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Friday, April 01, 2016

Delamination!

No foolin. Stripping away the thick gelcoat non-skid from the top of the cabin trunk has revealed large spots of delamination.

Delamination is something no (fiberglass) boat owner wants to discover. It is a condition where the fiberglass laminate has separated from the core material to produce small voids in between. When a professional marine surveyor taps on your boat's deck with a small plastic ballpeen hammer, delmination is what they are looking for. The impact results in a long 'thud' instead of a sharp 'tap' indicating a void in the laminate.

In this case, no tapping with a hammer was required as the voids can clearly bee seen manifesting as lighter color "splotches" instead of a dark consistent color. Modern sandwich boat construction use special composite cores designed to maximize adhesion. The Westsail factory, back in the day, used plywood as a core material, not unlike CDX grade plywood. The problem with plywood is that there is no end-grain on the face thus minimizing absorption of resin by the wood during the layup, creating a weak bond between the plywood core and fiberglass. The bond could have been improved by cutting numerous grooves in the plywood and priming it with resin before layup. But, if the replaced core at the main mast step is any indication, it appears this preparation was not done at the factory.

This is not as big of a deal as it sounds. With this boat, the fiberglass is too thick to present any structural problems. The main concern is keeping the core dry to avoid any 'soft deck' disease, as once the core is wet, it will never dry. The risk of water intrusion happens when deck hardware is mounted.

Fortunately, the fix for this is simple, if not tedious. Simply drill a couple small holes in the delaminated areas and displace the air in the void by injecting epoxy.

You cant see the delamination in the pictures below, but it is there, in many places.




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