Raymarine AP - st6002

[YOLLATA]

Ok....

Sorry for the length if this but when hand steering you avectime to type....

We have a full raymarine kit on board our lagoon 440. Currently in Belize. Currently hand steering. Any help will result in us ( and you if you are near) being very drunk and swearing to tell our AP we love it every day.....

1. Control head. - ST 6002. Purchased November 2012 in Gibralter.
Computer - X3(?) purchased January 2013 in St Martin. Installed and calibrated in St Maartin by an authorised Raymarine technician.

2. All working fine January 2013 until December 2013 - approximately 2500 nm completed in that time.

3. Left Panama December 20, 2013. Noticed a difference of approximately 30 degrees between control head reading and ships compass/ stand alone Raymarine MFD COG reading. We then noticed that this difference decreased and increased at times. Inconsistent. HOWEVER, when the autopilot was engaged it still functioned properly. Eg held course, held course to wind, tacked, and the control head heading reading, although incorrect , was fairly consistent.

4. 1st March 2013. Left anchorage and engaged autopilot.
Autopilot unable to hold course, usually veering to port, and completing 360 degree turns if left to steer the boat. Autopilot disengaged and re-engaged a number of times. Same result.

5. 3rd march. Attempted to recalibrate via sea trial calibration. First step - swinging the compass. Performed approximately 15 clockwise turns in calm seas and up to 15 knots breeze. Unable to receive a deviation reading.

6. 4 th March. Again attempted to recalibrate via sea trial calibration in very clam water and 3 kn breeze. Completed 10 turns each of which took approximately 2 minutes 30 seconds. Unable to receive a deviation reading.

We then identified the existing deviation reading of 4 degrees, and decided to move onto the next step in the sea trial calibration - heading alignment. When we reached the heading alignment screen on the control head, the reading constantly rolled around and was at times 180 degrees or more wrong. We used the +1, +10 , -1,-10 buttons to save an accurate alignment.

We decided not to perform the rudder alignment step of the sea trial and progressed to autolearning. The boat performed 10 manouevres under the autolearning phase and we received a ' pass ' reading at the end. During the autolearn process, the boat turned to starboard for a short time and then executed 2 x 360 degree turns to starboard. It then immediately went into 2x 360 turn to port. It then tracked out and executed 2 or 3 zig zag turns.

We then engaged the autopilot, but it continued to not work.

The main issues are;

- unable to hold a course. Whenever we engage the autopilot it veers violently to port ( usually port, but occasionally starboard) and if left to its own devices, will execute 360 degree turns. The control head will alarm 'off course' after we have turned through 90 degrees, but the autohelm will continues to complete the turn. If we then try to correct by requesting it turn to starboard, we need to request a turn of at least 100 degrees before it will even start to turn to starboard. Similarly, if we are eventually able to get the autohelm to turn to starboard, it is very difficult to then get it to turn back to port. Ie we need to request a turn of 100 degrees to port in order to effect a change in direction.
- Control head reading is grossly inaccurate and changes constantly even if we hold a constant course in standby mode. We have tried a number of times to perform the ' heading alignment ' step in the sea trial calibration, but the control head is unable to maintain the correct heading.

[ka4wja]

Yollata,
Thanks for the great details!!!

It's late and I'm tired....but in brief...
a) My first thought is that someone placed (or something fell by accident) something ferrous near your Raymarine heading sensor (fluxgate compass)....
(Years ago, I had someone throw a can of shaving cream in the space under a locker in my aft cabin, which is right near my heading sensor....and it took me about 10 minutes to find it....and all was well again!! TRUE STORY!!)

b) My second thought is a loose/corroded/bad connections on the heading sensor and/or its connection to the autopilot corepak (computer)....

c) My third thought is a bad heading sensor...

d) My forth thought is a loose/bad mounting of the heading sensor...

e) My fifth thought is any/all of the above four!!!


After you check/verify a, b, and d....you can test for "c", by holding the heading sensor in your hand, and turn it ever so slowly while watching the heading display on the ST-6002....it slowly and steadily show your changing heading, as you move the heading sensor around....note that it has internal gimbals, but it can still only be mounted in two (or three) specific positions and still get it to work correctly (I've seen Raymarine dealers screw this up, so don't take it for granted!!)
If it doesn't work here in this test (and you KNOW there is no ferrous metal nearby when doing this test), then it's most probably a bad heading sensor...

But since you've had some continued issues....my first thoughts about a ferrous object rolling around and/or a wiring/connection issue, to be pretty likely...



Although less likely, a faulty corepak (computer) could also present in this way....and/or even further loose/corroded/bad wiring connections, such as heading sensor and rudder sensor, etc...


That's the best I can do tonight....
Oh, and BTW, understand that the COG data is GPS derived and not measured/calculated by any sensors on-board (other than the GPS)...so at least you know that's working...


Fair winds and good luck...

John
s/v Annie Laurie

[YOLLATA]

Hey John. Thanks so much for the response. Going thru the process now. W e started to have the problems when we left panama a couple of months ago. Working back form that on the principle of " what the hell has changed on this boat". W removed the 78 - 90 cans of panama lager which was stored above and to the inboard side of the flux gate compass. I also pulled out the plugs etc from the course computer ( X30 smart pilot) and replaced them.

Went out, swung the compass in ten circles, and got nothing.

Went in, dropped the anchor, looked harder at the shaving cream can hypothesis ( act of desperation) and found about 12 cans, tin cans with fruit and veg in them and took those out. Going out in a few hours to swing the compass again.

God I hope this is it.

[undercutter]

Originally Posted by YOLLATA

Hey John. Thanks so much for the response. Going thru the process now. W e started to have the problems when we left panama a couple of months ago. Working back form that on the principle of " what the hell has changed on this boat". W removed the 78 - 90 cans of panama lager which was stored above and to the inboard side of the flux gate compass. I also pulled out the plugs etc from the course computer ( X30 smart pilot) and replaced them.

Went out, swung the compass in ten circles, and got nothing.

Went in, dropped the anchor, looked harder at the shaving cream can hypothesis ( act of desperation) and found about 12 cans, tin cans with fruit and veg in them and took those out. Going out in a few hours to swing the compass again.

God I hope this is it.

Will the AP follow a track but not a heading? Outside electrical interference such as heavy DC cables can cause a heading deviation in the fluxgate compass. Have you moved or done any wiring on the boat lately. Does this only happen when you are motoring and possible the batteries are charging from some source.

After we installed a new inverter/charger my wife turned on the kettle with the AP active and the boat turned sharply. Turned off the AP and resumed course but the boat heading was showing 180 deg out. As soon as the kettle was shut off the heading returned to normal. Turns out that the cable runs for the DC wiring to the inverter passed to close to the fluxgate compass so that every time there was a large load or charge on the batteries the compass was affected.

Good luck.

[Paul L]

I believe Ray has on their support site the resistance readings that should be in place on the compass wires. If this is the older, simple compass, they are pretty cheaply made and do occasionally fail.