I have spent a few days reading everything I can find on this subject in TF and also on the internet. The amount of information and conflicting opinions out there is a bit overwhelming. There are some really good TF threads, but some are a bit old and products and solution strategies may have changed(?)…so I’m sorry, I feel compelled to start another thread on this.
My 33’ boat is 10 years old and for the last three winters I’ve had to deal with (an ever-increasing number of) small blisters below the waterline. It used to be 25-50 blisters. As of the most recent haul-out, however, I think there may be a couple hundred or more. These blisters are, indeed, in the gel coat, not the paint. When popped, the fluid that comes out is clear, thin and watery. Not dark. The strategy my yard has used so far has been to grind each blister, fill and paint. The situation shows no signs of slowing. I am getting tired of this and am also concerned about the long-run implications of not fully addressing the problem, as I intend to keep this boat for quite some time.
A few weeks ago, I asked the manufacturer of my boat if they had any experience with this and if they could provide any recommendations. To my surprise, they responded rather quickly with a recommendation and, upon my asking, offered that I could purchase the work through them, even though the actual work would be done by a sub-contractor. There are aspects of this arrangement I find appealing. They would offer a two year warranty (but I have no specifics yet).
The manufacturer is proposing:
- Anti-fouling removal
- Complete gelcoat peel (entire bottom, even though blisters are currently only aft of midship.)
- Vinylester putty
- Spray on new gelcoat
- Anti-fouling primer (epoxy barrier coat)
- Anti-fouling paint
The manufacturer has expressed flexibility in letting me specify products for the “finish” work. This is both good and bad. While I think I may have some preferences, this is an area I know precious little about and find very confusing. I don’t want to specify something that might be, in the long run, a poor solution. As such, I’m grateful to have access to the thousands of years of cumulative knowledge and experience of Trawler Forum members ;-)
While I will be grateful to have any and all TF input on this, I will start with four specific questions:
1) My hull is polyester resin, as it’s one of their early models. Newer models use vinylester resin. From the research I’ve done, it seems that Vinylester putty should, indeed, be compatible with polyester resin. Does anyone disagree with this?
2) After removing the gelcoat, should I consider not replacing it and using some epoxy system instead? For example Interlux Interprotect 2000, International Gel-shield Plus, Jotun Osmoshell? Probably not WEST system, based on what I’ve read. BUT – can any type of epoxy coatings be used on polyester/vinylester ?? I have read about different flexibility characteristics of these two materials…that could lead to problems.
3) The boat has now been out of the water and inside a building for a year now (due to Corona). So, in one sense, it’s quite dry, but as I understand from reading a lot of drying (and possibly rinsing) has to occur after the gelcoat has been peeled. As such, I’m wondering if I should break the project up into a gelcoat peel in November and wait until March for the rest of the work. Would this be long enough for “natural” dry-out? Or, should I still be asking about HotVac or some other drying accelerator. Perhaps this question cannot be accurately answered until the gelcoat comes off??
4) Should through-hulls be removed for such a project? (My guess is that the answer to this will be “ideally, yes”)
Thanking you in advance,
ScottC
