Bottom paint (avoiding blisters?)

[James V]

There is a lot of discussion on all forums about Blisters. Nobody really has a good answer on how not to get them. A LOT of money is made by fixing them and I am wanting not to spend it. A few questions to the group for those of you who have kept a Mac in the water for a year or more.

Did you get blisters or not? How long did it take or not?
Please give details like, did a pro do the work, what you used on the bottom, how many coats and what location. If you did the work, what skill level are you.

From what I can tell the prep and aplication is just as important as the material used.

[Lorne Colish]

My 1998 26D and then my2002 developed thousands of tiny blisters after sitting at the dock for the summer.I jacked the boat up off the trailer and sanded the bottom lightly to open up the blisters,then left them to dry out over winter.I lightly sanded again in spring and rolled on 1 gallon of Interlux Interprotect 2000/2001(4 coats).
I left the 26D like that ,without anti fouling,and it was fine for years after;the got 2 coats of antifouling over the interprotect and it has been fine for the last 2 seasons.
The blisters were so small on both boats that I didn't need to fill them after sanding.
Goggles,paper masks and gloves used.
I did the job outside.
I'm a modestly, skilled do-it-yourselfer.
Sanding takes about 2 hours,painting takes 1-1.5 hrs. per coat.
Interlux has good detailed literature.

[Carl Noble]

I have a 2000 26x that has been in the water for 6 seasons now. ( Six to seven month season). The original owner applied 4 coats of an epoxy barrier coat and then 4 coats of an ablative antifouling paint. (Interlux) No blisters. The barrier paint protects the fiberglass from the water. Even very expensive boats can develop blisters and some manufactures apply bottom protection right from the factory. (Sea-Ray does this with their larger boats.) The nice thing about the barrier coat / antifouling coat is that you never have to repaint the barrier coat. I applied two more coats of the ablative paint this past spring and I feel that it will last at least another 3 seasons with some minor touch ups. It is not a fun job to do but it isn't very hard and really doesn't require much skill. Lorne is spot on on his discription of what is needed however I would add that a creeper, tyvek disposable jump suit and saftey glasses or googles are essential. I'm sure there are big differences between salt and fresh water coats so you need to check with your local marine supply stores for what's best in your area.

[Night Sailor]

After one year in warm fresh water with ballast always in tank, my X developed blisters. Hundreds of them 1-2 mm in diameter. Most were in a line with the interior ballast tubes. Due to time and space constraints I had my work done professionally. I requested Interlux 2000 epoxy coating but my yard convinced me it was not necessary, and was not a guarantee at all against blisters. Mine were so small he said, that a good sanding to open all blisters, and then a good bottom paint would be just as effective. I went with his advice.
After a summer in up to 86 degree water with Interlux Micron Extra with Biolux on the hull, 3 coats on it all, another foot wide coat fourth around the water line, there is no sign of either blisters, slime or algae. Although the paint is not as smooth as I'd like it, I can't tell any difference in boat speed over a bare hull.

[Craig LaForce]

Mine's a 97 always in the water, both salt and fresh, no blisters that I have noticed yet.

I just used a coat of epoxy bottom paint, and paint it each year. used ablative a few years, and now back to using epoxy. If I start getting too much buildup, I will go back to ablative for a few seasons.

Fresh water is supposely a little more apt to give blisters, but the quality and workmanship in the fiberglass resin mixture and layup can make the hull less prone to developing blisters.

[Catigale]

Ive trailered for 3 years and slipped for three years in mostly fresh water without barrier or epoxy and dont have blisters.

[baldbaby2000]

I bought my boat new and there was a lot of discussion on the forum about this about that time. I got nervous and just took mine to a professional and had the barrier coat and then anti fouling paint applied. I don't remember the types of paint but I can look it up if you like.

Daniel

[Night Sailor]

It's apparent from many discussions that water temperature where the boat is kept in a slip is a great factor in the amount of bottom growth, and seems to correlate well with blistering also. Most boats kept in cold water in northern latitudes seem to avoid both issues. Boats kept in southern latitudes where the air temps reach triple digits and the water temps reach mid to upper 80s are plagued with both.
I wonder if the temperature extremes in the water (in my case from 34 F. to 92 F. ) open and close tiny cracks or pores in the gel and expoxy layers to allow water infusion over a year's time?

[Catigale]

When slipped, the Hudson doesnt go much outside the range 50-70F in temp, so that would be consistent with the above at least. My gut feel is its more a MFG issue than an environment issue.

There are people who assert the whole blister scare is overdone and that a boat with blisters can be left with blisters...i.e. they dont impart structural risk to the hull....YMMV

[NiceAft]

The first year I had Nice Aft, I trailered her. I did not have any problems. The second year I had her in a slip, so I took the precaution of having four applications of Interlux 2000 done by a local marina. I did not have any anti fouling paint applied because I don't keep the boat in salt water. I don't have any concerns about barnacles in the Delaware River, or in Lake George. (Here's where someone chimes in about them having barnacles, or Zebra mussels up their wazoo, and they keep their boat in fresh water).

When I took the boat out last week, the bottom looked like it had a green fright wig. I sprayed on a coating of Slimy Grimy, and the green hairy stuff went by by! I think it was Chip who mentioned about Slimy Grimy. The stuff works.

The point is this. If you keep your boat in salt water, I would apply bottom paint over a barrier coat. If you keep it in fresh water, I would chance only a barrier coat. Either way, my feeling is a barrier coat should be applied if the boat stays in water. The cost and aggravation to correct a problem that probably can be avoided in the first place, is not worth it. On the other hand, the barrier coat isn't cheap.

Ray

[Lorne Colish]

Both of my Macs blistered after only one season in Lake of the Woods, just north of the 49th parallel,before I applied a barrier coat.Water temp. reaches 72F max....briefly.

[James V]

Thanks for the tips. Here is what I have found out.

2 basic types of blisters. Small Gelcoat and the bigger ones in the glass.

If your boat has been in the water and has blisters, then you probably will get them again. Drying out does not help much. Letting the blister weep does does help. The older blistered boats was mostly caused from the mistakes when the boat was made.

You need to put on a barrier coat if you are going to put your boat in the water for long to stop the blister (safer but not fool proof). Gelcoat and fiberglass is porous. Epoxy is not (as porous?)

Tar epoxy is the most flexable and strechable. 7ml thick or more is best. Do not sand between coats. Great Prep work is needed.

It does not last a lifetime. 5 to 7 years and you will need to remove and start over. Any nick and you will have to patch.

Blister may start from either inside or outside. No reports of blisters caused from water ballest. This may be false data. If it is false, I think that the water entering the fiberglass is caused by the water pounding the hull, more pressure.

[Catigale]

No reports of blisters caused from water ballest.

Ive never seen any in my quarterly endoscopic examination of the ballast tank interior...



(Insert High Tongue in Cheek factor)

[albion]

Bill I always use Calamine lotion when I get blisters on my bottom.

[tidalwave]

I kept my 2004 for four months in a central Minnesota lake during 2005...water temps varied from 45 to 78 degrees during that summer.
LOKI developed severe blistering!

This spring (2006) I took her in for sanding and bottom paint. Repair
shop said that any fibreglas boat kept all summer long in MN lakes would
have very bad hull in just a couple of summers without bottom paint.

Most of the boats around here have several coats of Interlux barrier epoxy with one or more overcoats of Interlus antifouling paint.

I have two coats of red epoxy beneath two coats of black bottom paint..if I get wear or scratches the red will start to show through...and time for touchup or recoating.