Adding a rudder angle indicator

[Ayb]

I'm having a hard time getting my rudder amidships in tight quarters (I have hydraulic steering so it's a bit vague) and the auto pilot display in the pilot house is hard to read from the cockpit. I've been wondering about the best way to add a rudder angle indicator in the cockpit and I'm hoping for some advice on how to do it efficiently.

The auto pilot is an old Robertson/ simrad AP20 which uses an RF300 sensor at the rudder post via a linkage. It looks like there were Robertson branded indicators that can be connected to that system but it's unclear which one fits what and they're all used and very expensive items.

I'm not sure if the AP20 actually provides rudder angle as nmea and if so where but maybe there's some kind of generic display that I could interface with that?

As an alternative I was thinking of purchasing a completely redundant system such as the Raritan rudder master. This would be a second angle sensor and an indicator with a junction box, I could add a second linkage or maybe they can "share" the linkage.

[Sivaa]

AP 20 is autopilot controller or control head . You need to see the details of autopilot computer alike AC 70 / AC 80 .

RF300 Cable goes to autopilot computer . Irrespective of its polarity terminals , parallel connection is given to rudder angle indicator . Second rudder feedback unit if preferred , direct connection to indicator & computer from each feedback unit - for a dedicated unit than giving parallel connection from computer ; is given .

Referring indicator for zero reading is more reliable than viewing on controller . Due to setting parameters through controller , offset is possible for zero rudder . Whereas rudder indicator will not be influenced alike. Even a single feedback is used for both of them, rudder indicator is more reliable and this gives assistance to select zero position reading while programming autopilot controller .

Connection details are described in autopilot installation manual as well as in operation manual . You can refer the single line diagram as well as drawing about computer terminal position and connecting details. Regards .

[Ayb]

Thanks, I have the j300x junction box and it looks like there is a rudder angle nmea output on that. I wasn't sure what I could interface so I'm going with a redundant system, a veratron display and vdo angle sensor. I'm planning to attach the sensor to the same linkage as the rf300 and wire everything independently.

[Ayb]

Here's the plan

[Sivaa]

This RF300 feedback unit is measured by means of frequency- by the Autopilot computer . This unit can support 4 indicators simultaneously , as per manual . NMEA output is not with this feedback . From Computer , SIMNET / NMEA port gives update to the system . For references . Regards .

========================

Based on attached shot , off-centre and inadequate clearance between two units are observed . Without base mounting second unit , you may please do the proto type testing . You may keep indicator, nearer to you as well .

By now , you prefer to connect two feedback units to the computer - though both will work . For clarification, please .

[Sivaa]

Two feedback units to the computer - I try to recollect from memory . Please check in manual , please . This is quick and gives conviction as well . Regards .

[bkcorwin]

the j300x has a single rudder feedback input. Cant see how two will work.

because the rudder feedback unit you have already is a frequency type you would want to find something like a robertson ri35 mk2 which works with that input natively.

B

[Sivaa]

Perhaps in AC70 manual . RF300 catalog may also have . I remember the ref for connecting upto 4 indicators for this feedback unit . I will try to get those details . Simrad technical help centre can also support . For references . Regards .

[Pizzazz]

Originally Posted by Ayb

Here's the plan

You can also connect the new 0-180 sensor directly to the old autopilot sensor, may be less work. But you are absolutely correct, you can get a sensor and a nice display for $50 vs. adding a Simrad display for $500. Go figure.

[pcmm]

If the hydraulics are working correctly you should be able to predict where center is. My system is an old Hynautics system an its 5 turns lock to lock (once properly bled) its 2.5 turns from lock to center every time.

[S/V Illusion]

Electromechanical gadgets aside, why not just add an indicator mark on your wheel? I have an indicator sensor but trust the visual mark more and it’s obvious.

[pcmm]

Originally Posted by S/V Illusion

Electromechanical gadgets aside, why not just add an indicator mark on your wheel? I have an indicator sensor but trust the visual mark more and it’s obvious.

Is your steering cable or hydraulic? With hydraulic, it can be many turns lock to lock. As an example, in my case its 5 turns. Having an indicator on the wheel doesn't really tell you where your rudder is without knowing how many turns you've gone.

[Ayb]

Yes, it's hydraulic (manual helm pumps). I'm having the rudder pulled and inspected and also checking the hydraulic components as there's a lot of effort needed to turn the rudder and I wonder if the helm pump is failing as well. An indicator would help me coordinate maneuvers in close quarters. Most recently I tried to swing the bow into a slip and overshot it as I tried to center the rudder too late, seeing the indicator would have really helped but I couldn't read the auto pilot display in direct sun.

[Ayb]

Originally Posted by Pizzazz

You can also connect the new 0-180 sensor directly to the old autopilot sensor, may be less work. But you are absolutely correct, you can get a sensor and a nice display for $50 vs. adding a Simrad display for $500. Go figure.

Right that's what I was thinking. I'm planning to rig up a vdo sensor completely redundant to the rf300 (but spaced well apart) and then a dedicated indicator (veratron) will use that. I'm trying to find a used ri35mk2 but they're more expensive and hard to find now that none of that stuff is in production.

[Bycrick]

My old AP20 showed rudder position as a line at the bottom of the display. The J300 output the RPI sentence so often that it would cause the old B&G Hydra system to crash. I never felt the need for a separate RPI display, because I needed to have the AP turned on to get any rudder indication. If you’re replacing the AP, the newer Simrad units have an optional RPI that outputs directly as N2K and can thus be displayed anywhere without the AP being involved.