Install an electric anchor windlass to your sailing boat

Find out more great boat and anchor windlass information. Given that the windlass is forward and the battery aft, the electrical supply cable is long. With the combination of high current loads and cable length it is subject to voltage drop problems, and windlass performance and therefore lifting capability is reduced by the installation of incorrectly sized and rated cables.

The windlass cables should be installed following the most direct route to the engine starting battery, and protected by a properly rated isolator and fuse or circuit breaker protection. Voltage drop should not exceed 5% and ideally be sized at 3%.

Typical working current loadings are in the range of 55 amps at no load, 110 amps at half load, and 180 amps full rated load.

Many windlasses have converted DC starter motors, and some use permanent magnet motors, typically in the range 600-1000 watts which simplifies construction and reduces weight and size.

I am frequently asked about the practice of installing a separate battery forward adjacent to the windlass, and I do not recommend it. While this is one more battery to maintain and also weight forward where you don’t want it, it also still requires charging.

This means that a cable at least 30-40% of the anchor-windlass cable needs to be run to also compensate for the voltage drops, so the real advantages are negated.

The engine starting battery should be used as it has a high cranking amp (CCA) rating and is more capable of delivering the currents required by a windlass at maximum loads.

A flooded cell deep cycle service battery is not designed for these loads. When surveying that prospective purchase of a boat examine the whole windlass system


Once the cables are installed they require proper protection. Slow Blow (time delay) type fuses are requirements of the ABYC and some manufacturers integrate this within the control box.

They are called slow as they are designed not to rupture on short transient duration over-currents that occur when breaking out the anchor, and only when sustained over-currents occur do they blow. Where solenoid control boxes integrate these and they are located forward close to the anchor windlass, the cable is unprotected, and a circuit breaker or fuse is required for the cable.

Make sure you carry a spare fuse as few do! If you have suffered a flat start battery and have put it down to a mysterious leak, check out the anchor windlass connections either at the control box, control circuit or motor terminals. It pays to turn the power off when the boat is unattended.


Circuit breakers with a suitable tripping curve are also used, and also may have the "slow blow" characteristic. They are like fuses and delay opening on low-level overloads, and trip only on sustained over-currents.

The circuit breaker or fuses should be installed on the supply as close as practicable and accessible to the battery as possible. Typically these range for 400 watt motor with 40 amp current a 50 amp breaker, 600 watt is 55 amp with 70 amp breaker etc.

Always use DC rated circuit breakers, usually available from the anchor windlass manufacturers, and not the AC rated units as some people install. Some boats have automatically resetting circuit breakers for overload protection, however the problem is that you have to wait until it resets, which is usually when you desperately need the windlass, and manual reset breakers offer you some flexibility, although when it trips reset and operate with caution.

If the anchor-windlass has tripped allow 10-15 minutes for the motor to cool down if it's possible as continued operation may burn the motor out.


Connections are a common cause of failures, mainly those at the motor and the control circuits. All main power connections should be made with heavy-duty crimped connectors. Do not solder the connections as dry, high resistance joints are commonplace and solder has been known to melt under maximum load conditions. Soldered joints also stiffen up the cables causing fatigue.

Always make sure that the terminal lug hole is a neat fit to the solenoid and motor terminals to ensure maximum contact and minimal resistance. Use a spring washer under the terminal nuts to prevent loosening and subsequent heating and damage under load. Coat the battery terminals with a light coating of petroleum jelly for corrosion protection.


Part 3 of this Series on the Anchor-Windlass covers the correct installation of boat windlass Control Systems and improve your systems reliability. Click on this link to read PART 3 and all you need to know. Find out more great boat and anchor windlass information