Changing autopilot from old Benmar to new Raymarine

[BonesD]

I’m changing out an old Benmar Compucourse 220 to a Raymarine EV 400 with type 2 rotary chain drive unit.
The Benmar has a hefty motor with a massive gear reduction The new Raymarine motor has some delron/nylon planetary gear reduction.
The Raymarine uses a pair of clutch wires and power wires that terminate at the ACU.
The old Benmar is in a case with some very old circuit boards, resistors etc.

I’m wondering if the Benmar can be used as suggested by another fellow here in the forum But with out the use of all the circuitry that is mounted in the Benmar motor box. I can switch polarity on the Benmar motor right on the back and it reverses direction.
The Raymarine ACU does all the reversing for its supplied unit.

I want to know if saving the Benmar as a backup is worth while and if it will function with just the power from the ACU directly to the Benmar motor only?
I would just harvest all the extra circuitry just to get it out of the way.

Thanks

[skipmac]

Short answer, yes.

If you can reverse the motor by switching polarity of the voltage to the motor and the Raymarine outputs enough power to operate the motor then should work fine.

Basically a motor or other AP drive unit doesn't know where the power comes from it just responds to the power it receives.

Without knowing more about the Benmar can't comment about the potential effects from removing the circuit boards. If their function is to reverse polarity of the drive power and you can just bypass that and feed the motor directly then should be good but also assuming the circuit doesn't change the voltage as well as the polarity.

[Frankly]

I don't think that will work (I will send you the address for proper disposal). That is a bigger drive unit and also must include an electric clutch (no mechanical clutch visible). Typically the clutch voltage is not bipolar but just 12V on/ off. Slide the circuit cards out and see if you can identify the clutch wires and try energizing those directly and see if the output shaft will rotate when you power the motor. Your RM ACU should provide a usable clutch signal.

IMO you should clean up the gear train reinstall the Benmar and carry the RM as a backup. Pack the RM unit well, cause you never going to need it.

I find it interesting that the two motor wires look like maybe #16 and your power unit is probably rated for 20 or 30 amp motor (unless the orange/ blue are clutch signal).

My yacht is not heavy on the helm, don't think I have ever seen motor currents over 3 or 4 amps YMMV.

Frankly

[BonesD]

Thank you both for the reply. I will take a look inside the Benmar and see what I can find an report back.
The disposal address might be close to your home right?

[BonesD]

Thank you both, I will take a look inside snd see if I can energize the motor differently.

[moseriw]

KEEP THE BENMAR. It will bring you always everywere. Even in 20 years.
Search the net. If you find someone with AP Problems, its a raymarine.

[Frankly]

I really think the reason you hear a lot about Raymarine is they just dominate the market. Going to be a few failures in any piece of equipment. I have operated from my sailing craft over the last 25 years ST4000, ST5000, S1, S1G, S2G, X-5, and now Evo. Never a single problem. I happened on a new Benmar std power unit in a Shelter/Harbor Island chandelier in 1990. $250 so I bought it just to play with (I spent 30 years designing automatic control systems for the US Navy) so have more than typical interest. When I purchased my IP 32 with the somewhat odd thru the legs rack and pinion steering I realized I had a marriage made in Heaven.

That Benmar unit has metal gears, oillite bearings, and a low friction mechanical clutch ( no parasitic clutch current). Going to outlast everything on my yacht including me. All them Ray Marine Auto Pilot power units know is they are producing a voltage to a load that accepts current, the rudder position transducer indicates something is moving and the vessel heating changes or doesn't (depending on which button is pressed). The rest is just software and pretty dam# sophisticated software at that.

I have 4 of the Benmar power units. I collect them just because they are such nicely engineered units. .

Everybody ought to own a couple.

Frankly

[skipmac]

Originally Posted by Frankly

I really think the reason you hear a lot about Raymarine is they just dominate the market. Going to be a few failures in any piece of equipment. I have operated from my sailing craft over the last 25 years ST4000, ST5000, S1, S1G, S2G, X-5, and now Evo. Never a single problem. I happened on a new Benmar std power unit in a Shelter/Harbor Island chandelier in 1990. $250 so I bought it just to play with (I spent 30 years designing automatic control systems for the US Navy) so have more than typical interest. When I purchased my IP 32 with the somewhat odd thru the legs rack and pinion steering I realized I had a marriage made in Heaven.

That Benmar unit has metal gears, oillite bearings, and a low friction mechanical clutch ( no parasitic clutch current). Going to outlast everything on my yacht including me. All them Ray Marine Auto Pilot power units know is they are producing a voltage to a load that accepts current, the rudder position transducer indicates something is moving and the vessel heating changes or doesn't (depending on which button is pressed). The rest is just software and pretty dam# sophisticated software at that.

I have 4 of the Benmar power units. I collect them just because they are such nicely engineered units. .

Everybody ought to own a couple.

Frankly

Strictly anecdotal but not sure if Raymarine dominates the AP market as much as the rest of their electronics. Of all the boaters I know and see around Raymarine AP is not a bit majority. See more Simrad/B&G units than any other, Ray seems to be second, a few Garmins and Furunos and the high end racers seem to use NKE.

Regarding Benmars, had them on a couple of boats years ago and have to use the cliche bulletproof. That being said, on my mixed Simrad/B&G AP I use a Rarmarine linear mechanical drive.

[BonesD]

I took a look at all the circuit boards etc on the Benmar and it is too much for my feeble mind to access what I am looking for or at. The only wires going to the motor are the two power leads.
Frankly, I think the power wires going to the back of the motor may be because it doesn't take much power to operate the steering because of the monster gear reduction assembly.
I will hang on to as is I imagine.
Thank y’all for the input.

[Seafarer7]

You can power the Benmar motor directly from your ACU400 but I found it does not work well unless you also connect the ACU400 clutch output to the clutch input / circuit board of the Benmar. Without the clutch connection the autopilot “fights” the gear and your can hear/feel how bad it sounds.
Once the clutch is connected the Raymarine+Benmar combination works very well. Use the Raymarine clutch 12v to power the Benmar circuit board / clutch

[BonesD]

I do have all the paper work. I didn’t think to look at that for connections. Thanks.

[Frankly]

If the plan is to abandon the Benmar as the primary might justify some more invasive surgery. Don't have a disposal address for the circuit cards, already have a box full of them.

On the smaller std drive unit, cleans up nicely with all that surplus electronics gone.

[BonesD]

Frankly, that is what I’m looking for. It looks as though you are only using the two motor power leads?
Thank you.
Bones.

[Frankly]

The small unit has a mechanical clutch (that is the operating link sticking out the side) so the motor is the only electrical part. The bigger units apparently have electrical clutching, but based on Seafarer's comments sounds like something else is afoot. Sometimes simple electrical devices will have an initial pull in voltage and after things are set, reduce the voltage to reduce the current draw. I just don't know.

One other little piece of info, there is a slip clutch on the model I have. Over the years in heavy winds and very badly trimmed sails I have managed to slip the clutch. It is a spring plate ball detent setup. I have tightened things up as much as practical but not sure on the upper yacht limit for that unit.

The recent Raymarine units monitor motor current (wheel pilots anyway). Rated current is 6 or so amps and alarm about 10. That clutch slipped before any electrical indication. My Benmar manual says the motor is rated at 6 amps but no detail about continuous or otherwise. Autopilot service is a highly varied load.


Unruly weather is not a great time to find that you have an over matched AP that you were depending on.


Frankly