I patched my Cub (covered with 21st Century fabric) by cutting the area out between the ribs (I cut the hole a 1/4" smaller all the way around and the sealed the edge to the side of the rib, then cut the patch 1/2" larger than the hole leaving a 1/4" over lap, sealed the edge with sealing iron on hot and the used a covering iron to shrink the patch. The patch is visible but only when looking for it, came out much better than I thought it would.