505/508 - B&G Auto Pilot

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B&G Auto Pilot

Printed From: myHanse.com
Category: Hints & Tips
Forum Name: 505/508
Forum Description: 505/508 Hints, Tips and News
URL: https://www.myhanse.com/forum_posts.asp?TID=9057
Printed Date: 27 March 2026 at 03:29
Software Version: Web Wiz Forums 12.06 - https://www.webwizforums.com

Topic: B&G Auto Pilot

Posted By: andyoliver53
Subject: B&G Auto Pilot
Date Posted: 05 June 2015 at 18:29

While my B&G auto pilot is in Navigation Mode the yacht lurches 20deg to port every 9 min on some days and 21 minutes on other days then comes back onto course.

It does not do it it in Auto Mode.

I have had 2 auto pilot computers replaced so far.

Last year it was every 5min to port. The auto pilot computer has been replaced since then ......

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The world is what you make it.
MMSI 503010060

Replies:

Posted By: High Time
Date Posted: 05 June 2015 at 20:00

Since it is stable in Auto mode I would suspect the GPS. This is supplying the cross track error data that the autopilot uses in Nav mode.

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Roger

High Time (415 #038)

Posted By: andyoliver53
Date Posted: 05 June 2015 at 20:54

Yes I agree and have tried different GPS source but so far it has made no difference.

What gets me is why on some days its every nine minutes and on other days its every 21 minutes.

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The world is what you make it.
MMSI 503010060

Posted By: panos
Date Posted: 05 June 2015 at 22:28

I think I know why. Even if the autopilot is in nav mode it actually is in auto mode and a part of the software which is responsible for the navigation is setting the course. But the problem is that it can only set integer values for the direction. Now suppose that to get to the next waypoint a course of 30.6 degrees is required. The navigation software commands the autopilot to keep a course of 31 degrees. This difference of 0.4 degrees with time adds up and the boat slowly escapes from the zone which is considered accurate and then a major correction is required. There is a parameter specifying what course correction the pilot is allowed to perform without a user intervention. You can set it to a lower value, for example 5 degrees, then the corrections will be more gentle.

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Panos

Hanse 630e - selling her -

Posted By: High Time
Date Posted: 06 June 2015 at 15:34

My Simrad autopilot (same as B&G no doubt) in Nav mode corrects for the cross track error continuously. It only deviates a few metres from the rhumb line and is immediately corrected by a small amount. This does not equate to the 9 minute or 21 minute corrections that Andy is experiencing.

I am struggling to think what works on a 9 minute or 21 minute cycle though. Are these times precise and repeatable or just approximations?

Maybe there is a parameter for the maximum cross track error that can be tolerated before a correction is made. I will have a look at the manual when I get a few spare minutes.

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Roger

High Time (415 #038)

Posted By: andyoliver53
Date Posted: 06 June 2015 at 17:17

Hi High Time.... and thanks for your input.

the 9 and 21 minutes are withing seconds.

Last year / season were were sailing down along the coast of portugal when this problem started and then it was every 5 minutes give or take a few seconds and as were were sailing long distances even overnight and it would happen every 5 minutes. Since then the auto pilot computer has been replaced by B&G for the second time.

B & G the company has been great but I am finding that some of the dealers are way behind the game.

-------------
The world is what you make it.
MMSI 503010060

Posted By: High Time
Date Posted: 06 June 2015 at 21:39

OK - interesting problem. It's difficult to imagine what could be affecting the autopilot at such regular and repeatable intervals.

I suspect the problem may not be in the autopilot computer if this has been changed twice by B&G, but may be caused by something else on the network or the power supply.

What else is connected to your network - plotter, AIS, laptop, GoFree etc?

Are you controlling the autopilot from the plotter or the AP24?

Where is the GPS data coming from and is it completely stable?

Does the interval (9mins/21mins) vary with boat speed/SOG?

Are your batteries in good shape and do you have a smart alternator booster?

Is there anything else you can tell us that may be loosely connected to the problem?

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Roger

High Time (415 #038)