Ralph Knowles wrote:This is a salutary tale about using the wrong material for deck patches.
I took a deep interest in this subject when I only just managed to recover my boat after one of my patches split. There are a couple more factors to think about.
One is the "tackiness" of the patch material. Some great-looking material is "low tack", intended that it can be re-positioned without too much trouble. For example, I have some transparent book-spine covering material that says (in the packaging small print) "Low tack"...
Another is the effect of exposure, specifically, ultra-violet sunshine, which usually causes plastics to discolour and, more significantly, become brittle and stiff. That was what had happened to my (non-Dacron) patch -- it was a patch that I hardly ever needed to pull off, so it just stayed there getting older and stiffer, until the time a little bump with another object (did I mention this might have been a boat on starboard?) split it end to end.
Final issue is one of temperature and humidity. The lower the temperature, the less sticky the material is, and the more likely there is some microscopic condensation on the deck. I've learned never to rely on a patch put on when temperatures are below about 8 C -- I saw mine just peel itself off while I was jousting at the start line one time, and again just made it back to shore.