If I remember rightly the Mythbusters made the same mistake, the thing was supposed to be a solid block with a hanger dug out of it and used in the North Atlantic in water were the temp. was around 32 degree F. Not a standard boat design with thin sides and bottom in a swimming pool or ocean with 70 degree water!
lamparty
I don't think the technique was ever intended for use in small boats! Was proposed for large aircraft carriers the size of Islands and also not in southern waters in the first place!