rhys wrote:
....

Buddy of mine in a Wallstrom-designed ketch checked with Wallstrom
himself who said it should displace 24,000 lbs. About 30% of that is
in the cutaway forefoot full keel.

Well, in the slings it weighs 36,000 lbs., which should create a new
category of "liveaboard displacement".

Still sails properly and is only a couple of inches south of its
waterline, however.


Its easy to do a little "napkin math" to figure the immersion factor.
Assume a 40 foot LWL, a 12 foot Beam at the WL, multiply and take 70%
(the pointy ends factor) gives about 350 square feet. Divide by 12 and
its 30 cubic feet of water displaced per inch of immersion. At 64
pounds per cubic foot, and we're at a little under 2000 pounds per inch.

Many 48 footers are at this figure, a Westsail 42 is about 1500 pounds
per inch. My lightweight catamaran has the volume of these boats, but
the immersion number is 700 pounds per inch, and three inches down would
seriously affect performance. No wonder I favor lightweight ground
tackle, etc.