Any experience installing a rotary drive AP on a GB 32?

[Tifkac]

Looking to install a an AP on my Grand Banks 32 with cable steering. Assume I’m limited to a rotary drive but not a lot of space under the helm. Any thoughts/experience with this specific application would be appreciated. Not worried about the electronics, just drive installation options.

 

[Jeff F]

Looking to install a an AP on my Grand Banks 32 with cable steering. Assume I’m limited to a rotary drive but not a lot of space under the helm. Any thoughts/experience with this specific application would be appreciated. Not worried about the electronics, just drive installation options.

I'm not familiar with the GB, but have installed a few on sailboats with cable steering.

Raymarine offers both rotary and linear drives. Either can be used - either the linear drive attached to the quadrant, or the rotary drive anywhere in the cable system. A linear drive may be easier and less expensive.

Both require an AP with a clutch output.

 

[Mike GB32]

I recently installed a Raymarine rotary drive on my 32. There was sufficient room under the flybridge helm. A previous owner had one installed up there and left a split sprocket on the steering shaft.
View attachment Drive.pdf

 

[Cigatoo]

We have an electric motor and chain that resides under the lower helm. There should be room there for yours also. If you can find an electric motor that someone has removed from their old boat grab it! The old motors are simple, heavy duty, reliable, and easily repairable by any good electrical shop. I think that a Raymarine drive will also work.

 

[SoWhat]

Raymarine offers both rotary and linear drives. Either can be used - either the linear drive attached to the quadrant, or the rotary drive anywhere in the cable system. A linear drive may be easier and less expensive.

Both require an AP with a clutch output.

In addition to rotary and linear drives Raymarine sells a hydraulic system that can be run in parallel with your existing cable system.
Install a bronze tiller arm on the rudder post ( above the existing quadrant), add hydraulic cylinder and pump, connect to your Autopilot and controller.

A tiller arm and linear drive is probably easiest to install. I would not use Raymarine and less expensive in the same sentence.

 

[Endeavor GB 32]

Our 32 has cable steering, and a hydraulic ComNav autopilot. Works great! Good luck.
Regards,
Scott

 

[Tifkac]

Gb 32 ap

Thanks to all for the useful input. A long time ago there was a rotary drive mounted upside down under the floor of the cabin helm cabinet. It worked I guess but appears to have been sacrificed to make room for a Purasan system.

For price and parts availability and what I believe requires less modification in my situation, I’m leaning towards installing. a Raymarine AP with a type 1 rotary drive attached to the upper helm. I have two unresolved challenges.'
Mike, can you tell me how yours is secured to the fly bridge? Maybe send a pic if convenient. Through bolting will require taking down some headliner in the salon and I don’t want to get into that.

For anyone., I’ll need to drill a 1/4” dia hole maybe 1/8-1/4” deep into the 1” stainless steering shaft for the sprocket grub screw but want to avoid dismantling the upper steering. Anybody have suggestions on feasibility of doing in place?

Thanks again to all for the quick feedback, I am amazed how responsive and helpful the community is.

Kevin
Papa Charlie
Key Largo

 

[Mike GB32]

Kevin-
I'm going to try to attach a couple of pictures to this post.
I made a substantial cradle (from 1/2" steel) for the drive and bolted it through the wall of the flybridge helm. Similar to the way the steering shaft is mounted. There's lots of adjustment in the cradle. I used four 1/2" countersunk bolts through two G10 plates (painted white) on the outside of the helm wall for support. Doesn't really look bad under the steering wheel. Sorry I don't have a pic from the outside of the helm and the boat is presently covered in snow.
View attachment Drive.pdf
View attachment cradle.pdf

To drill the shaft I would make an aluminum collar to clamp around the shaft as a guide and use cobalt drills.

Hope that helps.
Mike

edit- I don't know why the pictures appear as text instead of photos

 

[Tifkac]

One more question Mike, do you recall where you got the chain and tensioner?

 

[Mike GB32]

The tensioner is a from-
https://www.snapidle.com/
Their item #SI-40.
They tell me it'll outlast the boat by a long shot. Glad I used it. It worked out well.


The chain is a #40 to match the sprocket that was installed by a previous owner on the steering shaft. It's from a local supplier-
https://beardsleetransmission.com/
They sell it in 10' lengths with a removable "master link" to install it after it's cut to size.


I'm happy to help!

 

[Mike GB32]

Oh! another tip for you-
I got the sprocket for the drive motor from Beardslee too. I gave them the tooth count and the shaft size and they ordered it for me. The key size on the shaft didn't match the key in the sprocket but I found a "step key" to accommodate.https://www.mcmaster.com/products/shaft-keys/step-machine-key-stock/

 

[Mike GB32]

Ok- I'm getting a little carried away here... but here's some useful info that I dug up for my installation-
https://forum.raymarine.com/attachment.php?aid=3303

 

[Tifkac]

Gb 32 ap

All great info and much appreciated!
Kevin

 

[Max1]

I would strongly suggest you check out whether or not your boat can handle a linear drive. I believe linear Drive is more accurate, as there is a potential for a lot of backlash in the drive gear and cable system . Of course, this all depends on how many shafts and chains you have on your boat. Having backlash in your system means that your auto tiller would constantly be correcting as your boat will tend to meander side to side as the autopilot tries to catch up to the backlash.

Near the end of last season I got the itch to get an autopilot for my Marine Trader 36. My boat has multiple shafts and connecting chains , which introduces a lot of backlash. The downside in the ability to install a linear Drive in a cable Drive system, is the requirement that the rudder be able to be back driven to the wheelhouse. When I initially worked on my boat in 2021, I've had the impression that a lot of force was required to move the rudder and a linear Drive was not possible. I had resolved myself to using a rotary Drive system, and figured that I would also install some idler pulleys to remove any backlash from the system. However things changed in the fall of last year.

At the end of boating season last year, I discovered my final drive pillow blocks were wearing out, and replaced them. Once everything was reconnected, I took the opportunity to push & pull the rudder arm and much to my surprise I found it was quite easy to move, and only a mild amount of force was required to backdrive to the Wheelhouse. I guess the old, worn pillow blocks had something to do with the increased force required to move the rudder. Based on this, I'm positive a linear Drive would have no trouble driving the Rudder via Direct connection. I can always go to the option of a rotary Drive, but a linear Drive is going to be my first choice. Take a look at yours, and see if the linear Drive will work for you.