Re: hull blisters

Shamrock also has gelcoat blisters, we have a letter on file from Sam Morse regarding the problem; it seams back then, they figured if one coat of gelcoat was good, two should be better, not as the case turn out.

We did extensive research regarding the subject of gelcoat blister and laminate blisters over the years and promise not to bore you with the details.

Repair in the past has consisted of grinding off the gelcoat and subsequent layers of affected glass and re-glassing the hull and barrier coat.

The current tooling consists of a modified hand operated wood plainer, called what else, a peeler. The positive result is a more uniform cut in skilled hands. The key point here is skilled hands, the best tools in the wrong hand can make a mess of things. I have found two of these tools on the market, the best one on the market is call a Gelplane out of Europe at $3000, the other out of Canada runs around $1300 lacks the safeguards of dead man switch and handles to keep your little fingers out of the way, can't remember the name of their product.

There are two approaches to peeling, the single or double cut, in the single cut they make a shallow pass with the peeler removing the gelcoat only and see if there is delamination under the gelcoat. If delamination is present, a second pass is required. Obviously, the double pass technique is more expensive as there is twice the time and effort involved. On the other hand, a deep single pass takes off gelcoat and 2 layers of glass, ensures the usually affected layers are taken with a single pass; positive effect is lower peeling costs and faster drying times.

We priced the peeling cost for Shamrock at $3000, total cost for peeling, re-glass with two layer of angle hair glass, epoxy and bottom coat is $12,000.

This is where the critical choice comes in, most boats are built with angel hair glass mat (very fine random directional fiber mat cloth) near the gelcoat to prevent glass cloth print through effect, the checkerboard affect you see on some boats that apply bi-directional woven cloth against the gelcoat in the mold. Most critics of blister contend that the difficulty of saturating angle hair mat leaves voids, air pockets and uncured resins which lead to blisters; subsequently suggest re-glassing after peeling with glass cloth. Our local yard uses two layers of angel hair cloth bathed in epoxy and has no history of reoccurring of blisters. The choice is yours.

In either case, if you have the yard do the work, check the fine print of the warranty, longer the warranty the better. Go to a well established yard with a sound financial background, make sure they will be around for awhile. Generally, but not always, yards that give a longer warranty period usually have a good record of repair. Baring the case of the business idiot, most business know a repair will only last so long and provide a warranty that extends up to a point short of when the repair needs to be repeated. Ever have something that broke the day after the warranty expired?

In the early days of blister repair, when barrier coating was the panacea, many yards gave outrages warranties, 10 years in some cases, are subsequently taking it in the shorts so to speak as blisters are reappearing every couple of years.

Marty Chin, BCC Shamrock.


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