[TG] Autopilot Voltage

[Tom - Raymarine - Moderator]

Hello Offshore,

The ACU 100, 150, 200 and 400 (that is, all models except ACU300) output what's called a pulse-width modulated output (PWM.) They don't drive a straight 12V or 24V, they pulse the output with a high frequency (something like 40kHz from memory) in order to provide a softer start and stop and finer control over the movement. This is very standard in motor control systems. You will almost never measure a straight supply voltage on the output from one of these pilots with a multimeter: to measure the output properly you would need an oscilloscope. This is what an ACU200's drive output looks like on a low-cost PC 'scope:



Secondly: when a boat is not moving, the pilot will not react 'normally' and make strong drive movements. It's looking at speed data (GPS speed-over-ground or paddlewheel speed-through-water) and waiting for the boat to get moving in order to know how much helm to apply for the current speed. Don't be concerned if the pump doesn't appear to be moving correctly when dockside: once you get under way I'm sure it will be fine.

If you have problems with steering performance when underway, however, come back to us of course. Ideally call your nearest Raymarine Support office when you're on the water so we can talk through what's happening.

Regards,
Tom