I was in contact with Nat, at: www.GannonAndBenjami.com
where he said I should stay with a Marconi sail for the Gypsy sailboat.
I must make a small Jib and Main sail. I bought some polyester material that is water resistant at a local fabric store. Not much required, but I know that one can not just cut from a 2D plan the cloth and attach it to the mast and boom.
I have been studying how to make a Dacron sail.
https://www.instructables.com/id/Make-a-Dacron-Sail/