crush depths

[Fishmachine]

Originally Posted by Tobus

Wow, than the Germans really knew how to build u-boots with their 150m testdepth! Only Balao even comes close, and that was a late-war boat!

Remembering the Sh3 techniques, I crash dived my Gar to 100m after succesful salvo at a convoy on my first patrol and before I noticed, I got tons of "hull damaged" reports and never managed to surface. I guess I have to be much more careful with the american batthubs than with the german ones!

[mookiemookie]

Dad recently told me that when he was in the Navy back in the 60's he worked with an old engineman who was on the Trigger in WW2 and said that they took her down to 700 feet once. Take the story for what it's worth.

[seafarer]

Crush depth is just theoretical, calculated mathematically. It is not empirically determined for any sub class, and I'd imagine it would vary a fair bit (boats in a given class being made in different yards, by different people, using steel from different batches and different foundries, and so forth).

I know when they made the first DSV Alvin series submersible hulls of HY-100 steel, they tried to empirically determine crush depth by sacrificially testing one sphere, but the lid on the oil-filled chamber failed near 9700ft equivalent depth in 1964, with the hull sphere intact (it later became the hull for either DSV Sea Cliff or DSV Turtle, I can't remember which). When they calculate crush depth, and then set test depth, the USN Bureau of Ships includes a fairly generous safety factor.

The DSV Trieste's second sphere, of Krupp steel (~5 inches think) had no formal crush depth rating. We know it went safely to very near 36,000ft (near 11,000 metres, we had Lt. Don Walsh and Jacques Piccard as living proof of it) but nobody really knows what its crush depth is.

Of course, those are spherical hulls, not tubular, and with far fewer hull penetrations then a submarine. But it does make the point that the math used to determine crush depth is pretty conservative (for good reason, of course).

[M. Sarsfield]

The Trigger Maru mod let's you dive below test depth and also crash dive to test depth. I haven't used either function, yet, but it will come in handy.

[ReallyDedPoet]

Originally Posted by M. Sarsfield

The Trigger Maru mod let's you dive below test depth and also crash dive to test depth. I haven't used either function, yet, but it will come in handy.

Looking forward to using one as well


RDP

[Ducimus]

Originally Posted by CCIP

Actually all german boats had a 100m test depth :hmm:

Balaos later proved to be no weaker than German boats (as some extreme dives confirmed), except of course the VIIC/42.

Ahh, but the 7c/42 never existed except on paper! It's the boat that never was! I admit, i was fixated on that boat in my Sh3 days. I so wish it existed. It was arguably my 'dream uboat'. lol.



At any rate, US subs could go deeper then their rated test depth, but sub captains were strongly admonished when they did. I think the US Navy had a really strict regulation on deep dives for some reason. If one digs, around, you can find various accounts of deep dives. I think part of the reason was hull fatigue. Deep dives put a serious strain on the hull, which shortens the lifespan of the submarine.

[Ula Jolly]

Originally Posted by Ducimus

At any rate, US subs could go deeper then their rated test depth, but sub captains were strongly admonished when they did. I think the US Navy had a really strict regulation on deep dives for some reason. If one digs, around, you can find various accounts of deep dives. I think part of the reason was hull fatigue. Deep dives put a serious strain on the hull, which shortens the lifespan of the submarine.

I wonder if the American submarine branch can stem from the German in this. Germany saw a lot of submarine use during the first world war, and maintained their expertise until the rise of Nazi Germany. America, on the other hand, none or little. Am I correct in assuming that there was very little expertise on the American continent when it came to these things?
The German submarines also saw the need for depth against British forces that grew to a stronger force, forcing budgets to increase and in general put a strain on the industry. The Japanese didn't seem very potent at all in conducting ASW. Combined with the fact that a lot of the action that took place was near Japanese shores - therefore not calling for extreme depths - and that the Allies were the stronger ones in terms of radar, the American boats look to be products of an entirely different world than the German ones, therefore to a large degree making crush depth value comparisons rather unnecessary.
Still, if I am wrong, I'd like that to be pointed out. If some boats have been taken to extremes, that seems to conflict with my rather simplified take on the philosophies of the constructors/commissioners of both submarine navies.

[Ducimus]

Well, 3 items of interest:

1.) Allies were generally convinced that ASDIC nullified the submarine threat, a prewar mentality.

2.) US submarines were originally meant to act as scouts, or picket boats for the main fleet. (hence the term, "fleet boat") Its this prewar doctrine that made up their design.

3.)Germans were, up until pearl harbor, the only ones who had any experience in unrestricted submarine warfare. After pearl harbor, the entire mission of the submarine was scraped, and had to be rewritten on the fly.