Watertight compartments

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paul.mercer
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Watertight compartments

Post by paul.mercer » Mon Nov 07, 2011 12:04 am

Gentlemen,
Not sure where this topic lies so have put it under this heading.
My question is this, how watertight is a 'watertight' compartment? At this risk of sounding morbid, if a compartment was truly watertight would men trapped in it still be alive after the ship has hit the bottom - even at a great depth like Hood, Sharnhorst or Bismarck?

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Re: Watertight compartments

Post by Byron Angel » Mon Nov 07, 2011 11:54 am

Watertight is watertight. But, in that case, crushing depth would be the governing factor - the point where the the compartment's structural strength would be overcome by external pressure.

B

delcyros
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Re: Watertight compartments

Post by delcyros » Mon Nov 07, 2011 12:06 pm

As Byron outlined. Crushing depth gouverns this problem. There is no point in making a bulkhead watertight to say, 100m depth. At that point, the ship is long since, sunk and provisions for making bulkheads, access hatches or piping that watertight would result in a weight excessive design. Correspondingly, there are margins of safety in watertightness for each bulkhead and from memory, it appeared that these margins of safety were bigger in RN designs, then they have been in HSF ship design practice.
I recall that the Goodall report of the former german battleship SMS BADEN goes into some detail int his question.

lwd
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Re: Watertight compartments

Post by lwd » Mon Nov 07, 2011 2:44 pm

I thought cables and other fixtures ran through some "water tight" compartments. Fire, shock, or twisting can also impact water tightness.

dunmunro
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Re: Watertight compartments

Post by dunmunro » Tue Nov 08, 2011 12:52 am

paul.mercer wrote:Gentlemen,
Not sure where this topic lies so have put it under this heading.
My question is this, how watertight is a 'watertight' compartment? At this risk of sounding morbid, if a compartment was truly watertight would men trapped in it still be alive after the ship has hit the bottom - even at a great depth like Hood, Sharnhorst or Bismarck?
Most WW2 subs had crush depths of 500 to 1000ft. A surface ship's compartments would fail at much shallower depths than this, say ~100ft.

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RF
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Re: Watertight compartments

Post by RF » Wed Nov 09, 2011 7:12 pm

paul.mercer wrote: .
My question is this, how watertight is a 'watertight' compartment? At this risk of sounding morbid, if a compartment was truly watertight would men trapped in it still be alive after the ship has hit the bottom - even at a great depth like Hood, Sharnhorst or Bismarck?
I recall that this issue of men trapped alive or the possibility of being trapped alive was raised a few years ago in respect of the sunken Russian submarine Kursk after its bow torpedo room detonation. It appears that even a truly watertight compartment while keeping water out has no facility against oxygen depletion or extreme cold which is understood to be the fate of those crewmen not taken out by the initial explosion.
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lwd
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Re: Watertight compartments

Post by lwd » Wed Nov 09, 2011 8:38 pm

Water tight pretty much equates to air tight. If there is no external source of oxygen it's going to be a problem for anyone in the compartment eventually.

paul.mercer
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Re: Watertight compartments

Post by paul.mercer » Wed Nov 09, 2011 10:45 pm

Byron Angel wrote:Watertight is watertight. But, in that case, crushing depth would be the governing factor - the point where the the compartment's structural strength would be overcome by external pressure.

B
Thanks for your reply, presumably the walls of a watertight compartment on a ship like Bismarck would be extremely thick and would not crush very easily therefore would remain watertight (and of course airtight) to a considerable depth?

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Re: Watertight compartments

Post by alecsandros » Thu Nov 10, 2011 9:02 am

It would be interesting to see details from the ships sunk at great depths. Bismarck, Yamato, Hood. I know there were several expeditions that found all of them.
Maybe someone with more experience about the expeditions would tell us if there were, or might be, some intact compartments left ... ?

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RF
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Re: Watertight compartments

Post by RF » Thu Nov 10, 2011 9:50 am

Checking for intact compartments presumably means going deep inside these wrecks - as external inspection would not offer conclusive evidence?
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Re: Watertight compartments

Post by Byron Angel » Thu Nov 10, 2011 12:25 pm

paul.mercer wrote:
Byron Angel wrote:Watertight is watertight. But, in that case, crushing depth would be the governing factor - the point where the the compartment's structural strength would be overcome by external pressure.

B
Thanks for your reply, presumably the walls of a watertight compartment on a ship like Bismarck would be extremely thick and would not crush very easily therefore would remain watertight (and of course airtight) to a considerable depth?

..... From the internal ship diagrams and data that I have seen, internal bulkheads of even large surface ships of the period actually appear to have been pretty thin on average - perhaps as little as 6mm/0.25in. Then there are the inevitable piercings for piping, cabling, ventilation ducts, etc. My guess is that, while they were technically "watertight" at sea level or thereabouts, they were not designed to remain so at the significant water pressures imposed by any really great depth. The overall watertight efficiency of such construction is perhaps best evidenced by the frequent need for torpedoed ships to shore up internal boundary bulkheads which were resisting flooding in adjacent compartments.

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Jack B.
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Re: Watertight compartments

Post by Jack B. » Thu Nov 10, 2011 5:41 pm

One of the water tight bulkheads on the Titanic gave way while she was sinking, due to the water pressure on the other side. I believe experts claim the mass destruction of the stern was due to implosion of air trapped spaces.

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RF
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Re: Watertight compartments

Post by RF » Thu Nov 10, 2011 7:18 pm

I think the point you are thinking off when you say the compartment bulkhead gave way was when the ship split in two on its final dive, the point that the third funnel toppled over. The eyewitnesses did not see the actual split, this was discovered by Cameron.
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Re: Watertight compartments

Post by Jack B. » Thu Nov 10, 2011 9:17 pm

Leading Stoker Fred Barrett was on duty at the time of the collision in boiler-room #6. He managed to get into boiler-room #5 and was working the pumps when the bulkhead between 6 and 5 gave way and rapidly flooded boiler-room 5. Barrett was lucky to survive the sinking of Titanic and got off the ship in life boat #13

Source
Riddle of the Titanic by Robin Gardiner & Dan Van der Vat
A Night to Remember by Walter Lord

I also remember reading the same thing in a book that was dedicated to the British and American enquiry into the accident.

I just finished a book on the sinking of the Oklahoma, and in it, it described water tight compartments flooding for one reason or another. Some were because of pipes, while others were from air ducts.

I guess the point is that internal compartments are lightly built with some having pipes and electrical wires running through them. It would not take much pressure at all for them to flood completely. Submarine compartments are designed to withstand more pressure.

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Re: Watertight compartments

Post by Pandora » Thu Nov 10, 2011 9:24 pm

I think the only compartment that could stand water pressure in deep water would be armored conning towers with thick walls.

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