My favorite board is heading slowly into the Twilight Zone. I’ve never seen anything like it and wondered if anyone has some insight into the problem.
The board is Clark foam, RR epoxy, 9’-10" swallowtail. 3 1/4" thick.
The Problem is that sections of it are sort of “sucking in” or collapsing. It started at the nose, on the bottom. It looks like a wavey depression on either side of the stringer, from the nose and about 8" back. Then yesterday I noticed an area in the middle of the board on the bottom with some wavey bumps. And it was worse when I came in from an hour in the water! My first impression was that the board may have gotten hot, then shrunk when it hit the water. But I’ve put hot boards in the water before without this happening.
If anybody knows whats going on, I would really appreciate some help. I don’t know if it’s even fixable since the foam is compressing. Thanks for any insight. Doug
Doug: I had a similar experience with RR on Clark foam about three years ago. My first experiment with RR and I didn’t want to use EPS. I built two boards and one wound-up with collapsed foam along the stringer on the deck from tip to tail. It definately was not over-shaped and it’s not heel dents. The last thing I do in shaping is take a superfine shaving down the stringer, so the stringer wasn’t proud when it was glassed. I noticed the shrinkage probably about 6 months later. The good news it it hasn’t gotten any worse in over two years. The other board never had a problem (glassed at same time). Both boards are stored in a metal barn in Florida heat so they probably get up to 110 degrees or so. Pu/pe boards stored the same have had no problem.
I remember reading about a similar experience by R. Harbour on their website regarding an epoxy on Clark about 1-2 years ago. You can maybe do a search there.
Don’t know if this helps, but at least you’re not the only one.
Rich harbour had stated he had ran into the same issue. I asked him about this at Cerritos. For some reason Clark foam and RR epoxy doesn’t like each other and Rich told me it made the Clark foam really weak. It would dimple really easily and it was ding resistant, and wouldn’t crack as easily and pe resin, but it would dent much more easily, and pretty badly.
The effects were immedate though. Rich had mentioned for some reason the two didn’t mix and it wasn’t worth it for him to deliver a product that dents easily.
Howzit Doug, Had the same thing happen with a Clark blank even before I started glassing it, but it was the rails that were collapsing. Had to add a lot of extra glass in the bad areas to get them right.Aloha,Koka
Thanks for your replies. I’ve been wracking my brain trying to figure out what went wrong, but it sounds like it’s a simple case of incompatability between foam and resin. That points me in a positive direction: EPS for epoxy, and Polyester for my remaining Clark blanks.