C. Osmotic Blistering
effective in certain water conditions. See a Four Winns
dealer for recommendations on antifouling paint use in
Osmotic blistering or “boat pox” is an unfortunate but not
uncommon occurrence in fiberglass boats. Fiberglass
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 structure or lamina-
tion. Four Winns, along with most boat manufacturers,
regard gel blisters as a standard maintenance item.
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
mended by the antifouling paint manufacturer.
The surface must be clean and slightly rough to
ensure paint adhesion.
The repair procedure for gel coat blisters is similar to
and gouges. There is an exception however, in that the
hull must dry out for several days or possibly weeks
before repairs can proceed.
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 undercoat-
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.
P - 7
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.
Proper support of the hull while it is out of the water is
imperative. Due to the design complexities, Four Winns
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-
P - 6
Four Winns recommends antifouling or bottom paint for
boats which will be kept in the water for extended peri-
ods 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 protec-
tion against excessive water pollution.
Failure to adequately support the hull may
result in permanent hull structure damage
and will invalidate the hull structure war-
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
When attempting to raise the hull, never allow
one end of the boat to rise first, while letting the
nents could result. DO NOT place lifting straps
on underwater gear. Be sure the strap is against
the hull surface only.
Four Winns recommends reapplication of the antifouling
paint seasonally. The effectiveness of the paint will be
drastically reduced if used longer. Though Four Winns
Sundowner™ Owner’s Manual
|Categories||Four Winns Manuals, Four Winns Sundowner Manuals, Outboard Marine Corporation Manuals|
|Tags||Four Winns Sundowner 205, Four Winns Sundowner 225, Four Winns Sundowner 245, Four Winns Sundowner 285|
|Model Year||2003, 2004, 2005, 2006, 2007, 2008|
|Document Type||Owner's Manual|
|Product Brand||Boats and Cruisers, Four Winns. For support contact your dealer at http://www.fourwinns.com/locate-dealer.aspx|
|Document File Type|
|Wikipedia's Page||Outboard Marine Corporation|
(1 votes, average: 3 out of 3) Marine readers have rated 2003-2008 Four Winns Sundowner 205 225 245 285 Boat Owners Manual 3.0 out of 3.0 based on 1 product reviews.