Osmotic Blistering; Antifouling Paint; Hull Support - Four winns Horizon 210 Owner's Manual

More severe fiberglass damage, especially when struc-
tural, requires the expertise of an experienced fiberglass
repair technician. See your Four Winns® dealer for as-
sistance.
NOTICE
Improper repair techniques can lead to further
fiberglass component damage.
C. Osmotic Blistering
Osmotic blistering or “boat pox” is an unfortunate but
not uncommon occurrence in fiberglass boats. Fiber-
glass is water retardant, not waterproof. When a boat is
left in the water for a period of time, the fiberglass will
absorb water. It is a natural process that can not be
eliminated in production methods or material selection
and usage. However, there are ways to control and
possibly prevent blisters (see Section P-6). If you do
encounter blisters, be assured that the blisters are merely
cosmetic. They do not indicate a defect in the boat struc-
ture or lamination. Four Winns®, along with most boat
manufacturers, regard gel blisters as a standard main-
tenance item.
The repair procedure for gel coat blisters is similar to
the procedures outlined in the previous section on cracks
and gouges. There is an exception however, in that the
hull must dry out for several days or possibly weeks
before repairs can proceed.
To determine if the hull has dried sufficiently, tape one
square foot of household plastic wrap securely to the
hull bottom. Make sure all edges are sealed and let it
stand for twenty-four hours. If condensation has accu-
mulated under the plastic, the hull is still “wet” and must
be allowed to dry longer before repairing.
When the repair is completed, an application of an ep-
oxy barrier coat should be considered. This will help
prevent the possibility of reoccurrence of blisters. Your
Four Winns® dealer or local ship store will have informa-
tion on barrier coat products.
P - 6

ANTIFOULING PAINT

Four Winns® recommends antifouling or bottom paint
for boats which will be kept in the water for extended
periods of time. Antifouling paint reacts with water to
retard the growth of algae, barnacles and other marine
growth on the hull. In addition to marine growth, it offers
protection against excessive water pollution.
Horizon & Sundowner
Owner’s Manual
06/00
Antifouling paint begins reaction upon contact with wa-
ter. After a season’s use or sooner under certain condi-
tions, the antifouling paint may appear to be dissolving.
This is due to the paint’s chemical emission that in turn
retards marine growth. When this occurs, refinishing is
in order.
Four Winns® recommends reapplication of the antifoul-
ing paint seasonally. The effectiveness of the paint will
be drastically reduced if used longer. Though
Four Winns® has found the antifouling paints used to
provide good marine growth protection in most water,
other paints may be more effective in certain water con-
ditions. See a Four Winns® dealer for recommenda-
tions on antifouling paint use in your area.
NOTICE
During surface preparation, the hull should be
sanded only enough to remove any foreign mat-
ter, and loose paint. DO NOT sand deeply into
the gel coat, fiberglass cosmetic problems could
later result. After sanding, the surface should
be wiped with a rag treated with a cleaner recom-
mended by the antifouling paint manufacturer.
The surface must be clean and slightly rough to
ensure paint adhesion.
Prior to application of the antifouling paint, the boat owner
may consider coating the hull bottom with an epoxy coat-
ing. Four Winns® recommends this procedure as a pre-
ventive and effective means of controlling osmotic blis-
tering. Most major antifouling paint manufacturers also
supply a line of epoxy undercoatings. Consult your Four
Winns® dealer for recommendations on epoxy under-
coatings.
P - 7

HULL SUPPORT

Proper support of the hull while it is out of the water is
imperative. Due to the design complexities, Four Winns®
does not recommend trailers or storage cradles be home-
made. The boat is a valuable piece of equipment. DO
NOT risk permanent damage to the hull structure in an
attempt to save the cost of an adequate support. Improp-
er support can lead to serious and permanent hull defor-
mation.
Failure to adequately support the hull may
result in permanent hull structure damage
and will invalidate the hull structure war-
ranty.
Section P
Page 5