rotary drive autohelm

[voyager35]

I recently needed to look at the installation manual for the Raymarine rotary drive autohelm motor that is fitted to my boat. I was surprised to read that the chain connecting the drive to the steering system should be in a more or less vertical orientation. Mine is horizontal and has been like this for a long time as the drive has the old autohelm manufacturers label.
The question is does it matter and if so why .
I know i am probably answering my own question but on a lively downwind passage when the rudder was heavily loaded a couple of times
there was a very heavy bang from which sounded like it came from under the floor where the drive is. I cant prove it but i suspect the chain jumped.

 

[geem]

I recently needed to look at the installation manual for the Raymarine rotary drive autohelm motor that is fitted to my boat. I was surprised to read that the chain connecting the drive to the steering system should be in a more or less vertical orientation. Mine is horizontal and has been like this for a long time as the drive has the old autohelm manufacturers label.
The question is does it matter and if so why .
I know i am probably answering my own question but on a lively downwind passage when the rudder was heavily loaded a couple of times
there was a very heavy bang from which sounded like it came from under the floor where the drive is. I cant prove it but i suspect the chain jumped.

I also have a Raymarine rotary drive. Mine is installed vertically, such that the drive unit sits above the cog on the whitlock gearbox.
The bang you experienced is almost certainly the chain jumping the cogs. I had similar problem shortly after I purchased my boat. I guess it must have been like that for ever but it was not right. I found that the whiltlock gearbox installation would flex sufficiently to allow the chain to jump. To solve the problem I installed a tensioner. I did this by extending the whitlock gearbox shaft with an extension tube and shaft and mounting a bearing housing on the extended shaft and adjustable bar to set the shaft such that it was true and straight and with zero opportunity for flex. It works very well

 

[Ian_Edwards]

Could the chain just be slack?
I have a chain drive on the autopilot. It's vertical. The Lewmar Mamba (rotory drive) which drives the wheel, which then drives the steering system in the usual way.
There's adjustment in the Lewmar Mamba mounting bracket which allows any slack in the chain to be tightened up.
Is there anyway you can tighten the chain, which given it's age is likely to be stretched and worn?
Perhaps a new chain would solve the problem?

 

[Halo]

I chartered a 52 footer in Turkey. The first time it had been out was on my charter and the steering started making banging noises just 3 miles out. The housing securing one of the steering chain cogs was fixed to a plywood bulkhead with 6 self tappers. I got it back to the marina and they re fixed it. The root cause was a very slack chain that had not been tensioned since delivery but the fixing was also inadequate

 

[voyager35]

thanks for your responses.
The chain had a little slack in it , when I tightened it so it was tight the motor /gears or something inside the drive sounded very unhappy, so have beed juggling with the tension to find the sweet spot.
I assume nobody has come across a rotary drive with the chain running horizontally.
I will have to have a look at the set up next time it is working hard, It might be flexing where the steering gear box is fastened to the bulkhead

 

[geem]

thanks for your responses.
The chain had a little slack in it , when I tightened it so it was tight the motor /gears or something inside the drive sounded very unhappy, so have beed juggling with the tension to find the sweet spot.
I assume nobody has come across a rotary drive with the chain running horizontally.
I will have to have a look at the set up next time it is working hard, It might be flexing where the steering gear box is fastened to the bulkhead

That was my problem. The load on the bearings in the gearbox eventually destroyed them. Having a tensioner at the opposite end of the shaft would take the strain off the gearbox bearings, if it is anything like mine