Page 200 - The Complete Rigger’s Apprentice

Figure 6-3. To expedite layout organization, list rig-
ging pieces, their pertinent dimensions, and any notes Table 6. Wire Rope Constructional Stretch as
on an accounting pad. Percentage of Length (Courtesy MacWhyte Co.)

to our notes we want to subtract 1 ⁄2 inches from
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this length to add a toggle. If the old piece is 12 feet,
enter 11 feet 10 ⁄2 inches under “Finished Length”
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opposite “starboard after lower shroud.”
Now stretch out the port after lower shroud, imate constructional stretch in percentage of length
which is not necessarily the same length as its star- for various kinds of wire rope. Our 7 x 7 preformed
board-side counterpart. Slight irregularities in mast carbon steel will stretch 0.06 percent of its length.
or hull can easily make a significant difference. In This works out to a little over ⁄8 inch, not enough to
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this case the lengths match, and 11 feet 10 ⁄2 inches bother deducting from the length of the new wire, so
is entered for this wire, too. for both uppers we’ll just subtract 1 ⁄2 inches for the
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Repeat this procedure for the starboard and port toggle. For long pieces, such as uppers and jibstays,
forward lowers, then lay out the starboard upper. Its we also need to deduct for “working elasticity” (see
length is, say, 20 feet. In wire of this length we begin sidebar). Because long pieces are tuned tighter, they
to worry about “constructional stretch,” the initial stretch more than shorter pieces.
elongation of new wire as its individual strands set- If we were instead using 7 x 19 stainless wire for
tle into place under load. The short length of the the rig, constructional stretch over the same length
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lowers would result in negligible stretch, and it would have amounted to over ⁄4 inch, enough to
wouldn’t amount to much in a 20-foot length either; use up an excessive amount of turnbuckle slack; it
but to be cautious, refer to Table 6 showing approx- would have been better to deduct this plus the toggle

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