Thursday, August 21, 2014

Marine Hardware: Dinghys are Yachts Too!

If you maintain a "big boat" properly, you know that most hardware should be proper 316 stainless steel, excepting specific scenarios for avoiding corrosion due to dissimilar metals.  You also (should) know that all hardware penetrating a permeable material (like deck core) should be potted using thickened epoxy.  Hardware bases are also supposed to be sealed to avoid water ingress.  But on dinghys?

If it's cored, or has wood under an active stringer, then I'll buck common convention and cast my vote for properly potting everything that has a permeable core.  Why?  For the same reasons we do it on big boats.

As I was removing the bolts which fix the benches to the stringers I had a heck of a fun time due to the nuts being rusted in place.  That rust has also left stains in certain places on the hull where its had time to weep.  Proper 316 SS hardware would not have rusted in place and gripped the wood in the same way, nor would it have left stains.

A properly potted hole in a cored laminate also provides a compression post which keeps the outer laminate from cracking and admitting water.  I removed many nuts that had been tightened right into the laminate.  This made them not only difficult to remove, but it also damaged the underlying wood by crushing it, allowed water into the cedar core via the cracks, and over time may have allowed sufficient water in to freeze and expand causing failure of the stringer tabs.

Over time that same water which was trapped in the laminate would rot the stringer, or at least the area where the crack occurred, giving the appearance of a loose bolt.  After a few times being tightened, the washer and nut would crack their way right through the fiberglass.

Dinghys are usually not off-shore vehicles, and are not subject to the same loads that a "big boat" deals with.  But unless you plan a short life span for one of these boats, they need the same care to keep them structurally sound, and save a future owner the hassle of structural repairs.

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