i had this issue and after the 2nd boat i spent 2 hours digging a trench in my boat basin in the sea making sure there was no flooring when i docked my boat to the point where i floated in an area and waited for the tide to lower just to pickaxe one time and then doing it when the sea lowered me enough to swing my axe once and my boats are fine now, havent lost one since, knock on wood*