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Old 05-12-2012, 16:57   #16
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Re: Autopilot Choice

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Originally Posted by nhschneider View Post

The trivial issue first: Since the N2K network does provide a minimal amount of power, it's possible to have the circuit breaker for the autopilot turned off and still have enough power to bring the display up, indicating that the autopilot is on and fully functioning. But it isn't. There's only enough power to bring up the display and not enough to power the steering mechanism. Circuit breakers will trip and fuses will blow if you're not aware of this. The simple solution is to leave the circuit breaker for the autopilot on all the time.

The second issue we have is that about once every 24 hours, regardless of whether we're under power or sail, the autopilot display goes into alarm mode, it stops steering and says, "Cannot find autopilot computer". Canceling the alarm is easy (press any key) and the normal display returns instantly. Then we re-engage the autopilot and it's fine for another 24 hours or so. All three of us are so used to the problem that we can be back under autopilot control in a matter of a few seconds. I can see the mental gears of those reading this spinning away, thinking, "This guy is an idiot. It's either a wiring problem, an SSB or VHF transmit problem or maybe a refrigerator compressor that cycling that's causing his problem.". First, I'll match my skills at routing, dressing and terminating wires and cables with the most discerning of technicians. For 25 years I owned a low-voltage contracting company and spent way too much time doing it. I've isolated the ground, relocated the related cables away from any high amperage cables or sources. There is no correlation to the use of the SSB (although keying the SSB's mic does send the autopilot into a steering frenzy) or VHF. We have even gone to the extent of shutting down our refrigeration compressors to see if that would cure the problem. It didn't.

I bought a second AC42 but that has the same problem. I have been in touch with Simrad technical support and they want us to ship them the units. Now that we should be staying put in Australia for a while, we'll do just that.

Regardless, I still like the Simrad autopilot very much. Fortunately, our boat balances very well so it makes it easy to get the autopilot dialed in to where there is little correcting that has to be made, under most conditions.

Fair winds and calm seas.

We have the same autopilot as you. The first issue is as designed - the control head is powered by the N2K bus and the autopilot computer/drive by a separate supply. The head will be active (and providing data because it is really a MFD), but if you attempt to engage the pilot, you will get an error that the pilot computer is not available.

My first thought on the second issue is that there is something wrong with your AP (not with you or your abilities). Our system has never had the problem you describe, so I don't think it is endemic to the Simrad pilot. Probably a long shot and a difficult thing to do, but swapping your pilot into someone else's boat and going on a 2 day passage would tell you something...

Mark
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Old 05-12-2012, 16:58   #17
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Re: Autopilot Choice

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Originally Posted by 44'cruisingcat View Post
Maybe they've updated the software?
There is a new software update within the past couple of months. I just installed it and see no difference from the old software.

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Old 05-12-2012, 19:26   #18
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Re: Autopilot Choice

Dockhead:
I have an older Simrad pilot AP 25 on a boat comparable to yours (Kanter 52' Fast Cruiser) and have had no problems with it. When I installed it, I purchased two heads and still have the spare sealed in plastic... probably why it has lasted so long!!!

More importantly... what are you planning to use below decks???? I had redundant hydraulic units, which had difficulty steering the boat in some in extreme conditions. I changed the system to a direct drive to the rudder post, driven by a Lewmar planetary gear 24 volt motor ( weighs 70 lbs!!). This system was not cheap, but has been bullet proof for 5 years and tens of thousands of miles. It has steered the boat in extreme conditions with minimal maintenence (no hydraulics). Consider your below decks set up as carefully as your control head.
Fair Winds,
Michele
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Old 10-12-2012, 15:55   #19
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Re: Autopilot Choice

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Originally Posted by sailnautilus View Post
Dockhead:
I have an older Simrad pilot AP 25 on a boat comparable to yours (Kanter 52' Fast Cruiser) and have had no problems with it. When I installed it, I purchased two heads and still have the spare sealed in plastic... probably why it has lasted so long!!!

More importantly... what are you planning to use below decks???? I had redundant hydraulic units, which had difficulty steering the boat in some in extreme conditions. I changed the system to a direct drive to the rudder post, driven by a Lewmar planetary gear 24 volt motor ( weighs 70 lbs!!). This system was not cheap, but has been bullet proof for 5 years and tens of thousands of miles. It has steered the boat in extreme conditions with minimal maintenence (no hydraulics). Consider your below decks set up as carefully as your control head.
Fair Winds,
Michele
Hmm, I've never heard of such a system --do you have a link? I have a heavy-duty Raymarine hydraulic system below decks, a big hydraulic ram driving the quadrant through an electric clutch, and a hydraulic pump driving that. The pump failed last year and I replaced it; otherwise the system has been bulletproof in my ownership. I was not aware that better things are available; would like to hear about your system.
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