Request help with rudder feedback unit

[PJHoffnet]

BLUF: Looking for a hand with replacing the ‘arm’ of a Simrad RF300 rudder feedback unit/full replacement of the unit.

I have a Simrad RF300 rudder feedback unit that could not withstand the tremendous weight of my fat gut contacting it the a couple of months ago when I was doing some work on a nearby underwater light connection. I’ve worked in that ‘tight hole’ area before and was careful not to put any body part over the unit, but wasn’t careful enough this time and the ‘arm’ snapped off pretty darn close to the rotating top piece.

Yupp, stupid me. Oh well, JB weld has done a good job holding it together until this past weekend when I did a really fast wheel spin at the helm to avoid a ‘late seen’ crab pot. Crab pot survived, but the arm snapped at the repair line.

So, I went on Ebay and ordered a new arm, but when I went to scout out how to remove the old arm, I couldn’t get the ??? ‘set screw’ ??? in the middle of the arm to come loose. In fact, the ‘head’ of the screw snapped right off. Perhaps I was removing the piece incorrectly.

OK, before this drifts too far into TLDR territory, 1) Anyone have any insight into how to remove the screw/top rotating part of the unit? 2) If I decide that isn’t going to work, and I replace the unit, can I simply cut and splice the new unit to the existing cable, or do I need to re-run the entire length?

[smac999]

I have never tried to pull an arm off. it would need to be aligned to the base when installed somehow. otherwise the centering tabs would not line up. hopefully there is a notch or something so it can only go on facing one way?

you can just cut and splice the wires.

[PJHoffnet]

Originally Posted by smac999

... hopefully there is a notch or something so it can only go on facing one way?

The top rotating arm and the base both have alignment notches scribed on their exterior. Not sure if there is a physical alignment notch.

Originally Posted by smac999

...you can just cut and splice the wires.

Thanks, I was hoping for that. Having already run a few wires from the bilge to the helm on this boat, I was hoping to avoid that fun.

[ilCigno]

2) Yes, you can cut and splice. Rudder reference sensors are in fact potentiometers. A certain resistance is corresponding with a certain rudder angle. By splicing the cable resistance might change a little. I suggest to rerun the initiation proces of your autopilot afterwards.

[Bycrick]

Not all rudder position sensors are simple potentiometers. Some Simrad units had a variable frequency output. Others are NMEA 2K devices. Splicing the wires should make any difference though. Both my old Simrad, an even older Robertson, and a B&G supplied "network" connected rudder sensors.

[smac999]

Originally Posted by PJHoffnet

The top rotating arm and the base both have alignment notches scribed on their exterior. Not sure if there is a physical alignment notch.
.

yes but you can't use those to reattach the top. those notches are used to mount it in the boat. if you reattach the top offset these 2 outside notches would also be offset by the same amount

[deblen]

Originally Posted by Bycrick

Not all rudder position sensors are simple potentiometers. Some Simrad units had a variable frequency output. Others are NMEA 2K devices. Splicing the wires should make any difference though. Both my old Simrad, an even older Robertson, and a B&G supplied "network" connected rudder sensors.

Indeed. https://www.electro-tech-online.com/.../#post-1142950
Cheers/Len