CPT AP - power use, cruising

[Skipper]

The boat's Raymarine SPX5 works fine. P70 head. But the motor is noisy as hell; has been since new. Remedy has been to just keep it on #2 response level plus other dampening settings. I've got it dialed.

However, for long cruises, I've contemplated installing a CPT auto pilot. Maybe even in addition to the RM. They say it's quiet, uses less power, and with better longevity.

I can't stand the idea of a hideous windvane apparatus hanging off the transom, with big holes punched in my hull, installation nightmare, big expense. Am thinking CPT is possible alternative. Less worry of breaking it, power low enough (?) that solar can keep up, ...and quiet.
BUT, I've read that power consumption is about 2 amps an hour. Good, but is that really all that much less than the RM on the low settings?

My questions are: Has anyone measured power consumption CPT vs RM?
Has anyone used CPT on long cruises? What are comments?

If this has been discussed, please link.

 

[justsomeguy]

Has anyone measured power consumption CPT vs RM?

Got a CPT on my boat and just dug out the tech specs in the manual.
"0.013 amps standby current,
0.3 amps average current, varies with load and settings."

 

[Skipper]

Got a CPT on my boat and just dug out the tech specs in the manual.
"0.013 amps standby current,
0.3 amps average current, varies with load and settings."

.3 average? Geez that's low. That's like 1 LED nav light.
You could run it 24 hours on just 7 or so amp hours. That's almost free

 

[jlp0217]

.3 average? Geez that's low. That's like 1 LED nav light.
You could run it 24 hours on just 7 or so amp hours. That's almost free

My bet is that is just the autopilot computer, not the actuator (assuming electric, not hydrolic actuator). I can't imagine 16 gauge wire or smaller to the actuator.

 

[justsomeguy]

My bet is that is just the autopilot computer, not the actuator (assuming electric, not hydrolic actuator).

Hmm, could be.
Those were the only specs I could find in the manual.

 

[sailme88]

I have a solar panel ties to the battery that supports the auto helm. It's Raymarine as well and I keep it configured in RACE mode. No problems...

 

[Skipper]

I received this fantastic response from CPT:
"The short answer is the autopilot system usually averages 0.5 to
1 amp per hour. There are indeed a lot of variables. The autopilot will draw
the least current when the boat is balanced well with low wheel loads.

The most significant power draw of our system is the autopilot motor. The
motor draws about 0.75 amps with no load. As the load increases, the motor
will draw more current: 2-3 amps under medium load and 5-6 amps as the motor
approaches stall torque. The motor runs intermittently: the autopilot
detects a heading error and makes a correction by signaling the motor to run
to turn the wheel. After the first initial correction, the autopilot waits
for the boat to respond. Subsequent corrections are shorter until the boat
returns to heading, when the wheel is returned to equilibrium. The motor's
duty cycle varies depending on how off-heading the boat is.

The autopilot reaches stall torque at about 87ft-lbs (to the wheel). Here
are some wheel RPM/torque specs:
Torque Wheel RPM
No Load 6.5 rpm
20 ft-lbs 5.0 rpm
40 ft-lbs 3.5 rpm
60 ft-lbs 2.1 rpm
80 ft-lbs 0.6 rpm

The autopilot system draws 85mA when the motor is not running or when the
autopilot is on standby. The autopilot power consumption is definitely low
enough to run on solar power and many of our customers do this."

So 1 amp per hour. That's 24 amp hours per full day. A 100 watt panel could keep up with that, and that's assuming you're always using AP.
200 watts to run the whole boat on solar, including in my case Indel portable fridge, all lights, nav gear, etc.
A great case for using it for long passages, and tremendously less installation and cost, maintenance, etc than wind vane.