Bottom Job

[yachty]

Hey All!
I removed the gelcoat from the bottom of our Nauticat 33 with a gelplane. It had about 1000 gelcoat blisters but none had penetrated the layup.
The gelcoat was quite thick about 1/8-3/16".
The question is . . . what type of cloth should be used to build it back up using the WEST System. I want to avoid microballoons and build up the surface to the profile before planing and attempt to produce an impermeable surface.
Thanks,
Yachty

[camaraderie]

Steve D'antonio is one of the most often quoted experts on the peel and repair approach and his advice is:

"The relaminating process using VE
resin, after the hull has been peeled
and properly prepared,
must incorporate a minimum
of two laminate
layers or 1/10 of an
inch of laminate. This
depth of applied material
ensures that an
appropriate exothermic reaction or
heating takes place. This reaction is
necessary for the resin molecular
chains to interlink properly. Ideally,
the laminate that is removed should
be duplicated exactly, once again to
the previously stated minimums. Any
FRP material that is removed must
always be replaced. Although it is
tempting to add a little more, chances
are good that the naval architect who
designed your boat knew what he
was doing, and thus, his laminate
schedule is appropriate and is worthy
of duplication. For the same reason,
failing to replace some or all of the
removed material is forbidden.
VE resin has a higher tensile
strength and tensile elongation factor
than the original PE resin as well as
possessing excellent secondary bonding
attributes. Provided the moisture
analysis, peel, preparation and lay-up
are carried out properly, the relamination
should be quite strong and
immune to future blisters.
Epoxy barrier coat
The final step and what may be
termed the suspenders of a belt-andsuspenders
approach is the application
of an epoxy barrier coat over the
relaminated hull. My preference is for
a high-solids, epoxy-based, warranted
coating that is backed by a reputable
manufacturer of marine products.
Resist the temptation to use products
that make incredible or fantastic
claims. Instead, go with a proven performer
who has a long-term track
record of standing behind their product."

See complete article on blister causes and correction process here:
http://www.zimmermanmarine.com/docs/blisters%201.pdf

P.S....I think you got a lot more than gelcoat!

[sailingdog]

If you shaved 1/8-3/16" off... that wasn't just gelcoat. If the blisters were just in the gelcoat, I doubt they were more than a 1/16" or so deep. You might want to contact Nauticat and ask them what the laminate layup schedule was for the Nauticat 33. That way, you can replace the laminate you removed with similar weight cloth.

[TrueBlue]

Actually guys, Nauticat applied the thickest gelcoat on my prior NC33 I had ever seen, as was typical of all the boats they produced from their yard in Finland. It may be slightly less than 3/16" (.1875) but 1/8" (.125) seems right.

I still have a deck section of the solid glass (under teak overlay) I cut out while installing a new windlass, revealing evidence to this fact.