Excerpted from the excellent paper, as referenced by Rick I, at
http://www.zahnisers.com/
”BLISTERS & LAMINATE HYDROLYSIS” ~ by Craig Bumgarner
<quote ~ in part>
BARRIER COATS AS PREVENTATIVES:
“... We are occasionally asked about preventative use of barrier coats over an existing, unblistered
gelcoat. Unless the
boat has only been in the
water for a few years, getting the bottom sufficiently dry without removing the gelkote is a very slow process, often 12 to 18 months. The gelkote, while not sufficiently waterproof to prevent blistering, is still dense enough to slow drying down to a snail's pace. Most boat owners are not willing to give up their boat for a year for a preventative measure. Considering the
work will cost half of a blister
repair, most owners opt to wait until the bottom
blisters. Never the less, a properly applied barrier coat will greatly reduce hydrolyzation over the years. The cost of
maintenance of this barrier coat will, however, be rather high.
In the case of a
new boat, however, if the manufacturer has not applied a barrier or built the boat out of a non-blistering material such as vinylester resin, a barrier coat is highly recommended before the first immersion. It won't last forever, but it will forestall hydrolysis and blister formation. This is especially important if the boat
builder does not have a definite, long term, written policy on blister
repair warranty ...”
<end quote>