Gemini 105Mc Owner’s Manual
43
Copyright © 2004 Performance Cruising Inc.
velop a chalky appearance. Waxes may reduce this
but it is only cosmetic. The gelcoat used on the
Gemini are “buff-back” and can be compounded to
bring the color back. Commercial cleaners are avail-
able for removing oil, fuel, and metal stains on the
hulls. Once the stain is removed, the cleaner should
be washed off.
Bottom Paint
Gemini is delivered with bottom paint (Interlux Bot-
tomKote Black 779). However, the problem with new
boats is that the fiberglass is new and still releasing
Styrene. It is difficult to get bottom paint to stick,
even with coarse sanding. The procedure we follow
is recommended by Interlux. We use Solvent Wash
202 to remove traces of the mold wax. This is done
using many rags and taking care not to simply dilute
the wax and smear it over the bottom. No-sand
primer is then painted on the bottom. As soon as the
no-sand primer is dry we paint on Fiberglass Bottom
Kote. The bottom is not sanded as that will damage
the gelcoat.
There are two types of bottom paint. Paint with
copper in it at various percentages and a paint that
slowly washes off called an ablative paint. The cop-
per-type paint works well for the first 6 weeks be-
cause the copper is at the surface. As the surface
copper dissolves the bottom paint starts to loose its
efficiency. Unfortunately, applying numerous coats is
a waste of time. This loss of efficiency is true of all
bottom paints, even popular paints such as Trinidad.
The ablative bottom paints like Interlux CSC work
well because as the paint is worn off new copper is
exposed. The more coats that are applied the longer
the paint will last. These types of paint will last
many years. We recommend Interlux Micron Extra
5693 Black for the Chesapeake Bay area.
Because Trinidad and Interlux CSC are soft paints
they will fall off easily if the hull is new and still
releasing styrene.
The system applied to Gemini from new will start to
loose its efficiency in the first few months and will
need repainting in 9 months. At 9 months, there is
no need to remove the original paint. Simply remove
the barnacles and any growth, power wash, and al-
low to dry. If any voids are discovered below the
water line, fill with epoxy. If any voids are discov-
ered above the water line, fill with gelcoat paste. If
necessary, lightly hand-sand any white areas and
paint on Interlux CFC right on top of the existing
bottom paint. Paint the centerboards and rudders in
the same manner as the hulls.
We highly recommend keeping up with scheduled
bottom cleaning and painting.
Care and Cleaning of Fiberglass
For more information on bottom painting—see the
bottom paint FAQ on page 59 of this manual.
Blisters
Many years ago blisters were probably caused by
inferior, perhaps filled resins. A few years ago a new
problem started. With the explosion of the small
powerboat market, resin and gelcoat manufacturers
started to reformulate their resin for rapid cure.
With these resins a small hull could be gel coated in
the morning and be ready for release in the evening.
Unfortunately, a larger, more complex hull could
take several hours to just gelcoat. The skin-coat
could also take several hours and the skin-coat could
not be applied until all the gelcoat was cured. The
main lay-up would comprise several layers. Normally
all these layers are applied at once. With these
newly formulated rapid cure resins, the molecular
interlaminate bond between the gelcoat and the
skin-coat and then the main lay-up was not as good
as it could be. However, because the main lay-up
was all applied at once, there would be no suspect
interlaminate bond in the main lay-up. If there were
any problems with these boats the problem would be
obvious within two years. Coating with epoxy was a
good cure. It was not advisable to use sand blasting.
Simply removing any loose surface was suitable.
Recently, resin manufacturers have developed pre-
mium gelcoats, vinylester resins, and fine fiberglass
veils. Vinylester resins are the most waterproof.
Gemini has a 20-mm veil with vinylester resin ap-
plied just behind the gel coat and has not experi-
enced any major problems with blistering.
However, it must be understood is that there is no
such thing as a totally waterproof resin. Eventually
water will penetrate all fiberglass hulls. It is possible
that as the water penetrates the hull, any impurities
can be dissolved, forming a thick liquid that will ex-
pand to form a blister. If this should happen it will
be isolated and should simply be ground out and the
void filled with low-shrink waterproof putty.
As described in the Construction portion of this
manual, the Gemini is a difficult boat to build. Only
the best materials are used. Applying the fiberglass
to vertical surfaces from several feet away using a 6'
pole on a roller, can produce a situation where there
are air voids between the main lay-up and the skin
or gelcoat. When the boat comes out of the water
for storage or repainting, if there are any air voids
under the gelcoat they will be noticeable as a blis-
ter. These blisters should simply be ground out and
the void filled with low-shrink putty. The boat can
then be bottom painted. These blisters are almost
certainly not structural and can be easily fixed.
