I am trying to work out a formula for use on sails for boats. This is a complex art and is usually done at great expense by use of a CAD package to make life simple.

What i am looking for is a little hard to explain, so i will simplify as much as possible.

2 pieces of cloth are to be joined together. They are both square pieces with the same length sides. they will be joined square end to square end.

On the lower piece of cloth, a curve is drawn. This is an arc with apex touching the centre of this top side of the cloth. This curve is cut out to give 3 square sides and one bulging side.

This curve is then laid over the top piece of unaltered cloth and stuck in such a way that the curve is attached parallel to the straight edge of the top piec of cloth.

This forces shape into the 2 pieces that are now one.

I would like to know if there is a way of working out the relationship between the flat curve and the 3D outcome.

I say this because if a curve is drawn that is 10% of the distance across that panel, in 3D it will become a much greater depth of curve (perhaps something like 30% depth of the distance between edges of the cloth.

Cheers

Chris