Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 14-10-2010, 11:02   #16
Registered User
 
phantomracer's Avatar

Join Date: Aug 2010
Location: Boston, MA
Boat: 1968 Ohlson 38 Sloop
Posts: 773
Images: 9
Send a message via Yahoo to phantomracer
Just an update on this thread.

I finally got ahold of raymarine. The tech seemed to have a clue. his suggestion was to put a resistor on the joystick terminal, as it might be checking for a joystick and getting confused.

I have not done that yet.

Another thing I noticed..maybe it is a red herring.. but the other day, while sailing, I switched from the house battery to the starting battery, almost instantly the boat did it again! (I went from 2- both-1 so I never lost voltage)

Maybe it is a sudden voltage change that is maybe letting the unit lose its mind for a moment.. I dont know.. but I will try out their suggestion next season.. pulling the boat tuesday.
__________________

__________________
phantomracer is offline   Reply With Quote
Old 15-07-2011, 21:02   #17
Registered User
 
phantomracer's Avatar

Join Date: Aug 2010
Location: Boston, MA
Boat: 1968 Ohlson 38 Sloop
Posts: 773
Images: 9
Send a message via Yahoo to phantomracer
Re: ST7000 Autopilot Problem - Randomly Steers Hard to Port

Not sure if I fixed it, indirectly, or not..

But (as posted in another thread) I had to replace the heading sensor (nmea KVH) because it stopped working. Just before it failed, it was spitting garbage in the nmea stream.

I am wondering if, by chance, when the AP went wild, it was responding to a failing heading sensor occasionally spitting out the wrong sentence..and the AP going nuts with it..

Either that or I have has 2 trips using it, without any issue... yet...

lets keep our fingers crossed the AP doesn't go nuts again!! I still haven't done what raymarine suggested (putting a resistor across the joystick terminals)... but if it flakes out again.. I will do it.
__________________

__________________
phantomracer is offline   Reply With Quote
Old 15-07-2011, 22:24   #18
Moderator Emeritus
 
Pblais's Avatar

Join Date: Mar 2003
Location: Hayes, VA
Boat: Gozzard 36
Posts: 8,700
Images: 15
Send a message via Skype™ to Pblais
Re: ST7000 Autopilot Problem - Randomly Steers Hard to Port

Quote:
I am wondering if, by chance, when the AP went wild, it was responding to a failing heading sensor occasionally spitting out the wrong sentence..and the AP going nuts with it..
If it was, it would. One way to test a suspect sensor is to dock the boat, and unmount the sensor. The sensor operates in units of 90 degrees so the transition between the 4 quadrants is how to test it. Going clockwise and counter clockwise you can have someone watch the display while you slowly rotate it. It's also good for finding out they screwed up the install and placed the fluxgate in a bad place. It happens a lot more than you think.

FWI the rudder feedback is known to go bad too. Those are easier since they return a voltage you can measure.

You may have it fixed.
__________________
Paul Blais
s/v Bright Eyes Gozzard 36
37 15.7 N 76 28.9 W
Pblais is offline   Reply With Quote
Old 15-07-2011, 22:27   #19
Moderator Emeritus
 
Pblais's Avatar

Join Date: Mar 2003
Location: Hayes, VA
Boat: Gozzard 36
Posts: 8,700
Images: 15
Send a message via Skype™ to Pblais
Re: ST7000 Autopilot Problem - Randomly Steers Hard to Port

If you think it is fixed you MUST recalibrate the boat to make sure it all is fine.
__________________
Paul Blais
s/v Bright Eyes Gozzard 36
37 15.7 N 76 28.9 W
Pblais is offline   Reply With Quote
Old 16-07-2011, 05:23   #20
Registered User
 
phantomracer's Avatar

Join Date: Aug 2010
Location: Boston, MA
Boat: 1968 Ohlson 38 Sloop
Posts: 773
Images: 9
Send a message via Yahoo to phantomracer
Re: ST7000 Autopilot Problem - Randomly Steers Hard to Port

Quote:
Originally Posted by Pblais View Post
If it was, it would. One way to test a suspect sensor is to dock the boat, and unmount the sensor. The sensor operates in units of 90 degrees so the transition between the 4 quadrants is how to test it. Going clockwise and counter clockwise you can have someone watch the display while you slowly rotate it. It's also good for finding out they screwed up the install and placed the fluxgate in a bad place. It happens a lot more than you think.

FWI the rudder feedback is known to go bad too. Those are easier since they return a voltage you can measure.

You may have it fixed.
Since the sensor is dead (no output at all) i don't know how to test it. The new one i bought seems to be working quite well.

The sensor is inside the wooden table in the dead middle of the boat. No metal within several feet in any direction. best location I can see on the boat.

going out today...lets see how well it works. so far a couple of trips no drama..
__________________
phantomracer is offline   Reply With Quote
Old 16-07-2011, 05:24   #21
Registered User
 
phantomracer's Avatar

Join Date: Aug 2010
Location: Boston, MA
Boat: 1968 Ohlson 38 Sloop
Posts: 773
Images: 9
Send a message via Yahoo to phantomracer
Re: ST7000 Autopilot Problem - Randomly Steers Hard to Port

Quote:
Originally Posted by Pblais View Post
If you think it is fixed you MUST recalibrate the boat to make sure it all is fine.
yup. the fluxgate is always in calibrate mode for deviation. just got to make a couple lazy circles to do it.
__________________
phantomracer is offline   Reply With Quote
Old 16-07-2011, 08:56   #22
Moderator Emeritus
 
Pblais's Avatar

Join Date: Mar 2003
Location: Hayes, VA
Boat: Gozzard 36
Posts: 8,700
Images: 15
Send a message via Skype™ to Pblais
Re: ST7000 Autopilot Problem - Randomly Steers Hard to Port

Quote:
The sensor is inside the wooden table in the dead middle of the boat. No metal within several feet in any direction. best location I can see on the boat.
You can't always go by that. If it calibrates it could be fine. If not it can be the reason too. If you use the dock test above and manually rotate the compass you can see if it is a nice smooth reading on the control head. My last boat had some interference in a far forward locker and there should have been no metal at all. Moving it aft where I thought there should be a problem fixed it. That autopilot fluxgate was not properly located and the PO chased all throughout a trip up and down the east coast asking for help to fix the autopilot and it never got fixed nor was it fixed by the next owner.

It does not hurt to prove it.
__________________
Paul Blais
s/v Bright Eyes Gozzard 36
37 15.7 N 76 28.9 W
Pblais is offline   Reply With Quote
Old 16-07-2011, 09:10   #23
Registered User
 
speciald@ocens.'s Avatar

Join Date: Apr 2008
Location: On the boat - Carib, Chesapeake
Boat: 58 Taswell AS
Posts: 1,139
Re: ST7000 Autopilot Problem - Randomly Steers Hard to Port

My wife once put her Thigh Master in the locker above the flux gate compass - that really added to the deviation!
__________________
speciald@ocens. is offline   Reply With Quote
Old 15-08-2011, 06:53   #24
Registered User
 
phantomracer's Avatar

Join Date: Aug 2010
Location: Boston, MA
Boat: 1968 Ohlson 38 Sloop
Posts: 773
Images: 9
Send a message via Yahoo to phantomracer
Re: ST7000 Autopilot Problem - Randomly Steers Hard to Port

just an update.. i think the original problem, randomly going hard to port, is fixed.

Since installing the new fluxgate (KVH), the AP has worked perfectly, no locking, random turning, anything. Got about 4-500 miles this season since installing, without a problem. So (I am hoping) the issue all along probably was the fluxgate flaking out.
__________________
phantomracer is offline   Reply With Quote
Old 02-04-2012, 10:36   #25
Registered User
 
phantomracer's Avatar

Join Date: Aug 2010
Location: Boston, MA
Boat: 1968 Ohlson 38 Sloop
Posts: 773
Images: 9
Send a message via Yahoo to phantomracer
Not so fixed. Started doing it again late last season. Had the fluxgate checked. It is OK. Must be in the wiring, computer, or nmea stream.

Going to take the AP off the mux and feed only the fluxgate into the AP and try it like that.

I rarely used the GPS to control the AP.
__________________
Paul S
Blog - https://www.facebook.com/ohlson38project
website http://www.mildredrose.com
phantomracer is offline   Reply With Quote
Old 02-04-2012, 11:54   #26
Moderator Emeritus
 
Pblais's Avatar

Join Date: Mar 2003
Location: Hayes, VA
Boat: Gozzard 36
Posts: 8,700
Images: 15
Send a message via Skype™ to Pblais
Re: ST7000 Autopilot Problem - Randomly Steers Hard to Port

Don't discount magnetic interference with the compass. If you can put a longer wire on it and move it someplace else (any place else) and leave it connected you might be able to prove it. You also should recalibrate the boat after you mess with anything too. The fluxgate outs data with a quadrant value so each 90 degrees is independant to some extent and a probelm in any one can show up for all of the readings in that quadrant. It also can have problems "between" thenm as you change directions. This transition is another point of failure in the compass.

Another way to fully test the comapss installed is unscrew it and at the dock have someone slowly rotate it (rather than moving the boat) do it in both directions and read the heading at the helm. A bad compass reading would cause the computer to want a correction it won't need. The problem could be only in some directions of CTS relative to the current heading.

A bad rudder feedback sensor will have dead zones and cause the computer to over steer too. They too could be sporatic. Rudder feedback failure is most common and amazingly cheap!

My current course computer (for an ST7000) has a problem where the left and right sides connect through male and female DB 25 connectors. All the wires in and out go through these connectors. They can go bad over time as the mass produced wave soldering could make a weak joint. Someone I know resoldered both connectors to the board and got is sort of stable but now the actual connectors are a problem and can't be fixed. That problem would cause the AP to just shut down for a few minutes, an hour or a day.

No one I know will do this type of work. The guy that did mine was pretty old and is now in very poor health. He did a lot of board level repairs to a lot of marine gear and I learned a lot about bad autopilots since he fixed mine on both boats with the last time leading to a replacement on the course computer this week. I found a used one for a price.

Depending on the control head you can substitute a new course computer but they "ain't cheap".

When working well the ST7000 will steer you through hell. It cleary has proven to me over an over again it can steer the boat when you can't in very rough weather.

It's always best to prove what isn't working. With AP's the key to all of them is quality installation. A reasonable job might last 5 years and a good job more than 20.
__________________
Paul Blais
s/v Bright Eyes Gozzard 36
37 15.7 N 76 28.9 W
Pblais is offline   Reply With Quote
Old 02-04-2012, 12:20   #27
Registered User
 
sy_gilana's Avatar

Join Date: Jan 2005
Location: On board
Boat: Van de Stadt 50'
Posts: 1,101
Send a message via Skype™ to sy_gilana
Re: ST7000 Autopilot Problem - Randomly Steers Hard to Port

Follow KA4WJA's advice. We had a very similar problem, it NEVER went from STBY to anything else. It did go berserk occasionally with no apparent reason.
Used the Divide and Conquer method. Found the problem to be a seatalk multi display in the aft cabin next to my bed. It was occasionally throwing out a seatalk sentence that, for the next cycle or two of messages, over-wrote the real info coming from the GPS (Seatalk) We also noticed that there was a spike in the track points, usually due south to 0 degrees on the equator, three trackpoints were placed there then the GPS took priority again and the track continued normally. Took a while for my pulse to get back to normal. Disconnected the Multi Display, and viola!
__________________
Tight sheets to ya.
http://gilana.org
sy_gilana is offline   Reply With Quote
Old 02-04-2012, 12:58   #28
Registered User
 
phantomracer's Avatar

Join Date: Aug 2010
Location: Boston, MA
Boat: 1968 Ohlson 38 Sloop
Posts: 773
Images: 9
Send a message via Yahoo to phantomracer
Re: ST7000 Autopilot Problem - Randomly Steers Hard to Port

There is no metal within 5-6' of the KVH fluxgate compass, moving it ANYWHERE would move it near wires/metal. The only thing near it is wood, fiberglass and air.

Quote:
Used the Divide and Conquer method.
That is pretty much what I am doing. Eliminating the NMEA stream from the GPS, AIS, etc from getting to the computer. Just the Seatalk tridata and the KVH NMEA fluxgate will be inputs to the computer. Will also double check all the wiring and connectors as well.

The fluxgate (actually own 2 KVHs, naturally 1 is hooked up) was recalibrated and certified by the KVH factory last year (see other thread of mine - long story) to be (using industry terms) "dead on balls perfect". Naturally I have to turn the boat to get it to learn any deviation on the boat.

will keep the rudder feedback sensor in mind if it keep happening. Is the part still available for the ST7000? I assume the feedback sensor is the part in the attached picture with the red autohelm writing on it. Any idea on the part #?

I thought the problem was fixed with the new KVH. Was wrong. Bummer. Strange it went the entire season last year without failure..then started again on one of the last trips.

Paul
Attached Thumbnails
Click image for larger version

Name:	ruddersensor.jpg
Views:	127
Size:	409.0 KB
ID:	39417  
__________________
phantomracer is offline   Reply With Quote
Old 09-05-2012, 12:02   #29
Registered User
 
phantomracer's Avatar

Join Date: Aug 2010
Location: Boston, MA
Boat: 1968 Ohlson 38 Sloop
Posts: 773
Images: 9
Send a message via Yahoo to phantomracer
Re: ST7000 Autopilot Problem - Randomly Steers Hard to Port

Some progress..

installed the factory recalibrated fluxgate from KVH. Not getting any data at the ST7000. Nuts.

did a continuity test on the NMEA wires. I found one had a break in it. Nuts (well good that I found a bonafide problem). After disconnecting both ends at the computer (one end) and the junction (at the other end)..reconnecting them, I got solid continuity on both NMEA wires. Got good readings from the fluxgate.

Maybe the problem all this time was a bad connection at the junction.

For kicks, I am not sending the fluxgate to the Mux, just sending it to the ST7000. Try it out for the season. This just means I need the AP on for the heading to get to the GPS and the rest of the system. I can live with that.

Will keep an eye on the rudder sensor if it keeps giving me gas pains!
__________________
phantomracer is offline   Reply With Quote
Old 09-05-2012, 12:42   #30
Moderator Emeritus
 
Pblais's Avatar

Join Date: Mar 2003
Location: Hayes, VA
Boat: Gozzard 36
Posts: 8,700
Images: 15
Send a message via Skype™ to Pblais
Re: ST7000 Autopilot Problem - Randomly Steers Hard to Port

Quote:
For kicks, I am not sending the fluxgate to the Mux, just sending it to the ST7000. Try it out for the season. This just means I need the AP on for the heading to get to the GPS and the rest of the system. I can live with that.
You really don't want raw Fluxgate readings. They don't include the course computer deviations that it stores when you swing the ship during the on the water calibration. They don't get stored on the compass itself. The output from the ST7000 includes the mag heading along with all the other goodies. So yes, it needs to be on.

Good news! Rudder sensors are the cheapest part there is in an autopilot and replace easily. You can't fix them or recondition them. If they wink out as you go hard over and back then ditch the rudder feedback - they don't just act up and get better. All it does is output a variable voltage that the course computer calibrates to the center, port limit and starboard limit. Try a dockside calibration in case the settings are corrupted. That would also kick out a problem too. I would repeat the on the water now that the short is fixed too.
__________________

__________________
Paul Blais
s/v Bright Eyes Gozzard 36
37 15.7 N 76 28.9 W
Pblais is offline   Reply With Quote
Reply

Tags
autopilot

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Run Away! Hard to Port! SNOW! MarkJ General Sailing Forum 9 09-04-2010 02:57
Raytheon ST7000 Autopilot goes AWOL?? Borden Marine Electronics 6 22-07-2008 16:01
ST7000 Autopilot Brain markpj23 Classifieds Archive 0 07-08-2007 12:22
ST7000 Autopilot Brain markpj23 Classifieds Archive 1 02-07-2007 17:59
ST7000 Autopilot - 12v or 24v?? markpj23 Marine Electronics 5 28-06-2007 07:52



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 20:11.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.