Blisters

[dagerman]

I''m considering at a 1984 Morgan 32 that has a significant number of blisters. The brokers says the hull needs stripped, dried for about 6 months and then a new gel coat reapplied. Anyone have any experience with this process? Is this a long term fix or am I looking at long term problems. Other than that the boat is in beautiful condition.

Thanks,

Dave

[RichH]

It all depends on what the size of the blisters are and if they have been previously repaired. Blister info .... http://www.yachtsurvey.com/blisters.htm

[Jeff_H]

First of all, if your broker has specifically told you that you need to re-apply gelocat, he probably does not fully understand the blister repair problem. The best blister repairs in terms of longevity involve doing a ''peel'' which is removing a roughly uniform thickness of the gelcoat and laminate using a specially set up power plane since that produces the least heat and the fairest hull to work from. ''Bad areas'' are further peeled down to solid laminate. Drying time can be reduced with a peel depending on the climate where the work is being performed.

Gelcoat is not reapplied. Instead the best and most permanent repairs involve laying up at least one layer of fiberglass cloth with either Vinylester or Epoxy resin. (A case can be made for either.) All fairing materials should be either epoxy or vinylester based and matched to the layup materials. The fairing materials should have a compatable barrier coat applied.

Osmotic Blisters can come from a pretty wide range of causes. 1984 is near the end of the period during which the worst forms of blistering occurred. In the worst forms of blistering the blistering comes both from the interior and exterior of the laminate so that bilge water can trigger blistering and the damaged areas can extend through the whole laminate rather than simply the exterior submerged surface of the laminate. This form of blistering is not really permenantly repairable. Other forms of blistering can be dealt with quite successfully and permenantly, and in some cases can be ignored for long periods of time.

Jeff

[Silmaril]

That is close to the process you need. Stripping must be done using a tool designed for the job, sort of a surface planer for fiberglass. You cannot grind it, as the excess heat from grinding will damage the fiberglass. After the primary stripping, the hull needs to be inspected for futher damage, as some of the blistering may have gone deeper than the surface. Osmotic blistering will vary depending on the manufacturing/layup of the original hull. Some blistering may be only through the gelcoat. While others can have deeper penetration of the hull itself. The use of moisture meters is still suspect. There just is no truly reliable method to measure it. (Well, a gamma backscatter basis weight monitor would work, but at over $20,000US I don''t know of any surveyors who use them) Then the hull needs to be dried out. 6 months sounds a little excessive. A couple of months in a heated enclosure with a dehumidified atmosphere should do the trick. Then an epoxy BARRIER COAT (not gelcoat) needs to be applied. After the barrier coat, prime and paint. The barrier coat needs to be renewed about every 10 years or so to prevent further blistering. This is obviously a major undertaking and can be quite expensive, so the seller may have to be prepared for a big hit on his asking price.

[Silmaril]

Yeah, what Jeff said too....

[dagerman]

I think I may be using the wrong terminology. He did say the surveyor said it needed to be peeled, and soon. It is in Florida so I"m assuming the humidity may have something to do with the drying time? I''m just afraid of spending the money to have the repairs completed, haveing the boat down for months only to have the blisters return. I was looking at this as an intermediate boat for the next 5 yrs +/-.

Dave

[jbanta]

I don''t think you have blisters. Sound more like a delamination. If it is blisters peoperly repaired they will never come back. The damage must be completely removed. I have 3 on my boat I ground the out one penitrated all the way through the hull! I cupped out the damaged area and laid in new glass. after all the glass was replaced and the SANDING done I primes and sealed with a high quility epoxy paint 10 years now and NO blisters. I give the credit to the epoxy not to me...

[TrueBlue]

Delamination could be a final stage effect resulting from osmosis (blisters). Similarly to a medical prognosis, it is near impossible to form a conclusion of any value through the internet . . . only probable assumptions can be made from detailed descriptions of the symptoms.

My surveyor discovered very tiny osmosis blisters on the outer layer of the gel coat. I bought the boat after receiving a detailed estimate for repair, with subsequent application of Interlux''s Interprotect 3000 epoxy system by my boat yard. My surveyor gave a two-thumbs up approval of the finished project.

However, once conditions are present for osmosis, there is always the risk they will reappear. The barrier coat (like medicine) will eventually breach and the malignancy may come out of remission.

Steve

[capnjim02]

if its blisters then peeling is the way to go. my boat is a 1979 O''Day. when i bought it in 1989 it had small blisters all over the hull. surveyor said i did''nt need to worry for 4 or 5 years. i bit the bullet and did the peel in 89. i then used interprotect 1000 primer then 6 coats of 2000. to this day i hav''nt seen any reoccurence of blisters. 15 yrs isn''t too bad. done properly, you should''nt have any more problems. i believe the key is DRY, DRY, DRY.
mine was dry in about 2 weeks after peeling.

[newburyport]

Unfortunately, I''m in the same "boat" as daggerman :-( I was considering the purchase of a 1987, 40'' hershine built/taiwanese trawler that has 1000''s of pin head size oozing "holes" on the hull, below the waterline. For those like capnjim02 who have done a peel, I''d like to know how expensive a repair I might be faced with. I know there are a lot of factors that go into this and my surveyor says that the hull has not delaminated but I need data points. Is this a $10,000 repair? $20,000? $50,000? Please advise.

The more I read, the more I am concerned that blisters, especially this many, are much more than a cosmetic issue. They can lead to more serious problems that compromise the integrity of the hull and need to be repaired sooner rather than later. Would you agree?