prv
Well-Known Member
If strops could be put under the hull, wouldn't it be possible to tie these around water-filled oil drums, either side, before pumping air into the drums to expel the water? A kind of inexpensive salvage bag, but without the need for the depth bags require...?
Yesss...
Trouble is, you'd need to fill all the drums at exactly the same rate, otherwise the first one to get positively buoyant will rise first, as it rises the pressure reduces and air expands, so it rises faster, etc, and the whole thing becomes unstable and may even result in the boat slipping out of the strops. See this story: http://www.yachtmollymawk.com/2011/02/the-fall-and-rise-of-duck/ for an example of how difficult it is to get a controlled multi-bag lift even with multiple divers, clear water, and a small boat.
You'd also, I guess, need a hell of a lot of drums to lift this trawler.
Pete