Pre-Purchase Inspections
July 2010 - Wet Core

A boat builder I once met said to me, during a discussion regarding technique for installation of hardware, "there are many ways to build a boat and most of them are right". I politely but firmly disagreed. When it comes to the installation of hardware on cored fiberglass structures, this includes everything from windshields and cleats to navigation lights and name boards, there is, in my opinion, only one way to do it right. Anytime the cored structure is penetrated, accessed, cut or drilled through, the core itself must be properly sealed to prevent water ingress. "Sealed" can be a misleading term. Many installers and builders believe that sealing means coating the exposed core with resin or epoxy. In fact, nothing could be further from the truth.

Sealing or "closeout" as it's called within the industry involves removal of the core material for some distance from the hole's opening and replacing or backfilling it with a thickened epoxy mush. This process is sometimes referred to as reefing and backfilling. As an alternative, if the builder of the vessel anticipates installation of standard hardware items (and he or she should), such as rail stanchions, windlasses and cleats for instance, then solid fiberglass or proprietary high density, "waterproof" and "crush resistant" core should be laminated into these sections. Custom, aftermarket installations such as the aforementioned name boards, antennas and EPIRB shelters all require the reefing and backfilling approach. With rare exceptions, simply bedding the hardware in sealant is not an acceptable means of preventing core saturation.

While some core material is more resistant to degradation when wet than others, balsa, plywood and other organic core deteriorates when wet, while foam and other synthetics typically do not, water entry into any cored structures is always undesirable. Even if water entry did not lead to core degradation, core crushing in the area of hardware installations remains an issue.

In the image shown in this month's ad, taken aboard a new vessel, water has entered the cored stringer through an unused screw hole, probably drilled in error while installing support for bilge pump wiring. The core material is almost certainly timber, evidenced by the familiar brown staining that occurs when wood becomes wet in a low oxygen environment, inside the laminated stringer in this case.

If you're interested in finding out more about Pre-Purchase Inspections like the one described above, system inspections, vessel selection assist, the Captains' Club (simply click on these words to be taken to the relevant sections of this website) or other services offered by Steve D'Antonio Marine Consulting, email or call 804-776-0219.