[PUP] Catamaran tunnel height

[Truelove39@aol.com]

Rod, webre jealous. In  our sailing around in the Windwards and Leewards, we
often see power cats (as  well as sailing cats) speeding through 8-10 foot
seas at speeds approaching  twice our 7-8 knots. Some of the power cats appear
to
have wave-piercing hulls  and are traveling at speeds approaching 20 knots,
but we have never been close  enough to be able to see the design, although we
have seen what we thought was  the same or similar at anchor. The French seem
to have to greatest numbers of  power cats, from huge, impressive ferries to
30-footers.
As much as we like  bgoing slowlyb inshore, we would be certain to enjoy
faster passages offshore,  and as we age, less roll would be welcomed,
paravanes
notwithstanding.  Unresolved, for us is the cat "lurch" in head or following
seas. We aren't sure  if we'd trade that for the pitching we experience with
either the sailboat or  the troller, which is really a cutaway full-keel
sailing
hull.
I hear you  regarding the air cushion. And yet what we have heard  from
sailing cat owners is that a boat with a greater tunnel height is  better.
Webd be
interested to hear how this is reconciled with what we perceive  is a smaller
height in order to generate the cushion you speak of.
Regards,
John
"Seahorse"
> The weather had  deteriorated even a bit more. For more than a day he was
taking white water over  his flybridge . . . but, as with most cats, he also
found that despite the  comfort afforded by the built-in stability of two,
widely-spaced hulls at lower  speeds, there was the added benefit (known to
all cat
users, whether their cats  are 10' or 70' in length), that as the water gets
rougher, adding speed  (completely unlike with a monohull), gives an
increasingly MORE comfortable ride  because -- starting at about 11 or 12
knots -- a
"cushion of air/foam" begins to  develop between the hulls.

I've experienced this running from FL. to the  Bahamas. As anyone who has run
the  Gulf Stream there knows, when the wind clocks around (about every
7-to-10 days),  and blows from the north, directly against the northward
moving
stream, the seas  build up into blocks -- not waves as we normally know them,
but
blocks  (flat-sided "hunks" of water from which boats "fall off of" for
distances of 4  to 6 feet or more). Frankly, I was plain frightened when a
skilled
cat captain  took me out in those conditions and launched us off some of the
"blocks." It  initially seemed crazy to me that he'd INCREASE the catamaran's
speed in these  flat side blocks of water. And yet, very quickly I discovered
this "built-in  cushioning effect," afforded by the tunnel -- the cat's hulls
and the bridgedeck  (horizontal platform between the two hulls) -- that
pockets
this air/foam and  creates the cushion.







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