Winches 101

This entry is part 1 of 1 in the series Winches 101

winchToday we will take a look at winches.

So the question is “What exactly is a winch?” A winch is a machine that uses mechanical advantage to decrease the effort exerted by you to manipulate a load. In short when a line is tightened by using a winch and handle you are able to move a much heavier load than if you simply were pulling on the line directly. In their simplest form (not geared) a winch’s mechanical advantage is determined by dividing the handle length by the radius of the drum. For example, a winch with a 4-inch drum and a 10-inch handle will result in a load reduction of 5 [10/ (4/2)=5]. So a 100-pound load can be manipulated with 20 pounds of effort. Most winches today use gear reduction to further increase their load reducing abilities. If the winch in the previous example has a gear ratio of 5:1 (for every turn of the handle the drum rotates 1/5 of a turn) the formula becomes [10/(4/2)*5=25]. So now the 100-pound load only requires 4 pounds of effort to manipulate it. This second formula is the “Power Ratio” of the winch and this ration is stamped on top of the winch. So, if you have a Lewmar 36 winch, the power ratio is 36:1 (1lb of effort = 36lbs of result). All of these ratios are theoretical. They do not take into account friction in the rigging. So, as the old saying goes, ”Actual results may vary”.

Types of winches

There are many variations of the simple winch such as non-geared, geared and multiple speed. In addition electric and hydraulic power winches are available. Further more winches may be standard (the line is secured to a device after leaving the winch) or self-tailing (the line is held under tension by an device located on top of the winch). Two speed winches are very common on boat. This is accomplished by rotating the handle in one direction for the first speed and the other direction for the second speed. The drum of the winch only travels in one direction. Gearing is accomplished inside of the winch. The number on the winch is the power ratio of the final gear (if applicable).

Don’t underestimate the power

Inside the winch drum there are several gears, bearings and pawls. The pawls are small doors that drop between the teeth of the top gear and prevent the drum from rotating backwards. Electric and hydraulic winches operate the same way as manual ones except there is an electric motor or hydraulic pump that replaces the winch handle. All winches, especially motor assisted ones are very powerful. If one is not careful sever damage can occur to sail clews, furling drums or what ever is being pulled upon. NEVER, EVER USE A WINCH OF ANY KIND WITH OUT CAREFULLY WATCHING WHAT YOU ARE PULLING ON!!!!!!!!!

Proper winch use

Winches should be loaded with three or more wraps of line prior to the line being fed to a holding device such as a cleat, jamb cleat, v-jamb cleat or self-tailer. The approach angle to the winch by the line is critical in the successful use of a winch. Often, particularly with jib sheets, turning blocks will be mounted on the boat to assure proper feeding of the line to the winch. If this angle (generally between 3-8 degrees below perpendicular to the drum) is not correct an override can occur. An override is the resulting mess from a middle line wrap jumping under the wrap above it and then over the wrap directly below it on the drum. If not immediately detected AND corrected, as added tension is applied to the line (interpreted as you keep pulling like a mule) the override will tighten into an impenetrable knot that cannot be undone until there is no tension on the line. (We will discuss proper winch use in a later article). The end result? Most often the expensive and highly technical maneuver know as a knife tack (btw, if you have to do one of these make the cut at the clew of the jib so as not to destroy the entire sheet).

All winches require periodic maintenance to be reliable for years and years. All winch manufactures have rebuild kits and special grease to use. Overhauling a winch isn’t hard nor does it take very long but it does require organization. Never take apart several winches at the same time.

What size winch do I need?

Proper winch sizing is not a mystery. There is a simple formula that will give you the load that needs to be handled. That formula is: sail area x apparent wind speed squared (times itself) x .00431 = load. So, for a typical Catalina 350 with a 135% genoa (about 485 sq. ft.) it looks like this: 485 sq. ft. genoa in 20 knots of apparent wind results in a 836lb load (485 x (20 x 20) x .00431).   The typical adult male can handle a load of about 35lbs comfortably (significantly more for a very short duration). Take the 836lb load and dividing it by 35 getting a result of slightly under 24 (23.8897). Any winch under a 24# with a shorter handle than 10” will be uncomfortable to be used for this scenario by the average male. 20 knots of apparent wind means true wind in the range of 12-15 when sailing close-hauled. The standard primary winches on a new Catalina 350 are 46#. Take the load of 836lb and divide it by 46 and the result is 18. This is a very manageable load for men and women to handle. Good job Catalina. Always look at the worst-case scenario when sizing winches and if your results are close to the limit of a winch move up in size.

One more thing.   Everyone wants faster tacks, right (well don’t ya)? There are two real choices. Hire young guns with unlimited amounts of energy (your wives might like this) or use shorter winch handles (resulting in faster winch revolutions, but less power). The choice is yours or maybe hers.

There you have it. Now, go out and sail. See ya later On the Water…With Captain Frank.

Next installment on winches: http://onthewaterwithcaptainfrank.com/always-really/