An anchor winch, or windlass, is a motor and spool — called a capstan — used to draw an anchor and line. The size and power of the anchor winch depends on the weight and length of the anchor and line it will pull. Those criteria are based directly on the size and weight of the boat.
There are two basic types of anchor winches based on design and installation. The first is the vertical anchor winch, which is installed with the capstan above deck and the motor below. This is the most popular design since it takes up less space. In some cases, there is no convenient access point to below deck, so a horizontal winch is installed. Its mechanism is situated on either side of the capstan.
An anchor winch is usually powered by electricity or hydraulics. Electric winches use alternating current (AC) or direct current (DC). AC winches are used when the boat has an on board generator to create electricity. A DC winch is battery powered. Hydraulic winches are usually only found on large boats which have hydraulics for other systems.
For boaters who want to reserve their power for other purposes, there are manual winches. These require human force to draw the line and anchor. Typically, they use a crank system to wind the winch. Manual winches are inexpensive and popular with hobby boaters, not only for drawing anchors but for winching a boat onto a trailer.
Winches are rated on pull capacity and pull speed. The pull capacity is expressed by two numbers: maximum weight and working load. The maximum weight is the heaviest load that the winch is designed to carry. The working load is what the winch actually carries.
As a safety precaution, it is recommended that boaters install a winch with enough power to pull three times the actual working load. To calculate the amount of pull capacity needed in an anchor winch, boaters take the sum of the anchor, chain or rope, and multiple it by three. This gives the maximum pull that the winch ought to have.
The pull speed is how many feet per minute of line the winch can bring in. Sixty to 80 feet per minute (18 to 24 meters per minute) is considered a reasonable speed. Much slower and retrieving the anchor takes longer than necessary. Any faster, the anchor may damage the boat in transit.
The winch must be able to pull not only the anchor but the rope or chain as well. For many boaters, rope is the preferred anchor line because it is light and strong. Chain is used when there are abrasive materials underwater which could cause the line to fray or sever. In some cases, boaters use a combination of chain and rope, with several feet of chain connecting a longer line of rope to the anchor.