On Mon, 20 Aug 2007 13:20:50 -0000, "
wrote:

Why put up with a boat that has a designed-in flaw of being more
stable
upside-down than rightside-up?

That is nearly everything. All the ships and most smaller boats.
Subs are stable, but they mostly submerge and avoid the issue of wave
induced capsize.

Why do some manufacturers of cats claim unsinkability ?

Probably because they are.Many very small boats are. I have never
seen[1] an outboard boat that didn't have flotation. We had an sixteen
foot inboard that would sink like a rock if you flooded it, but that
is another story. All big ships sink easily and some big ship is
proving it, somewhere, most of the time. Cruise ship went down not too
long ago. Foam is cheap.
Subs are close to immune to wave caused flooding especially when down
deep. You can put holes in them, however.
The unsinkable stuff can pound on rocks until the foam is in tiny
pieces. Metal lasts a bit longer than wood under those conditions, not
that it matter in the least.

What is the big deal about sinking? Many subs do it every day with no
lasting ill effects.

1. Under twenty feet. I think it is legally required, actually. I dont
know about the larger, and triple 250's will push something big. The
biggest ones probably do sink. I am from Iowa, lakes only, waves under
four feet. They have a few ballasted sailboats that will sink. The
monohulls. We do have 35 MPH sailboats. Class A scows. 38 foot
unsinkable monohulls. Those guys like our 20 foot deep 5700 acre lake,
for the Nationals, because when[not if] they capsize there isn't space
for them to go all the way over. Masts are forty feet tall. Scows
sometimes go over and are righted without any flooding. Not so
uncommon for small planing type sailboats.

Casady