Hauling the boat next month to redo the bottom and a few other things. We will be taking it down to the gelcoat. What does a barrier coat do? Do we need it in addition to bottom paint?
Thanks.
Thanks.
Do I need a barrier coat?
- Thread starter McZube
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Unless your boat has been in the water for a very short time or you have plenty of time to let the hull dry out - Just leave it as is. And dry doesn't mean dry to the touch - It means the moisture meter says its dry. If you keep the boat in the water year round, that could be months of drying. The exception would be if it already had a barrier coat - then you would be just renewing it - You will need to still check if the hull is dry though before reapply the barrier coat.
If you barrier coat a wet hull you will likely cause, or make worse, the problem your trying to prevent - namely blisters.
The barrier coat is slowing the absorption of water to hopefully prevent hydrolysis (which weakens the outer laminate and can cause blisters), but if its already wet, the barrier coat will seal in water, acids, etc and speed the whole process up.
Here is a link on blisters - but just know that few, if any, boats have sunk because of them and most of the time are just cosmetic and a slight hit on resale value:
http://www.oceannavigator.com/May-June-2004/Blister-analysis-and-repair/
If you barrier coat a wet hull you will likely cause, or make worse, the problem your trying to prevent - namely blisters.
The barrier coat is slowing the absorption of water to hopefully prevent hydrolysis (which weakens the outer laminate and can cause blisters), but if its already wet, the barrier coat will seal in water, acids, etc and speed the whole process up.
Here is a link on blisters - but just know that few, if any, boats have sunk because of them and most of the time are just cosmetic and a slight hit on resale value:
http://www.oceannavigator.com/May-June-2004/Blister-analysis-and-repair/
I believe that Hunter was paying for barrier coating of these boats. Do you know if there is a barrier coat or not? Ours was done when we purchased our 31 new.
I would be sure that it has not been done. These boats did NOT have any big problems with blisters so I am wondering if yours may already have a barrier coat.
If it does not, I would consider having it done. Once you pay to have the bottom paint removed down to gelcoat the price for the epoxy is cheap.
I would be sure that it has not been done. These boats did NOT have any big problems with blisters so I am wondering if yours may already have a barrier coat.
If it does not, I would consider having it done. Once you pay to have the bottom paint removed down to gelcoat the price for the epoxy is cheap.
An epoxy barrier coat is designed to prevent water permeation in your hull. Gel coat has been found to not be water proof, but epoxy is. If you sand your gelcoat, you are making it more vulnerable to water permeation (blisters) without having a barrier coat. Antifouling does nothing to prevent water absorption into the hull. It prevents or slows the growth of fouling. Some hulls on newer boats come out of the factory with blister warranties. If so, it means they either put on an epoxy barrier coat at the factory or laminated the hull below the waterline with a vinylester (epoxy modified resin), which prevents blisters. If you have an old boat and have blisters, then before you do any barrier coating, you have to make sure your hull is dry, or you will be wasting a lot of money. The blisters should be sandblasted off (gelcoat blasted off), or stripped with a machine designed for that task. Sanding the blisters smooth does not solve the problem because the water permeation is in the laminate. You have to open up the hull gelcoat and let it dry completely and then begin with the process such as Interlux' Interprotect system.
I'd love to renew the barrier coat on my 31, but if wetass is right, who can afford to leave the boat on the hard for months to dry out the hull before renewing the barrier coat and repainting the bottom..
If the barrier coat has kept your hull dry, then you can renew it. You only have to dry it if its wet - Generally if you DONT have a barrier coat and its been stored in teh water, then it will take a long time to dry. If your barrier worked - your likely good to go. STill check it with a meter though - But your probably only talking a short amount of time to dry if you have a barrier coat already.
I don't know how old your boat is or the condition of its bottom. But if your boat is say 10 or more years old and has not developed blisters to date, I would pass on putting a barrier coat on it now as it probably is not going to develop blisters later in its life. In my mind, the propensity for a boat to develop blisters occurs when the mold for the boat is poured and how carefully, or not, it is cured. I've had five used boats over 40 years and none have had barrier coats and none have developed blisters. But if you do decide to put a barrier coat on, make sure the hull is thoroughly dried out, as per the other posters suggestions, or you will be wasting time, effort, and money -- and you could be making the situation worse.
Thanks, all. Very informative, as usual. The boat is 28 years old. we've owned it for less than a year and, at survey, there were a few blisters but not enough to warrant shaving the hull. I don't know whether it already has a barrier coat, but will find out when I start on the bottom. I want to have the boat out and back in the water within a 30 day window, so if it doesn't have a barrier coat, sounds like it's not gonna get one.
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