You can use any sail you want on a Puddle Duck Racer. There are no restrictions as to style or size. People have sailed with sails as small as 32sqft and I think 105sqft is the largest to date.

This plan shows how you can make a 65sqft Balanced Lug sail out of a 10x12 polytarp.

For complete instructions on how to make polytarp sails - and an excellent source for polytarp sail material, check out www.polysail.com

For more information on PD Racer sails: PD Racer sail page