Chuck Gould wrote:
Harry Krause wrote:

On 11/7/2006 9:51 AM, Chuck Gould wrote:

Harry Krause wrote:


BTW, no matter what anyone tells you or what you read, if you see
evidence of osmotic blistering on a boat you are thinking of buying,
move on. Those in the broker business will try to convince you it is
"only cosmetic," but it can have a far greater impact than that. I was
looking at a boat that had had some blistering repaired and noticed that
more pustules were breaking out elsewhere.


Please do tell how the typical gelcoat blisters found on most used
boats have a "far greater impact" than cosmetic.

David Pascoe, a surveyor who hates dealers and brokers as much as
anybody possibly could, has written that the idea the blisters damage
the structural integrity of a boat is a "misperception" and states that
after examining 4000 used boats with some degree of blistering he found
only about 10 where the blisters actually created an issue with
structural integrity. By my math, that's 0.25%- hardly the sort of
probability that should foster a rule of thumb "run away quickly if you
spot a blister". If a prospective buyer hires a decent surveyor and the
blisters are classified as "cosmetic", there would be no reason to pass
on a boat that was otherwise attractive. In fact, it's pretty common to
demand a further discount once blisters are discovered (most of the
time they are under the waterline and won't be seen until the survey
haulout), and then once the deal closes boat for many many years
without doing a darn thing about the unsightly but harmless pimples on
the bottom.

Pascoe's entire text on the subject:

http://www.yachtsurvey.com/BuyingBlisterBoat.htm


Please elaborate on your rule of thumb.



Not worth the effort, but here is someone else's opinion. Note the
reference to delamination. SeaView site.




Glad you liked that Seaview article, it happens to be one of mine. I
did that interview with Phil for the magazine several years ago, and
they use it for their website.

When I had my boat in for its redo last spring, I had planned to have
the bottom completely stripped, a barrier coat applied, and new bottom
paint. Seaview stopped stripping off the old bottom paint when they
found some blisters. At no charge to me (at least for that) they did
some "test peels" where the skin out mat was removed and the laminate
below was examined. In each and every area tested there was *no*
evidence of delam below the mat, and that is the case in the
overwhelming majority of boats with gelcoat blisters. Seaview didn't
want to proceed with a barrier coat because of the possibilty that
blisters might continue to form and that could be confused with a
warranty issue in the future, but even Seaview agreed that there would
be no need to address the blisters unless I was concerned about
cosmetics.

Blistering can be evidence of delam, but there is no basis to conclude
that whenever one sees a blister there is likely delamination as well.
Nor is there any evidence that blistering will "lead to" delamination.

Thereby leading to my opinion and an opinion shared by a probable
majority of people who have looked into the blistering issue; in most
cases a blister is entirely cosmetic and a decent surveyor will be able
to tell a prospective buyer whether a specific case of blisters might
be that rare situation where the blisters are a visible indicator of a
deeper and structural problem.


"it happens to be one of mine" Love it Chuck:-)

Clearly peeling various depths including the glass laminates
themselves, to exploratory check "if" the blisters are cosmetic or other
is always the best way, but somewhat destructive & if now properly
repaired can cause more harm than the original blister(s); however FYI
here some surveyors still use & swear by, those sophisticated electronic
moisture detectors.

They definitely can detect moisture below the hull surface indeed
depending on the setting can read straight through most fibreglass hulls
(even the bilge, builtin tanks etc need to be totally dry). They can
track the perimeter of the moisture reading & give it an outline
(usually drawn on the hull in texta). If it's substantially bigger than
the blister itself then they go exploratory digging, but if it's
consistently over numerous blisters "just" the blister that contains
moisture then it's declared cosmetic.

Very few glass strands in a laminate, the strands being what the
moisture travels along, go vertically "through" the hull scantling but
they are always oriented along the hull in the layers.

Care & ingredient X (experience?) are always needed because sometimes
the size of the blister is oft little related to the moisture below.
i.e.a small surface blister can sometimes when checked with a meter have
moisture well out from it irregularly patterned literally like a cancer
growth.

K