Nearly hit a Cardinal Buoy at 20 knots, how can that happen!

[SC500]

Had a near miss with our princess 430 on Saturday when on route from Harwich to Woodbridge in the river Deben and am trying to understand what went wrong. Boat is fitted with AUTOHELM ST600 Autopilot and a Garmin Plotter; the ST600 is not connected to the plotter and is only used to hold direction between Waypoints. On this occasion I was driving manually from the lower helm with my partner beside me in the helm seating enjoying the ride, a bit wet up top. ST600 was not being used and was set to “STANDBY”. My route took me past a Cardinal buoy denoting the Harwich Channel, the clearance from the buoy was 50 metres and we were cruising at 20 knots. When we were near adjacent to the buoy the boat suddenly veered on instant full lock directly at the centre of the buoy at 20 knots. I reckon about 8 seconds to impact. It took me a few seconds to realise I had lost all steering with the buoy getting bigger by the second. I then throttled back to Neutral, put the engines into reverse stopping short by no more than 20 feet, that buoy was big, directly in front of us and dead centre! I used the engines to steer away from the buoy but this was not easy as the steering was impeded and I thought I must have caught a rope or something. I then looked at the ST600 and saw the screen was showing “MANUAL” setting, I have never seen that before in the manual. Pressed “STANDBY” and the helm then transferred back to the helm with full control. I had not touched the ST600 unit and thankfully my partner sitting beside me witnessed the near catastrophic incident, if she had not of been there she would be saying "I must have done something" and possibly lost confidence. I assume when trying to steer away from the buoy prior to realising the ST600 had been activated that the rudders controlled by the ST600 kept trying to steer me back to the buoy, the rudders being one way and the intended direction under engines being opposite.
Not really relevant I guess but the Cardinal buoy was not entered as a Waypoint, She just homed in quite violently, if we had not been sitting I am sure we would have been on the floor with the inevitable consequence of hitting the buoy at 20 knots. Really shook me up for 24 hours however we got away with that one. I assume the Flux gate compass suddenly picked up some form of signal from the large metal buoy and as I said just homed in. Anyone else experienced this and how can this happen. On my return journey I re-routed to a clearance of a quarter mile and felt trepidation when approaching. Not an experience I ever want again. However we had a great weekend, the incident not spoiling that, but you do wonder what if and how do I explain that to the insurance company.

 

[pmagowan]

Is your autopilot called HAL9000?

 

[Elemental]

That sounds extremely similar to this . Another Autohelm, with a similar symptom and a suggestion for a solution...

 

[jfm]

That sounds extremely similar to this . Another Autohelm, with a similar symptom and a suggestion for a solution...

It does indeed.

I guess the fact it aimed at the cardinal is a red herring and total coincidence.

Remember also the st6000 stores its previous AUTO heading, which always seemed strange to me when I had one 1999 to2003. If you are driving along in standby, and press auto for 1 second, the thing does not hold the current heading. Instead it selects the last memorised heading, maybe from the day before. Very odd software imho. So if an "auto" switch shorted it could do this.

Best to buy a new a/pilot computer and 2 new control heads and be done with it, in view of the consequences of a repeated occurrence

 

[pmagowan]

It does indeed.

I guess the fact it aimed at the cardinal is a red herring and total coincidence.

Remember also the st6000 stores its previous AUTO heading, which always seemed strange to me when I had one 1999 to2003. If you are driving along in standby, and press auto for 1 second, the thing does not hold the current heading. Instead it selects the last memorised heading, maybe from the day before. Very odd software imho. So if an "auto" switch shorted it could do this.

Best to buy a new a/pilot computer and 2 new control heads and be done with it, in view of the consequences of a repeated occurrence

But don't let it hear you say that, and remember, it can lip read!

 

[SC500]

I assumed it was Flux gate related and the reference to previous history of Autohelm could be the first step towards resolution. Am convinced the buoy played a significant part. What I can say is after she banked hard to make the turn she straightened up and went straight for it, the target being the bouy. I have emailed Raymarine for any clues why this may happen.

 

[Deleted User YDKXO]

Wow really scary. I've got nothing to add other than I don't see how it could be the fluxgate compass. Yes these can be affected by metal objects but normally these objects have to be very close to the compass and in any case, the autopilot wasn't engaged at the time of the incident so the pilot wasn't following the compass heading.
Btw it is possible to damage the steering gear by using the engines to steer against the autopilot. I once snapped a steering connector arm on a previous boat by using the engines to try to spin the boat whilst the autopilot was still engaged. All in all, I'm with jfm; for peace of mind junk the pilot and replace it.

 

[alant]

Had a near miss with our princess 430 on Saturday when on route from Harwich to Woodbridge in the river Deben and am trying to understand what went wrong. Boat is fitted with AUTOHELM ST600 Autopilot and a Garmin Plotter; the ST600 is not connected to the plotter and is only used to hold direction between Waypoints. On this occasion I was driving manually from the lower helm with my partner beside me in the helm seating enjoying the ride, a bit wet up top. ST600 was not being used and was set to “STANDBY”. My route took me past a Cardinal buoy denoting the Harwich Channel, the clearance from the buoy was 50 metres and we were cruising at 20 knots. When we were near adjacent to the buoy the boat suddenly veered on instant full lock directly at the centre of the buoy at 20 knots. I reckon about 8 seconds to impact. It took me a few seconds to realise I had lost all steering with the buoy getting bigger by the second. I then throttled back to Neutral, put the engines into reverse stopping short by no more than 20 feet, that buoy was big, directly in front of us and dead centre! I used the engines to steer away from the buoy but this was not easy as the steering was impeded and I thought I must have caught a rope or something. I then looked at the ST600 and saw the screen was showing “MANUAL” setting, I have never seen that before in the manual. Pressed “STANDBY” and the helm then transferred back to the helm with full control. I had not touched the ST600 unit and thankfully my partner sitting beside me witnessed the near catastrophic incident, if she had not of been there she would be saying "I must have done something" and possibly lost confidence. I assume when trying to steer away from the buoy prior to realising the ST600 had been activated that the rudders controlled by the ST600 kept trying to steer me back to the buoy, the rudders being one way and the intended direction under engines being opposite.
Not really relevant I guess but the Cardinal buoy was not entered as a Waypoint, She just homed in quite violently, if we had not been sitting I am sure we would have been on the floor with the inevitable consequence of hitting the buoy at 20 knots. Really shook me up for 24 hours however we got away with that one. I assume the Flux gate compass suddenly picked up some form of signal from the large metal buoy and as I said just homed in. Anyone else experienced this and how can this happen. On my return journey I re-routed to a clearance of a quarter mile and felt trepidation when approaching. Not an experience I ever want again. However we had a great weekend, the incident not spoiling that, but you do wonder what if and how do I explain that to the insurance company.

Was it being used as a waypoint?

 

[omega2]

So there is another "Triangle " up there as well, we have to contend with the Brightlingsea triangle, go back to manual and ignore ALL electronics, cannot beat the mark one eyeball.

 

[[2068]]

So there is another "Triangle " up there as well, we have to contend with the Brightlingsea triangle, go back to manual and ignore ALL electronics, cannot beat the mark one eyeball.

Which part about "he was driving on manual from the lower helm" did you not quite get?

 

[jfm]

I assumed it was Flux gate related and the reference to previous history of Autohelm could be the first step towards resolution. Am convinced the buoy played a significant part. What I can say is after she banked hard to make the turn she straightened up and went straight for it, the target being the bouy. I have emailed Raymarine for any clues why this may happen.

My strong hunch is that this isn't fluxgate related and the cardinal buoy is a coincidence. I reckon it is duff electronic hardware in your a/p unit, especially after seeing the link posted by Sea Spray. Remember the legend "manual" isn't part of st6000's normal display iirc (I had one for several years). The only reports of "manual" showing in the display are yours and SeaSpray's link. Time for a new a/pilot...

 

[jfm]

Was it being used as a waypoint?

As I read it he clearly said it wasn't. From the description given by AP, there are no waypoints in play here, as his a/p is not connected to any plotter so the a/p functions just as a heading hold device not a track-to-waypoint device. I think ...

 

[fisherman]

This is the fourth incident like this that I know of resulting in collision, and at least one other skipper swears blind the pilot altered for the buoy.

 

[Beamishken]

Wow scarey stuff it makes me happy I have to live with old fashioned cable steering with power assistance from the drive steering ram
After all the volvo gremlin threads recently I'm glad we have old fashioned mechanical engines and cable gears too
Electronics are great but when they go wrong the result can be catastrophic especially with no mechanical back up
Hope you get it sorted I'd be terrified to go above displacement speed!

 

[omega2]

Which part about "he was driving on manual from the lower helm" did you not quite get?

he still had the gear running????

 

[[2068]]

he still had the gear running????

Being slightly more serious and a bit less sarcastic for a moment (apologies), I don't think most people would think to electrically isolate the Autopilot if steering manually. For starters, it might be on the same circuit as the compass.

Setting it to "standby" (= logical 'off') would usually be enough, but it sounds as if for some strange reason it switched modes of it's own volition.

 

[superheat6k]

I have the older ST6000 system and will be on alert for this one certainly. A bit left field but could a false input on the Seatalk system be a contributory factor.

Angus MacDoon from the PBO forum supplied me his excellent YAPP for sending wired remote signals into my AH via the Seatalk. Also when in AH Auto control I can hear various ticks and buzzes through my Raytheon Loudhailer. Possibly an incorrect 'tick' on the system could send the AH into Auto, although in that case it should display 'Auto' rather than Manual.

Might be worthwhile asking Angus direct about this problem.

 

[omega2]

Being slightly more serious and a bit less sarcastic for a moment (apologies), I don't think most people would think to electrically isolate the Autopilot if steering manually. For starters, it might be on the same circuit as the compass.

Setting it to "standby" (= logical 'off') would usually be enough, but it sounds as if for some strange reason it switched modes of it's own volition.

We have always experienced anomolies in this part of the world, our set up turns into "exocet" mode in certain areas, fortunately we know were this will occur and "kill" the guidance system as we enter the zone, in the olden days our Decca numbers resembled a pin ball machine and the later Navstar almost jumped off it's bracket. There is a warning at the point of switch on for all these gizmos which roughly translated says "DO NOT RELY ON ME" as I could be wrong!

 

[MarieK]

If you dont replace the AP system completely then you should dampen its responsiveness to the lowest setting. I forget the exact setting for this but its in the menu somewhere and should result in a more gentle turn. If it was to happen again but with a gentle turn rather than violent change of direction you have more time to catch it and allow you to troubleshoot the problem. If it does happen again, take note of the heading displayed at the time, it could be that your course computer has an issue.

This used to happen to me but it was a known issue with the course computer and Raymarine did a product recall and fixed FOC (they also replaced the cover which was cracked FOC, great service).

My issue always arose while on a southerly heading, was perfect on a northerly. Take the boat out and do some runs on the AP on different headings and see if you can replicate OR do as JFM says and replace the lot without the hassle.

 

[SC500]

Thanks for your input, quite enlightening. I have emailed Raymarine asking how the AP can change and display a “MANUAL” setting and what did this mean. No response back yet, but will keep you informed of their answer. I find this "MANUAL" display quite confusing, how can it show that when there is no setting. Beyond me at the moment.
As mentioned, I was driving manually using the Garmin plotter for route guidance only, the AP being in “STANDBY” mode when it occurred, next Waypoint probrably 2 miles away.
Of interest, I had a look on the Internet to check these Buoys and found that many transmit weather and sea information and have a Flux Gate compass fitted to support this data stream enabling the supply wind and current direction. Is it possible the Buoy Flux gate had a stronger signal than the on board unit and took over from 50 metres distance? That’s what it felt like. Will be passing at 100 metres in future.

Am going to boat tomorrow, will check AP settings, reduce response if necessary and go through the motions to recalibrate the unit. Next time I have the opportunity I will take her adjacent to the same buoy at low speed to see if this situation recurs.

Is there an area within the AP setup where you can change the unit’s sensitivity to external objects, like buoys?