Figure 1: The winch is a rotating lever with the
fulcrum of the winch face and force applied by the handle. Internal gearing
compounds the leverage. In this case, the advantage is four
to one.
Figure 2: The turning block next to the
stanchion feeds the line to the winch at a good fair angle. Note the shockcord
running from the turning block's becket to the lifeline; this arrangement keeps
the block from falling down and fouling when the line is slack.
Figure 3: A self-tailing winch ingeniously eliminates
the need for a human tailer. Note that the lead is above horizontal - a wrap is
sure to happen.
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winch definition
Figure1 illustrates the principle of that magnificent rotating lever, the winch.
The winch handle is the lever arm, the barrel axis is the fulcrum, and the load is
applied at the barrel face. Divide the distance between fulcrum and face into the length of the handle, and the
result, in an ungeared winch, is the amount of your advantage.
Internal gearing
in two-and three-speed winches in effect lengthens or shortens the lever arm so
you can take up slack quickly when the load is light, then switch gears for greater leverage as the load increases.
Fair Lead essential
Several turns with the hauling line around the barrel is the winch equivalent of reeving; the grip of
the turns allows force to be applied. The hauling part should form a 95-to-100
degree angle with the winch drum, or a "wrap" (override) many
cult—either or both parts becoming bound up in the turns. Very bad news,
especially if you need to get the line off the winch in a hurry. When the
hauling part's lead isn't fair, a turning block is added between the load and
the winch (Figure 2). The tailing part is, well, tailed, either by a crew
member or one of a variety of "self-tailing" gizmos (Figure 3).
Efficiently Applied Force
These things are expensive, so you might as well get some performance out of them. To
begin hoisting or sheeting-in a sail, leave the handle off for the moment, make
your turns (three or four), and begin taking up slack by hand.
Pull with your
palms away from you to get a full range of motion as you work your arms in
alternation. Keep your hands well away from the winch in case a sudden load
slips the turns. When the slack is out, the person with the handle plugs it in
and begins cranking while you tail, or you can do both jobs yourself, slowly
and carefully with a normal winch, slick as you please with a self-tailing
model.
For maximum cranking efficiency, get your weight over the handle and
keep it there. Use both hands when possible. When you're running a capstan use
a straight-arm, palms-on-handle technique to take up slack, then switch to the
low and slow crooked-arm technique as you take a strain.
Winch Size
Winches, unmatched in their combination of speed and power, predominate aboard today's shorthanded high-tension
vessels.
Sheets can be controlled by blocks alone or by
blocks compounded by a winch, depending on how much strain the weather is
giving. Running backstays and the halyards for full batten or gaff sails are
two more candidates for block-and-winch teamwork. An extra part or two on a
purchase means you can go with a smaller winch that will receive less strain
A modern sail plan comprises a few large, very
powerful sails. The intent is to produce greater efficiency and less complexity
than the traditional approach of more and smaller sails. But the modern sail
plan concentrates forces to such an extent that the winch is the only
practicable way to make things work.
In determining adequate winch size, work
generated by the sails is the obvious consideration. But work generated in the
winch itself is nearly as significant.
How big then does a winch have to be to
overcome both the pull of the sails and its own drag? The answer starts with
how much effort is acceptable for you. For most people, 35 pounds (15.9 kg) is
a comfortable maximum sustained load. Most production boats have maximum loads
more like 45 lbs (20 kg). That's why it's so hard to sheet that genoa in.
Bear in mind that we're talking about loads
that you'll only encounter going to weather in a stiff breeze—a
relatively infrequently encountered situation, but one in which boat motion,
fatigue, and discomfort physical efforts. It's a situation in which you're most
appreciative of adequate mechanical advantage. By investing in a
worst-case-scenario power level, you also get extra easy sail handling in
lighter airs. A final bonus is that the large drum size means more surface
area, and thus more gripping friction on the rope for every turn you make
around the drum. So, fewer turns to put on and remove, and better control when
easing slack around the drum.
Calculating Winch Power
To calculate desirable sheet winch power,
figure your foretriangle area (the area bounded by the forestay, foredeck, and
mast); multiply it by 6 (or 29 if you figure your foretriangle area in square
meters), a number that accounts for friction and sail force; and divide the
answer by 35, your desired maximum input force in pounds (or.15.9 kg). The answer you
get will be the rated mechanical advantage in second gear (low gear) of your
optimally powered winch.
For example, start with a foretriangle of 300 square
feet (28 square meters): 300 x 6=1,800. Divide that by 35 and you get 51.4; you
want a winch with about 50:1 advantage. If you felt comfortable with more or
less than 35 pounds (15.9 kg), your optimum winch would be somewhat less or
more powerful.
If you want to know what the maximum handle
load on your current winch is likely to be, start with the same Sail Area x 6
(or 29) number, then divide by the rated mechanical advantage through chandlers
and manufacturers). The result will be the maximum hand load in pounds (or kg).
If we stay with our 300-square-foot (28-square-meter) foretriangle and assume a
winch with a typical 40:1 advantage, we get 1,800-40=a typical 45-pound load
795-40=19.9 kg). Too high!
Efficiency Alternatives
If the cost of a big enough winch is too high,
or if you're driving a race boat and the extra weight is a consideration, there
are four other ways to get more from your winches:
Brawn
Two-hand handle |
Keep a very large, muscular, and willing individual around to do your winching.
This is the traditional option for racing craft.
2. Handle Leverage:
A winch is a form of lever, with leverage from internal gearing compounded by leverage from the
handle. For example, a 12-inch (305 mm) handle will provide 20% more leverage than the
10-inch (254 mm) handle your winch is probably fitted with now. This advantage
is somewhat qualified by the slowness and awkwardness of swinging the handle
through a wider arc, but many people hardly notice the difference, and love the
ease. Also consider getting a two-hand handle, either 10 (254 mm) or 12 inches
(305 mm) long, so you can make better use of the leverage you have, getting the
strength of both arms completely into the effort.
Compound Advantage
By combining a
winch with a block and tackle, you compound your mechanical advantage. So a
40:1 winch hooked to a 4:1 block and tackle yields 160:1, minus friction. For
quick, coarse take-up
Combine a winch with a block and tackle to compound mechanical advantage. |
at low loads, you can use the block and tackle alone,
hooking up the winch for power and refinement. This setup is the rule for
mainsheets, but it's not generally a good idea for staysails; blocks hanging
from sail clews can be really crew-killing deck floggers. On large traditional
boats, with clews well above deck, it's still the viable option that it's
always been.
Another old practice is to put a block on the
head of a sail, for a 2:1 advantage, to be compounded by the halyard winch.
With a 50-percent-lower load on the winch, you can use a much smaller, cheaper
winch. This generates savings that offset even the long-term costs of the
50-percent-longer halyard. These days 2:1 halyards are popular on boats with
full-batten mains. The extra power means you can get the sail up faster and
with less effort, before putting the halyard on the winch.
Fairleads, Big Blocks, & Lubrication
By using a minimum number of large, high-quality, strategically
placed turning blocks, you reduce friction. By being one of the minuscule
minority of sailors who strip down and lubricate their winches on a regular
basis (at least once a year), you reduce friction by a lot more.
Whether your winches have help or work by
themselves, protect your investment with regular, careful inspection and
maintenance; it's amazing how many people just crank 'em till they freeze up,
treating them like convenience items instead of well-bred tools.
Brion Toss—The Complete
Rigger's Apprentice
Links:
Brion Toss Website: www.briontoss.com
Harken article: www.harken.com/servicingwinchesmikelee.php
Harken article: www.harken.com/Harken_WinchesMagnifyPeoplepower.php
Harken article: www.harken.com/charts/captivereelwinch.php
