Barrier coat recommendation
- Thread starter Isla-Mae
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If you are going to go to the time and expense, read don Casey's recommendation for barrier coating in his book. The thing most of us fail to consider is that it takes a long time for the hull to completely dry out. This results in failure of the barrier coat. It is worth reading.Isla-Mae said:
If your boat's hull has blisters you should repair it and go with a good bottom paint. I've been using Super Shipbottom Ablative bottom paint for years now and I like it. This paint has a high copper content and it can be painted over bare Fiberglas and most bottom paints. It has it's own primer built right into it. You only need one coat which should last about two seasons with touch ups. I wouldn't bother applying a barrier coat.
http://www.supershipbottom.com/PAINT SPECS.htm
Have to agree with only barrier coating a dry hull and that doesn't mean dry to the touch. Unless its been dry stored so the hull has a chance to dry out over the winters, out of the water for a very long time (Months to years vs weeks), or been peeled, chances are that its not dry. Better to just forget the barrier coat or you can make what is a minor issue (if an issue at all) a much worse problem.
Barrier Coat
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As you can read there are opinions both ways.
Some basic information found about FRP boat hulls.
Most older boats are polyester resin. Polyester resin hulls are not water proof merely water resistant. Which means that there is moisture intrusion into the FRP.
Moisture interacts with the resins to form blisters. Most occur between layers such as between gel coat and main FRP. Gel coat is done for several reasons.
Gel Coat is the fancy highly polished finish. Done here for beauty and selling sailboat.
Gel Coat is more moisture resistant and done for water proofing.
So why barrier coating and what is barrier coating? It is a two part system that usually is epoxy based. Epoxy is more water proof or moisture resistant.
So barrier coating is to increase moisture resistance and reduce damage from moisture intrusion.
It is done to preserve hull integrity.
How long should a hull be dried out before barrier coating.
How should hull be dried?
Older commentators insisted hull be dried for 6 months or more. Most marinas do not follow this recommendation.
How can drying be speeded up?
Use of space heaters inside of hull speeds up drying.
Acetone which draws moisture out of FRP helps. That is wash hull immediately after taking out of water. If you find blisters, mark immediately and cut into them to drain fluid which is acidic because of the chemical reaction between moisture and FRP.
Wait a day or so and wash with acetone. Again wait a day or so and wash with soapy water.
Repeat this process in couple of weeks and even third or forth time depending on condition of hull.
This process reduces drying time and removes acid residue.
Fill and fair any blisters before barrier coating. Some apply penetrating epoxy layer before barrier coat to seek cracks and defects before barrier coat. Remember if doing so, to apply barrier coat as soon as epoxy is dry to touch. And apply bottom paint as soon as barrier coat is dry to touch.
Check archives for much prior discussion on this subject and for sources of materials mentioned above.
Yes, you should barrier coat.
Ed K
------------------------- //----------------------
As you can read there are opinions both ways.
Some basic information found about FRP boat hulls.
Most older boats are polyester resin. Polyester resin hulls are not water proof merely water resistant. Which means that there is moisture intrusion into the FRP.
Moisture interacts with the resins to form blisters. Most occur between layers such as between gel coat and main FRP. Gel coat is done for several reasons.
Gel Coat is the fancy highly polished finish. Done here for beauty and selling sailboat.
Gel Coat is more moisture resistant and done for water proofing.
So why barrier coating and what is barrier coating? It is a two part system that usually is epoxy based. Epoxy is more water proof or moisture resistant.
So barrier coating is to increase moisture resistance and reduce damage from moisture intrusion.
It is done to preserve hull integrity.
How long should a hull be dried out before barrier coating.
How should hull be dried?
Older commentators insisted hull be dried for 6 months or more. Most marinas do not follow this recommendation.
How can drying be speeded up?
Use of space heaters inside of hull speeds up drying.
Acetone which draws moisture out of FRP helps. That is wash hull immediately after taking out of water. If you find blisters, mark immediately and cut into them to drain fluid which is acidic because of the chemical reaction between moisture and FRP.
Wait a day or so and wash with acetone. Again wait a day or so and wash with soapy water.
Repeat this process in couple of weeks and even third or forth time depending on condition of hull.
This process reduces drying time and removes acid residue.
Fill and fair any blisters before barrier coating. Some apply penetrating epoxy layer before barrier coat to seek cracks and defects before barrier coat. Remember if doing so, to apply barrier coat as soon as epoxy is dry to touch. And apply bottom paint as soon as barrier coat is dry to touch.
Check archives for much prior discussion on this subject and for sources of materials mentioned above.
Yes, you should barrier coat.
Ed K
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