Osmotic Blistering - Four winns SL series Owner's Manual

cosmetic and can be treated. Cosmetic surface dam-
age can be repaired as follows:
1. S and the surrounding area with medium or fine grit
sandpaper. Clean all marine growth, dirt, anti-foul-
ing paint, etc. from the immedi ate area. DO NOT
excessively scratch or gouge the sur round ing area.
2. Use a hard, pointed tool to open the gel crack.
Take care not to damage the sur round ing gel coat.
3. Sand the crack or gouge so the edges are smooth
and will allow proper "feathering" of the area.
4. Clean the area thoroughly. Make sure the area is
dry before proceeding.
NOTICE
Be sure the structure and the ambient tempera-
ture are above 60 degrees F (15 degrees C)
and the relative humidity below 70% immedi-
ately before, during, and after the repair.
5. If the nick or gouge is deep and pene trates
through the gel coat, fill the area with fiber g lass
patching paste. Follow the directions on the can
when mixing the paste with the cata lyst.
6. A fter the gouge is filled and has dried, sand the
patched area. Begin by using medium-fine grade
sandpaper. Progres s ively use finer grade sandpa-
per until the surface is very smooth. If necessary,
add filler and then sand the surface again.
7. A pply two or three light coats of matching fiber-
glass gel coat to the repaired area. Enough gel
coat should be used so that the entire area is
covered.
The gel coat must be cata lyzed using up to 2% MEK
Peroxide which can be pur cha sed at a supplier han-
dling fiber g lass rein f o r ced products. Contact your Four
Winns dealer for assis tance.
8. After ample drying time, sand the area using very
fine wet/dry sandpaper. If the appear a nce of the
area is still not satisfac tory, repeat steps 2 through
8 as neces sary.
9. If above the waterline, polish the area using a
fiberglass rubbing compound and then wax. If
the repaired area is below the waterline, the area
should be primed and painted in accor dance with
the anti-fouling paint manuf actur er's instruc tions.
Gel coat, like paint, will change colors with time
and exposure to sunlight (ultraviolet). For this rea-
Fiberglass and Hull - Section P
son, "matching" gel coat obtained from Four Winns
may not match the gel color of a boat that has
been exposed. However, this is the closest match
commercially available. A fiberglass/gel coat tech-
nician can tint the gel to be used in the repair to
provide a closer color match.
More severe fiberglass damage, especially when
structural, requires the expertise of an experi enced
fiberglass repair technician. See your Four Winns
dealer for assistance.
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 water proof. 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 selec-
tion 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 indi cate a defect in the
boat structure or lamination. Four Winns, along with
most boat manufacturers, regard gel blisters as a
standard maintenance 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 pro ceed.
To determine if the hull has dried sufficiently, tape one
square foot of household plastic wrap secure ly to the
hull bottom. Make sure all edges are sealed and let it
stand for twenty-four hours. If condensa tion has ac-
cumulated 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
epoxy 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 prod ucts.
Owner's Manual Page 122