Page 154 - The Complete Rigger’s Apprentice

tively short unsupported lengths by shrouds, stays, the top, as well as angle-providers for intermediate
spreaders, and partners. It can be lighter than if it shrouds. Because all these spreaders break the mast
had a huge unsupported length. And this is good, into shorter unsupported lengths, the mast section
since a lighter mast can translate into a more effi- can be significantly smaller or thinner-walled.
cient sailboat. Spreaders, on the other hand, have Multiple spreaders are no placebo. On moder-
a short overall length but no intermediate supports. ate-height rigs, they’re just so much extra clutter and
Overall length, in their case, is the same as unsup- expense. And the virtues of multiple spreaders are
ported length. Spreaders therefore can only be made regularly abused by race-crazy sailors. They want
to resist deflection by being made stiffer and heavier.
And the longer they get, the stiffer they have to be Figure 5-13. A double-spreader rig. To calculate
for the same load. So there is a balance between the maximum load that would bear on the upper
shroud angle and spreader stiffness which tends to spreader, solve graphically as in Figure 5-10, or use
limit spreader length (the alternative being massive the formula, Total Compression = Tension 5 Width ÷
scantlings of objectionable weight and windage). Length of one leg. Substituting, we get 6,300 5 4.5 ÷ 8
In any event, the maximum practical length for = 3,544 pounds of compression load, or 1,772 pounds
spreaders is about half the vessel’s beam at the mast. on each spreader.
Otherwise you risk snagging docks or other people’s
spreaders in close quarters. And very few boats have
even half-beam spreaders, because spreader length 11°
limits how closely you can trim your headsails. Leg = 8 ft,
⁄32" 1 x 19,
7
Which is why all racers and not a few cruisers sport 6,300 lbs
dinky little spreaders, increased mast and rig loads
be damned.
Bear in mind that by putting a few spreaders
on a mast, and running a few wires over them, you 2.25 ft
create a structure much more complex than any
sling. The spreaders thrust laterally, and must be
checked by still more wires, which in turn load up
other spreaders, which . . . well, you can see why
rig design is so varied, with each designer trying to
juggle the variables to match the demands imposed
by a given boat and a given client.
With very tall rigs, the game of long-or-short
spreaders becomes even more complex. A big
height-to-beam ratio means that even a very long
set of spreaders won’t produce an acceptable stay-
ing angle. And the great unsupported lengths
above and below these spreaders would necessitate
an extremely heavy mast section to resist deflec-
tion. That’s why designers go with multiple sets of
spreaders. The topmost set gives the upper shrouds
a good lead to the masthead, and because they’re up
high, they can do this and still be stubby enough not
to poke a hole in the jib. Lower sets of spreaders are
way stations for the upper shrouds on their way to

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