Blisters

Shoaldrafter · Dec 2, 2008

blisters continued

You did not say where the boat was/is used. That actually matters. While blisters occurr in all waters they intensify in warmer waters.

Most O'Day boats in southern or warmer waters develop blisters. In fact, even the brands that claim not to, actually do get blisters especially in southern waters.

Most common are gel coat and paint blisters. Follow standard methods of treating and repairs last varying amounts of time. There is no 100% cure.

Several sealing coats of epoxy or epoxy based paints seem to help. A single coat is never the answer. At the age of O'Day boats around, even those boats that appear to have intact Gel Coat would benifit from several coats of sealing epoxy. As the gel coats age they just may become more pourus. And the original gel coat has thinned thru normal use and wear.

If you are repairing the blisters yourself, read several sources of information available about blisters. West Systems puts out a good booklet that is worth the few bucks. There are several good books or chapters in books about maintaining and repairing frp boats. And there is much information on the web.

If the number of blisters is high, not withstanding all the admonitions not to, I recommend sandblasting the hull. Then grind out the blisters. Wash with soap and water. Wash with acetone. Wash again with rinse water. Wash hull every four to six weeks until you are ready to repair holes.

Blisters are known to weep. The stuff that weeps should be removed constantly as directed above.

The sandblasting will destroy the finish but give you a surface that epoxy will adhere to. As stated above, several coats of epoxy will give you a stronger surface.

While Interlux is a well known name it is not the only source. First, find out what is sucessfull in your local area. It is not alway Interlux. If you need other sources just ask. Or search the archives as they have been posted over the last few years.

Use the 'Ask an Oday Owner forum'.

Again, read more than one source and proceed. All it takes is elbow grease, aka work and funds. Yes you are on the right tack.

Ed K

rajhnsn said:
I have recently purchased a 1985 Oday 35. During the survey there were a few blisters that were negotiated into the deal. After the boat was pulled at the end of the season, it was soda blasted to determine the extent of the problem. It became clear that there were actually hundreds of blisters in the gel coat smaller than a dime. I have started to bore them out. They appear to be dry. The plan is to open them up for the winter and then fill them with an Interlux product, barrier coat and bottom paint. Has anyone else had this experience and am I on the right track?

Shoaldrafter · Dec 3, 2008

Blister repair continued

Bob,

I bought a O'Day 26 project boat. It was not as much a project boat as two other 26's discussed in the archives of the owners forum. It had many tiny blisters as you describe.

I used a method similar to what you describe. That was to first remove all bottom paint, then grind out each blister. That was two and a half to three years ago.

I recently pulled the boat to see how it went and apply more bottom paint.

Most of the hull is in very good condition. However, there are some more small blisters which I plan to treat locally, that is specific repairs to those blisters.

I believe that those blisters, generally in three small areas were small blisters not caught the first time. That is why I recommend the common practice in yards around here to sandblast the hull.

I am retired and have to watch how a couple of yards do this project. I have changed my opinion to say that while sandblasting does initial damage to the surface of gel coat it also opens or identifies more small blisters than just the grinding route. I believe that had I sandblasted, I would have caught the few spots I will repair now.

As to fillers, there are alternatives. First, one yard I am familiar with says to stay away from Interlux filler. They claim it softens up after time in water.

The alternatives are real epoxy paste that you make yourself. West system tells you how to do and the pros and cons of the different additives.

Evercoat makes a vynal ester product that sticks like fresh dog shit. It is sold under their label and West Marine label. Vinyl ester is supposed to be more water resistant than polyester products.

In addition to the West System additive products, those same type additives are available from various sources. Long fiber is available elsewere and pigments help hide the repairs. Pigments are available in larger containers than at the local boat supply stores.

When fairing after filling voids use a good random orbital sander. Porter Cable makes a good one that cost about $170. Smaller ones take too long. Bigger ones are too heavy to work. The model of the one I got is #7335. I learned this from a guy who does bottom jobs.

Ed K

rajhnsn said:
Thanks Ed. All good information. I'll continue reading a variety of sources as you suggest. I found a good one from one of the forums on blisters here called yachtsurveyors.com. It suggest that there is a difference between larger quarter size blisters and smaller pea size. I have possibley hundreds of pea size blisters. I knew that some of them were there from the survey but I had the hull soda blasted after it was pulled. That's when I found the rest of them. I knew the risk going in but I really wanted the boat. I think if I do this job right, I can save its value.

There had previously been at least one barrier coat but it did not stop the blistering. The boat was originally in the Philadelphia area but it spent the last four years in Wilmington North Carolina. Its possible that they developed in the warmer climate. I now keep the boat in Rock Hall, MD.

In any event I am about 1/4 of the way threw boring them out. I'm using a dremil tool. I'm going about a 1/4 inch deep-just past the mat. They seem to be dry. I have not seen any weeping. My yard recommends Interlux products and is setting up a seminar with their rep. in March. I'll listen to what they have to say. I like the idea of using a thin 1st coat of epoxy to wick into the roaving but I'm not sure how the epoxy will interact with the Interlux filler. Obviously more investigation is needed. Thanks for the vote of confidence too.

Bob

Shoaldrafter · Dec 5, 2008

Compatibilit issues

I ran into what I think was a compatibility issue with epoxies one time years ago, I understand the question.

First, West Systems has a good customer service department who will answer questions of this sort. They even do test and publish results. The have a good publication which is free and accessible online:
http://westsystem.com/ewmag/

My reaction to your question is that using West System products to fill and fair repairs should not preclude any overcoats if directions are followed. When painting over any epoxy you should use a primer made to go over epoxy. When painting over epoxy there are two other general rules that are used. First, apply epoxy primer before the epoxy cures or, second, ruff surface with sandpaper to get mechanical adhesion.

If you are doing the whole project by yourself, I recommend doing just small areas so that you can do it the recommended way. I had help for the filling, fairing and painting. My project was done over many weeks, but once we applied epoxy sealer, we applied first coat of epoxy primer quickly and then followed first bottom paint also before primers fully cured.

Understand that while epoxy may be dry to touch it takes 48 or 72 hours or in cold weather more to cure. So you can work an area on Saturday and finish on Sunday. Just follow directions of supplier.

Keep in mind that besides Interlux and West there are other suppliers of good products. Others use System 3, MAS, Bluewater paints, Shipbottom Paints, Pettit Paints and http://www.epoxyproducts.com/.

Ed K

rajhnsn said:
Ed,
What do you think about the compatability issue of West (or other) filler products with Interlux barrier coats such as 2000/2001, 3000?
Bob