOWN, REPULSE and TIGER.

How do you mean that the Kongo would have been at a disadvantage versus the Tiger? I would think it a rather equal (and interesting) matchup. Or even all the four British ships you mention vs the four Kongos!