How does water get inside the fiberglass laminates?
There are several ways for water incursion to happen. Below the waterline, the pressure
exerted by the water will push the water through gel coat into the laminates. Gel coat is not
totally waterproof and some types of resins are more permeable than others. Vinylester and
epoxy resins are most resistant. Be careful to use the right products for hull repair. Above the
water line, damage to the gel coat will admit water. Poorly sealed or loosely mounted hardware
will allow water to penetrate the protective gel coat skin and follow the glass cloth like a wick
into the core material. In the north you can imagine what freezing and thawing of this moisture
will due to the laminate structure. Water incursion can be prevented by careful manufacture of
the fiberglass laminate. Modern methods such as SCRIMP molding all but eliminate voids in
the laminate. Correctly mounting seacocks is vital to prevent seawater seeping around them
into the hull structure. All deck-mounted hardware should be painstakingly sealed, and
resealed every 7-10 years.
There are several ways for water incursion to happen. Below the waterline, the pressure
exerted by the water will push the water through gel coat into the laminates. Gel coat is not
totally waterproof and some types of resins are more permeable than others. Vinylester and
epoxy resins are most resistant. Be careful to use the right products for hull repair. Above the
water line, damage to the gel coat will admit water. Poorly sealed or loosely mounted hardware
will allow water to penetrate the protective gel coat skin and follow the glass cloth like a wick
into the core material. In the north you can imagine what freezing and thawing of this moisture
will due to the laminate structure. Water incursion can be prevented by careful manufacture of
the fiberglass laminate. Modern methods such as SCRIMP molding all but eliminate voids in
the laminate. Correctly mounting seacocks is vital to prevent seawater seeping around them
into the hull structure. All deck-mounted hardware should be painstakingly sealed, and
resealed every 7-10 years.
From the Surveyor's Notebook
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