OK here ian interesting question.
If I were to make a minor repair to cracked gel coat and the damaged fiber glass on a production kayak using epoxy with silica and some white dye would it last??
I have done this to get someone back on the water within a day and while I told them to bring the boat back for proper sanding and gel coat later I wonder what would happen should they never return. The damage was a worn spot caused by dragging the fiberglass boat up a concrete ramp. OUCH!! The epoxy was West Systems GFlex.

Thanks,
John VB