I remember reading a submarine book once about the "Crazy Ivan" tactic, where a skipper would turn the boat abruptly 45 degrees to port or starboard without warning. We have renamed our Raymarine 4000 autopilot to Crazy Ivan. He only goes to port and usually only 20-30 degrees, but it is definitely without warning. He usually comes back to course, or close to it, in about 2 minutes. This weekend I played with some variables trying to identify the source of the problem but couldn't. My clues are below. They may be related or just misleading. Toss out your theories though. I have a week on the boat coming up starting Friday, so I'll have a chance to check them all out. This is a '97 MkII.
(1) I used to think it was voltage fluctuation problem when the fridge kicked in as my batteries were weak. However, I just replaced the batteries two weeks ago with no change.
(2) I played with the circuit breakers trying to isolate possible interference. I turned off the fridge for a couple hours and still had problems.
(3) It happens with the engine running or not.
(4) While I've never been happy with the heading control on the autopilot, I've sailed her for seven seasons and it wasn't always this bad.
(5) The fluxgate sensor is mounted below the head sink, a whopping 12" from the engine block and alternator. She was apparently delivered this way and I haven't found enough cable slack for a better position.
(6) I recently hardwired my GPS in for power using cables from a previous GPS. However, the new one is not connected to the NMEA/SeaTalk interface, just power. I think the problem was this bad before the GPS hardwiring. Interesting to note that I have an Autopilot breaker and a Nav/Com breaker (depth+knotmeter). The GPS is on the autopilot breaker.
(7) I was below yesterday adjusting my stuffing box with only the cabin light breaker on and only a Hella fan running. While I was working, the fan pitch noticeably changed at one point, like the fan slowed down. It could have been a voltage fluctuation or just dirt in the fan. I thought it might be related.
(8 ) I don't have a good volt meter on board as my current one is a Harbor Freight special, good for telling 6 from 12 volts, but not 12.4 versus 12.6 volts. I can probably stock a better meter for the trip.
OK, I'm sure you have ideas or questions. Even diagnostic tricks would help. Let me hear your thoughts. I want Ivan exorcised before the end of the trip. Thanks in advance.
Brian,
I too have a Crazy Ivan. In my case, he shows his head when the alternator kicks off (it overheats during high charging, and turns off). When it turns off, the boat will abruptly turn 15 or 20 degrees. It will turn the other way when it kicks back on. I've always assumed the autopilot is reacting to a voltage spike or abrupt change in voltage, though I've never measured. It doesn't happen often enough to make me want to fix it. I just know to not venture too far from the helm when the autopilot is on, and the batteries are low! I think your Harbor Greight DVM will likely be sufficient to measure a voltage change large enough to alter the pitch of a fan. If it's a spike causing the issue, you'll need something more complex to see it, such as an oscilloscope. Try playing more with the breakers to narrow it down. Are any circuits bypassing the breakers (bilge pump?) Good luck.....
Bob
Most of the time we use a hand held VHF in the cockpit. The first time we used the vhf at the Navsta (antenna at the mast head) we got the hard turn to port with every tranmission. After some investigation we found the coax to the antenna was routed almost on top of the flux gate. Rerouted the coax, problem ended.
The location under the sink has it close to alot of electrical interference. The alternator as was mentioned, the ground cable to the electrical panel, etc. Might want to get some lead foil or something to shield the flux gate it.
So far, two camps, voltage fluctuation and magnetic interference.
Interesting, I've always thought about moving the fluxgate, not shielding it.
If the problem is voltage fluctuation, my first choice would be to eliminate the cause. Second choice would be to limit the effect. Could I stick a capacitor or resistor on the autopilot circuit to smooth the voltage? I used to do this with car stereo's.
Typically bad connections and bad grounds are the first place to look for mysterious voltage noise. The battery connections, being new, were recently cleaned. What other connections are suspect?
Ken may be on to something....my alternator controller is located about 24" above my fluxgate compass (both in the hanging lacker). A voltage spike can interfere with electronics much like a VHF radio can, as both emit electromagnetic energy. I'm curious that you had only your cabin light breaker on, and experienced the shift in fan pitch. I'd continue that experiment using your DVM. The good news is that a week on the boat provides many opportunities to experiment and wait when hunting for intermittents. Since it seems this change in autopilot heading is not an isolated event (the 3 of us and who knows who else have experienced it), I wonder if the Raymarine website FAQ or technical support may be of help.
Brian,
I think you're on the right track. Here are my initial notes on your first post:
Go to Radio Shack and break out the big boat bucks for a DVM. Could be all of $20. I've had mine for 35 years!
Keep asking the question: "What cycles ON/OFF in (those) 2 minutes?"
What's the battery voltage. Doesn't a Mark II come with a voltmeter in the panel? Even my aftermarket analog voltmeter in my nav station works well enough for me to see varying voltages.
What's the voltage at the control head? Disconnect it and turn it on and see the voltage(s).
What's the voltage at the batteries? Whether they're new or not, only YOU know how you charge them and what condition they are in.
What charger do you have? Is it connected when you're testing? What stage is the charger in: bulk, absorption or float? Have you tried the test without the charger connected? (Obviously out on the water, but at the dock, too?)
What is the display on the control head saying? Does it simply change headings all by itself?
Keep asking the question: "What has changed recently?" The autopilot should really be on its own breaker, based on all the directions in all the manuals I have ever read.. Try switching the GPS over to the Nav/Com breaker. The depth sounder and knot meter are less susceptible to voltage fluctuations, as is the GPS. Have you read the recent posts about belts on the 4000? Are yours clean? (I put our new subwoofer - maybe takes an amp or two - on the sump - shower - switch.)
I don't have an answer, but these are the things I would do, playing detective, if it was my boat.
Finally, when it comes to electrical, "It's the Connections, Stupid!" Really, almost always. When was the last time you checked your engine ground? Not by just looking, but by pulling on it, removing it and really checking it?
Good luck, keep us posted.
Brian : When we went down the ICW, I met someone (at what seemed every stop) that was waiting for the return of their Autohelm 4000 from repair!! Made me feel good that my Wheel Pilot worked flawlessly and still does 20 years later!
Anyway, I'd check the connections as recommend by Stu. One of the most helpfull things I have on the boat is a can of "TurnerCleaner" from Radio Shake. Just squirt some on a connection and it's lubed/cleaned. A thought
Hi Brian,
Having the fluxgate compass mounted under the head sink is likely the root of your problem. I spent many hours crawling all over my boat with a hiking hand compass looking for a location that was actually a reasonable place for the fluxgate, and then rigging up a temporary mounting of the fluxgate to see if the AP would produce a reasonable "deviation" number after the "auto-calibrate" for the compass at a couple of "pre-screened" test locations.
When we bought this boat, the fluxgate had been located on the aft bulkhead under the port settee. The compass was about 10 inches above the macerator pump, which meant it was also about 6 inches below the large bundle of DC and AC wiring that routes around the same bulkhead. The AP was totally useless, going from doing nothing to taking off random directions. I can also confirm that below the galley sink is a constant magnetic storm...... I finally found a good location for it and it now works very well given its modest level of "smarts". Mine is a 4000+.
The best location I found was behind the interior liner directly behind the toilet, about half way between the head floor and the top of the counter behind the toilet ( a least on a Mk I ). I installed a 6 inch round access port, mounted the compass to the wide side of a piece of 2x4, and then screwed the 2x4 along the 2 inch side through the fiberglass liner with 2 #8 stainless steel screws. I had more than enough cable length once I went back and cut about 30 nylon cable ties off of the various places the compass cable was tied to anything that wouldn't move ( much... ) all the way back to the control head. You could probably do the same unless someone "tidied up" the wiring by cutting off the unused length of cable. Even if they did, the fluxgate compass wires can be lengthened with additional shielded 5 conductor cable to get where you need to go.
You have to appreciate that the magnetic forces being sensed by the fluxgate compass are very small, and getting smaller all the time ( literally... ). It doesn't take much DC current through a piece of wire in proximity to the fluxgate to change its perceived heading. While you can compensate out fairly large magnetic disturbances, that only applies to magnetic disturbances that remain fixed in location and strength relative to the fluxgate compass. A changing current through a wire nearby can't be compensated out.
My original practical education with fluxgate-compass-based autopilots on sailboats was in my first sailboat, a Hunter 25.5. I almost immediately installed a Navico TP5000 that we called "Nevil". Early on I noticed that sometimes when I would change sides in the cockpit, "Nevil" would go crazy for no apparent reason. After many observations through beer goggles, I finally realized I had car keys or a pocket knife in one of my pants pockets, and when that magnetic disturbance either arrived or departed the area near the self-contained fluxgate compass in the TP5000 while on an established heading, the AP would react robustly and unpredictably to the magnetic disturbance change. After that I always cleaned out my pockets when I got to the boat, and all was well with "Nevil".
In my experience, the Autohelm/RayMarine 4000 series is not particularly sensitive to low voltage unless it gets really low where other instruments and radios on the boat are acting weirdly or not working at all. As Ron mentioned, it as very sensitive to RF energy over a fairly broad range of frequencies. It certainly wouldn't hurt to go over every connector and make sure all is well, since loose connections can do all sorts of things that defy description and prediction. As Stu and I constantly say, "Check the connections first!".
Hope this helps you get to the bottom of your problem, and potentially others that have experienced the "Crazy Ivan" maneuver.
Regards,
John
1988 C34 hull 728 SR WK
Otra Vez
I have the same problem, this week the thing just went nuts again, the compass heading on the screen abruptly changes anywhere from 30 to 100 degrees off from the mounted compass, I tried calibration to no avail, I quit using it, and while sailing today, I noticed the compass heading on the unit was the same as the mounted compass, so, with one eye to caution, I activated it and the thing worked. I was pretty happy, went for a couple hours. and all of a sudden the boat did a fast turn to land, I shut it off and the compass screen was 140 degrees off from the compass heading. I will check the connections. Other than that, I don't know what to do, and will be following this post to see if I can correct what ever is wrong. The thing worked well for the first 3 years I had the boat, only this summer it has been "crazy Ivan" and all I have done electrically is installed the solenoid upgrade and put a positive battery terminal post above the alternator door. In all honesty, I am not sure where the flux gate compass is located on the boat. I'll have to run it down.
For trouble shooting purposes, the following data will be very useful in tracking down your problems with the "Crazy Ivan" maneuver with your 4000 series Autohelm/RayMarine AP.
1. If the heading readout changes while the AP is engaged and the boat steers toward the new displayed heading, the problem is not the fluxgate compass. The AP displays only the selected heading that the AP is trying to maintain when the AP in engaged and does not change in response to movement of the boat.
2. If the heading display remains the same with the AP engaged, and the boat steers away from the displayed heading, then the problem is associated with the heading that the fluxgate compass thinks it sees.
As soon as you put the AP in Standby, the heading display changes from the selected heading to the heading it thinks it is pointing at that instant.
In Case 1 the problem is likely internal to the controller/computer unit. It could be a problem with the membrane +10 or -10 switches, or could be at the controller circuit board. In this case, the heading commanded for the AP to follow is spontaneously changing and the rest of the AP control loop is just following instructions.
In Case 2, the AP suddenly thinks it's on the wrong heading ( i.e. - not what the commanded heading is that is shown on the display with the AP engaged ) and the AP control loop is again just following instructions. In this case, it could be caused by magnetic interferences that I discussed in my previous posting, or it could potentially be a problem in the fluxgate external wiring, or even an internal problem in the fluxgate compass. If the new heading the AP tries to maintain is a anything close to 120 degrees, the problem is likely the loss of one of the 3 output leg signals from the fluxgate compass. In this case, the changes will probably be somewhat consistent in the heading change amount each time you get the "Crazy Ivan" event.
As another potential root problem for Case 1, the problem could be a software glitch in the microprocessor inside the controller/computer unit. It would be useful if those of you who have experienced this problem would get your user manual and read how to display the software version in you unit, and the specific model variant you have on your boat and post it here. From past experience with "new" products from RayMarine about 10 years ago, their initial software release on "new" products was often far from debugged: they let their customers do that for them..... If you complained within the warranty period, they would update your software for free. Once you were out of warranty, TS for you.... For some rather astounding price they would update the software, but ...
Again, the first things to check are the simplest: the connections. After that, if you are experiencing the Case 2 scenario, find out where your fluxgate compass is mounted and what is around it within about a 12 to 18 inch radius, then report back here.
The most important thing, however, it to determine which failure scenario your "Crazy Ivan" fits: Case 1 or Case 2.
I will try to respond promptly to any posting on this subject, particularly if you have fairly specific observations you can share. Maybe we can get Crazy Ivan back on his meds on your boat.
Regards,
John
1988 C34 sr wk hull 728
Otra Vez
Thank you John very much, I definitely have the case one scenario, however when I shut off all power to the unit, and turn it back on, it powers up with the display still off by 30-120 degrees. and then low and behold, I look down and it is matching my compass course again and will work, albeit for a while. Thanks John, Bob
Hi Bob,
That is definitely a weird problem.....
A few more data points, please:
1. What model/vintage is your AP?
2. When you just disengage the AP after an "Ivan" event ( i.e. - go to Standby from Auto ) what happens on the heading display? How does it compare to your ship's compass and the heading you were originally try to hold?
3. When you cycle power to the AP ( pull the CB ), does is the power-up heading shown the same as when you powered it down ( assuming a steady heading, of course, during the power cycle)?
4. On the times that the unit displays a heading in Standby that is significantly different from your ship's compass, and later shows agreement, have you maintained the same heading or changed headings significantly during the wait time?
Let me know and I'll see if I can come up with a better analysis than just "weird".
Thanks.
John
John to answer your questions, not at the boat right now
1> not sure what year, the boat is a 88, it is a 4000
2> When I go to standby from auto, the heading still reads off by various degrees, 10 to 100 or so
3> When I power the unit down and then up, the heading stays the same, that is, still off by many degrees
4> The course is maintained within a few degree,
John I am not at the boat right now and trying to answer from memory, the unit is hard to diagnose because it my go for a few days flawlessly, then just take off. This week from Sunday to Wednesday, Sunday it worked, shut if off at anchor for a couple hours, and it wouldn't work again when I started it up Sunday night, it worked a half day on Tuesday, and half day on Wednesday, I shut the unit off wed about 11 am, turned it on about 12 am and crazy Ivan started up again, that's where it sits now, am going to the boat today, Thanks Bob
OK, I just got back from a week plus cruise on the Chesapeake with "Crazy Ivan". True to form for intermittent problems, this one didn't resurface when I was ready for it. It didn't reappear until the last day on the boat. I was able to do some diagnosis, but it was limited as I had nine people on the boat for the last four days (yes, cruising with 9 onboard, 4 adults and 5 kids ages 10-15). Here is my secondary set of notes:
- It is an Autohelm ST4000 vintage 1997, not a plus.
- I found some spare cable bundled up under the head sink, so I moved the fluxgate sensor 3 feet further to port and away from the engine. The new location was right behind the head trash can. This was done before the problem resurfaced.
- "Crazy Ivan" happened twice within 30 minutes of each other, both times while motoring north. This was after the fluxgate sensor was moved.
- The change was still the same, 20-30 degrees to port, returning pretty close to the original course within 2 minutes.
- After the first incident, I unplugged the GPS and ran it on it's own internal battery. It happened again while the GPS was unplugged (GPS is on the autopilot circuit).
- After the second time, I turned off the refrigerator but also had to change course to go upriver. I went 30 more minutes without issue but then I was home.
- Most of the previous trip when the problem was bad I was heading north. I was mostly motoring on that trip but it also happened under sail, also heading north.
- Most of this recent trip I was heading south and Crazy Ivan was mostly on holiday.
- Batteries were in good condition when the problem arose, having been plugged in at dock the night before.
- All during the week I could still hear the cabin fans changing pitch occasionally. The integrated voltmeter on the panel didn't show any discernable jumps. With that number of people on board, I was unable to pull the cushions and clip a digital meter on the battery posts for better readings. Turning most equipment off for diagnostics also wasn't an option at the time.
So I still haven't fired Crazy Ivan. However, if we go back to our original question on whether the problem is voltage fluctuation or magnetic interference, I'm leaning towards magnetic interference. Of course, my experience is that the hardest problems usually have two causes which screws up diagnosis. If I have any more to add after my Labor Day cruise, I'll post it here.
Thanks for all your suggestions.
Hi Brian,
Thanks for the more detailed information. One thing you didn't note was what was happening to the heading readout during the "Crazy Ivan": did it remain steady at your selected heading, or did it shift to the new heading the boat would try to hold and then back to the original heading?
Since your boat is a Mk II, I am not as familiar with what all is in the areas under the head sink. The thing you will want to be aware of back there is any DC power cables that happen to run through the area, particularly ones that carry any significant amount of current. If you were hearing fans speeds changing while underway, you were definitely having non-trivial DC loads cycling on and off. The "usual suspects" are refrigeration, bilge pumps, and fresh water pressure pumps. Since both episodes occurred while motoring ( i.e. - alternator producing output), I would be particularly observant of how and where the alternator feed runs to the Nav station and the DC distribution panel.
Hopefully, your Labor Day outing will be a little less "populated" and you can do a bit more variable elimination. Don't forget, too, that people and the stuff they carry with them in pockets or purses and also create transient magnetic disturbances, so you have to also be aware of where your guests or crew are relative to the fluxgate sensor during a "Crazy Ivan" event.
Regards,
John
I wasn't able to tell if my original "A" heading number on the control head was maintained as I didn't write it down every time I set it. However, I can tell that over the two minutes that it took to return to course, the "A" heading never changed. I think that puts it in case 2 from a previous post.
On fluxgate location, there seem to be wires everywhere. There is bundle near the rail and the fluxgate now being at counter height in the port aft corner of the head is near it. One easy mounting location option would be the flat bulkhead that I think is in front of the fuel tank. I had assumed the metal tank might cause some issues. I could also attach to the outer hull almost anywhere in the head using epoxy and a monting block. I'm wondering if the head location in general is my problem though. The main panel for the whole boat is only 16" in front of of the head.
Who has a MkII with a happy ST4000 and where is your fluxgate mounted?
Mine is mounted in the bilge area.
mine is mounted on the bulkhead- in the vbirth- port side. It has always helped my wife and I keep "our bearings" while spending the night.
Ken
This problem sounds like my life some time ago. I finally concluded that the fluxgate compass was my problem and relocated it from LOW in the wet locker aft of the nav station to HIGH in the same locker on the fwd wall. Voila! It worked and Ivan quit taking a notion of its own ever since.
I have concluded having it low put it too near the cables under the floor boards from the battery to the instrument panel. I reasoned that every time something electrical happened the surge in the cable gave the fluxgate something to worry about.
After relocation, I re oriented the compass by making the prescribed turns until the resulting number was reasonable.We are now at peace with each other. :clap
Brian,
The fuel tank should be aluminium, should not cause any problems. The installation instructions say the fluxgate should be at least 3' from electrical/ferrous metal sources. Not sure you can get that much under the sink. I don't know how the space under the aft cabin in the Mk II is set up. Can you move the fluxgate aft away from the engine/trans and wiring?
My fluxgate for the auto is also located in the bilge area, and has worked fine for the last 3 years
Mine is mounted under the setee in the rear berth facing the oven. It's been working good there so far.
Mike
From the factory, mine is located under the port settee, forward of the holding tank.
I don't know where mine is, still looking, the auto pilot has lately been working, although the heading display is off 60 degrees from the compass reading. the + and - both work, everything is ok, keeps my course, if I didn't look at the display heading I would think everything is ok, if I go 10 degrees either way, the display heading acknowledges albeit, wrong. I do see in the manual I may be able to correct this. Just not sure how it all happened in the first place.
Brian, mine is mounted in the aft cabin, on the starboard side in the storage under the seat. It's pretty far from any "field" still a reasonable distance (almost under when you think of it) from the pedestal.
It work perfectly and it's always bang on with the compass...if you give time to the compass to ajust to your new bearing...since the digital is instant.
The only thing that I didn't notice is route for the cable..I'll look for it during the w-e....but I suspect that it's under the floor, bed all the way to the stern and then climb up from there.
Good luck
Hi guys,
A couple of comments on the last several posts.
Once you have run the auto-calibrate on the fluxgate sensor per the manual instructions, if you have a reasonable deviation value per the instructions, the next thing to do is to adjust the heading correction. During this part of the calibration procedure, you align the autopilot heading readout with your ship's compass readout. If your deviation number is relatively small ( <5 degrees ), you can pick almost any compass heading on which to make the AP heading agree with the ship's compass and the AP heading should agree with the ship's compass heading within about a twice the deviation number you get after the auto-calibrate sequence. If you want to be a little more accurate, you can record the difference you observe between the 2 heading source on 8 equally spaced headings and average the net differences you see, then offset the AP heading readout by the negative of that number at the heading with the largest absolute difference recorded. If you are like me, you only use the AP heading as a relative number, and the ship's compass is the primary heading reference, so if you are reasonably close on the AP heading display, that's good enough. If you read your manual, the heading correction process for the AP is pretty easy after you get a reasonable deviation number using the auto-calibrate procedure.
On the second point, the routing of the fluxgate cable in general shouldn't matter too much relative to heading accuracy or intermittent heading disturbances unless the cable is very close to a very noisy power lead: a high power DC motor drive, a VHF or HF antenna feed coax cable, or the input or output of a square wave ( i.e. - "quasi-sinewave ) inverter, as examples. Other than that, it is pretty hard to disturb the heading signal from the fluxgate compass through coupled interference into the output cabling of the fluxgate sensor.
I am not thrilled about mounting the fluxgate compass sensor in the bilge area having had bilge pump and/or switches fail on several boats leaving water levels in the bilge almost up to the floorboards on unattended boats, both mine and customer boats. While the fluxgate sensor is nominally sealed, I wouldn't want to place any bets on its survival for any lengthy submersion in salt water...... Your boat, your decision.
I think the common thread here on "Crazy Ivan" so far is that magnetic disturbances are probably the primary root cause of the problem, with Brian's problem being the possible outstanding exception since his problem involves a change in displayed heading on the AP control unit during the "Crazy Ivan" thing. I would encourage others who have experienced this problem in its various forms to tell us about what you have experienced in the context of the previous postings describing the 2 possible types of problems. The more information I have the better, the better I may be able to sort this all out.
Thanks to all who have made postings on this topic. Keep them coming!
Regards,
John
Just to add to the data base on this topic, I have also been visited by "Crazy Ivan".
My fluxgate compass is mounted in the storage compartment at the base of the mast. (I have a Catalina 36 so my interior may be different)
I had replaced the fluxgate compass a few seasons ago so it is relatively new. I have an ST 4000 autohelm about 1993 vintage.
I get a Crazy Ivan (always to port) whenever I am in auto mode on a magnetic heading. About 15 to 30 minutes after engaging the autohelm seems about the right time. It happens on any point of travel but I do much more north and south as apposed to east and west.
It does not happen when I am in a "go to" mode of autohelm operation. My solution is to place the cursor on my Raymarine C80 Chart Plotter, to a point I want to go to. I engage the autohelm and immediately the chart plotter makes its initial course correction while I manually maintain a course that is very close to that shown by the plotter. After a few minutes the autohelm makes a second course correction and then I engage the clutch. In this mode I have gone 30 miles or more with out touching the wheel or the autohelm.
As soon as a crazy Ivan begins I disengage the autohelm clutch, manually correct the course and in a minute or two, the autohelm returns to the previous course. The interesting thing is that when the autohelm starts a crazy Ivan, it try's to turn the wheel (and therefore the boat) much more to port than I let it, but seems to quickly accept the manual heading I hold, I does not "give back" what it takes from the original course. I know this may sound a little confusing but if the crazy Ivan try's to turn the boat 90 degrees to port, if I hold the proper course manually by quickly disengaging the clutch, when the autohelm comes back to starboard it seems to know I am not that far off course and picks up the manual course (I reengage the autohelm) and it makes a few small course adjustments before all is forgiven and the original course is followed again.
This small give back after a crazy Ivan doesn't smell like a magnetic interference or magnetic field fluctuation to me. It seems to be more connected to a GPS vs magnetic disagreement. Since I get no crazy Ivan when in a "go to cursor" mode of navigation, I think that the Autohelm 4000 unit gets confused when both magnetic information and GPS heading information is available to it.
My question, does anyone know, will the Autohelm 4000 work without the fluxgate compass attached? Won't the Autohelm just use the GPS heading information?
Also, I am curious, is anyone having Crazy Ivan's with no chart plotter installed?
I have one of the newer X-5 auto pilots and I was having some strange issues when I would hit the track button on the auto pilot to go to a waypoint. It would veer off about 40 degrees or more to one side or another.
There is a function on mine called "reset XTE" and I don't know if that function on the older models but that fixed my problems.
I think that if you have the AP set for a compass course for awhile and then switch to "track" it will mis calculate XTE and cause the problem of the course differential.
This may be altogether different than the trouble the rest of you are having but I just thought I would put it on the table.
Mike, the XTE is the cross track. This is the distance your boat is "off track" from the course you originally put in to the autohelm.
Hitting the Reset XTE button tells the system to recalculate your course to the destination from this new point.
Perhaps a simple way to think of XTE it is to imagine you are in the 5th lane of a 10 lane highway (counting left to right). If you drift to lane 8 you may still be heading toward your destination but you are 3 lanes off your original track. This distance from lane 8 to the original lane 5 is the XTE (Cross Track Error). The Autohelm will overstear to the left until your boat is back in lane 5. Resetting the XTE tells your Autohelm that your present position in Lane 8 is fine and it should navigate to your destination from Lane 8.
Veering off the 40 degrees you mention sounds like the "Crazy Ivan" maneuver we are trying to solve.
Bill Matley
Catalina 36
1252
Thanks Bill,
You're absolutely right! And I believe cross track error is also the difference in your compas heading and the course the boat is actually moving. So I'm thinking it (the gps/chart plotter together with the auto pilot )actually compensates for set and drift and that could explane the difference in heading, although 40 degrees is a bit much.
Quote from: Mike and Joanne Stimmler on August 24, 2009, 09:21:10 AM...And I believe cross track error is also the difference in your compas heading and the course the boat is actually moving.
Mike,
Sorry, nope, not true.
Cross track error is the distance . LEFT OR RIGHT, that you are off course from the line between where you originally entered the GO TO (your "start" point for lack of a better phrase) and the waypoint you are going towards. That original line. Period. Nothing more, nothing less.
Reason I know this is that we started with a Loran and moved to a digital-only Magellan GPS way before charting GPS became available.
Kinda a separate issue, but as far as your "quote," Mike, think of this situation:
You're heading up a river and get caught in a whirlpool. The river runs due north-south and you're heading north. Your boat gets caught by the whirlpool and now the bow is pointing due east. But the boat is still moving due north through the water. Your heading is still 0 degrees (north) 'cuz this is the direction the boat is moving) but your compass reads 90 degrees (due east). Your cross track error is zero, so your example has nothing to do with cross track error.
Stu,
Thanks for setting me streight. You have such a good way of splainin things.
Mike
A link to here has been added to "Wacky Autohelms" in the wiki (electronics)
The only time I engage the auto pilot is to lock the wheel while I adjust sails, we call it "Iron Mike"
Ralph
Here's one no one has mentioned:
Mine was was all over the place, it would work ok then take a turn in either direction or it would jitter back and forth then settle down a bit. I never let it go long enough to see it it would come back.
I finally took my 4000 home and opened it up. It was wet inside with about 2 tablespoons of water sloshing around inside. I dried it out cleaned off the corrosion, cleaned any removable connections and it now works perfectly. I use it all the time when single handing and I never keep out in the wet weather. Mine is mounted below the port side engine control panel. (use just a little anti-static precaution and you'll be fine, just don't rub your feet on the carpet and then touch the board)
Brian - and anyone who has got this far because you have problems with the Autohelm Raytheon ST4000 Autohelm Wheel Pilot:
When mine - also on a 1997 MkII - went intermittently awol a couple of years ago, after considering the electrical possibilities, I took the drive unit apart and found the belt worn out. Replacement belts are available from 1-800-859-7659, www.polybelt.com, 26 West First Street
Clifton, New Jersey, 07011. Item number BAT5-750AUTOST4000. Price (then) $19.95. The belt I had met these criteria:
belt measures 750 mm in length; tooth groove is 1.16 mm in width; distance between tooth grooves is 3.22 mm. Groove is a U with a V at the bottom of it. Belt is 2.93mm thick and 9.33 mm wide. There are 150 sections between grooves in the full length of this belt. The thickness of the belt from the back to the bottom on the V is 1.67mm.
Brian, it may well be that your problem is not so simply remedied - and perhaps if I read your postings more carefully I would know that - but someone else might find themselves reading through your interesting postings and have a belt problem, so for what its worth.