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On 29 Nov 2004 10:52:52 -0800, (Yanie) vaguely
proposed a theory
.......and in reply I say!:

remove ns from my header address to reply via email

Doable. Doable well, to allow sustainable use, is going to take some
thought and probably trial and error.

Apart from what has already been said:

If you are in any sort of waves at all, there can be problems. Imagine
the situation where one canoe is going up a wave and the other down.
You have a lot of twist between the hulls. This means that the
cross-beams have to be able to allow this twist, or you either start
dipping the bow / stern of one boat, or break the spars.

This would be exacerbated by using the canoes, which have a relatively
broad beam whereas cats tend to have narrow hulls, so thay do not move
as much.

Either the spars need to be able to twist, or the mountings need to be
able to allow it. The "standing" rigging of the sail can help a lot,
by providing a pyramid. The breakage problem could come if you lowered
the mast and left the boats lashed together. There are plenty of cats
out there that would not be happy in waves without their rig, although
the spars are fine with the rig. However the rig will worsen the
problem of dipping one bow. Cats usually are completely enclosed, and
can afford to have a bow go under without shipping water.

Having said that cats have their rig set well back on the boat, quite
often, and are balanced to allow for this.

I actually agree with you that a diagonal may well not be needed. But
you will need to attach those beams very firmly to both gunwhales of
each boat. Remember that all this is complexity and weight.

You will need a dagger or lee board.

On the up side, you have two boats to share the rigging. So a bit more
complexity is maybe not too bad.

Someone recently mentioned to me the idea of a long river trip, and we
were debating different types of craft that we could use. Somehow I
became hooked on the idea of joining two canoes into a catamaran, as
in the linked diagram. The spars and crossbeams would all detach when
there is no wind, and be readily assembled when the wind picks up
again. I've seen plenty of articles and posts about different rigs for
a single canoe, but none for joining two.

I'd think the benefits would include greater stability and the ability
to carry a bigger rig.

I assume someone has thought of this before, so what are the
disadvantages? Is the idea feasible?

http://www.beowolf.org.uk/misc/sailing_canoe.png