want to build a catamaran

[ArtM]

Originally Posted by builder bob

I wanted to make a wood boat and put a layer of glass over it. then try sewing together the wind surfing sails to make a little jib and main. I have sailed a hobie kayak with a sail and I thought it was a neat idea but it's slow and pretty boring, so no I do not want to use some kayaks.

My "Gut Feel" (not a marine engineer ) is that a very small wood-composite catamaran would have a poor bouyancy ratio.

How about a glass-over foam construction? This is how composite aircraft are built. The foam can either be left in, or scraped out to provide a hollow hull. Foam is easy to shape. Proper molding foam is different from conventional packing foam, many of which will disolve in the fiber-gel.

You could get creative, perhaps, and use things like old milk jugs, an old inflatable airmattress, etc as mold supports, or create a light-weight framework and apply fiberglass over that - I believe chickenwire is sometimes used for that purpose.

I'm about 95% certain that this will be a costly approach, though potentially rewarding to you. Complete hobie cats are widely available for < $1000, very often for $500 with heavy sun-rot.

[David_Old_Jersey]

Originally Posted by builder bob

I wanted to make a wood boat and put a layer of glass over it. then try sewing together the wind surfing sails to make a little jib and main. I have sailed a hobie kayak with a sail and I thought it was a neat idea but it's slow and pretty boring, so no I do not want to use some kayaks.

Basically it is a size thing - too small and you have a raft with sails .

How about a Kayak or a board with a kite? .

[Stumble]

The reality is that small multihulls have very, very limited load carrying capacity, which is what restricts the practical minimum size to around 12'. Below this you can certainly build them, but there is little to no advantage over a monohull, and a lot of negatives.

Generally in this size the lightest way to build is tortured ply, or stitch and glue. Glass over foam is actually lighter since it has to be thicker to achieve the same stiffness that ply can.

[builder bob]

Originally Posted by David_Old_Jersey

Basically it is a size thing - too small and you have a raft with sails .

How about a Kayak or a board with a kite? .

ya I guess I can't make a little ride able sailboat.

I've got a kayak and a kite that can pull me but it's not the same as being on a sailboat. I i'd realy like to learn to kite board though

Originally Posted by Stumble

Generally in this size the lightest way to build is tortured ply, or stitch and glue. Glass over foam is actually lighter since it has to be thicker to achieve the same stiffness that ply can.

what is tortured ply and how do you do stitch and glue?

[Cotemar]

Do a Goggle search on:stitch and glue boat building method
This is the DIY method using thin plywood and copper wire or zip ties to hold it all together until you epoxy it together. It’s a cheap way to make a boat.

http://en.wikipedia.org/wiki/Stitch_and_glue
http://www.pygmyboats.com/kit-construction-process.html
http://www.glen-l.com/methods/mthdsg01.html

[builder bob]

ok that's what I thought it was.