Uber surveyor Dennis Smith got to run survey on a couple of 25 year old KHSD CM multihulls. Both had minor rot places. Both spots were inside the hulls at remote locations where epoxy was skimped. The trouble is inside, not the outside. The take-away lesson is coat inside thoughly and make sure any damage is repaired.  Cove all the joints.  Epoxy hulls still need to be ventilated.  Note they were both the $6 door skins and not the 6566 that we use now.  But coat it good inside!