When not to trust your AutoPilot

Bertramdriver

Well-Known Member
Joined
27 Jan 2013
Messages
1,491
Location
Oxford
www.williamsandsmithells.com
Left Aegina in high spirits and did the 25 miles to the eastern entrance to the Corinth canal at a steady 15 knots in good conditions. As we entered the passage towards the canal we hit the notorious headwind / current and speed dropped to 11 knots so had to go off the plane. As usual there was a lot of hanging about at the entrance as canal control shuffled boats around and gave conflicting instruction "get ready" "wait" etc.
Whilst we were hanging about I noticed the Bertram was getting difficult to control and the combination of wind,current and crazy response to controls was perplexing me. Then we were called to tie up on the quay to pay the fees. Trying manoeuvre to Dock became a nightmare. The helm wouldn't respond and the engines had no effect on close manoeuvring at all. Never the less I shuffled the Bertram onto the quay, collecting some serious scratches on the gel coat and an angry tirade from the wife.
Went into the office to pay my dues, and by then the fuel tanker had arrived so I took the chance to top up. All these distractions took my mind off the key issue. Why wasn't the boat steering?
Just as I cleared all the fussing the control called to tell me to lead the next convoy through the canal so I fired up and the wife let go the warps. Then chaos. The boat wouldn't steer and to get off the key I had the pump the throttles hard. The result was that the mixture of over revs, wind and current sent me sideways across the canal entrance. By now the rest of convoy had closed up, restricting the space even further and as I shuffled backwards and forwards ( the canal entrance is less than 50 metres wide) the sightseeing crowds in the cafe and on the trip boats were audibly gasping at my increasingly frantic manoeuvring. Isn't it funny how the more people scream at you the quieter it goes in your head.
Anyway after 5 minutes of death defying boat handling I called quits and requested assistance from canal control. The pilot boat came over, took our warps and towed us back out into the bay, leaving an angry hum from the delayed convoy and the finger pointing laughter of the sightseers. As we were towed the boat screwed over to starboard on a parallel track to the pilot boat so it became obviousness that the rudders had locked over.
Once anchored I was able to check all of the systems and could see that the autopilot was very unhappy, with the pump clicking away beside me in a locker. I disconnected the pump, switched off the autopilot and hey presto I had steering.
On the next convoy through they put the Bertram in front with the pilot boat behind and held the other boats well back. Now being a little stressed at this stage I held speed at 1100 rpm which would normally be 8/9 knots but was only getting 4 knots in the current. Steering was good and I started to relax, then the pilot boat came up behind (very close) and shouted for me speed up. I ignored him knowing what would happen. By the third time this happened I lost it and snapped.
I cranked up the revs and hit the hump, up she went and 17 tons of water went barrelling down the by now 30 metre wide canal. The pilot boat shot up into the air and then did an impression of a cork in a washing machine. My last glimpse was of the pilot stuck sideways across the canal trying to get his bow round. The exit in sight I throttled back to pootling speed and we motored serenely into the sea of Corinth.
I have now idea of what caused the autopilot to behave like that, and further investigation and testing have not revealed any solutions, neither have I been able to recreate the problem. But I don't think we'll be going through the canal again anytime soon.
So the moral is make sure you can isolate and turn off your autopilot before you try anything fancy

Thanks to Alf for giving me the courage to own up, and apologies to any boat following last week who found their passage through the canal a little scary.
 
Last edited:
Sounds pretty horrific and not something I would like to face .

Incidentally do you have a rudder indicator that might have given you some hint of the problem?
 
Always told to "man the helm" in tight situations, Auto robots should not be trusted, especially when there are other boats close and big lumps of iron playing fast and loose with your compass.
 
Good on you Jon!!

Kept smiling all day and could not get the image of the frustration and worry ... followed by rising temper by the actions of the pilot boat pushing you along, then as a final event, the somehow satisfying thought of "I knew that would happen" when the bow up of the pilot boat rises up in the air as she skews sideways in the inevitable growing stern wave of the Bertram, out of my mind .... as I said earlier today ..... dang, where was the camera !!! :) :)
 
Last edited:
Always told to "man the helm" in tight situations, Auto robots should not be trusted, especially when there are other boats close and big lumps of iron playing fast and loose with your compass.

I don't think the autopilot was engaged, just 'on' as in 'on standby'.

I'd be surprised if the op was trying to berth using the a/p!!
 
Who knows he did not say, advice still stands turn the thing off and I mean OFF.

In principle I would agree ... I've done similar stuff myself.... twice actually ...

Once in Caledonian canal after crossing Loch Lochy and going into canal stretch (after lock) ... putting coffee cup up next to AP, I must have pressed the "Auto" button (obviously not switching off completely) ... was a bit awkward when exiting lock trying to keep off other boats wanting to enter... and once when trying to enter a harbour after a long(ish) passage of 120NM late PM/Night... got a bit fraught on both occasions when helm not responding as expected :) :) ... funny now, but pretty worrying when it happened....
 
To clarify a few issues
The Bertram has two rudder indicators. The OE is a semi mechanical and the raymarine AP controller
Before chaos ensued the OE showed hard left (which it has done in the past when the connector cable is dislodged) and the AP showed dead ahead. Just more to confuse.
When we were waiting I put the AP onto standby. It's overhead mounted so no risk of inadvertent switching.
I think the mistake I made was a lot of manual overrides to the AP when approaching the canal entrance whilst the AP was still engaged. Wind, current and circling may have confused the AP which I did not put into standby until I was called onto the toll quay. Then when in standby it decided to do its own thing.
Next job is an isolator switch on the AP to break the link with the plotter.
 
To clarify a few issues
The Bertram has two rudder indicators. The OE is a semi mechanical and the raymarine AP controller
Before chaos ensued the OE showed hard left (which it has done in the past when the connector cable is dislodged) and the AP showed dead ahead. Just more to confuse.
When we were waiting I put the AP onto standby. It's overhead mounted so no risk of inadvertent switching.
I think the mistake I made was a lot of manual overrides to the AP when approaching the canal entrance whilst the AP was still engaged. Wind, current and circling may have confused the AP which I did not put into standby until I was called onto the toll quay. Then when in standby it decided to do its own thing.
Next job is an isolator switch on the AP to break the link with the plotter.

I'd be inclined to fit the isolator switch in the pump supply. Just cutting the link to the plotter won't stop the a/p having the ability to do unexpected things...
 
sWITCH IT off

I agree with you but helming for up to eight hours can be tedious. when refitting the nav system I bought into to the "sort the route on your plotter and let the AP do the work" sales patter. I'm now splitting the system up and isolating each part to stop this happening again.
I think the key point is "Standby" does not mean off. Only a switch in the system can truly persuade the A P to lay down.
 
I also had a very bad experience with Autopilot with near diisaster. I covered it on here under the heading "Nearly hit a buoy at 20 knots, how can that happen". Since then another MB in the same marina had exactly the same issue with a different buoy, however his system has now been updated to prevent these issues from happening.
Sounds to me as though you AP changed function, this possibly being caused by the same hardware/software issue. Suggest you check out my previous postings on this under that heading, it explains the problem and remedy. If yours is a similar type I would modify it anyway.
Hope this helps.
 
I agree with you but helming for up to eight hours can be tedious. when refitting the nav system I bought into to the "sort the route on your plotter and let the AP do the work" sales patter. I'm now splitting the system up and isolating each part to stop this happening again.
I think the key point is "Standby" does not mean off. Only a switch in the system can truly persuade the A P to lay down.

I advised switch off when in close quarters, not when you are out in the open!! carry on as you are (cyber space) and you will surely become a cropper given time. Almost every manufacturer of these gizmos advises " Do not rely on this equipment" even TOM-TOM. With regard to sales patter It's to sell it to you not to use it!!
 
Last edited:
Cheers for owning up. I'm relatively new to boating and reading about various problems people have helps me learn what might happen so i've got a mental checklist of things to compare it to if "odd things" start occurring to me. It's invaluable to read this stuff.
 
Top