I built a 14 foot sup about 4 years back and in cleaning off for spring i notice there are some patches where threads are visible through the coatings of epoxy and varnish. Cannot figure how to make them go away. Theyw erent originally visible when i completed the board. I cannot imagine sanding down to wood and starting over again. TIA
Have you kept the board varnished?
Check out John C. Harris’s article in his Life of Boats blog titled What Happens When Stitch-and-glue Boats get Old?. It’s a 2-parter and you answer is in part 2. Look at the case studies for S&G Night Heron Hull #1 and the Night Heron Strip version.
The quick and dirty synopsis is that it’s either a lack of sufficient varnish that has allowed UV degradation of the top layer of epoxy or repetitive flexing causing fatigue damage to the epoxy/glass lamination.
In the first case, sanding and varnish will fix it. In the second, it’s now a permanent feature of your boat, but another layer of glass will keep it from progressing to structural damage. John gives more details.
Judging by the fact that it’s happened after 4 years and that SUPs tend not to flex that much, my vote is for option 1.
Good luck,
Laszlo