Have a '77 CHB in Marina in SoCal, never go out. Paint has deteriorated to poor, have been told gelcoat is very thick and not to bother re painting. Have it cleaned monthly.
If you never go out why bother with a diver??
Menzies:
Are you saying that marine growth can actually cause delamination of a FG hull? The hull shown looks like FG laminated over wood??
Would not have expected any damage other than increased build-up of marine growth.
A past dock neighbor left the bottom of his Marine Trader 44 unpainted for years. It was a real mess when it was hauled but no permanent damage when he finally decided to paint the bottom and go cruising.
Given the comments about going to the junk yard, and the give-away value of the old boat, why bother to do anything??
As Chrisjs points out that picture is a glass sheathed wood hull, and lightly sheathed at that. It is not a solid fiberglass hull. The chance that having the hull scraped by a diver frequently over many years might wear away the gel coat is just about 0%.
Honestly this is really freaking me out. I would never not bottom paint. Worth of a boat is determined by its worth to the owner. Although my boat is a 1986, the work put into her, restoring her is priceless to me. Why would I not bottom paint? I have a diver go down once a month. I just had it painted a month ago.
I would suggest the hull be spray coated with hot tar its quick and cheap to apply .I know of barges that have been treated this way and it lasts for 5 years