I wanna rest my boat on the bottom...

[Nisgeis]

Originally Posted by jmr

In the book Iron Wolves, the author mentions one instance where he and the crew thought they were doomed because they couldn't get their bottomed out boat out of the mud. I forgot how long it took but it basically involved the crew running fore and aft to rock themselves free.

Yeah, the mud creates a seal around the hull and trying to move it out creates a suction effect. If you watch any wreck detectives / sea hunters type programs, they sometimes have problems with cables snapping due to the massive increase of weight the suction creates. It also happened in Loch Ness, where the raised the Wellington bomber. They'd calculated the weight of the bomber, (in the air - it weighs less in the water) built a frame to withstand twice that weight as a margin of error and first time they tried to lift, the frame was destroyed due to the suction of the mud.

As far as keels not being able to withstand the weight, I believe the keel carries more weight on the surface than submerged due to the near buoyancy of the sumberged sub. Several WW2 subs are displayed 'mounted' on sand and the subs I have seen in dry dock have all been supported on a very narrow strip of the keel on railway sleepers.

Of course accidental grounding would cause problems, if things like the supersonic emitters weren't secured by being withdrawn through the hull.