Simrad AP48 autopilot glitch

[woodscrew]

Leaving the St Lucie lock December 29th west bound. First boat in and there fore out as well. Angling slightly off the wall, idling out and suddenly no steering. Now heading for the opposite wall. It felt like the auto pilot was engaged. It had gone, by itself, from Standby mode (S) to Follow Up mode without any input. The icon for Follow Up mode is, most appropriately, FU. No I didn’t mistakenly touch the wrong button, or any button. Was able to kill the power to the unit and save the day.I admit I know nothing about the many modes this autopilot has. A for automatic and S for standby. That’s all I need or care to know. For proof of this glitch it did the same damn thing with my wife at the helm and me on the bow. Approaching a bridge. I looked aft through the windshield to see my wife turning the wheel with no effect and a panicked look on her face. I ran back to find a big FU on the screen. Powered it down again. Now I shut it off when entering any marina or lock. Nerve wracking to put it mildly. Anyone else seen this?

 

[HeadedToTexas]

My old AP16 spontaneously shuts down from time to time. I suspect corrosion on contacts somewhere along the network, but no evidence of that. Shutting down is better than engaging, I suppose.

 

[Flatswing]

Do you have a Simrad MFD? Compatible MFD’s can drive the AP. Just a WAG.

 

[sunchaser]

Metal surroundings possibly affecting compass, remote or control logic. Some years ago a vessel going under a bridge in Vancouver Harbor suddenly veered with loss of life. Investigation pointed to metal bridge screwed up heading sensor. Accident follow up found not an unusual occurrence with either onboard placement of metal or external iron works.

 

[twistedtree]

I assume you have FU controls? How many? As I recall they operate over N2K (Simnet) using data messages. I virtually impossible for a bad electrical connection to erroneously and spontaneously create a valid message, so the problem isn't in the N2K network. I'll bet one of the FU controls (maybe FU80s?) is going back such that the button to enter FU mode is going bad. That would make the FU think someone pushed the button, and it would tell the AP42 to go into FU mode. If you have multiple FUs, the trick will be to figure out which one is bad. I'd lead towards any that are outside and subject to water, or one that perhaps gets the FU button pushed much more frequently.