Hull difference....german, american

[Dantenoc]

Originally Posted by Penelope_Grey

Simplyfying it is what I was trying to do, in simplistic terms the bigger an object is the more area there is for the pressure to exert therefore the overall sum of the pressure is higher than on a smaller object generally, this assumes that the structures/materials of said object are similar or identical.

No, that doesn't matter... if you want to think about it in those kind of terms (it may seem intuitive to you) counter it with this: true, the bigger boat has more weight to deal with (same pressure but bigger area), but it all evens out because it is "more boat" to begin with.




A story book way of looking at it:

Imagine you and I are sections of pressure hull destined to be installed on two different but identical small subs. We are both rated to withstand a pressure equivalent to 1 unit (whatever). You get installed in your sub, I get installed in mine. Both our subs dive side by side until we both receive 1 unit in pressure. You do your thing on your sub, I do mine in my sub. Do you hold? of course you do, you were rated for 1 unit of pressure. Do I hold? yes, of course, I too was rated for 1 unit of pressure. Here is the important question: did the fact that I held, helped or hindered you in holding? No, of course not; you don't care about me, and I don't care about you. As pressure plates all we care about is doing our job of resisting pressure and will do it based on our own merits.

Now for a twist on the story: There's a screw up on the sub plant, and instead of being installed on two separate small subs, we both get installed into the same big sub. We are now being used in a different way that was originally intended, but what the heck? You're still you and I'm still me, right? so we cope as best we can. The big day comes and the sub finally goes out to sea. The big sub then dives and we reach the exact same depth as the two previous small subs... Ok, pressure plates, time to work: that's you and me! it's up to us, in a team effort, to defend the integrity of this sub! . But whait..... you start to get nervous about it... what's the pressure down here? I know it's supposed to be only 1 unit because it's the same depth as before, but this sub is twice as big as the other small ones... whait, does that mean that the whole sub is receiveng 2 units of weight now?!?! oh my God, I'm only rated to withstand 1 unit of pressure !!! I don't think I can hold, the big sub is doomed !!!

But.... Time goes by and to your surprise you do hold !!!!! what happened :hmm: ? Well, true the bigger the area the bigger the weight, but the sea isn't evil and "decided" not to put the whole weight of the sea just on your section. The sea is good so pressure is allways evenly distributed. So out of the 2 units of weight crushing down on the whole sub you got 1 on your section and I got 1 on my section (for a total of 2 units). Can you manage your 1 unit? yes, you where rated for 1 unit. Can I manage my 1 unit? yes, I too was rated to withstand 1 unit. My working over here did not make your job of withstanding your 1 unit of pressure any easier or any harder. You worked out your share of the pressure based on your own merit. Viceversa, I didn't care what you or any other part of the ship was doing, I just did my thing.

So, the moral of the story is, as long as there's no "weak links" in the work force, and as long as everybody does his part, size of the boat does not matter, and all hull plate sections lived happilly ever after.

The end

P.S.: and yes, Jazman makes a fine point. It's not just about strength of the materials, but the structures that they make with them and how they're held into place.

[Palidian]

There is the issue that the command tower is not in the pressure hull, and it will collapse first.

[Sailor Steve]

No, it won't. The conning tower is it's own pressure hull.

The pressure hull, designed to withstand the sea pressure, houses most of the ship's machinery and provides the living quarters for the officers and the crew. It is divided into eight watertight compartments, separated by pressure bulkheads provided with watertight pressure resistant doors. The ninth compartment, the conning tower, in the shape of a cylinder placed on its side, is located above the control room and connects with the control room through the access hatch.

http://www.maritime.org/fleetsub/chap3.htm#3A
http://www.maritime.org/fleetsub/app...es/figa-01.htm

[scrag]

One point still not elaborated on is hull fittings and Valves.
The size of the hull is partically a mute point. The single largest contributing factor to keeping water out of the people tank is the number of "openings" it has that are controled by either valves or have something stuffed through them (i.e. the shafts).