Winches
The following is summarised from this article in the BoatUS Tech Guides
Wikipedia doesn't say much.
A winch is a machine, hand or engine-powered, to pull a rope, wire or chain. Technically, a "winch" stores the excess rope on a windlass, but on most sailing boats, the word "winch" refers to a "capstan", where only enough rope to create the friction required to grip the rope is stored on the drum of the winch, the excess being tailed-off. The tailed-off rope is kept under tension to maintain the capstan's grip. We use "winch" ratheer than "capstan" from here on.
Winches are expensive, they create a mechanical advantage that multiplies the results of your efforts, making the work easier. Bigger is better.
How Big?
Winch size is often recommended on the basis of boat length, but sail area is more useful in determining minimum sizes. The number, experience and strength of the crew are important factors - racing boats tend to have large numbers of big strong crew - cruisers tend not to, but then aren't always in such a hurry as a racer. There are formulae to help calculate the optimum size for your sails, Storm Force Marine is run by experienced ocean racing sailors who will be happy to advise.
Winches are described in terms of power ratio: what multiple of pull is achived for the effort expended in pressure on the handle. The higher the power ratio, the less rope is pulled per turn of the winch and the longer it takes to crank the sheet in. The power ratio will be affected on your boat by friction losses along th eline of the sheet being pulled in.
Winch Placement
Every turn in the line and change of direction enroute to the winch produces friction. Place winches to avoid as many of these as possible. You must have a proper lead angle to the winch. Heavy load lines should be run through turning blocks to ensure the proper angle of entry to the winch
Winch Materials
Aluminium and Carbon winches are lightest, but of course the drums tend to wear out fastest. Traditionally winches were made out of bronze (and then chrome plated). Stainless steel winch drums are now available which have the advantage of relative lightness compared to bronze winches, as the steel is much thinner for the same strength and steel being much harder wearing, has a correspondingly longer life.
Single-Speed Winches
These are usually direct drive winches with a gear ratio of 1:1, usually used for halyards or main and mizzen sheets. A big single-speed winch is faster and allows more turns around the drum.
Two-Speed Winches
Wound in one direction they are used for rapid sheeting-in; in the other direction a lower gear ratio permits a slower speed/higher pull for luff and tension adjustment.
Placed well, a single two-speed winch can perform several tasks and the money saved by not having a second winch can be spent on a larger single winch., Don't try and manage more than three lines per winch.
Self-Tailing Winches
Self-tailing winches have a device that maintains the tension of the sheet on the drum while stripping the excess turns off. This allows small, frequent adjustments to sail trim and halyard tension, and more importantly, the winch to be operated by one person.
Electric Winches
If your boat has the power, then electric winches with a manual backup will save much labour.
Winch Handles
10" handles are the industry standard because they're the most comfortable length for most crewmen. A shorter 8" handle can be used in light wind conditions, when speed is more important than power. Winch handles should be stored in a holster when not in use.
Storm Force Marine represents the folowing firms who manufacture winches:
Andersen Winches (stainless steel winches)
Antal (racing winches).