The old freshwater VC17 needs to be replaced with saltwater bottom paint. I've had a diver keeping her clean in saltwater so far. Interlux demands that it be fully removed to replace with any of their products. Pettit says it can be "heavy sanded" then covered. That's very attractive, as full stripping estimates are between $5k and $10 alone and seem fairly damaging to the hull.
Does anyone have familiarity with what they mean by "heavy sanding". As you can see from their chart below, it differes from "removal".