On Sun, 30 Dec 2007 19:29:48 GMT, "Dennis Pogson"
wrote:

maybe there IS something in this water ballasting
after all! Perhaps it stops Mari Chai 1V from taking off and becoming a
flying machine!

Water ballasting and water roll stabilization are two different
things.

Our boat is a Grand Banks 49 trawler displacing in the neighborhood of
60,000 lbs dry, 70,000 loaded. It has a substantial flybridge deck
located about 12 feet above the waterline, and about 12 feet wide.
Since we have frequently had a dozen people up there with no obvious
ill effects, I'm assuming we could also get away with several thousand
pounds of water, especially at anchor. The boat already has dynamic
roll stabilizers which are quite effective underway but are expensive
to maintain.

I'm aware of at least one other boat in this size range that is
successfully using water stabilization. They had their system
designed by a Naval Architect which is no doubt the right way to go
for guaranteed results. I was more interested in cobbling up
something cheap and dirty for some informal testing of the concept on
our boat. Key variables are tank size, tunnel size/shape, and
gallons/pounds of water.

Any suggestions for a starting point?