I am going on memory here but if you were to dig through the ROW Mod threads you would find a lot of documentation in regard to this "flying boat" effect. Leovampire ran into this problem as he develope Living Breathing Ocean and then Reflections on the Water.
Pantherhercules was also working on this
http://www.subsim.com/radioroom/showthread.php?t=129705 his thread is now buried so I do not know the status of his work. I do not know if this will shed any light on the situation.
Hope it helps.