Yngmar, thanks for the response. I wonder if epoxy would have held up had it been applied correctly too?
The critical words are "had it been applied correctly." And the answer is yes, it would have held up. The problem is that unless the contractor is pinned down with a properly worded contract specifying exactly how the keel had to be prepared, and subjected to inspection by someone who can be held responsible in the event of failure of the coating. That also needs to be combined with ensuring that the atmospheric conditions are such that condensation does not occur on the prepared but uncoated metal of the keel, and throughout the period while the paint coating is being applied. In addition the epoxy coating needs to reach a certain thickness, and lastly for the coating to be tested to ensure there are no pinholes.
I was involved in just such procedures back in the late sixties and seventies where the scantlings in ship construction were allowed to be reduced, but subject to an effective paint coating (epoxy) being applied prior to the ship being floated. These coatings were applied both on the outside of the hull, and on the inside of the cargo, ballast, fuel and water tanks, and resulted in a huge headache for shipyard staff until they got the message. After that the days of the floating rustbuckets became numbered. However, ongoing maintenance to ensure that areas of damaged paintwork was properly dealt with, also became something of a headache until such time that jolly Jack also got the message that use of a high performance paint coating also required high performance in all areas of ongoing maintenance of that coating.