Q & A — February 2005
By Capt. Ken Kreisler
| How water infiltrates a fiberglass hull, bleeding a hydraulic steering system, and more.
How does moisture get into a fiberglass hull, and what happens when it does? B.W., via e-mail
If your boat was built using polyester resin, keep a close eye out for blisters, although damage can occur without their appearance. Fortunately, they often can be easily and quickly repaired before the laminate is damaged by hydrolysis. Addressing the problem as soon as possible is vital.
Without a core sample, moisture content is difficult to ascertain. The suspect areas must be as dry as possible before work can begin. During this process, which can include tenting, using dehumidifiers, and keeping the interior and bilges dry, you can use a pinless moisture meter. However, most experts agree that a moisture meter should not be the sole determinant, and readings should be done at regular intervals above and below the waterline along the entire length of the hull.
Another method of determining moisture content is to tape a six-by-six-inch square of six-mil plastic to several locations on the hull, both above and below the waterline, sealing the edges tightly. As the hull dries, moisture condenses on the plastic. Remove the squares every few days, note the amount of condensation, and apply new squares until little or no moisture is present. This is a relative test of moisture content, meaning you must account for changing humidity and temperature.
Qualified personnel familiar with the intricacies of the job should be called in with this kind of problem. Gougeon Brothers, manufacturer of the WEST SYSTEM® line of products, has an excellent series of manuals that deal with this and other fiberglass problems. For more information visit its Web site at www.gougeon.com.
Next page > Part 2: Bleeding a hydraulic steering system, and more > Page 1, 2, 3
This article originally appeared in the January 2005 issue of Power & Motoryacht magazine.