Can I put an A/B switch between the AP and the ram?

[Alaris]

Boat has an ancient but functional Alpha Marine 4404 autopilot that is heading only. I’m upgrading everything but the ram. Is there any reason I can’t put an A/B switch between the ram and each pilot in to allow me to use the old system as a backup if the new system malfunctions?

I recognize I may just be creating problems when comparing a 40 year old Alpha Marine system to a new B&G H5000, but belt and suspenders right?

 

[El Borracho]

Should work well. Switch both leads — DPDT. Is there a rudder sensor?

 

[Alaris]

Should work well. Switch both leads — DPDT. Is there a rudder sensor?

Only one unit (the B&G) has a rudder sensor.

 

[jamhass]

I did exactly this with an Alpha 3000 ram (same as the 4000) and a Raymarine course computer. Things to watch out for:

1. Can the CC handle the ram current?
2. The Alpha CC senses the ram position with its own internal (to the ram) sensor. Thus, the BG CC has no idea where the ram is if it is NOT mechanically connected to the rudder, and damage to the ram is likely. Remember, the Alpha ram uses a mechanical disconnect. You need to provide some type of lock-out signal to keep the BG CC from driving the ram if it is NOT connected to the rudder.

I don't know the BG CC. The Raymarine has a clutch circuit that I used to drive a relay (wired to interrupt current to the ram) via a microswitch (located on the Alpha mechanical dog.

PM me if you need more info. Note, I don't often notice the PM alert, so be patient.

 

[Alaris]

I did exactly this with an Alpha 3000 ram (same as the 4000) and a Raymarine course computer. Things to watch out for:

1. Can the CC handle the ram current?
2. The Alpha CC senses the ram position with its own internal (to the ram) sensor. Thus, the BG CC has no idea where the ram is if it is NOT mechanically connected to the rudder, and damage to the ram is likely. Remember, the Alpha ram uses a mechanical disconnect. You need to provide some type of lock-out signal to keep the BG CC from driving the ram if it is NOT connected to the rudder.

I don't know the BG CC. The Raymarine has a clutch circuit that I used to drive a relay (wired to interrupt current to the ram) via a microswitch (located on the Alpha mechanical dog.

PM me if you need more info. Note, I don't often notice the PM alert, so be patient.

Yeah I’m not sure what to do when the clutch is disengaged with the B&G. Wouldn’t it just sense through the rudder sensor that its inputs were not affecting the rudder and throw a fault?

Looking at this diagram, I wonder if there’s a way to get the B&G computer to actuate the clutch.

 

[jamhass]

"Wouldn’t it just sense through the rudder sensor that its inputs were not affecting the rudder and throw a fault?"

Don't know B&G, but the Raymarine WOULD indeed keep driving the ram. I used the Ray clutch circuit to drive a relay via a microswitch wired to be closed only when the Alpha RAM was fully engaged. Pretty easy setup as the Alpha tiller arm is aluminum and easy to drill/tap to accept a microswitch. One advantage of the Ray clutch circuit is it is a constant 12v whenever the CC is active, and no power when off or in standby.

 

[CapDave]

Boat has an ancient but functional Alpha Marine 4404 autopilot that is heading only. I’m upgrading everything but the ram. Is there any reason I can’t put an A/B switch between the ram and each pilot in to allow me to use the old system as a backup if the new system malfunctions?

I recognize I may just be creating problems when comparing a 40 year old Alpha Marine system to a new B&G H5000, but belt and suspenders right?

I think jumping through hoops to keep an antique enabled is not a good use of resources. Make the upgrade, remove the old kit. You're going long weekend cruising, not solo-circumnavigation.....