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autopilot power budget
01-14-20, 10:37 AM (This post was last modified: 01-14-20 10:33 PM by Tom - Raymarine - Moderator.)
Post: #1
autopilot power budget
I'm refitting for an extended cruise and bought an EV100 tiller pilot and associated parts. I'm trying to figure out a reasonable average power draw to use in my battery bank sizing and charging calculations.

The manuals with the equipment give draws for the electronic pieces of the system (e.g., 30 mA for EV-1), and max draws for the tiller actuator, but I need an idea of average draw under normal conditions (or even better under very light conditions).

I would note that my actual demand will certainly be less than normal, since the tiller actuator doesn't connect to a tiller but instead to a control arm on my wind vane steering. Moving that control arm requires at most a pound of force then the vane steering applies all the power to the rudder. I used this for years with great success with an older model Autohelm tiller pilot (which had a virtually identical drive unit). I think Raymarine bought Autohelm at some point.

Anyway, guidance on power budgeting would be much appreciated.
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01-14-20, 11:05 PM
Post: #2
RE: autopilot power budget
Hello OceanGuy,

The average power consumption is essentially a factor of the load on the drive (how hard the motor needs to work in order to move it), how far (how long) it needs to drive in order to achieve course corrections and how frequently it needs to drive (how well balanced the sail trim is, the sea-state, the pilot's Response level setting, the keel length, point of sail, steering vane efficiency and response and so on and so on.) Think of the fuel-consumption variables in driving the same car start-stop versus steadily on a motorway, on the flat or on steep hills, towing a boat trailer or not and the like.

If you want to you can estimate these values and do some back-of-an-envelope calculations yourself ( is a fair place to start), but the short answer is that for similar work, the power consumption will also be very similar to the old pilot.


Raymarine since 1999.
Interests: Diagnosis of problems in sonar/fishfinders, NMEA2000, ethernet comms, autopilots, thermal cameras
Location: Sydney, Australia.

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