NAC 3 autopilot driving rotary motor

[felizcortez]

I currently have a Cetec Benmar Coursekeeper 210 installed in my boat that only wants to turn to port. I believe the motor in the drive unit is still good. I have purchased a NAC3 autopilot computer from Simrad and was planning on getting the corresponding RAM to drive the rudder. However since I already have everything installed from a quadrant and chain drive point of view, is it possible to have the NAC computer drive the rotary motor already installed on the boat? I know the old autopilot has two separate motor drive cards in the case so I believe I would need to hook up to the motor directly and bypass the drive boards. Any thoughts here?

[felizcortez]

I have been digging into this a bit deeper and believe I have found the potential connection points. The drive has circuitry built in that I would bypass if I understand this correctly because the NAC3 would handle the motor control and the limits of the rudder would be based on the rudder position sensor.

I believe the NAC3 autopilot computer can be hooked up directly to the motor via these two terminals in the picture. Anyone see any issue with this? I would remove the cables from the terminals that are there and replace with different wiring.

For the electric clutch I believe I have identified the jumper and it looks like it is a 12V clutch.

Am I missing something here or does anyone else think this should work?

[BB-Honu]

Hi,

Were you able to make your Benmar drive unit work with your NAC3? I have the same problem and I am getting power to the unit, Thru NAC3, but my connection to the “drive engage” on the NAC3 doesn’t work.i am not sure I am using the right wires. If you made it work, I would really love to know what are the connections you used.

Looking forward to your reply. Regards.

Bernard

[felizcortez]

Originally Posted by BB-Honu

Hi,

Were you able to make your Benmar drive unit work with your NAC3? I have the same problem and I am getting power to the unit, Thru NAC3, but my connection to the “drive engage” on the NAC3 doesn’t work.i am not sure I am using the right wires. If you made it work, I would really love to know what are the connections you used.

Looking forward to your reply. Regards.

Bernard

I actually removed the old drive unit and replaced it with a hydraulic ram so I abandoned this idea. I believe it is a 12v clutch for the drive unit, but never tested this. I think you need to bypass all the circuitry and go straight to the actual clutch actuator. I would test it with a 12V supply separate from the NAC3 to make sure it works first before introducing the NAC3.

[Frankly]

I have used a Raymarine X-5 to drive a Std Benmar rotary drive unit for a number of years (mechanical clutch). Just connected the X5 motor output directly to the Benmar drive DC motor leads. Throw the rest in the trash. Works like a charm.


My stereo uses more electricity than my AP under normal conditions (seaway/ volume).


Frankly

[BB-Honu]

Thanks for the fast reply.

Will have to do more research. I got the power working fine, it is just the command from the NAC3 that I have problem with, and the tech at Benmar Marine is not replying to me, so more input from anybody else will be really welcome.

The issue is from the “drive engage” connection on the NAC3 where do I connect on the Drive Unit?

Thanks for the input.

[felizcortez]

If you look at the pic I posted of the schematic I believe you need to connect it to where my finger is pointed assuming you have the same unit.