Page 48 - The Complete Rigger’s Apprentice

BLOCK AND TACKLE Cunninghams

In Figure 2-2, a line is led up from the load, through A Cunningham is a block and tackle on the luff
a block, and down to the hauler (force). The only of the mainsail that adjusts sail shape. Originally
advantage here is convenience—the force is equal to used by racers as a way to get untaxed luff length,
the load, and you can haul something light up over it is of great benefit to cruisers, since it allows for
adjusting the luff without having to mess with
your head. the halyard, and especially without tightening the
In Figure 2-3, the line comes down from an over- leech. Because a Cunningham pulls from the bot-
head support, through the block, which is attached tom of the sail, where the greatest area is, it is more
effective at moving draft around, and with less
to the load, and thence to the hauler. Now the hauler effort than the halyard.
shares the load with the overhead support, so the Cunninghams are also a great idea for the
load is halved; you can pick up a much heavier load genoa, for the same reasons as for the main. They
than before with no more effort, but you can’t pick are particularly useful for roller-furling headsails,
since a properly located halyard swivel limits the
it up far unless you add another block, as in Figure range of halyard adjustment.
2-4. This one, like that first single block, adds no
advantage. As we keep adding parts, it will become
difficult to figure out when we’ve added advantage the moving block means that you are devoting some
and when the lead is just being redirected. The basic of your effort to pulling sideways, leaving less to
rule is that you count the number of parts coming pull up. The wider this angle is, the more effort is
out of the moving block(s). In Figure 2-4, the block siphoned off.
that is attached to the load moves as the load is In Figure 2-5, a small type of block and tackle
raised. There are two parts coming out of that block, called a handy-billy is set up to the load. The lower
so there is a two-part purchase. The other block block shows us that there is a three-part purchase
doesn’t move, so it adds no advantage. here. Figure 2-6A, B shows the same gear inverted—
Important detail: We show the upper blocks resulting in a four-part purchase. Again, we have
separated here for clarity, but in the real world this gained height by adding a block aloft, as in Figure
would cause a loss of power; the angle formed on 2-4. We could use two fiddles to the same effect
(Figure 2-6B), or we could make up a purchase as
in Figure 2-7, simultaneously changing the lead and
Figure 2-2. Figure 2-3.

Figure 2-5.

Figure 2-4.

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