Simrad AP

I can't figure out how to "zero" the rudder angle indicators on two IS20s (Rudder version), which are part of a system that includes two AP28s and 6 jog lever controls. The system has been installed and working fine for the past 10 years, although I have a vague recollection of the rudder angle indicators having previously lost their center.

The problem now is that with my rudders centered, both AP28s indicate centered rudders, but one of the IS20s shows the rudders 1/8 to starboard and the other shows hard over ("1" on the instrument's scale) to starboard. If I turn, every indicator adjusts to show the turn (so a small turn to port shows 7 on the AP28s (different scale), centered on one IS20 and 7/8 on the other. Everything would be fine if I could just get the two IS20s to center when the rudders are centered. I have read the documentation but from what I can tell the IS20s are supposed to be self-calibrating. I have tried rebooting the entire system, but the IS20s went back to their prior positions.

I am hoping someone else with a Simrad AP system has figured this out. I sent an email to Simrad but got a response back indicating that it will take weeks to get a response.

Thanks for any advice. -Rick

Rick,

In this Simrad IS20 Analog Instrument manual check out page 38 - Configuration - Setting the rudder zero position. It looks like it could apply to your situation.

https://www.psicompany.com//man-prod-info/simrad/is20opman.pdf

Thanks Larry. I have tried that but it seems to set center the ruder without setting the display needle to the centered position. Perhaps I should try again.

MYTraveler said:

Thanks Larry. I have tried that but it seems to set center the ruder without setting the display needle to the centered position. Perhaps I should try again.

Click to expand...

IRRC the Rudder feedback calibration consists of two operations, Adjusting the maximum rudder angle and Setting the rudder zero position. I think I would try both. Then select the menu item to Display the actual rudder angle to compare with the AP28's.

If that fails, I would perform an Instrument reset and start the rudder feedback calibration process again. I believe you might have to perform this procedure on each of the IS20's, but that's above my pay grade.

I no longer have that system on my boat as I changed out my entire electronics suite to Garmin, including the A/P. I miss the AP28 and particularly the FU steering lever a lot. Best autopilots I have ever used.

Makes sense. I will give that a try. Thank you!

A buddy also "upgraded" APs from Simrad to Garmin (the factory rep at a boat show sold him to explaining that Garmin's was the only AP that would work in reverse), but now misses his Simrad. The irony is that, from what I am told (hope I am wrong), Simrad no longer makes the AP 28 or anything comparable.

Simrad AP44?

MYTraveler said:

Makes sense. I will give that a try. Thank you!

A buddy also "upgraded" APs from Simrad to Garmin (the factory rep at a boat show sold him to explaining that Garmin's was the only AP that would work in reverse), but now misses his Simrad. The irony is that, from what I am told (hope I am wrong), Simrad no longer makes the AP 28 or anything comparable.

Click to expand...

At the risk of thread drift, who do you guys look to for support on legacy Simrad equipment like autopilots? My boat has an AP16 at each helm and they randomly shut down. Frustrating.

I adjusted the physical linkage on the Simrad rudder angle sensor to get it zeroed without any software resets so as not to face this issue of having to reset the zero in software. We were only dealing with one sensor though and the setup had turnbuckles on it that made adjusting relatively easy.