Ragbird.

It's taken a few trips to the pond to get my correx built creation "Ragbird" (named after my favorite band)  sailing well, the sail came from my Paddle Duck footy which sailed very well but the mast position was copied from a full sized plan which took all the guess work out of finding it's position. Even set this far forward it still sailed violently into the wind so i added a jib which is good for easy trim adjustment. Note that the main sail doesn't have a conventional boom but a loop of piano wire in the style of a sail board which saves weight.