Need a Barrier Coat?

kito · Dec 17, 2015

I am applying barrier coat because I do have a blister problem. Doesn't matter who's to blame.....just need to fix it so I don't get any more blisters. It is the factory's fault due to poor materials or processes, but that doesn't make it any better.

centerline · Dec 17, 2015

" If boat manufacturers thought their boats needed barrier coats, they would come with them, like caulked seams and annodized spars."... as much this may be a statement that one would like to believe, sadly, it is an incorrect statement.

"I continue to believe that the "need" for barrier coats is the result of a very successful marketing ploy on the part of the makers of barrier coat products." this belief is wrong on many levels, only because the previous statement is incorrect.
barrier coat manufactures only exist because the boat manufactures cant/dont seal the polyester laminate as good as needed for long term submersion.

its true that not all polyester boats experience the blistering, and it also true that some boats experience it worse than others, but they are all susceptible to it, and will probably all experience it at some point if the water conditions get right and the hull is submerged in it long enough...

with all the blister problems since FRP has been used to build boats, there has been a lot of research and discussion that has determined that only boats that are layed up with epoxy or vinylester, (or is made out of wood or metal), are the only ones impervious to blisters... this leaves polyester resin (commonly known as fiberglass) hulls susceptible to blistering if it is kept submerged.
salinity and temperature levels play together along with the quality of materials used and the layup process, to cause the blisters to happen... no one knows exactly what combination and levels are the worst, but they have determined that if you remove the water ingress/absorption from the equation, the problem disappears. this is done by using waterproof products like vinylester and epoxy.

at one time the best repair solution for blisters was to peel the gelgoat and then build back with a barrier coat product, but this is expensive... and because of that, other companies have looked for a faster and cheaper way to get the same results for less money, which by any standard is better.
there is now a very good, simple to apply, single part barrier coat product available offered by Interlux. so if one is going to sand down completely and do a premium bottom job on their boat, why not add a barrier coat to it just to get the best protection available without much more cost....

if the boat spends a lot of time on the trailer, then you probably dont need a barrier coat, but if it is kept in the water and its a nice boat with a polyester hull, you should have a barrier coat in an attempt to protect the value of it....

but... if you have a 30year old boat and it doesnt have blisters yet, you probably wont get them. but if the boat is ever moved to different water conditions, they can begin to appear.
but then, why wait for blisters to appear before protecting the boat?... in my opinion, an active and careful boat maintenance program is fixing potential problem before the failure, rather than afterwards....

DougM · Dec 17, 2015

It seems as though the big issue with hull blistering appeared in polyester resins in the 1980s. Some time after that, manufacturers were beginning to advertise ten year hull warranties with regard to blistering. That was at about the same time the manufacturers switched over to vinylester resins. When that occurred, apparently the blistering issue either went away or was greatly minimized.

The boat I own was purchased new in 2004 and so far I have not had a blistering issue with the hull. I never barrier coated it and the only issue I have is that the bottom paint (VC17) comes off in spots when the bottom is lightly pressure washed at winter haulout. Not a huge deal because I repaint annually anyway. I thought at first the bottom paint was not adhering because the dealer had not thoroughly removed the wax from the molding process, but even after thoroughly bottom sanding and solvent cleaning the paint still wears off somewhat.

Where I encountered a major blistering issue was with the iron keel. It was barrier coated at the factory, however they apparently did a lousy prep job. Evidently, it was enough of an issue that when boat owners started looking for remuneration from the keel supplier, the company either declared bankruptcy or completely abandoned the business. The boat manufacturers themselves in at least some cases would not admit any liability for the problem.

I ended up taking the keel all the way down to bare iron about 4 years ago and re barrier coated it. I have not had a problem since. No problem with the bottom paint adhering to the keel either.

Roland5048 · Dec 17, 2015

Had the hull of Fraulein II barrier coated on '02. There were lots of small and some big blisters. Have been hauled three times since. No blisters. Getting ready to haul in Jan. I expect no blisters. To barrier coat or not? Depends on the condition of the hull and how the owner feels about it. I would assume that very few production boats, especially older boats like mine, came of the line in perfect condition. Your boat, your call.

weinie · Dec 17, 2015

Got at least 7 more years on my old catalina with no barrier coat after grinding off over 20 years of old bottom paint. Probably would've lasted another 20 more easily.
Just my humble opinion, but you normally don't see fiberglass absorbing moisture unless it has been penetrated.

ETA: the boat yard was the one to talk me out of it. And the one I used would sell you gold plated screws if they felt they could get a few more cents out of you.

Gunni · Dec 17, 2015

Consider yourself lucky Warren, there is a long and well documented history of hull blistering which dogged the industry and put builders out of business. For many years the cause was not well understood and boats continued to blister, but we now know that gelcoat is not a barrier to moisture migration and when water gets to the underlying composite laminate it can absorb, swell, and blister. Vinylester resins seal the composite, but if you are disturbing the lay-up (sanding), an epoxy barrier coat is cheap insurance.

Companies with deep pockets (Beneteau) spent beaucoup re-doing blistered hulls on boats that were only a couple of year old. They actually had teams of trained techs, and guess what they used? Epoxy barrier coats. And Beneteau will still tell you that properly sanding your hull invalidates your blister warranty. Why? Because they don't trust you to not scuff off the vinylester. They tell you to use medium sandpaper...which would take you 100 years to get old paint off, and provide poor "tooth" for new paint. So barrier coat is the way.

May you never have a blister!

Sanfelice · Dec 17, 2015

I have owned 2 Catalinas, late 70's, and one Hunter 1986. Only a few small blisters (pimples) which receded after out of the water for a couple of weeks. Boats stayed in water 3 years at a time with water temp in the 80s. I saw 1 year old Catalina with extensive blisters. I also have seen Windmill day sailer that was trailered develop bottom blisters after being stored in limestone cave which had constant temp and humidity. These caves are used for storage of old films because of the natural climate control. IMO blisters are the result of poor layup and/or materials. FYI this is nice treatise on the subject.

http://www.yachtsurvey.com/blisters.htm

woodster · Dec 18, 2015

from my viewpoint blisters are caused by polyester resin not being saturated in the cloth and matt 100% before setting up thus causing a place for water to wick or sponge in the the non saturated material and microorganisms to grow causing a swelling of the composite and it can either come from the outside or the inside if flooded i took my hull down to the matt removing all gelcoat and replacing with 6 coats of west epoxy with additive ...in about 2 more years i will know how that worked or maybe less only time will tell ...but i feel i have done all i can at this point with what is available to the common man oh i also have three coats of trinidad bottom paint before launch...the water can get in from anywhere including scratching the surface and around any penetrations such as through hull fittings if not sealed properly ...so my advice is don't rush your work and do it correctly or it may wind up like deep frying a frozen piece of meat

Bob J. · Dec 18, 2015

My present boat after sanding who knows how many coats of bottom paint off, seems logical to barrier coat. There's a couple of places that the hull "popped" but nothing to be concerned about. To me if one is going thru all that work to get down to a clean & smooth bottom, just seems like the right thing to do. For a couple of hundred bucks I feel it's not worth the gamble not to.

Pat · Dec 18, 2015

Interesting discussion to me.....we bought our O'Day 272 in late 1986...put it in the water the following Spring, and it basically remained in the water on and off for 15 years......used the high pressure wash at the crane each year and no signs of any, i.e. zero blisters....the Wichita dealer had used the Interprotect line of epoxy from Interlux. About 10 years ago we bought a trailer and began taking it out every fall.....then we got blisters, hundred's of small ones, described in literature as pencil blisters.....we opened them, had the boat bottom blasted with a talc and let the boat sit idle in the Kansas sun for most of the spring 'drying out'...read all of the West System literature, even spoke with them and used their products after drilling them out with various tools...put the boat back in the water in 2013.....have taken it out each year since and it is back on the trailer with no blisters...none, nada. Do I feel confident about next year.?..yes and no,...but we do paint the bottom each spring.....I'm not certain anything is foolproof.... To make this story more interesting, we would help our local boat dealer at the boat shows, and we actually had one brand new Catalina 22 show up for the Spring Boat Show direct from the factory in California with blisters at the trailer bunk locations...where we suppose the boat had set for some time before being delivered to the local dealer for the boat show.. Although we may get them again, I do believe in the West Systems approach to repair....my wife actually though repairing the blisters was fun....fun yes, but a lot of work as well....Patrick

Need a Barrier Coat?

Warren Milberg

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kito

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centerline

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DougM

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Roland5048

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weinie

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Gunni

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Sanfelice

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woodster

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Bob J.

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Pat

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Warren Milberg

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