"Bruce in Bangkok" wrote in message
...
On Thu, 14 Apr 2011 10:34:05 -0400, "Wilbur Hubbard"
wrote:

"Bob" wrote in message
...

The next major project was to clean off the bottom of the boat so we
could
do a new bottom coat.

Between the blister repairs we did in our original,

We'll also be doing a new barrier coat - special paint which will keep
water
away from the fiberglass, which can aborb moisture, leading to
blisters,
later. We've taken most if not all of the barrier coat which was
applied
over a "peel job" (removing all the original gel coat, the factory
means
of
applying a barrier to the fiberglass during manufacture) at a very long
time
ago in a prior owner's history, during our blister repairs in our
initial
refit


Dear skip
please describe your bottom history.
im very interested in you "peel job" and "barrier coat" and blister
job... and how your bottom looks now?


You should be able to imagine the hapless "Flying Pig's" condition
yourself
if you've spent time in various boatyards.

"Flying Pig's" bottom, after having been stripped (peeled) of paint as
Skippy indicated he was doing, would look like a patchwork of
roundish-outlined epoxy blister repairs with some new smaller blisters
rearing their ugly heads in between. Also readily visible are the largish
repairs using polyester resin and matt where he's run aground several
times.
Most notable would be on the port side rounding of the bilge where the
"Pig"
lie on her side pounding on a rocky shelf in the Florida Keys that he
would
never have grounded on if he were paying attention to navigation. Also in
evidence would be way too many tired through hulls (probably about 12-18
all
told) for various unnecessary systems which through hulls probably ALL
need
replacing at this stage due to electrolysis, oxidation and galvanic
action.
Some of them are probably little more than soft lumps of patina at this
stage.

For a blistering boat bottom, a barrier coat is but a band aid that
doesn't
usually work so well as moisture already in the layup will remain there
under the barrier coat where it will still fester and pop up new blisters.
The only effective way to get rid of the moisture in the layup is to store
the boat on the hard in Canada where humidity is low and winters are
brutally cold. About two years of dry storage using heat lamps in the
summertime will dry out the soggy lay-up sufficiently so then and only
then
is an epoxy barrier coat of greater worth than dubious.

I hope this helps.

Wilbur Hubbard
Master of "Cut the Mustard" (no blisters-ever!)

Err Willie-boy, you seem remarkably ill advised..... perhaps a
subscription to one of the better boating magazines would be of
advantage. Rather then just trying to read the free magazines down at
the drugstore.
Cheers,


Um, Bruce, I am NOT ill-advised. The ONLY way to get the saturation out of
the laminate which causes the blisters in the first place is to dry it
thoroughly. The fastest way to dry it is a very low humidity environment.
Everybody knows that the colder it is the lower the humidity the air can
carry. Skippy's idea of spraying the bottom with fresh water is just plain
ludicrous and ignorant. You've got to view the hull that sits in the water
as a membrane. Anybody knows a membrane won't work as a membrane if it is
impermeable. This is the idea behind the barrier coat - impermeability. But,
if all you do is trap moisture in the laminate under an impermeable layer on
the water side you still get a soggy laminate from the inside as a membrane
will work from inside out just the same as from outside in. Very few boats
have a dry bilge. So, the only solution is to DRY the laminate thoroughly
and this can take up to two years in a low humidity, cold environment.
Checking the laminate with a moisture meter is the test. Never barrier coat
a laminate that isn't in compliance with a healthy dry laminate and if you
want to be thorough barrier coat the dry laminate both inside and out. Now,
run along, you're ignorance bothers me.

Wilbur Hubbard