New barrier coat?

[jssailem]

Yes @Sanfelice. Dave has some down to earth information about boats.

 

[kampuniform]

If you have an existing barrier coat and it is deteriorating, I could see the need to replace it or at least spot treat.
If there is evidence of osmosis / blistering, I could see the need for removing blisters, drying, and barrier coating.
If the only problem is flaking antifouling paint, sand it back to the gelcoat without removing gelcoat and recoat with new antifouling paint. Beneteau uses vinyl ester resin beneath the gelcoat to inhibit water intrusion and blister formation. You do not need a barrier coat because of the vinyl ester resin. Would a barrier coat be nice to have...sure, but at what cost? You definitely need to ensure that the yard personnel know what they are doing, because they can do more harm than good by removing too much gelcoat.

With regards to the keel.. You need to check the composition of the keel. Some 331's of your vintage had lead keels and some had cast iron for sure. I believe the shoal keels were lead and the deep keels were cast. If it is a lead keel, clean it up and recoat with antifouling paint; if it is cast iron, follow Gunni's advice to blast and epoxy coat prior to applying antifouling paint.

Note that barrier coating is another service / money maker for boat yards. The previous owner of my boat had the boat in Chicago for 5 years, meaning that it was on the hard for at least 6 months every year. When he moved the boat to Charleston, the yard had him do a barrier coat. I am happy that he had it barrier coated; however, I think that it was overkill. The boat had no blisters and with it being on the hard for half of each year, there was minimal moisture content in the hull. I really believe that the yard charged him a considerable amount for a service that was unnecessary. Most manufacturers that incorporate vinyl ester into their lay ups do not advise a barrier coat and doing so may void the warranty on a new boat.

Excellent.

If your make/model of boat has a history of blistering, then slather on some barrier.

Recommendations from boatyards and paint manufacturers (5 coats!) are for numpties who are easily parted with their cash.

If they could get away with it, these rapacious chancers would recommend 100 coats of every mystery mix on the market, and would only stop recommendeding products once you’re broke.

 

[DougM]

My 2004 Beneteau had some minor keel blistering that apparently was the result of faulty prep work by the keel manufacturer. Because it is an iron keel, it began show some signs if corrosion beneath the blisters when they were opened up. None of the blisters at the time were larger than dime or quarter size.
I took the keel down to bare metal, not the easiest job I have ever done, and recoated it with 3 coats of 2000e, each coat applied while the undercoat was tacky. Then finished with VC17 which is an annual ritual anyway. Its been at least six years since I did it and there have been no signs of any keel blistering.

 

[Crazy Dave Condon]

I have said the best advice on paints is to see what works best locally and for coastal North Carolina where I was a dealer, Trinidad was the best to use while others do elsewhere. I did suggest to inspect the barrier coats and also advised of two other excellent yards.

 

[71Irwin32]

After all the prep work involved, there's not much difference between 3 and 5 coats. 2000e is an excellent product and after all the investment....I'd say 5 coats. Just make sure ALL the prep is well done, including drying out any and fixing blisters, or other issues.

 

[Gunni]

If you feel the need to go slack on barrier coats, Pettit sells slacker barrier coat - High Build barrier coat. 3 coats will get you to the 10mil thickness you need.

 

[njlarry]

My vote would be 2 to three max barrier coats over previous barrier. There is much more time involved with two extra coats. Here's my thinking. The barrier coats need overnight to dry before the next coat. Each coat needs dry weather that is not too hot not too cold not too wet not too dry not too sunny not too windy etc. The odds of six days in a row like that in the northeast are nil. That means all the work of sanding the entire hull after every break. Two barrier coats and the first bottom coat could be reasonably done in three days or a long weekend. Waiting for the right conditions for seven coats could take three to four weeks vs three days plus the additional labor of sanding the entire bottom.
Your boat your choice.

 

[Davidasailor26]

That means all the work of sanding the entire hull after every break.

Not with Interlux. You can go several months between coats of Interprotect without sanding. (See its product guide.) The only time sensitive coat is applying the bottom paint after the last coat of barrier, which should be done while the surface is still slightly tacky.

 

[walnetto]

How much 2000E would cover a 29' Watkins? I am going to have a painting company blast my boat. They did it two times before, for the previous owner, but also painted it. The last two times they painted with Interlux Trilux 33. I want to go to VC17m. Do you think they will take off the barrier coat when blasting, or could they hold off?

 

[Gunni]

They should use nut shells or similar and be able to control the blast cut, leaving good barrier intact. Interlux can help you figure coverage. <2 gals / coat.

 

[dlochner]

How much 2000E would cover a 29' Watkins? I am going to have a painting company blast my boat. They did it two times before, for the previous owner, but also painted it. The last two times they painted with Interlux Trilux 33. I want to go to VC17m. Do you think they will take off the barrier coat when blasting, or could they hold off?

Don't pay them to apply the VC 17, it is very easy to apply. You'll need 2 cans for the first year and only 1 can after that.