Reinstating the Anchor Windlass - Part 1

Pachuca has not a working electric anchor windlass since 6 Feb 2011 when Brenda and I were lucky to not lose the boat and swim for our lives in an electrical fire during the passage from Isla San Francisco and the fishing village of San Evaristo in the Sea or Cortez.  (see http://pachucaroundtheworld.blogspot.com.au/2011/02/fire-and-water.html)

I knew that basic cause of the electrical fire was the direct connection of the house bank of batteries to the windlass battery with two fairly light gauge wires and no fuse, diode, resistor, or any other protection measure in the circuit.  I vowed not to restore the windlass until I was confident that I was using a safe design.  The problem was how to somehow trickle charge the windlass battery from the House bank. In the subsequent six years I have raised anchor manually using a winch handle on top of the windlass.

Fortunately my brother Arnold is an electrical engineer, and he was able to send schematics of possible solutions.  However, it was not until face-to-face discussions with him during my recent visit to the USA that I felt confident enough of my understanding of the designs to actually do something.

The basic design is:



The design addresses the analysis that the fundamental problem is the amperage not during normal recharge, but whenever the anchor is being raised when the windlass battery is at low voltage, which passes the entire load of the windlass motor, an Orca VE2000 rated at 1500 watts, to the house bank.  Thus the key component is a relay which cuts off the connection between the two banks while the windlass is energized and the anchor is being raised and reestablishes it when the windlass is idle.

I started off by purchasing a new windlass battery.  I was first offered a lead-acid battery for about $300 but I'm done with lead-acid batteries on boats and insisted on an AGM or gel battery.  I purchased an “Ultimate Xtreme” 110 a/h, 546 CCA AGM battery for $449.


At this point Stephen, Brenda's son, became interested and he provided invaluable help that complemented Arnold's ongoing assistance.

A fundamental question was the gauge of wire sufficient for connecting the House bank to the new windlass battery.  Arnold had calculated that the current along the wires would be well below 5 amps, so I settled on the thickest wire in the shop that would fit into a large crimp connector, which has an area of 4 mm sq giving a capacity of about 12 amps.

Then it was time to procure a relay, something that I knew nothing about.  Stephen pointed me to Jaycar where I purchased a 10-amp car relay.   I learned about the 5 pins on the relay from Youtube and most important, that I had to use pin 87A instead of 87 because I wanted the connection to be made by default and broken when the trigger activated the relay.

Stephen educated me on resistors where heat generation and dissipation was a big issue and we settled on a pair of .47 ohm resistors.

Then it was diode time and I purchased a 6 amp diode, the largest capacity available at Jaycar,

Stephen then salvaged a large heat sink from an amplifier that he was dismantling for part.  This went a long way to solving the heat dissipation problem and also provided a platform for the other components.

Heat Sink

Stephen also introduced me to a wonderful circuit simulator that allows him to define any circuit that he chooses them run it to see what happens.  We verified that the design would work and were able to explore the interaction between the strength of the resistors and current flow, particularly when the differential voltage is low.

At this point I have the system almost completed and ready for testing (gulp!).

15 amp in line fuse

 The heat sink "board" is tucked high at the end of the sail locker, protected from water and encroachment by sails and equipment stored in the space. The green electrical tape along the lower part of the board is to prevent short circuits.  Stephen thought that it was a good idea to put an in-line fuse at the beginning of the cable run.  It is a blade-type fuse inside of the small red plastic case along the wiring.

I have mounted the relay at the top right corner of the board.  When the relay is triggered the connection will be made and current will flow through the two resistors (white) and the diode (small, black and gray).  The idea of the diode is to prevent the charging of the main house bank by the windlass battery.

Heat Sink and Components

I wanted to use a 15-am breaker at the main switch panel, but the panel is full to capacity I deemed freeing up a breaker to be too difficult and dangerous.  (The rebuilding and extending the main panel is a project for the future.)

Instead I purchased a 15 amp breaker from Jaycar and mounted it by drilling a small hole in the electrical panel.  This style of breaker cannot be manually set and reset, but fortunately there was a free switch (Test Bat 1, Test Bat 2) that works so that I will have the capability of manually shutting down the entire circuit.

In parallel with this was the repair and installation of the windlass itself, which will be covered in another blog entry.