> I have read that spruce is good 3/4"X
> 1/2", are we talking about stuff you can get at home depot here, or
> some special stock? Can you use other substances, eg. plastic, metal? How
> long?

As long as the piece of spruce you use is straight, has an even grain and no knots, you should have no problems. 1/2" x 1/2" square is good. Choose a piece that bends evenly over its entire length.

I used a $2 piece of maple molding that had about the same flex as my plywood and was fairly evenly grained, and I had no problems, the boat looks great. I built a Guillemot S&G, I lofted the offsets right onto the plywood sheets, used the molding to mark the curves, no prob.

My batten was about 10', but it would have been better if it were a few feet longer.

You can use just about anything that curves evenly over its entire length and has an edge that will guide your pencil, a sail batten would make a good one, or a strip of metal. As long as it gives you a nice even curve its a good batten.

Hope this helps,

Paul.