Page 182 - The Complete Rigger’s Apprentice

corresponding strength; turnbuckles are made to fit Compatibility is the key to gear selection for a
swaged 1 x 19 these days. Spectra standing rigging good working rig. Make lists, check catalogs, com-
is also a little larger in diameter than the 1 x 19 it pare specs, think things through. Do you need to
might replace, but it is possible to get turnbuckles for have every line leading to the cockpit? Are there
it nowadays, from the Blue Wave company. enough of them to make color-coded rope worth the
For your mast’s standing rigging, there’s noth- bother? Will the boat look funny with sheer poles
ing wrong with using galvanized steel turnbuckles with belaying pins in them? Will the boat work well
with either stainless or galvanized wire, as long as without them? Are you going to regret having a
it’s above the water. But don’t mix the two metals spinnaker, or not having one? Sop up all the data
where galvanic action is likely to be severe, as on you can, let it slosh around inside for a while, and
the lower ends of boomkin shrouds and bobstays. then solve by association. You probably understand
For further discussion of galvanic action as it affects the boat pretty well by now; just pay attention to
rigs, see the accompanying sidebar. the engineering and use what suits—the gear that

Tangs

The tang is the intermediary between the mast Reinforcing plates on or in the mast will spread
and the standing rigging. In the tang’s short, shiny the load still further, so they’re a valuable option,
length a miracle happens: the tension from the wire particularly on wooden masts, or thinner-walled-
is absorbed, makes a near-180-degree turn, and is than-usual aluminum masts. The plates are secured
somehow translated into compression on the mast. with screws or rivets, and both throughbolt and com-
A well-made tang will accomplish this miracle pression tube run through the plates.
through a zillion rig cycles; a poorly made tang will The bolt hole and clevis pin holes in a proper
drop the mast in the water. Here are some details that tang are no less than ⁄100 inch, and no more than
1
will keep the mast in the boat. 1 ⁄64 inch larger than the pin or bolt that goes through
them. That is, the hole is big enough that you don’t
Fair lead have to hammer the bolt or pin in—and out—yet
External tangs are angled laterally to point outboard small enough that you don’t get “point loading.” If
to the chainplate (or to the spreader tip). If your rig- your holes are too big or too small, or if your mast
ging bends as it leaves the tang, you have a foul lead. can’t take the strain, you have a foul load.
Tangs are also angled fore or aft, depending whether
the chainplate is forward or aft of them. This angle Fair angles
can change according to mast rake, backstay tension, The clevis pin on an external tang bisects the tang at
and rig load magnitude. Therefore, the best way to right angles, if the holes are drilled in the right places.
get an appropriate fore-and-aft angle is to hang the Likewise, the throughbolt must bisect the mast at
tang on a throughbolt, so it can pivot. right angles. If pins or bolts don’t go through square,
you have foul angles, and thus concentrated loads on
Fair loading some points.
The throughbolt can manage the load if you just
make it the same size as the clevis pins (or the next True throughbolts
size bigger for double tangs). But the concentrated Ideally, both ends of the throughbolt will be threaded
load can be hard on your thin-walled, softer-material to hold nuts, which contain the tang laterally. That
mast. That’s why it’s a good idea to run the through way you can remove a tang from either side without
bolt through close-fitting, heavy-walled, flanged removing the entire assembly.
bushings, for a fatter bearing surface. Ideally the By far the most common tang flaw is bolt thread-
bushings will run through the tangs as well as the ing that extends under the tang; a bolt is weaker
mast. Bushings are superior to full-length compres- where it’s threaded, and can invite corrosion, so
sion tubes, in that they are lighter than a compara- this is a too-frequent failure point. Get your bolts
bly thick tube. They also do not require that you threaded on a lathe so the threads stop at the tangs.
cut them to a specific length, as you need to with This threading will also assure that there is no danger
the tube. of buckling the mast wall when tightening the nuts.

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