WesWorld

Gentlemen,

what do you know about pump capacity on WW1-era and WW2-era warships, escpecially capital ships?

I seem to remember that German ships had much higher pump capacity in WW1 than their British counterparts (as found out by the British when they had German ships at hand in Scapa). However, I have no detailed sources at hand.

And what about WW2-era design of all kind?

How to define a ships pump capacity in general?

What kind of pumps were used and could fail to what effect (i.e. power shut down, steam pipes ruptures)?

How much water enters a hull through an underwater hole that i.e. a 38cm shell leaves in a belt when penetrating? How many holes to overcome pump capacity - leaving subdivision out of the equationn?


Thanks,

HoOmAn

I have Warship 2006 and it features a very good article on pumping arrangements of battleships circa 1930s and WW2. I'll have a look tonight and see what I can dig out for you.

It is part of a series but I haven't got the other preceeding parts, only the final part.

That would be nice to have. Do you have a scanner and can you provide some scans of that article?

That was "The Underside of Warship Design" set by Steve McLaughlin. The first part covered pre-dreads and the second part covered the dreadnoughts. I haven't read it yet. My impression is that pumping is one of those things that's hard to compare from navy to navy. If there is an objective way to make a comparison, I'd like to know it. Which probably means I should read the article. Emergency power is a similar topic--very important but rarely covered.

Here is a brief summary of "The Underside of Warship Design" by Steve McLaughlin. It is a long and interesting article and as I lack a scanner I've skimmed the best bits and left out some of the older ships (Dreadnoughts) and concentrated on the pumping arrangements of some of the ships. As McLaughlin states information is very sketchy on pumping systems and many ships have no records and so he used only a few samples for which he had the best information.

HMS Hood had her system explained in great detail. On completion she had;
Boiler Rooms: 4 1000 tons/hour pumps
Boiler Room Fire and Bilge: 4x 75 tons/hour pumps
Engine Room Fire and Bilge: 6x 75 tons/hour pumps
Torpedo Rom: 1x 300 tons/hour pump
Submersible Salvage Pumps: 9 350 tons/hour pumps
Other: 4x 100 tons/hour and 10 50 tons/hour pumps
Steam Ejectors: maybe up to 900 tons/hour
Total pumping capacity was therefore 10,000 tons hour but note only 4450 tons of water per hour could be pumped out outside of the engine and boiler rooms (Baden could pump 8,100 tons in similar situations) and also note that the main circulating pumps to the bilge are not included in the total.

Postwar the ‘ring main’ was re-introduced with the ‘main suction’ system, basically a loop through the citadel with branches fore and aft to cover almost the entire ship. The loop ran just under the lower deck so it stayed drier until the sip was much nearer sinking condition than the old main drain system. Vertical suction pipes led down to the bilge.

The KGV Class showed the advances of the 1930s, she had 6 1,000 tons/hour emergency turbo-bilge pumps, 14 350 tons/hour salvage pumps and 11 50 tons/hour fire and bilge pumps for a total of 11,450 tons per hour not counting the main circulating pumps.
Vanguard showed more improvements; 8 1,000 tons/hour emergency turbo-bilge pumps, 18 350 tons/hour fire and bilge pumps, 13 50 tons/hour fire and bilge pumps and six portable 50 tons/hour pumps for a total of 15,250 tons per hour not counting the main circulating pumps. Note the use of portable pumps to get extra capacity to areas damaged outside the citadel. Portable 75 tons pumps in 1942 were allocated 12 per ship due to war experience rather than the initial 6.
British cruisers and carriers often had 300 tons/hour steam ejectors (two in each boiler room and one in each engine room).

Bismarck had 22 watertight compartments served by ten rotary salvage pumps wt a capacity of 600 tons/hour plus engine room pumps and the usual circulating pumps but there was no main drain. Some compartments were connected so other compartments could be pumped out be adjacent ones, this was based on Baden’s layout.

In Yamato each row of engine and boilers rooms (4 in all) had a main drain, each engine room had 2 500 tons/hour pumps and one for each boiler room (total of at least 17) and an unknown number of 250 tons/hour steam ejectors.

The Italian cruiser Bartolomeo Colleoni had 20 electric pumps, two 50 tons pumps in each of three boiler rooms and both turbine rooms with two more in each the torpedo warhead store and fore and aft well rooms. Midships magazine had two 60 ton pumps and one 150 tons/hour pump forward of A magazine and aft of Y magazine. Total capacity 1,220 tons per hour not counting the main circulating pumps. Italian ships did lack enough portable pumps.

The Colorado Class with TE drive had much more subdivision of spaces with four main drains linked by a cross-drain with 2 206 tons/hour motor-driven salvage pumps. This was duplicated into fore and aft engineering spaces. There was a secondary drain forward with s 170 tons/hour centrifugal pump and a smaller 57 tons/hour pump. Also fitted were 2 British-pattern 100 tons pumps and two submersible 32 tons pumps and two 115 tons/hour sanitary pumps linked to the main drain. Total capacity 10,255 tons an hour. Higher pressure boilers in later US ships reduced the main condenser circulating pumps requirements and numbers needed fell from 64,200 tons in Lexington to 4,800 tons per hour in Massachusetts. This had a knock-on effect on pumping power for drainage. Later ‘jet pumps’ replaced some of the reciprocating and centrifugal pumps and worked like steam ejectors using high-pressure water jets rather than steam to suck up bilge water using the venturi effect. Draw backs include a reliance on the fire main for water supply and the fact they needed 182 gallons of water at 100psi a minute to ‘entrain’ 151 gallons of bilge water a minute and dump it overboard. Massachusetts had five ‘jet pumps’ at 275 tons/hour, five 50 tons/hour bilge pumps, four 275 tons/hour pumps and with circulating pumps made a total of 7,525 tons and hour. Note the low capacity compared the German and British practice. The USN did use portable gasoline-powered pumps too.


Hoo, I hope this stuff helps!

That´s a lot data. Thanks for sharing it.

Does the article state what developements/experience drove the enhancement of pumping systems over time? How was battle damaged examined and used to improve survivability of ships by pumping water in (counterflooding) or out?

From memory Q = Cd * A * (deltaP/density)^0.5

So a larger hole thats lower down in the ship will let more water in.

Pressure is density * g * h so for a hole 8m down = 80,000Pa

Assume Cd = 1 and pressure inside the hull is atmospheric

Q = A * 8.94 m^3/s
Mass flow rate per hour = A * 32000 tons per hour

A 1m^3 hole seems quite large until you consider that a torpedo hit causes a big gash around 8-10m long in the hull. For a 381mm shell hit you've got around 4000tons per hour coming in through the side.

You've got to consider that its only possible to flood the compartments that are open to the sea.

Its worth noting that in the flooded condition, the hydrostatic pressure acting on the bulkheads will increase with depth as well. This was one of the major considerations in the low draughts of the large light cruisers and Hood (though Hood was redesigned, put on weight and around 8ft deeper in the water)

formula seems right

Quoted

Does the article state what developments/experience drove the enhancement of pumping systems over time?

I think its a pretty simple case that more pumping capacity is better. Even better if you don't have to rely on steam turbogenerators to supply the power so more diesel pumps started to be used. The RN got bitten a few times in WWI with the older Dreadnoughts as it was possible to flood one half of the engine room as there was a bulkhead down the middle. This gave a big list and eventual capsizing. e.g. HMS Audacious though the heavy weather didn't help there either.

I'd think pump size would be subsumed into general damage control. It clearly depends on the age of the design and the amount of combat experience a navy has. In this respect the SAE would be infront of most other navy's.

Cheers