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1982 Skye 51
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379 Posts
Discussion Starter · #1 ·
I am upgrading from a mechanical rotary to a hydraulic linear autopilot drive and was thinking that, if I install the tiller arm aft of the rudder stock, the unit would be much more protected and I would not have to modify/lose my LP lockers. I had a Raymarine Type 2 mechanical rotary drive (which they claimed to be a direct replacement for my Neco unit...wrong) that was consistently overpowered in moderate conditions. Now I am stepping up to the Type 3 Hydraulic linear.

New unit is rated to 77,000lbs displacement and I am, at most, 44,000lbs when cruising loaded, full fuel, water, etc. The rudder is fully unbablanced and skeg hung. It should handle things...

I have room to mount a tiller arm on the centerline, facing aft. The manual says to make sure the tiller arm in facing forward but I doesn't seem like the orientation should matter. No explanation given. When I go through the initialization process, the course computer should glean info from the fluxgate and the rudder angle indicator to control the drive's movements. Right? Maybe I am way off and, please, someone correct me for my own sake!

Maybe I could see not mounting it perpendicular to the centerline but just turning it around 180 deg and leaving it on the centerline...?

Someone who knows more about this than me, please chime in.
 

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I would think you could mount it at any angle around the rudder post. Mine is at about 30 degrees to port as there is a locker in the way of the drive. Just make sure everything is nice and square in every axis to the rudder post.
 

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Are you just changing the drive unit? Can the controller head (or the drive) be set for direct or reverse action?

If the controller 'thinks' the arm is pointed forward, seems the drive would go the wrong way and you'd end up with a positive feedback situation - in which case the helm would simply go hard over one way or the other and never find a balance.

EDIT.. it should be workable either way but may require the drive to be on a particular side of the arm.
 

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1982 Skye 51
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379 Posts
Discussion Starter · #5 · (Edited)
Yes, just the drive unit. The corepack is still fine, I just kept eating up planetary gears (made out of HDPE!!) on the mechanical rotary drive.

Very good point about the sides. If I work out the directions of push-pull, I really can't see any reason not to mount it facing aft

Edit: Even if the arm and unit are mounted forward of the post, you run into the same problem!
 

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Can't see any reason for having the tiller arm in any particular orientation.
It's important that the arm of he linear drive is perpendicular to the rudder shaft.

I most autopilots you can adjust (reverse) the direction of travel) if not just reverse the polarity to the drive unit as the "brain" switch polarity to change direction.
 

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If youre contemplating the use of an 'auxiliary' rudder stock/shaft (bronze?) tiller arm ... and you need to have that aux. tiller at 180° from 'spec'., consult the set up manual for the control circuits .... most times this 'problem' is solved by simply reversing the polarity (wires) of the power leads to the electro-mechanical drive. Verify with your manual or call the manufacturers 'application engineering' department.
;-)
 

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1982 Skye 51
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379 Posts
Discussion Starter · #8 ·
If I were to mount the drive forward to the rudder post on the port side, the motions would be the same and the boat steer the exact same way as if I mount it on the starboard side aft of the post. That's exactly where i want to mount is, so maybe it will all just sort istelf out?!
 

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If I were to mount the drive forward to the rudder post on the port side, the motions would be the same and the boat steer the exact same way as if I mount it on the starboard side aft of the post. That's exactly where i want to mount is, so maybe it will all just sort istelf out?!
Sounds like it.. should be good to go!
 
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I would go ask Raymarine on their tech support forum. The forces on the rudder post are different depending on the length and angle of the ram's tiller arm relative to the rudder. Ideally you want the tiller arm for the ram to be at the same angle the tiller would be. Also short tiller arms apply more side load to the rudder post I think. Again, if you don't know why the mfgr says something best to go ask them why. They probably have a reason. Then you can decide for yourself what is best.
 

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You can put the rudder angle sensor on the same arm as the Ram. The Raymarine ram can be reversed by simply switching the motor wires. The position sensor maybe not. But you don't need to worry about that. Neither the sensor or the motor have a compass, and they cannot *see*. Heh. So they have no way to know they are installed behind the rudder post.
 

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1982 Skye 51
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379 Posts
Discussion Starter · #13 · (Edited)
rudder sensor is already happily attached to the steering quadrant with a nice mounting pedestal glassed in, left over from the old unit. i can't see any drawbacks. just like you said, the ram is "dumb", it just pushes or pulls, based on the rudder angle indicator's telling it where the rudder is, until the fluxgate reads the correct heading. thanks for the input, everyone
 

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The sensor can be programmed for either direction. It's part of the commissioning process. Also, swapping two of the wires on the sensor will flip it's direction. You just have to swap the right two wires. I can't see why your idea would not work.
 

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1982 Skye 51
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Discussion Starter · #16 ·
Thanks for the help guys. After a few trips to the machine shop to get things right, the arm is installed facing aft and the new mount for the ram is curing as we speak.

Now, I have another issue. When the unit arrived, there were no clutch wires, just a relay and 3 points of attachment (labelled 1,2, and ground). The unit is supposed to come with the wires ready to be attached so, now I'm on my own. I found nothing on the internet and have been waiting for a reply from Raymarine, but their customer service is appalling sometimes.

Since the clutch cables can be swapped anyway, does it matter which way I hook them up. It seems like I should just try and if the unit moves in an oppisite manner than expected, switch the cables over. Just thought I would check with the collective mind before doing something stupid.
 

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Thanks for the help guys. After a few trips to the machine shop to get things right, the arm is installed facing aft and the new mount for the ram is curing as we speak.

Now, I have another issue. When the unit arrived, there were no clutch wires, just a relay and 3 points of attachment (labelled 1,2, and ground). The unit is supposed to come with the wires ready to be attached so, now I'm on my own. I found nothing on the internet and have been waiting for a reply from Raymarine, but their customer service is appalling sometimes.

Since the clutch cables can be swapped anyway, does it matter which way I hook them up. It seems like I should just try and if the unit moves in an oppisite manner than expected, switch the cables over. Just thought I would check with the collective mind before doing something stupid.
The documentation from Raymarine is usually good, I don't know your model.
But there is a wiring diagram here https://raymarine.app.box.com/s/uiywcmdws48mwehcl0j0/1/1787123049/15857529539/1

More documentation here Raymarine Manuals and Documents
 

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1982 Skye 51
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379 Posts
Discussion Starter · #18 ·
thanks, knut, but i have that already. my unit came without any of the clutch cables shown on the wirind diagram, so I have to wire my own. just wondering which of the contacts on the relay to attach them to.
 
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