Page 65 - The Complete Rigger’s Apprentice

makes you work harder. That’s why it’s so hard to Efficiency Alternatives
sheet that Genoa in. If the cost of a big enough winch is too high, or if
Bear in mind that we’re talking about loads you’re driving a race boat and the extra weight is a
that you’ll only encounter going to weather in a stiff consideration, there are five other ways to get more
breeze—a relatively infrequently encountered situ- from your winches:
ation, but one in which boat motion, fatigue, and
discomfort all conspire to render you least capable 1. Brawn. Keep a very large, muscular, and
of concerted physical effort. It’s a situation in which willing individual around to do your winching.
you’re most appreciative of adequate mechanical This is the traditional option for racing craft.
advantage, and hang the extra cost. By investing
in a worst-case-scenario power level, you also get 2. Handle Leverage. A winch is a form of
extra-easy sail handling in lighter airs. A final bonus lever, with leverage from internal gearing
is that the larger drum size means more surface compounded by leverage from the handle.
area, and thus more gripping friction on the rope A 12-inch (305-mm) handle will provide
for every turn you make around the drum. So, fewer 20 percent more leverage than the 10-inch
turns to put on and remove, and better control when (254-mm) handle your winch is probably
easing slack around the drum. fitted with now. This advantage is somewhat
qualified by the slowness and awkwardness
Workload Formula of swinging the handle through a wider arc,
Mechanical efficiency aside, winch load is deter- but many people hardly notice the difference,
mined by sail area and apparent wind speed. You and love the ease. Also consider getting a two-
will find details on this on page 371, but here is an hand handle, either 10 (254 mm) or 12 inches
example: You have a 700-square-foot Genoa, and (305 mm) long, so you can make better use of
the apparent wind speed is 25 knots. Since wind the leverage you have, getting the strength of
force varies directly with sail area, but with the both arms completely into the effort.
square of wind speed, we multiply 700 5 25 2 , which
equals 437,500. That’s the foot-pounds of force on 3. Compound Advantage. By combining a
the sail. Now we have to isolate the load on just the winch with a block and tackle, you compound
clew of the sail, because the other two corners don’t your mechanical advantage. So a 40:1 winch
load the sheet. This involves some fairly complicated hooked to a 4:1 block and tackle yields 160:1,
number-juggling, which Wallace Ross (author of the minus friction. For quick, coarse take-up at low
wonderful book Sail Power) mercifully compressed loads, you can use the block and tackle alone,
into a constant: .00431. Multiply our number by hooking up the winch for power and refinement.
this, and we get a clew load of nearly 1,900 pounds. This setup is the rule for mainsheets, but it’s
Divide this by our desired handle load of 35, and we not generally a good idea for staysails; blocks
need a winch with a low gear rating of at least 50:1. hanging from sail clews can be real crew-killing
Note that if we reduce the wind speed by just deck floggers. On large traditional boats, with
five knots, we get a significantly lower load of 1,200 clews well above deck, it’s still the viable option
pounds, while going up just five knots results in a that it’s always been.
load of 2,700 pounds. This is because of that square Another old practice is to put a block on
function of wind speed. So when you are choosing the head of a sail, for a 2:1 advantage, to be
winches, be sure of the conditions it will actually be compounded by the halyard winch. With a
handling. And note that it is apparent wind speed, 50-percent-lower load on the winch, you can use
so a faster boat will have higher loads, and thus a much smaller, cheaper winch. This generates
need bigger winches, than a slower one. savings that offset even the long-term costs of

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