There are two major complication to repair.
First, carbon fiber items are made in a mold. Repair doesn't have access to that mold, so you've got to build your own. You can get a good approximation from casting an adjacent part, or the opposite side - otherwise you have to improvise and sand it to match. Catastrophic failure, like when the bow is broken more than a few degrees, requires an alignment jig to keep the boat straight.
Second, carbon fiber works best when it's a laminate - e.g. a carbon/foam/carbon sandwich. So most designs are tubular or involve a stackup. This is tricky if the inside layer isn't accessible. Or a high-performance inner layer is used, like delicate honeycomb aluminum. Rebuilding something that was custom-made to tight tolerances is difficult.
I'd think that a degradable epoxy would be best for recycling applications; repair has a lot of other challenges.