Understanding Auto Pilot

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Nov 12, 2004
160
Hunter 37.5 Kemah, Tx
I have a ST 4000 Auto Pilot installed on the Hunter 37.5 we just bought. I'm having trouble understanding how it works. It seems to work fine when I first start sailing but when I disengage it and change course it wants to go back to an old bearing, not necessary the one I was just on. It doesn't aquire the new heading. I know from reading the manual that you can tack automatically and that you can return to a previous bearing but shouldn't the unti aquire the new heading if none of these features were used? I'm sure I sound like a complete idoit but I'm realy struggling to understand this device. It doesn't appear to be that difficult. What am I missing?
 
D

Don

Disengage?

From your description, not sure if you are simply disengaging the locking arm or actually putting the pilot in standby too, the latter being a prerequisite to acquiring the new heading. Don
 
Jun 8, 2004
2,959
Catalina 320 Dana Point
As Don has said, to engage lock clutch first

then hit "auto" button and display should change from "standby" to "auto". Disengage by by hitting "standby" button and unlocking clutch. Pilot takes it's heading from reading of fluxgate compass which is on display,when the "auto" button is pushed. If you watch this you will see that it varies from moment to moment based on sea conditions, Etc. Wheelpilots work best with minimal wave & chop because of this and if you can maintain a steady course for a moment before engaging the do better. To "auto tack" you hit both the 1 & 10 degree buttons on side you want to turn at same time and boat will turn ~ 110 degrees that direction then come back a little.
 
Nov 12, 2004
160
Hunter 37.5 Kemah, Tx
Thanks for the Info

I thought I was pushing "Standby" before disengaging the Auto Pilot but maybe that's the problem. I think what is confusing me is I thought the heading showing while the unit is in Standby mode would be the heading of the boat but of cource that's not correct. "Standby" by description should be the heading I was on not the current heading. Okay I think I understand it now.
 
Jun 8, 2004
2,959
Catalina 320 Dana Point
Yeah, I think you got it, when on "standby"

it's giving you your current heading (+ or minus whatever "swing" you are getting) and when you hit auto it sets at a heading which remains on the display. Since the fluxgate may not have been reading exactly the heading you wanted you adjust with the 1 degree buttons.
 
Oct 7, 2004
106
Hunter 260 Abundance - H260, Las Vegas, NV
ST4000

I'm not sure Tom has it right - on my newly installed ST4000, the present heading is displayed on the control head in standby. It is an electronic compass. Here's a copy of text from the owner's manual: 1. Press standby. • in Standby mode, the display shows the boat’s current compass heading. (From Page 7) There is a feature that might cause this behavior: (page 9) Returning to the previous locked heading (LAST HDG) If you have steered the boat away from the selected locked heading for any reason (for example, executing a dodge maneuver or selecting Standby), you can return to the previous locked heading as follows: 1. Press auto for 1 second. The display shows the previous locked heading (LAST HDG?) for 7 seconds. Note: The direction-to-steer indicator shows the direction the boat will turn. 2. To accept the previous heading, and resume this course, press auto within this 7 second period. =========== Here's a link to the manual: http://www.raymarine.com/raymarine/SubmittedFiles/Handbooks/Autopilots/ST4000plus_mk2.pdf
 
D

droop

Your boat is

TOO BIG FOR A 4000. YOU NEED THE 6000 FOR THAT SIZE BOAT.
 
F

Franklin

Depends

I have an ST4000 on my H376 and it does fine as long as I don't overpower the helm with too much weather helm and truthfully, I don't like to have that much weather helm anyway, so I usually flatten or furl the main. Last weekend though I was on a broad reach and had the main out full so when I tacked to cross the shipchannel through our little crossway, I didn't have the space or time to mess with the main and had a lot of weather helm and the autopolit couldn't handle it...but boy was I moven. So, the answer is it depends on how you sail. If the sails are balanced right, the ST4000 works fine.
 
May 28, 2004
175
Oday Widgeon Beech Bluff, Tn.
Right on the limit

Morning: Being the user of a 4000+ for several years now, I can promise you that they work, just getting used to them and their tickiness. They pretty much have to be tuned to your boat and conditions and it takes a while sometime to get it worked out. Droops comments may be close to right though. The 4000 max's out at 17,500. I believe that the 37.5 displaces 16,400, so throw in your water, fuel, supplies, and other misc. stuff that you have on board, you might excede the max that the 4000+ is designed for, at least be right on the edge. My boat gross displacement is 14,000 and the 4000+ works fine in just about any conditions. BUT,like Franklin says, they will work, however, it will depend on wind speed, water conditions, trim, etc. You might be limited to light wind conditions and motoring during it's use. Heavy weather and wind conditions would probably over power it. Sorry for the bad news.
 
Nov 12, 2004
160
Hunter 37.5 Kemah, Tx
Several Thoughts

Yes I do believe from previous listings on this site that the ST 4000 is not the right auto pilot for my boat but it's what I have. I prefer to steer manually in heavier conditions anyway. Mostly do daysailing and the first mate is not big on busting through waves with the rail in the water(darnit)so I think I can live with the 4000. Back to the heading displayed in the Standby mode, I'm sure but I think I have a problem with the unit. I noticed sitting at the dock that it was displaying the same reading as the compass, well close anyway, and when we first went out it displayed the boat heading. Auto pilot worked fine but when I changed course, the unit did not pick up the new heading and never worked properly for the rest of the day. I'm wondering if the problem is in pressing Standby prior to disengaging the auto pilot. I'm not sure I did that. What is very strange is that it keeps going back to the heading we were on during the sea trial ride, over a month ago. I don't know, I'll play with it this weekend and report back. Thanks again for all the information. David, I do have the manual so I'll go back and re-read that section you mentioned.
 
May 28, 2004
175
Oday Widgeon Beech Bluff, Tn.
Keel

Just a thought. Do you have a cast iron keel? If you do, the Fluxgate compass location could be the problem as it might have a constant attraction to the keel causing the original heading to maintain. It's supposed to be mounted somewhere on the centerline of the boat, but may not be possible if you have an iron keel. If all else fails, get up on the attached web and see if information from the pros will help. Good Luck!
 
F

Franklin

Two thoughts

1) The Fluxgate compass is what tells the autopilot where to go. Mine once in a while flips out and I have to go down and turn off the power to the instruments and autopilot and turn them back on. It's only happened twice in 20 times out on this boat. Sometimes I forget that I have the wheel lock snug and that causes the autopilot to have troubles too and the autopilot has to be turned off and back on to reset it after the wheel is freed. 2) All this talk about the autopilot not being able to handle windy days is nonsinse. I've had mine out in 25 kts and 6' waves going in all wind angles without a problem. The problem is that you need to reef or furl to get the helm controlable. As long as it's not a gale, then it doesn't matter how strong the wind is, it matters how much wind per sail you have up and the trim on the sail. If you have your leach hooked that's going to cause a lot of unnecessary heel and a ton of weather helm that the autopilot can't control. If you have your full main out in 15+ kts (for that boat), then your going to have a lot of heel and weather helm. Reef it down and it's just like sailing in 10 kts.
 
Nov 12, 2004
160
Hunter 37.5 Kemah, Tx
All Good

Thanks Franklin and J.B., just as a note, my fluxgate compass unit is located under the cockpit in the aft cabin. Not sure if that's a problem or not. Franklin, we learned this psat weekend about the importance of reefing in 15+ wind. We had 12 - 15+ on Saturday and it was somewhat unconfortable. Put a reef in on Sunday and shorten up the head sail and it was much better, got a nice balanced helm and was making over 6 knots, close to 7 on the GPS at times.
 
Jun 8, 2004
2,959
Catalina 320 Dana Point
Even on my 27 the wheel pilot is not really

useable in real heavy weather, just long enough to dash into cabin to switch on lights etc. I think they just don't have the ability to maintain a heading like a below decks pilot in more severe conditions. Always works better upwind and it's at it's worst downwind with a following sea. Below deck pilots have a Gyro and a rudder position sensor to mediate the input from the fluxgate. It's my understanding that the addition of the rudder sensor (~$300) improves the performance of a wheel pilot greatly. Units also need to be calibrated for local variation, procedure in book, need a calm day & you can compare with mag compass, also handy to have a hand bearing compass to compare for accuracy of your binnacle compass. It's nice when they agree or are at least close.
 
Apr 26, 2005
286
Beneteau Oceanis 390 Tsehum Harbour, BC, Canada
Handheld VHF Interference With Autohelm ST4000

Last week I discovered that my Standard Horizon handheld VHF seems to be driving my Autohelm crazy. Standing at the helm and pushing the transmit button to talk to a friend, my Autohelm suddenly turned Tula 30 degrees to port. I checked a couple more times and the same thing happened. Then went to the foredeck and pushed transmit. Nothing happened. Anyone had this problem?
 
R

Ron

calibrate your fluxgate

I have the same autohelm on my C320. Once in awhile it would suddenly take a new direction, as if it had a mind of its own. To correct this, I calibrated the fluxgate compass by motoring around in a large circle. I now do this first time out in the season. No problems ever since.
 
R

Ron

fluxgate note

I should add that when turning the boat in a large circle to calibrate the fluxgate compass, the autohelm must be on in the "standby" mode to work.
 
Feb 27, 2004
142
Hunter 29.5 Lake Travis, TX
Past the limit

Droop and J.B. Dyer are correct. The ST4000 is underdesigned for the h37.5. According to Raymarine, Autopilot choices are based on laden displacement which is design displacement plus 20%. So in the case of the h37.5 this is 16,400 plus 3,280 lbs or 20,000 lbs. The ST4000 manual specifically warns against its use with boats 20,000 lbs or more. The limit is 17,500 lbs. Even the ST6000 may not be enough with a limit of 22,000 lbs. My life experiences have taught me to never depend on equipment that is being used near or over its maximum limit. My rule is a maximum of 80% of rated use for extended periods. For daysails and light conditions you may just get by with the ST4000. For anything more, at least take a couple of spares.
 
Feb 27, 2004
142
Hunter 29.5 Lake Travis, TX
Peter...

Where is your fluxgate located? If its near the helm that may be the problem and if so review the manual for a more suitable location. Hope this helps.
 
Jun 1, 2004
227
Beneteau 393 Newport
Stby

You mentioned that you disengage the pilot and it wants to go back to course. You said nothing about putting the control head in STANDBY (STBY). If you don't do this you have merely disengaged the motor from the wheel. You must disengage the control from the motor. To acquire a new heading (other than the one you were just on), from the standby mode, press Auto to enter a new course. Jim
 
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