April 2002 — By Diane
Best Face Forward
|Part 3: Delamination|
There are different ways to repair blisters, depending on their severity. If they’re near the surface and limited to a small area, you can tackle the job yourself. First carefully open the blisters with a sharpened object like an ice pick and let them drain; if there’s any damaged fiberglass, you’ll need to grind it out as well, being careful not to grind into the hull. Next let the area dry out thoroughly over the course of a few days. Consider purchasing a heat gun or using a hair dryer to aid the effort and a moisture meter to monitor the progress. This drying step is crucial, since if any moisture is left, the blisters will only recur and perhaps spread. Once the area is thoroughly dry, fill it with epoxy resin and sand it down. The thoroughly wipe down the area with a clean cloth and fresh water, letting it dry before applying a barrier coat, available from the major paint manufacturers. This will help block future moisture intrusion. Finish up with your regular bottom paint.
If the blisters are spread over a wide region, all of the gelcoat should be removed so that the moisture is completely exposed to the air. Even if you’re handy, it’s best to let a good repair yard tackle this, since the job is labor-intensive and involves a lot of sanding or grinding, plus requires applying a good deal of fairing after the grinding is completed. Pros often use peeling agents or sandblasting.
The next step typically involves using fresh water and a stiff brush to thoroughly remove dust and other debris that, if left behind, can cause blisters to reappear. Once the hull is completely dry–here’s where a moisture meter comes in handy again–the epoxy can be applied and sanded down. Then it’s time for the barrier coat and final painting.
If the blisters caused pitting, the yard will need to examine the area carefully to determine the degree of damage. The affected laminate may need to be cut out and new layers applied before the experts put on the epoxy, barrier coat, and paint.
When delamination occurs, the affected area weakens and becomes soft to the touch. It’s not enough to simply drill into the weakened spot and inject epoxy to firm it up; the delaminated section could still be wet inside, and your problems will only worsen. Instead, call in the pros, who will need to cut the delaminated area open so they can clean out the damage (including any coring) and let it dry thoroughly. Once that step is complete, they will recore and/or refiberglass the structure. Admittedly, this can be expensive, but it’s better than risking catastrophic problems down the road.
As they say in sports, the best defense is a good offense–and when it comes to your boat, the best defense against stress cracks, blisters, and delamination is diligence in inspecting her surfaces every time you take her out of the water. Hopefully you won’t ever encounter any of these problems, but if you do, you’ll be better prepared.
This article originally appeared in the January 2003 issue of Power & Motoryacht magazine.