Blister repairs

Ed Schenck · Dec 22, 2009

Not sure about Hunter but I know what I would want to do. The first step would be to get the bottom down to spotless gelcoat. Hunter will probably do that anyway. Or maybe you already have. Then clean, dry, and fill all the "wet" ones. I would not worry about the little pencil eraser size blisters. After a good sanding of the bottom put on five or six coats of barrier coat. In 1999 I had some of those little ones on my '79. Ten years later not a sign of blisters.

orion · Dec 22, 2009

I bought a Sabre 10 years ago with many blister problems. The yard as part of the sale ground the gel coat down to the mat and then re gel coated the bottom. They then put on a barrier coat and two coats of bottom paint. The job was well done and no complaints.

Jeff · Dec 22, 2009

It's hard to tell from the photos. Are these just located around the sling locations? I'd expect to see them elsewhere too. I suspect the entire bottom will be sanded to gel coat to allow for a barrier coat to be put on. But first, you (Hunter) need to open up all the blisters and let them dry out for a long as possible over the off-season. A Dremel tool works great for this. When I did mine a few years ago there were several hundred. The fluid in there kind of smells like vinegar. It takes more timing than anything. Don't get me wrong epoxy, fillers, barrier coat and new bottom paint all add up but to get these materials to chemically bond you need to be onsight within specific windows of time to re-apply coats of material. There are many manufacturers of material to use. I choose Interlux. Here is a link to their website for help. http://www.yachtpaint.com/usa/default.asp

BobM · Dec 22, 2009

Tell them you want a deal on a new one...hold the blisters this time!

I can't believe they still produce $100L+ boats with blister problems since the solution is a couple of hundred bucks worth of barrier coating. They didn't barrier it from the factory? I'd let it dry out, have them fix it, but ensure that the fix includes them paying for a barrier coat. However, from what I have seen the only real fix is to peel it and fix it. It could be attorney time.

Mich222 · Dec 22, 2009

I am with Bob M on this one: the only real fix is to peel the gelcoat.

Tom Spohn · Dec 22, 2009

Gell coat will have to be removed and then the bottom must be dried out thoroughly before putting on epoxy and barrier coats. The usual procedure here is to build a tent around the boat to keep the weather out until it dries. This can be a few months or more than a year depending on how wet the glass is. Some yards here apply hot "blankets" to cook out the moisture or put fans in the tent to speed this process up. No one can accurately predict how long this will take before hand.

Hermit Scott · Dec 22, 2009

What year is your boat Ken?

Shell · Dec 22, 2009

A lot of work to do it properly.
Strip all bottom paint. soda blasting is recommended.
Grind out all blisters, even the small ones.
Clean them out and let them dry.
Fill with epoxy. Sand smooth.
Barrier coat the bottom.
I did it on my 1986 Catalina.
Took forever to do it right.
See pics http://www.sailthehudson.com/bottom.htm

BobM · Dec 22, 2009

2008

Hermit Scott said:
What year is your boat Ken?

per his profile

Ed Schenck · Dec 22, 2009

Your last picture is one that I see quite often in the marina in the winter. And not just on Hunters. I always wonder when I see a new boat come off the trailer and watch the early stages of commisioning. Those gorgeous white gelcoat bottoms are immediately taped off and slathered with a couple coats of gold VC17. I have never seen a new boat get a barrier-coat. And when that was the first thing that I did to my "new" twenty-five year old H37C many on this board said I was wasting my time. Maybe, but it felt good and was not that expensive.

Prime Time · Dec 22, 2009

Lemon

Ken Honeycutt said:
Ed,

I'm kicking myself for not having the Hunter dealer barrier coat mine before taking delivery. I had a certain payment I could afford and I was pretty much at the limit.

I would not be satisfied by a simple repair. On a 2 yr old boat this is a manufacturing defect and this is inexcusable. Even if the proper repair is done, the value of your boat would be dropped significantly. Fixing the blisters piecemeal would not do it. I would pressure Hunter to replace your boat. Get a lawyer.

Hermit Scott · Dec 22, 2009

Ken, They need to do this right; stripped down, ALL blisters ground out filled faired...etc. the whole 9 yards. I would want that gel coat off of the bottom. Something was not done right at the factory. They need to barrier coat that after it has been stripped to the glass. This is going to keep happening and ruin your boat.
I would have it fixed now. I would not wait any longer. The warranty only lasts so long then they wash their hands of it. I would not let them put a bandaid on this and push it a little further along toward the end of the warranty.

Steve Dion · Dec 22, 2009

Ken:

Are you sure that these are "gel coat" blisters? I am NOT saying that they are not in the gel coat, but quite often the paint will blister.

I am sure that if it were less expensive to do it different the mfg would take that course.

Once the paint is removed I think the problem will be a lot more obvious.

I see that you mentioned that the bottom was NOT barrier coated. If this was the case, then the dealer probably did NOT sand the bottom (I think it would void the warranty).

Good luck and keep us posted.

PS: Boats that cost a LOT more than Hunters also get blisters. I think that your problem is a lot more unusual today than it was 10-15 years ago. I know that does not make you feel any better but that is the way it is.

rpwillia · Dec 23, 2009

A little more info

Could not find the article, but I remember seeing an article from the chief engineer from Pearson Yachts stating that blisters indicated mostly a failure in the manufacturing process. That one the gelcoat was sprayed in the most it was important as each successive layer was sprayed that the next layer needed to be applied while the previous layer was still tacky so they could mix and chemically bond together.

I have seen a few owners of older hunters have a ton of blisters, and most simply just grind them out, let them dry for a few months and then fill in and barrier coat and keep on using their boat. As I say that, these were older boats and not 2.5 year old boats. IMHO, barrier coat or no barrier coat, there should not be any blistering.

Interlux seems to be the barrier coat of choice, although I recall reading in practical sailor that sometimes it was not much better than oil paint.

http://www.mckaymarine.com.au/Surveying GRP.htm

http://www.practical-sailor.com/marine/
"Hull Blisters: Know the Enemy
At Tillotson-Pearson in the early to mid-1980s we looked long and hard at the blister-generation problem, but never fully understood exactly what caused it. Bits and pieces of the puzzle were lying around waiting for someone to properly assemble them. Many other researchers who looked at this problem drew shallow conclusions and created misconceptions where causes were concerned. For example, gelcoats were the initial recipients of the blame for blistering. After all, it was the gelcoat that had all the bumps showing on it. It soon became evident, however, that hulls with blistered gelcoats all had wet laminates underneath. We already knew a lot about the moisture and chemical resistance of various resins, so it made sense to look at their possible role in keeping water out of hulls. We eventually learned through iterative lab studies that higher-quality resins helped the problem significantly. Soon we knew that building with vinylester resin could yield relatively blister-free hull laminates. By 1985, the practice developed by TPI, working with Interplastic Resins, was to build the layers closest to the exterior gelcoat finish using vinylester resins, then switch back to lower-cost resins. This process is known today as skin coating. Interplastic went on to market the use of their resins nationally as a blister resistant "skin coat" product."

Terry in Naples · Dec 23, 2009

blisters keep coming

Here is even more bad nerws. Even if you repair the blisters that you see the fact that the barrier coat is not doing its job remains on the rest of the surface and those areas not already blistered will eventually do so. the only way to do this is a peel job and the new barrier coat. Not taking care of the small blisters lets them joinup and make big blisters. These then finally cause delamination of the hull. This and the absorption of so much water causses the boat to be a slow sailor and unsafe. I speak from first hand experience on an older ODay sailboat I had. I eventually spent about $15,000 overall in the 15 years I had the boat , just on reparing blisters. Just maybe, Had i done a peel job the very first time I would not have had all the other problems.

Maine Sail · Dec 23, 2009

Steve Dion said:
Ken:

Are you sure that these are "gel coat" blisters? I am NOT saying that they are not in the gel coat, but quite often the paint will blister..

I have refrained from comment on this because I am in Steve's camp until we know for certain that these are actually into the gelcoat. I have seen this before where the dealer prep did not de-wax the hull sand and then de-wax again and the paint fish-eyed and peeled.

Despite my gut feeling that this is likely a paint issue, these could still be blisters perhaps due to a bad isothermic reaction, a bad mix or contamination.

If it is into the gelcoat, and they are real blisters, the only prudent repair is to peel the hull. Drilling & filling will not likely stop these from re-emerging and they will re-appear through the new barrier coat if the entire problem is not taken care of. Also the labor to drill & fill those thousands of blisters will likely cost more than a professional peel and re-lamination.

Keep working with Hunter and discussing this repair with local professionals who specialize in blister repair & bottom jobs. Many yards are unskilled, not proficient enough or just plain choose to ignore or even follow the basic directions supplied by the barrier coat makers so you need to be careful, and know this stuff in-side and out, so you don't get stiffed..

When it comes to blisters and barrier coats a horrifyingly large number of yards do these repairs improperly so be careful whom you talk to and please do your own research beyond just the forums..

Blister repairs

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