Sailboat shrouds are
connected to chainplates at deck level.
Typically made of
stainless steel, the top of the
chainplate – really a stout stain-less-steel bar – extends above
the deck and provides an attachment point for the shrouds
that support the mast. A failed
chainplate can easily bring the
mast crashing down, and if
it’s like this one shown, you’ll
have had very little warning
before the fact.
Many think that stainless steel
is impervious to corrosion. But
there’s a kryptonite for stainless
steel, and that’s lack of oxygen.
The anti-corrosion properties of
stainless steel rely on oxygen
to maintain the exterior oxide
coating that prevents corrosion
from forming. Without oxygen,
and in the presence of saltwater,
even stainless steel can’t main-
tain its strength and corrosion
resistance. Chainplates are often
bolted to interior sections of the
boat hull in areas that are oxygen
deprived. Some chainplates are
even installed within the hull’s
fiberglass layup. Without a fresh
supply of oxygen, stainless steel
moves way down on the galvanic
scale. That is to say, it will rust.
And, eventually, the chainplate
Look for signs of rust or water
intrusion at the chainplates
wherever access can be gained,
and do it at least once a year.
Be sure the deck is well sealed
to prevent water from entering
around the chainplate. If your
boat’s more than 20 years old,
you should really do a thorough inspection. Remove the
chainplates and have them
examined by a pro.
While we’re on the topic of rigging, you’ll find this little fellow
just above the chainplate. It’s a toggle at the lower end of a
sailboat shroud, and in this case, it’s the weak link that’s being
called upon to keep the sailboat mast from toppling over.
This picture again brings home the point that no metal
on a boat lasts forever. The crack in this fitting is very evident, and should this fitting fail under a heavy load, it would
spell disaster. Corrosion and cracking this dramatic screams,
“Inspect the rig! All of it!” Rigging has a finite life – perhaps a
longer life span in colder freshwater environments, but finite
nonetheless. There’s not much to prevent corrosion on fittings like this one. You just have to be vigilant. Get out your
magnifying glass and spend some
time on your hands and knees taking
a close look at your deck fittings, and
if one is bad, odds are that other similar fittings on board aren’t far behind.
Use your camera and its zoom lens to
get at least a cursory look at rigging
above deck level. If anything suspicious is spotted, make arrangements
for an up-close inspection.
Captain Doug Alling is an American Boat & Yacht Council Master
Technician, the principal surveyor for Rum Line Marine Consultants in
South Carolina, and a member of the Knox Marine Consultants team.
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