just wondering if anyone has had any experience trying to repair cracks along the seams of these boards. I seem to remeber something about it being hard to establish a bond with the polyethylene and was wondering whether epoxy or polyester would have a beter chance of success. The crack is about 1 inch in length and very thin.
while I have never tried to fix a bic… back when I carried windsurfer brand sailboards they sold ( and I used ) a hot glue repair method, standard hot glue gun and some glue sticks from windsurfer inc. which I’d assume were the same polyethylene material as the hull skin. Now, those are long gone, but something is available that’s even better: http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=41592 which will actually weld the stuff together.
Beware, though, of melting through the thinner areas of skin material, which are also where ya find most cracks. Back then, I also found that a soldering iron or hot knife would melt the cracks together again, but it was kinda tricky to do without burning through the stuff while still melting enough of the plastic to really do anything useful.
Oh, and those actually are not seams on a roto-molded board - those are parting lines where the two halves of the mold come together. If the mold is a little out of alignment, then they probably smooth it all off at the factory which makes the material thinner right there and prone to cracking. We used to get factory second windsurfer hulls like that - molds outta whack by up to 1/4", hit 'em with a block plane and sell them as paddleboards for lifeguards which worked out rather well.