For salt water:

34,500 / (64 - weight of foam per cubic foot) = cubic feet of foam
required if you want your wreck to be just neutrally buoyant. Since
that won't be much use for survival and would sink if you are carrying
even an extra wrench, you should add 10 - 20% to insure that something
remains above water to cling to and provide visibility to searchers.

After you do these calculations, you'll see why more boats don't have
foam in them.

--

Roger Long



wrote in message
nk.net...

DSK wrote (in another thread):
Actually, I think it would be a good project to add positive
flotation to any cruising boat that ventures out into big water.
Some care should be taken with the volume distribution , so that
stability is mainatained, as well as ensuring sufficient volume.
You could utilize the interior angles & odd nooks so as to not
lose too much stowage.

How do I figure out how many cubic feet of foam I need to add
to a 46' Tayana Pilot without filling it with water ?

Hull: Fiberglass
Displacement: 34,500 lbs
Ballast: 11,000 lbs

For more details see http://www.tayanayachts.com.tw/V460.htm
and http://tayana46.tripod.com

It has a watertight bulkhead in the bow and a large storeroom
(lazarette) in the stern. Do you think it would be enough to just
put the floatation blocks in these areas ?