[CCIP]

Originally Posted by AVGWarhawk

Big one right there brother. Probably the biggest issue to keep you from diving. Exhaust ports would not close also a problem. Really any port that allows air in will prevent the dive.

Exhausts too (they don't let air in, technically, but can sure let water in....). Some U-boats had serious problems with exhausts not closing properly and water constantly leaking in through them at depth.

Likewise torpedo tubes - while there's a lot of precautions to ensure that the outer and inner doors are never open at the same time, it can theoretically happen by mistake. Not sure of any precedents though.

Funny as it may sound - the toilet systems on many types of boats could pose a major potential hazard. Again, unsure of any precedents happening - but I read about a close call in "Grey Wolf, Grey Sea" where a crewman didn't operate the toilet properly and ended up loosening a valve he wasn't supposed to, opening a leak - it said that if this had happened while the boat was submerged, it would've been impossible to plug the leak.

Obviously fouled air and other problems of the sort on board would have a similar effect. Battery leaks and explosions were not unheard of, and while they wouldn't destroy a boat, they would certainly force it to surface pretty quickly (you couldn't dive on a boat with no air, or air being rapidly consumed by flame). The battery doesn't have to be destroyed for that to happen. USS Cochino, a Balao-class boat, was lost to battery explosions.

Jammed dive planes or damaged ballast tanks would also interfere with its ability to dive or, conversely, surface. If a boat cannot maintain trim, it is fatally dangerous to dive it - and a punctured trim tank or jammed/destroyed dive planes would do that.

U-boats would not be able to dive, or dive soon enough, for most of the time while loading their external torpedo reserves into the hull. I don't believe a boat was ever caught in that situation though. This would be true of most boats undergoing some sort of torpedo replenishment at sea (well, in the worst case, I guess they could drop the torpedo, close the torpedo hatch, get the crew off the deck and dive fast! - but that'd take time too). I guess crew on deck, generally speaking, would take some time to clear off. A boat would generally not dive with crew on deck, unless in complete emergency. Depending on what was going on at the time, crew could take some time to get off the deck. If the boat was involved in some kind of resupply, troop landing or surface action - this could actually take a bit of time.

Finally, any sort of electrical failure, while not terribly likely, could knock out important systems on a boat and prevent any number of them from working. On fleet boats, there was actually a lot of electronics involved in controlling the boat, so they would certainly be susceptible to that. (While not a case of "not diving" - rather a case of diving too much - the Balao-class USS Chopper is an example of what can go wrong if electrical systems fail - nice read here http://www.geocities.com/Pentagon/Qu...8/deepdive.htm)

Hope there's some thoughts for you here!