It feels like Groundhog Day :-)

https://www.clcboats.com/forum/clcforum/thread/41420.html

should answer your questions.

Laszlo

When I was at CLC last year I thought I saw some catamaran crossbeams but I don't recall what hull they were for.

Is there something abot the hull shape of catamarans that would make this impractical?

Hugh,

   Why not build something designed to be a catamaran (or catamaranish) like the Outrigger Junior, instead of trying to invent the wheel?

The advantage of Catamarans (or Boats with outriggers or trimarans) is that the hulls can be very very slender to make up for the drag of having two hulls. Sure a kayak is slender, but not as slender as a catamaran hull can and should be.

The hulls of a Hobie 16, a very popular and fast catamaran, are way narrower than a kayak.

Check out the Outrigger Junior and maybe that is your boat.

Joel

I like the idea of having two kayaks that could be paddled by two people or could be converted into a single cat that could be sailed by two people.

I see that CLC sells a saiing trimaran conversion for their kayaks so I was hoping a similar setup could be used to make a catamaran.

It's not really a trimaran, it's outriggers. They provide stability and a place to hang a leeboard.

There's no reason that you couldn't do what you want with 2 kayaks, just don't expect a good cat as the result. It'll be a lot of fun in the right conditions, but without the performance of a true catamaran.

Have fun,

Laszlo

If you have not already, I suggest that you read blog by John (https://www.clcboats.com/life-of-boats-blog/kayak-sail-fun-evolution-of-a-kayak-sailing-rig.html).  It discusses the hull shape/speed issues others have highlighted.

Two other considerations.  First, the cat approach is much harder structurally than either the proa or tri approach.  Both (tri/proa) use existing structure (hull and deck) to support a free standing mast with very little added weight.  To make a cat, you have to create that structure between the two hulls which adds weight, windage and complexity.  The other approach is to go with a stayed rig but that creates huge compression loads, so again you are looking at a heavy strong complicated structure.

The second consideration is performance.  John points out the speed issues, but I would be even more concerned with maneuverability.  I don't know if you have ever sailed a cat, but even the good ones are hard to tack in light air.  I suspect that bolting two slower kayak hulls together would only make that worse.

I would suggest that a tandem kayak with CLC sail rig would be a better approach to what you are looking for.    

   Thanks for the link to the blog post. It seems I want a unicorn. Back to musing about what to build.