Sound of Hand Smacking Forehead

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billdomb

billdomb

Veteran Member
Joined
Nov 12, 2019
Messages
61
Location
United States
Vessel Name
Activated Eau
Vessel Make
Vantare
Had been having some issues with our autopilot, so had a tech come onboard to assess/fix things. He did so, but in only a week it started going nuts again doing crazy Ivans at random times.

Had the tech back and he tested everything again.

"What's this?" he asked.

"It's just a little light to help see in this hold."

"Well, see where it's sitting?"

"Yeah, so?"

"That metal box you stuck your light on holds the fluxgate compass. Your light is holding on there with a strong magnet and screwing it up royally."

Sound of hand smacking forehead...

Working fine again.

 
Every time an autopilot does a crazy Ivan it’s either a failing flux compass or a magnet placed close to the flux compass.
 
That's kind of odd to me. Yes, the magnet is going to pull your fluxgate compass heading off but permanently, not randomly. If you're running a straight heading in auto and the pilot starts making crazy Ivans, something else is affecting the pilot. I'd make sure no motorors are coming on near the flux (A/C pumps, bilge pumps/refrigerator compressors etc. What I've found in most cases like yours is a failing rudder feedback. Make sure the feedback is indicating your rudder position with a smooth, flowing motion on the indicator. A jumpy rudder position indication means a bad feedback and will give you the exact symptoms you're having.
 
Greetings,
Our first "trawler" was a 1974? 34' Marine Trader DC. Our maiden voyage and delivery trip was from Mystic, CT to Kingston, ON, Canada via the Erie Canal. It did have an AP. At one point we were on the canal with the AP set and we passed under a steel truss bridge. Boat took a hard-a-port turn as we went under the bridge. I tried to correct but of course Otto was in charge and NO wheel response/control. Somehow I had the presence of mind to turn off the AP and steer away from the concrete support pier. I DID have spare under drawers aboard...

1722687167136.jpeg
 
I had a new boat which came from the dealer with the microphone clip installed right below the compass. The compass always pointed N unless I was using the radio.
 
I had a similar thing happen to me while helping a friend move his boat. All of a sudden the autopilot went crazy.

My friend didn’t know where the fluxgate was so I started searching. First the bilge, no. Then the cabinets inside although I knew that the fluxgate needs to be installed near the centerline.

Then I checked behind the helm on the flybridge and it was there. But no wires or magnetic things nearby. Then I looked on the bench seat and sure enough my friend had left his YETI cup there just behind the bulkhead and within inches of the fluxgate.

I picked it up and the autopilot immediately settled down. I was surprised that the SS cup would affect the fluxgate, but some SS alloys have magnetic properties and this must have been one of them.

David
 
Had a customer tell us that every time he crossed the wake of a Bayliner 4588 his autopilot did a crazy Ivan. He didn’t have issues with other boats. After inspecting his boat we relocated his fluxgate compass away from his stereo speaker. Problem solved. I can only conclude that the 4588 wake was steeper than other boats and that put the compass with in the influence of the speaker.
 
BTDT! Here's my version from the Summer of 2018:

Enroute to Meyer's Chuck this morning my autopilot in heading mode made a hard-over to starboard, definitely making me sit up and pay attention. Turned it off and on, got same response....hmmm. switched it at the breaker; no help. Turned it on to see if there was a limit. It rolled out 120 degrees off course...hmmm.

Then I recalled, we are passing a place called Magnetic Point, and sure enough, there's an explanatory chart note...AAH!

So, I hand steer for a half hour or so and it slowly dawns on me that the compass isn't doing anything dramtic...hmm. Hand-bearing compass is equally stable.

I cast an accusatory glance at the autopilot flux detector and realize that while moving stuff off my chart table I had moved my Bose bluetooth speaker (think two-pound magnet) a critical foot closer to the...you guessed it: flux sensor.

DOH!
 
Not completely unrelated: I noted that when I was cruising on a westerly course and
got a bit too close to an anchored container ship to port, the autopilot veered toward
the huge steel vessel. Fortunately it was a gradual course change that I was able
to correct but the autopilot, on its own, would have steered us right into the ship!
 
tiltrider1 said:
Had a customer tell us that every time he crossed the wake of a Bayliner 4588 his autopilot did a crazy Ivan. He didn’t have issues with other boats. After inspecting his boat we relocated his fluxgate compass away from his stereo speaker. Problem solved. I can only conclude that the 4588 wake was steeper than other boats and that put the compass with in the influence of the speaker.
Click to expand...
No, the 4588 has a magnetic personality.
BTW crossing over a shallow underwater electrical cable does a crazy ivan
 
For info.....

www.armystudyguide.com

Handling A Compass - Army Education Benefits Blog

COMPASS HANDLING
www.armystudyguide.com www.armystudyguide.com

Handling A Compass​

COMPASS HANDLING
Compasses are delicate instruments and should be cared for accordingly.
a. Inspection. A detailed inspection is required when first obtaining and using a compass. One of the most important parts to check is the floating dial, which contains the magnetic needle. The user must also make sure the sighting wire is straight, the glass and crystal parts are not broken, the numbers on the dial are readable, and most important, that the dial does not stick.
b. Effects of Metal and Electricity. Metal objects and electrical sources can affect the performance of a compass. However, nonmagnetic metals and alloys do not affect compass readings. The following separation distances are suggested to ensure proper functioning of a compass:
High-tension power lines …………………………………………. 55 meters.
Field gun, truck, or tank ………………………………………….. 18 meters.
Telegraph or telephone wires and barbed wire ……………. 10 meters.
Machine gun …………………………………………………………. 2 meters.
Steel helmet or rifle …………………………………………………. 1/2 meter.​
 
Thanks. Very enlightening. I've found certain hand-bearing compasses are incompatible with wire-framed glasses.
 
Ha! This explains the hard turn to starboard when cruising down the east side of Texada Island.
 
psneeld said:
For info.....

www.armystudyguide.com

Handling A Compass - Army Education Benefits Blog

COMPASS HANDLING
www.armystudyguide.com www.armystudyguide.com

Handling A Compass​

COMPASS HANDLING
Compasses are delicate instruments and should be cared for accordingly.
a. Inspection. A detailed inspection is required when first obtaining and using a compass. One of the most important parts to check is the floating dial, which contains the magnetic needle. The user must also make sure the sighting wire is straight, the glass and crystal parts are not broken, the numbers on the dial are readable, and most important, that the dial does not stick.
b. Effects of Metal and Electricity. Metal objects and electrical sources can affect the performance of a compass. However, nonmagnetic metals and alloys do not affect compass readings. The following separation distances are suggested to ensure proper functioning of a compass:
High-tension power lines …………………………………………. 55 meters.
Field gun, truck, or tank ………………………………………….. 18 meters.
Telegraph or telephone wires and barbed wire ……………. 10 meters.
Machine gun …………………………………………………………. 2 meters.
Steel helmet or rifle …………………………………………………. 1/2 meter.​
Click to expand...
I just moved my machine gun and now my boat steers straight.
 
Last edited:
Some allisions have been attributed to running a boat on autopilot under a steel bridge.
 
In my mind this all points to a satellite compass being a good addition to any autopilot if budget allows.
 
Let’s not go off the rails. We are talking about rare failures here. Most auto pilots go their whole lives and never perform a Crazy Ivan.
 
Pretty sure a lot of the older flux gate compasses were cheaply made and their bearing would hang up causing erratic steering. Especially if it tended to hang in just one direction.
 
Years ago I chartered a old Taiwan trawler out of Comox BC. at the time I had a Krogen 42 and met the owner of the boat. Since I was an experienced trawler guy, he pulled back the panel and hooked up the autopilot for me which he normally unplugged because it would go Crazy Ivan for no reason. As a ingenious "safety measure" he installed a gigantic red round ball kill switch on the dashboard.
I was putting along in a narrow channel opposite a tug and a tow of huge logs when one of the guests on the boat went down below to shave. Activation of the water pump was accompanied by a 90 degree port veer toward the log tow.
Hit the red button.... no problem.. those darn Canadians are so clever.....giggle
 
I didn't see anyone else mention this so I will.
You should run updates on all of your navigation equipment.
You didn't mention what you have but with Garmin when I do a chart update the Active Captain front end checks to see if any of my equipment on the NMEA 2000 network needs updating and if so downloads the necessary files.
Glad you found your issue and got it resolved.
 
Boomerang, I think what happens is if you are running in no drift mode on your autopilot your compromised compass takes you off course and then your GPS calls for a course correction. Then the cycle repeats. I made the mistake of setting a tool bag in front of my compass once and after a few cyclic auto pilot maneuvers I figured it out.
boomerang said:
That's kind of odd to me. Yes, the magnet is going to pull your fluxgate compass heading off but permanently, not randomly. If you're running a straight heading in auto and the pilot starts making crazy Ivans, something else is affecting the pilot. I'd make sure no motorors are coming on near the flux (A/C pumps, bilge pumps/refrigerator compressors etc. What I've found in most cases like yours is a failing rudder feedback. Make sure the feedback is indicating your rudder position with a smooth, flowing motion on the indicator. A jumpy rudder position indication means a bad feedback and will give you the exact symptoms you're having.
Click to expand...
 
We had a 42 GB, running under autopilot when my wife put something in the microwave. Immediate hard left turn! Never made that mistake again. ;-)
Regards,
Scott
 
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