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The gelcoat on a 24-foot
Four Winns Vista sparkles
while anchored along
Pictured Rocks National
Lakeshore in Michigan.
ASK THE EXPERTS
SOLUTIONS FROM THE BoatU.S. TECH TEAM
IS MY GELCOAT DAMAGE
I’ve scrubbed the freeboard and gunwale of my 1998 Cruiser Yachts 3850
with a Scotch scrubber sponge (like for pots and pans) and 409 with bleach
each spring, followed by applying a 3M rubbing compound with a buffer.
This season the shine didn’t last and I have discoloration at the waterline
(brown; boat is white). I’m worried I destroyed my gelcoat and am wondering how to assess the state of it. Is it gone? Does it need wet sanding? Does
it need polishing (same as rubbing compound I think), followed by waxing to
bring back the shine and protect the gelcoat?
Bel Air, MD
DON CASEY: Gelcoat is relatively soft, and for sure you did yours no favor by scrubbing it
with a pot scrubber. The good news is that gelcoat starts out relatively thick, so it can tolerate
quite a bit of abuse before it’s unsalvageable. What the condition of yours might be I cannot
say, but you need to stop using harsh abrasives and chemicals. Your boat is plastic, not stainless steel or cast aluminum. Waterline discoloration is typically caused by tannins and other
contaminants in the water. If you’ve made your gelcoat more porous by scrubbing with too
much bleach, this type of staining happens
more easily and becomes more difficult to
remove. Removal often requires a specialized
waterline cleaner, which typically contains
acids (this should only be done onshore).
The last thing your gelcoat needs is acid
attack, but you may be out of options. If your
gelcoat hasn’t been thinned beyond redemption by all of your earlier abrasion, you might
extend its life by polishing it a final time with
a very mild cleaner polish — not a rubbing
compound — followed by a double application of a good paste wax such as Collinite No.
885. In the future just wash and wax; you’ve
already done too much polishing.
If the brown discoloration isn’t from
staining, if it was there before you launched,
you may have rubbed away so much gelcoat
that you’re seeing the fiberglass laminate
behind. If that’s the case, you can’t save the
gelcoat. The hull will have to be re-gelcoated
— an expensive, labor-intensive process —
or you’re faced with painting the hull to