The gorilla five minute epoxy is what I used, and the marine fiberglass kit here’s what I plan to use. I will seek out a boat yard that does repairs on fiberglass and see what they say. Thanks for the advice.
If the separation is more than 10-25% I would likely remove the box to be able to adequately clean the surfaces. Wiping won’t remove rough “fiberglass” material in the joint or contaminates materials in the crack.
I assume the pic is from outside bottom of an experienced boat. Stuff could be/have been growing in there. If so you need mechanical cleaning.
I’d remove box and clean out the fillets on inside so I could reinstall fillets and cloth. …and have smooth adhesive surfaces.
I wish I knew more about two things. One is if epoxy will stick to the plastic (phenolic?) of the box.
The other is about differing expansion rates of the two materials.
I would try G-flex to fill the gap first. If further work needs done, fill the skeg slot with something like plumber’s putty, glass a solid piece across the area. When it is dry cut out the slot and clean it out, paint accordingly.
OK, an update. The problem is the skeg box is not straight-sided, it has a lip that fits under the fiberglass hull, about 1.5" down. From inside the kayak, you could see the hull had moved and was wider than the skeg box lip. I think they should have been flush. Got the WS G/Flex 655 for plastic. This is what I did. Your mileage might vary.
Sanded, cleaned, and applied acetone, then used popsicle sticks to separate the skeg box from the hull to see the lip. Filled the gap with epoxy, pushing it down with a popsicle stick to the skeg box lip. To make sure the epoxy was all the way down, I made sure the epoxy was oozing out of the gap between the lip and the hull from inside the kayak.
Next, I put a board inside the box and used tree wedges to push and hold the box to the hull. From inside the kayak, I wedged two pieces of wood between the curved part of the hull and the part of the hull that was wider than the skeg box lip. That pushed a little more epoxy out but now the box and the hull are flush. Hope you can make sense of the photos that illustrate the process.
Thanks for all the help. This repair wouldn’t be done right without it.
This is a controversial subject. Annapolis Canoe and Kayak recommends that no lubrication be used. They feel that dry lubes tend to wash off and wet lubes tend to attract sand and grit, in addition to the risk of petrochemicals degrading the tubing. They just recommend periodic rinsing with fresh water.
I’ve been doing this with my boat for 22 years and still have the original cables and tubing.