The dreaded pox- whats the worst that could happen?

[oldharry]

Evadne - was just wondering '36 year old GRP in 1989 makes her 1953 - one of the very earliest GRP boats. I owned for a while 1960 moulded boat. Clearly the builder didnt trust GRP and had built her to around 75cms thickness - everywhere! NOTHING moved at all! But she was heavy - 19ft LOA and she weighed in at nearly 2.25 tons!! She is still going strong, having just been sold again and as good as new.

But The gel coat had been removed and replaced long since. Seems to me 50s technology hadn't sussed gel coats, so perhaps your experience was normal for boats of that period? Glad to hear you managed to save her though.

 

[Lakesailor]

Old boats should be cheap. If it's got a bit of blistering afte 30 years it's not doing badly. If it's absolutely covered, move on. No amount of digging and filling is going to do any good, so don't waste your time.
If it's just a few blisters blather it in antifoul and enjoy it. When you come to sell it, you may get a bit less than you'd hoped, but if you'd allowed for that when buying that shouldn't be a problem.

Treatments are just not worth it on an old boat. You could buy another boat for the cost of having a treatment.