Sail-powered SWATH catamaran
 

Several navies have introduced SWATH catamarans and found benefits like
high speed, stability, and fuel efficiency. Worthwhile advantages, yet
no sailing versions of the SWATH concept seem to have emerged. Anyone
know of any examples sailing anywhere?
Reducing the scale of these military vessels down to regular sailboat
sizes would create a very tender boat since each hull would be only 50%
buoyant. So beefing up to perhaps 100% in each hull would be a first
design step. Apart from this pre-requisite, I see no serious drawbacks
to creating a superior performance and wave-piercing catamaran.
Anyone care to differ, ... or offer further design refinements that
might help make this the catamaran of the future ?

SailNut.

Sail-powered SWATH catamaran
 

I see no serious drawbacks
to creating a superior performance and wave-piercing catamaran.

Somehow wave piercing and sails aloft seems pretty unlikely combination.

Sail-powered SWATH catamaran
 

wrote

I see no serious drawbacks

That's why you have no business taking such an idea beyond idle
chatter and daydreaming. Seeing the drawbacks and figuring out how to
work around them is the essence of developing new technologies.

--

Roger Long

Sail-powered SWATH catamaran
 

wrote:
Several navies have introduced SWATH catamarans and found benefits like
high speed, stability, and fuel efficiency. Worthwhile advantages, yet
no sailing versions of the SWATH concept seem to have emerged. Anyone
know of any examples sailing anywhere?
Reducing the scale of these military vessels down to regular sailboat
sizes would create a very tender boat since each hull would be only 50%
buoyant. So beefing up to perhaps 100% in each hull would be a first
design step. Apart from this pre-requisite, I see no serious drawbacks
to creating a superior performance and wave-piercing catamaran.
Anyone care to differ, ... or offer further design refinements that
might help make this the catamaran of the future ?

SailNut.

The Swath design doesn't look like a good match to sailboats. Wave
piercing has been used, though the most famous case was not a great
success:
http://www.solarnavigator.net/team_phillips.htm

Sail-powered SWATH catamaran
 

wrote in message
ups.com...
Several navies have introduced SWATH catamarans and found benefits like
high speed, stability, and fuel efficiency. Worthwhile advantages, yet
no sailing versions of the SWATH concept seem to have emerged. Anyone
know of any examples sailing anywhere?
Reducing the scale of these military vessels down to regular sailboat
sizes would create a very tender boat since each hull would be only 50%
buoyant. So beefing up to perhaps 100% in each hull would be a first
design step. Apart from this pre-requisite, I see no serious drawbacks
to creating a superior performance and wave-piercing catamaran.
Anyone care to differ, ... or offer further design refinements that
might help make this the catamaran of the future ?

SailNut.


I suspect that the required size and strength of the rigging would prohibit
the success of a SWATH cat. Fully submerged hulls would have serious mass,
requiring a LOT of force to move. Further, the vessel remaining more or less
stationary relative to pitch and roll would mean that wind forces could not
be spilled by heeling -- not even to the (relatively) limited extent of
regular catamarans. So I envision ever-increasing sailplans requiring
ever-more-massive rigs to control them spiraling ever-outwards until the
physical structure of the vessel itself is incapable of containing them, all
just to travel slower than a rowboat.

Sail-powered SWATH catamaran
 

...So I envision ever-increasing sailplans requiring
ever-more-massive rigs to control them spiraling ever-outwards until the
physical structure of the vessel itself is incapable of containing them, all
just to travel slower than a rowboat.

I think you're right. I made some napkin calculations (and did a
little mitchlet modeling) on this idea seven years ago and came pretty
much to the conclusion that you'd need to do something pretty radical
to make a true swath cat move in light air. The wetted surface is what
really does one in. A friend of mine did a compromise design with very
long bulbs down in New Zealand and he was happy with her, but she was
always a motor sailer and is being refit to be a mostly motor whale
watching platform. The real advantage of swath is that it makes sea
kind boats. At some speeds they may also be efficient but only where
wave drag dominates and only if you can get the displacement far from
the surface. I've noticed with the local swath boat (Navtec) that they
create a pretty energetic wave train, but she's a comfy boat in most
weather. As others have noted you'll also need to think a bit about
stability if using sail plans that have a heeling moment (really big
kites might work). Foils plus some kind of reserve bouncy (ie. hulls
near the surface) seemed likely candidates to me but both add drag.
There were lots of other issues with making the thing work and making
it maintainable (eg. access to the hulls, control surface linkages
&c.). And it would be a bugger to build and expensive... Seems like
the kind of boat project that keeps folks from getting out and
cruising...

-- Tom.

Sail-powered SWATH catamaran
 

Sail-powered SWATH catamaran
 

Sail-powered SWATH catamaran
 

As far as CRUISING goes, who cares.

Why not try the site: rec.boats.misc.not.relevant.cruising

or

rec.boats.starshipenterprise.vulcan.cruising

Cap'n Ric
S/V Sezaneh

Sail-powered SWATH catamaran