I've Made a Mess of My Autopilot

[Dockhead]

Originally Posted by Kenomac

When do you head off to Greenland?

2 June, and I have two business trips between now and then. I'm going to try to break the back of this problem this weekend (sorted the generator yesterday -- hurrah!), failing which I might need to call in the cavalry.

[Dockhead]

OK, so here's the latest:

I have been through the section of my diagnostic procedure.

Dockside commissioning failed at every point, with and without using the rudder sensor.

But when I jumped the clutch, it closed. And when I connected the pump directly to power, it works fine in both directions and moves the ram where it should.

So that means the problem is in either the wiring or in the pilot computer.

I can't image what could have happened to the pilot computer, but I did have a mysterious failure of my depth transducer, so perhaps there was some kind of electrical disturbance on my boat.

The wiring is very simple and has mostly been checked already. Pump power, clutch power, N2K, rudder position sensor. I'll go through the wiring again tomorrow, and meticulously, but I just can't help but think that the computer is on the fritz. The rudder sensor could be suspect, but if the computer were OK, I should be able to commission the system without the rudder sensor, by using the virtual rudder feedback.

Has anyone had a failure like this? I've never heard of these units (which I believe are actually Robertson) just blowing up. What a PITA. At least the bloody hydraulics are good and I've got it well narrowed down -- before today the problem could have been anything.

[cowelld]

Here's the test for the RF300. You'll need an O-scope or other frequency measuring tool. You didn't mention what your front end for the AC42 was. Are you using an AP unit or have a NSS/NSE/Zeus MFD front end? If you have one of these you should get indication of the rudder indicator in the systems if the AC42 is registering it correctly, The RF300's have been reliable as a rock unless you somehow hit the wires with a high voltage. (That's why they use a shielded pair.) Navico has an updated firmware for the AC42 which is supposed to do nothing new but you might (re)load it anyhow.
Hope this helps.

[Dockhead]

Originally Posted by cowelld

Here's the test for the RF300. You'll need an O-scope or other frequency measuring tool. You didn't mention what your front end for the AC42 was. Are you using an AP unit or have a NSS/NSE/Zeus MFD front end? If you have one of these you should get indication of the rudder indicator in the systems if the AC42 is registering it correctly, The RF300's have been reliable as a rock unless you somehow hit the wires with a high voltage. (That's why they use a shielded pair.) Navico has an updated firmware for the AC42 which is supposed to do nothing new but you might (re)load it anyhow.
Hope this helps.

Thank you!!

I will try this. My multimeter does do frequency.


I have remade absolutely all of the wiring connections and tried again to do the dockside commissioning.

The computer definitely does not find the RF300 as there is no rudder indication at any point in the process. When I get to the rudder position calibration, it asks for me to put the wheel over hard to stb then hard to port, then to center the wheel. At that point, the process simply hangs up.

Then I do "reset autopilot" and try to commission using virtual rudder feedback. This worked once or twice, a few days ago, but now does not. I get as far as "is the wheel turning to starboard?" and it never does.

I have a feeling that I need to do a global reset of the computer so it once again initializes itself from zero, registering what kind of drive etc. I have. But I cannot find any procedure to do this.

I'm trying to get through to Navico tech support in the U.S. (oddly, they don't have a tech support line in Europe).

I'll do the RF300 test, but if I can't get any further with the diagnostics, I'm going to have to just start replacing stuff, and hoping to sell off any of it which turns out to be good. I only have 10 days before departure.

[hpeer]

Dockhead,

This must be driving you nuts. Just thinking of all the effort you put in to have redundancy and backups, then to have this. Must be frustrating.

When it’s over, perhaps when you get back, I’d like to hear your reflections on this topic.

To chew on, our boats are quite odd with respect to steering.

Big boat has wheel (chain and wire) and a tiller to the rudder. CPT on the wheel (and spare), Aries to the tiller, tillerpilot to the Aries.

Small boat has wheel (chain and wire) and a aux rudder vane. A tiller pilot drives the aux rudder, I have a spare tiller pilot.

None are sophisticated, but pretty robust.

[Dockhead]

OK, so here is what it was.

As is usual in these cases, it was something maddeningly simple which I somehow couldn't diagnose, leading me down all kinds of rabbit holes.

The shipwrights who dropped my rudder out got the rudder position sensor on backwards.



A hint from Navico tech support in the U.S. (a friendly, knowledgeable, and helpful person BTW) got me onto this -- at centered rudder, the wire coming out needs to be opposite the arm.

Once I got this sorted out, I was able to get it to work -- gradually. The system is cranky, crashes, etc., but I finally got it commissioned and sorted.

What happened was this, and I hope it helps someone else --

The RF300 has a deadband around where the arm is aligned with the wire. The computer won't detect the rudder sensor if that's where it is lying.

The Navico tech led me to the N2K network menu to see what the source of rudder position was -- in this case, nothing. It hadn't occurred to me that this would show up there, because the RF300 is not on the N2K network -- it is directly connected to the pilot computer. It should show the AC42 as the source of rudder data, and in Devices and Data, you should see the rudder angle.

The virtual rudder feedback commissioning is -- according to the Navico tech -- very much hit or miss, so don't read anything into failure of this, as I did.

So after burning up two or three days of time I desperately needed for other things, I now have a working pilot once again. At least I hadn't gotten as far as buying expensive new components I didn't need.

[Dockhead]

Originally Posted by hpeer

Dockhead,

This must be driving you nuts. Just thinking of all the effort you put in to have redundancy and backups, then to have this. Must be frustrating.

When it’s over, perhaps when you get back, I’d like to hear your reflections on this topic.

To chew on, our boats are quite odd with respect to steering.

Big boat has wheel (chain and wire) and a tiller to the rudder. CPT on the wheel (and spare), Aries to the tiller, tillerpilot to the Aries.

Small boat has wheel (chain and wire) and a aux rudder vane. A tiller pilot drives the aux rudder, I have a spare tiller pilot.

None are sophisticated, but pretty robust.

KISS is a great thing on boats -- I'm here to tell you

The key of being a good mechanic is really excellent diagnostic procedure. It takes brains and logic and experience. I keep disappointing myself with my own skills, although I have been wrenching on stuff since I was a little boy, and even spent a summer being paid to work on old Jags. I just have to keep doing it and keep trying to get better and work smarter.

[donradcliffe]

I had a RF300 go bad after about 50,000 miles. It started to send glitchy signals near the dead center position. Rather inconvenient as the closest land was the Andaman Islands, and the Indians are very prickly about stopping there.

I asked for help on the VHF, and a local ship captain directed me to an anchorage. I moved all the crap which was over the RF300, rotated it all the way to one end of its mounting system (its held on by three screws in slots) and recalibrated it. That got the glitchy spot out of the range of my normal rudder movement, and it worked until I got to Sri Lanka where I flew in a replacement at great expense and inconvenience.

The police boat showed up just as I was finishing and inspected my boat for stowaways, but let me depart.

After that I always carried a spare RF300.

[Dockhead]

Originally Posted by donradcliffe

I had a RF300 go bad after about 50,000 miles. It started to send glitchy signals near the dead center position. Rather inconvenient as the closest land was the Andaman Islands, and the Indians are very prickly about stopping there.

I asked for help on the VHF, and a local ship captain directed me to an anchorage. I moved all the crap which was over the RF300, rotated it all the way to one end of its mounting system (its held on by three screws in slots) and recalibrated it. That got the glitchy spot out of the range of my normal rudder movement, and it worked until I got to Sri Lanka where I flew in a replacement at great expense and inconvenience.

The police boat showed up just as I was finishing and inspected my boat for stowaways, but let me depart.

After that I always carried a spare RF300.

Just goes to show, I guess, that absolutely any part of an autopilot is subject to failure. I now have a spare complete pump, spare clutch, and spare seal kit for the ram. I guess I should add a rudder sensor and computer to that.

[donradcliffe]

A good idea. I usually keep on eye on Ebay for spares, but always test them first.

[Suijin]

Originally Posted by Dockhead

KISS is a great thing on boats -- I'm here to tell you

The key of being a good mechanic is really excellent diagnostic procedure. It takes brains and logic and experience. I keep disappointing myself with my own skills, although I have been wrenching on stuff since I was a little boy, and even spent a summer being paid to work on old Jags. I just have to keep doing it and keep trying to get better and work smarter.

Well as much as NMEA2000 is great, it seems that every vendor has their own take on it and they love to introduce their own peculiarities, often with no documentation or mention of the variation from the standard. Which in turn makes understanding what's going on difficult and diagnosing problems even more difficult.

The RF300 is in fact a Simnet/NMEA 2000 device. You can wire it directly into the computer or plug it into the backbone with a drop cable. Checking the device list is always my first move if something is not showing up, then moving onto the the data source list.

[Dockhead]

Originally Posted by Suijin

Well as much as NMEA2000 is great, it seems that every vendor has their own take on it and they love to introduce their own peculiarities, often with no documentation or mention of the variation from the standard. Which in turn makes understanding what's going on difficult and diagnosing problems even more difficult.

The RF300 is in fact a Simnet/NMEA 2000 device. You can wire it directly into the computer or plug it into the backbone with a drop cable. Checking the device list is always my first move if something is not showing up, then moving onto the the data source list.

Ah, I think you're thinking of the RF25. The RF300 is an old Robertson device which is definitely not an N2K device. It needs 15 volts and will give back a frequency which varies according to rudder position. Straight ahead is 3400 herz, and the frequency will change by 20hz per degree.