This is the first time I've had the problem. I'm reading Teredos are found in brackish water and this area would be warmer. Anyway, they have trouble getting through paint and can't get through epoxy and glass. The bottom is fir plywood-bottom paint, which they haven't gotten through, yet.

I think it is the end grain of the plywood on the scarfed patches, rubbed raw from beaching, that they love to get into. You can pull the dinghy but they can live for up to 6 weeks, closed up in the wood. Nasty little mollusks!