This reinforced X-ply monofilm (a clear polyester film with a black thread running through it) is another choice for windows in sails. (It can be used for windsurfer sails.) It is very light in weight, yet quite stable and durable.
Installation is made easier if Seamstick (double-sided tape) is used to adhere the window material to the fabric before sewing and cutting. After the material is sewn in place, use scissors to trim away the fabric and expose the window.
X-Ply Reinforced Monofilm Features:
Sold per yard
54" width
4 mil
4.2oz per sailmaker's yard (28.5" x 36")
100% polyester