Revised by BoatUS editors in April 2012
Choosing a winch may appear to be a trial and error process. Unfortunately, winches tend to be rather expensive, meaning that this is probably not the best way to go about it. What you need to do is to decide what you want from a winch. This is based on a number of factors, including the type of boat that you have and the jobs for which you will use the winch. The one basic rule is that the larger a winch, the better it will function.
Comparison shopping for a winch (and we recommend that you do) can be a little confusing. This is largely because winch manufacturers love complicated mathematical formulas. The favorite is to use the "power ratio" of the winch as the basis of choice. Simply put, this is how many pounds of pulling power you will get from a winch for every pound of pressure that you put in. The formula is actually very simple:
(handle length/drum radius) x gear ratio = power ratio
Technically, this means that a winch with a 10:1 power ratio will produce 100 lbs. of pulling power for every 10 lbs. that you put in. In reality, this is only a rough guide. There are other things that need to be factored in, such as the number of turns in the line, the friction produced by the lead blocks, and the operation of the winch itself. However, as a basis of comparison, the ratio is useful.
Some manufacturers make size recommendations based on boat length. While this is useful, a better option is to consider the job it will do, if you can. For example, typically the larger the sail area that a winch will have to control on a sailboat boat, the larger the winch needed. There are also other factors to be considered. How many crew do you have? How big and experienced are they? Where do you intend to place your winches? What are you planning to use your winch for? What type of sailing are you going to be doing? If you have a power boat, what will you use the windlass for. Some mount winches simply to help pulling someone out of the water if they go over, others use winches for small steadying sails or for lifting dinghies. And then, there’s the eternal question: How much are you willing to spend?
When you're deciding on the correct size winch for controlling your headsails, use the sail area of the working jib or the 100% genoa. The smaller sail may seem like an odd choice, but bear in mind that it's used in heavier winds, so the sheets are subjected to higher loads. You can clearly see this by taking a look at the formula for load:
Load (lbs.) = SA x V2 x 0.00431
SA is the sail area, and V represents the apparent wind in knots. Therefore, a 300 sq. ft. sail set in 20 knots of wind will produce a load of 517 lbs. Using a 5:1 gear ratio winch with a 10" handle and a 4" diameter drum, you'd need to apply 21 lbs. of pressure to the winch to sheet in the sail. You may find that your boat's requirements fall between two sizes of winch. In this case, it is always better to step up to the bigger of the two, rather than making do with the smaller model. Even if your boat's requirements match a result, it's still always better to have more than less because you never know what’s going to happen at sea and what needs you'll have.
Remember, every change of direction that a rope makes en route to the winch causes friction and reduces the effectiveness of the equipment. When placing winches, avoid twists and turns, while also making sure that the rope comes into the winch at the proper angle. This means that normally blocks and fairleads will be necessary. For genoas and heavier load lines, a turning block is needed to ensure the correct angle of entry to the winch. This should be between 3 degrees and 8 degrees below the winch's perpendicular axis. Ideally, the winch's output gear should be in line with the angle of entry. You will have to disassemble the winch to see this, but you can usually sight the entry angle fairly easily, without having to tear the equipment apart.
Undoubtedly the best material for winches is stainless steel. It's strong and durable, but also expensive. The cheaper alternatives are anodized aluminum and chrome-plated bronze. Wire can damage both of these materials by rubbing the coating off. In addition, aluminum requires more upkeep and is particularly prone to corrosion and damage from impact and stress. Straight bronze is very good, weathering to a classic greenish color that appeals to traditionalists.
Normally direct drive with a gear ratio of 1:1 winches are perfect for halyards, cunninghams, or main and mizzen sheets on small and mid-size boats. It's better to buy one that ratchets, allowing you to crank the winch from both sides of the drum. This means that you can "push and pull" on the winch handle, rather than having to crank it through 360 degrees in one direction. This is particularly helpful if you are unable to brace yourself against something to get your whole body into the cranking process. It's less tiring too!
These are normally used as the primary sheeting winches and halyard winches on larger boats. With both a high and low gear, these winches allow you to crank in ropes quickly to start with, then more slowly in a lower gear as the grinding becomes difficult. Gear selection is made by reversing the cranking direction.
If you get the placement right, it is possible to use one winch for multiple purposes. This allows you to buy one winch rather than several. However, we recommend that you carefully consider the different demands on the winch to avoid the difficult situation of trying to use one winch for several lines at the same time!
These winches are generally more expensive, but they're worth it. They allow one person to crank in without needing another person to tail, or without trying to do the difficult job of tailing while cranking. A lot of these winches are offered with spring-loaded, self-adjusting jaws that accept lines of different diameters.
Larger boats may need a winch with a 40:1 power ratio or higher. In this scenario, you may be tempted to go for an electric model. Provided your craft is equipped to handle the 50-140 amp DC power drain, there shouldn't be a problem. 24v winches are available to reduce the power draw. If you do decide on an electric winch, it's important that it has a manual backup in case of failure. Some boats even have hydraulically powered winches. You can get electric winches with high and low gears.
Despite 10" handles being the industry norm, primarily because of their comfort and the leverage they provide, you should consider an 8" handle for lighter conditions. Here, speed is more important than ultimate power, and an 8" handle allows for faster cranking. As you can see from the formula for power ratio, the length of your winch handle is important. If you find that you are getting insufficient power from a winch, try a longer handle before replacing the winch itself. Needless to say, this is a far cheaper option! A winch's power can also be increased if you use double-grip handles, allowing both arms to more easily grind the winch at the same time. We recommend that you use locking handles whenever possible to avoid losing them overboard.
As with your rigging, winches need some looking after if they're going to remain at their best. Be sure to rinse them in freshwater and cover them after every use. In saltwater, even more care is needed. They should be disassembled, inspected, cleaned and lubricated at least once a season. For aluminum models, this should take place three or four times a season to prevent oxidation. Always follow the manufacturer's recommendations as to maintenance and all other aspects of use of the winch.
Winch Selection Guide, from Lewmar.com