It sounds like there was not a good bond between paints, hence the power-washer chipping it away.
Some ablatives are not compatible with each other. Unfortunately, you'll probably want to take it down to the barrier coat, if not the gel coat or fiberglass someday. But for now just repairing the chips will do.
Shawn & the crew of S/V Windgeist
1982 Tartan 37 CB - Hull #358
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