I have a "95 Catalina 320 wing keel. After my haul-out I had noticed about five gelcoat blisters. I was aware that the boat had minimal amount of blisters when I had it surveyed. The overall hull is in good condition. The hull has a few coats of antifouling with an inter-protect below it. I have sanded a few area down to the gelcoat and as for the blisters i had sanded them down to the fiber mat. As it looks now I have areas of antifouling blue areas and bare gelcoat. Once the blister areas are repaired with epoxy I wondering if I can only repaint these areas with inter protect and then use antifouling paint or do I need to strip all the previous antifouling off. Seems like a lot of work given the year of the boat and given that the boat is now in fresh water and hauled out for six months of the year.
Hull blister repairs
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If the areas are repaired with epoxy, you don't need an additional barrier coat. You may want to slightly rough up the repair to get the bottom paint to stick. I would paint all those areas down to the mat with interlux 2000 to try and keep as much water out as possible.
How old and what type of antifoul paint do you have?
How old and what type of antifoul paint do you have?
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Sanding down to bare hull is a lot of work and I would avoid doing it, but, with several coats of bottom paint on it, it might be something to consider. Most of us on Lake O use vc17, which is extremely easy to maintain from season to season and gives you a very nice, slippery bottom.
Where on the lake are you sailing out of.
Where on the lake are you sailing out of.
Given that the boat is a '95 Catalina and looking at the build up of antifouling layers, definitely a number of coats including the original coat. On the day of the survey the hull was covered with barnacles that needed a scraper to have them removed. If in the areas that do not have any blistering I smoothen the antifouling layer, is there a barrier paint that will work on the both antifouling and epoxied areas where the blisters where repaired. Prior to my ownership the boat was located in the brackish waters off the Chesapeake therefore it had the appropriate antifouling for those waters.
Most of my sailing is in the area of Lake Ontario
Most of my sailing is in the area of Lake Ontario
When I asked where you sailed I meant a more specific location than just Lake O. I am located in the US on the south shore 18 miles west of the Niagara River.
You do not want to put barrier coat on top of existing anti fouling. Barrier should only go on a bare spot, or on top of existing barrier, but then you will need to know what the existing barrier type is - I think.
Do you know what your anti fouling is? Your barrier coat?
If I knew your precise location, perhaps I could recommend a knowledgble and free source for advice.
You do not want to put barrier coat on top of existing anti fouling. Barrier should only go on a bare spot, or on top of existing barrier, but then you will need to know what the existing barrier type is - I think.
Do you know what your anti fouling is? Your barrier coat?
If I knew your precise location, perhaps I could recommend a knowledgble and free source for advice.
Thanks, as you can see without a proper history on the hull it's hard to determine what type of barrier or fouling was applied.
The boat is presently located at the foot of Toronto near the east channel
The boat is presently located at the foot of Toronto near the east channel
There are a few different schools of thought on what to do about the blisters. Some will say haul the boat sand off everything down to and maybe including the gel coat, then let dry in a tent for 2 years.
The point is there is water getting into the hull through osmosis. If you don't mind not using your boat for a year or two, that is the best thing to do.
I think that the best thing you can do if you are going to keep it in the water and use it is to sand or chemically remove all the bottom paint. Sand the gelcoat, or whatever is under there, let it dry for a couple of weeks then barrier coat the whole thing.
This is why I think that way, though it may be wrong; if remaining moisture in the hull reacts and turn into more blisters, then you can deal with those in the years to come. Then barrier coat over those places as you repair them. Eventually there will be no more water that will react and no more blisters. The theory seems sound enough, but I don't know what the time line would be. I suppose it depends on a few different factors.
The point is there is water getting into the hull through osmosis. If you don't mind not using your boat for a year or two, that is the best thing to do.
I think that the best thing you can do if you are going to keep it in the water and use it is to sand or chemically remove all the bottom paint. Sand the gelcoat, or whatever is under there, let it dry for a couple of weeks then barrier coat the whole thing.
This is why I think that way, though it may be wrong; if remaining moisture in the hull reacts and turn into more blisters, then you can deal with those in the years to come. Then barrier coat over those places as you repair them. Eventually there will be no more water that will react and no more blisters. The theory seems sound enough, but I don't know what the time line would be. I suppose it depends on a few different factors.
Why not just do the whole enchilada
Since you seem to have concerns about multiple areas, why don't you strip the whole thing and re-do. There are chemical peelers out there that can take the old bottom paint and barrier coat down to bare gelcoat. Then you will be able to do a detailed inspection and grind out any bad spots, let them sit for a few months to dry out, fill em and apply new barrier coat and bottom paint before re-launching. Have not seen too many Catalina's do this, but it is fairly routine for some of the Hunter's (especially mid-70's to mid 80's).
Biggest part is the stripping, but if you are going to do part, then why not do it all. Better living through chemicals.
Since you seem to have concerns about multiple areas, why don't you strip the whole thing and re-do. There are chemical peelers out there that can take the old bottom paint and barrier coat down to bare gelcoat. Then you will be able to do a detailed inspection and grind out any bad spots, let them sit for a few months to dry out, fill em and apply new barrier coat and bottom paint before re-launching. Have not seen too many Catalina's do this, but it is fairly routine for some of the Hunter's (especially mid-70's to mid 80's).
Biggest part is the stripping, but if you are going to do part, then why not do it all. Better living through chemicals.
Oh yeah you live in the cold where they haul their boats for the winter. Strip it now and wait until spring launch to do any repairs or painting to give it as much time as possible to dry.
Up north here, most will not strip a bottom just to take care of a few blisters, especially if the blisters are not in the actual fiberglass laminate. Use West Epoxy on them, after you pop them and allow them to dry out. If it gets to the point where you cannot keep up with the blisters, then it is time to get more aggressive. This is what my readings and my discussions with boatyard personnel have recommended. This is also what I have seen most owners do in my 40 years in the boat yards. My '73 Irwin used to get a few each year and I handled them that way until I did for quite a few years until I did finally take off the old bottom paint and barrier coated. I certainly would sail the boat this coming season and see what the bottom looks like when you pull out in the fall.
Come over next year to Olcott YC for a visit and I will buy you a beer. Where are you slipping the boat next season?
Come over next year to Olcott YC for a visit and I will buy you a beer. Where are you slipping the boat next season?
Thanks for all the feedback. I will not strip the bottom but repair only areas needed. Given that the blisters are only on the gelcoat, I did open them and sanded them to the fiber mat. I will then follow through with the West system in the early spring.
If I'm in the area I'll take you up on the offer. In the summer I keep the boat at The Boulevard Club
If I'm in the area I'll take you up on the offer. In the summer I keep the boat at The Boulevard Club
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