Hey Guys, Long time, no post. I hope everyone had a good winter (if there is such a thing!). Anyway, I have a question to those of you with Raymarine ST4000+ MkII AND a rudder reference transducer: Did the rudder reference transducer improve performance? The Raymarine rep says that the rudder reference transducer will GREATLY improve course keeping performance so I'm thinking of installing one. Can anone back up that statement?? I'd like to hear from a couple of people before going through the trouble to install. Allen Schweitzer s/v Falstaff C-30 Hull# 632
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Excellent question!
I am very interested in hearing the answer. I have a boat that is too big (22,000 lb) for the ST4000+ MkII but I went ahead and installed it anyway on the grounds that it was so much less expensive, and I rationalized that I only wanted it for motoring on a hot windless day. It does well under those conditions and in light-moderate winds, but just loses it completely in about 20 knots or more and some seaway. My friend with an identical boat with an ST6000 is not affected by the wind at all. So - I would be most interested if a rudder reference would help. Derek
I am very interested in hearing the answer. I have a boat that is too big (22,000 lb) for the ST4000+ MkII but I went ahead and installed it anyway on the grounds that it was so much less expensive, and I rationalized that I only wanted it for motoring on a hot windless day. It does well under those conditions and in light-moderate winds, but just loses it completely in about 20 knots or more and some seaway. My friend with an identical boat with an ST6000 is not affected by the wind at all. So - I would be most interested if a rudder reference would help. Derek
I'll let you know!
I have one on the way and plan to install it. I'll let you know how it works out if no one else responds and if you are in no hurry.
I have one on the way and plan to install it. I'll let you know how it works out if no one else responds and if you are in no hurry.
Look in the archives
I have had similar problems with mine, I even resorted to returning it to Raymarine to have it tested...... nothing wrong ! If you look in the archives you will see correspondence on this vary topic, the advice I was given was to tighten my steering cables to eliminate any play, this according to many will eliminate the straying off course problem. I launch in a month ( weather permitting) and can't wait to see if this resolves my 4 year old problem. Try it on your and let me know. JS
I have had similar problems with mine, I even resorted to returning it to Raymarine to have it tested...... nothing wrong ! If you look in the archives you will see correspondence on this vary topic, the advice I was given was to tighten my steering cables to eliminate any play, this according to many will eliminate the straying off course problem. I launch in a month ( weather permitting) and can't wait to see if this resolves my 4 year old problem. Try it on your and let me know. JS
To J:
Hey J, Funny you should mention the archives...I was the one who posted that suggestion to you!! Funny how small a world this forum is. Even with everything optimal (settings, cables, etc.), I still have a +/- 5 degree "hunt" on a run or with following seas. The Raymarine rep said the only thing that will cure that is the rudder reference transducer. I'll let you know how I do. I explained to the Raymarine Rep at the Boston Boat show (who was incredibly knowledgeable, by the way) that I had ALL Raymarine electronics on my boat & loved them except for the autohelm. He sent me a rudder transducer for free, overnight. I got it in 2 days. I couldn't believe the level of service. Anyway, I'm looking at my quarterberth and installing this is going to be a pain in the neck. I want to know if it's worth it before fashioning a block to mount it on, epoxying it to the hull, etc. Good luck with the steering cables. Tightening those made my autopilot performance acceptable. I'm hoping the rudder reference will make it perfect. --Allen
Hey J, Funny you should mention the archives...I was the one who posted that suggestion to you!! Funny how small a world this forum is. Even with everything optimal (settings, cables, etc.), I still have a +/- 5 degree "hunt" on a run or with following seas. The Raymarine rep said the only thing that will cure that is the rudder reference transducer. I'll let you know how I do. I explained to the Raymarine Rep at the Boston Boat show (who was incredibly knowledgeable, by the way) that I had ALL Raymarine electronics on my boat & loved them except for the autohelm. He sent me a rudder transducer for free, overnight. I got it in 2 days. I couldn't believe the level of service. Anyway, I'm looking at my quarterberth and installing this is going to be a pain in the neck. I want to know if it's worth it before fashioning a block to mount it on, epoxying it to the hull, etc. Good luck with the steering cables. Tightening those made my autopilot performance acceptable. I'm hoping the rudder reference will make it perfect. --Allen
To J. Simmonds
I just spent 30 minutes searching the archives and can find nothing related to the effect of a rudder position transducer on ST4000 performance. All I found was a couple of (very well written
) posts by me, saying exactly the same thing as I said above (my memory is going *grr ) Can you point us in the right direction? Derek
I just spent 30 minutes searching the archives and can find nothing related to the effect of a rudder position transducer on ST4000 performance. All I found was a couple of (very well written
) posts by me, saying exactly the same thing as I said above (my memory is going *grr ) Can you point us in the right direction? DerekA slightly different ST4000 experience.
I just had an ST4000+ installed on my C320. I calibrated it carefully according to note I found in the sailnet e-mail archives. While undersail, it performs very well. But under power, it tends to overcorrect and steer an S pattern. I'm presuming this is do to the prop wash hitting the rudder and being deflected, thus accentuating the power of the rudder while under power. Any thoughts?
I just had an ST4000+ installed on my C320. I calibrated it carefully according to note I found in the sailnet e-mail archives. While undersail, it performs very well. But under power, it tends to overcorrect and steer an S pattern. I'm presuming this is do to the prop wash hitting the rudder and being deflected, thus accentuating the power of the rudder while under power. Any thoughts?
Rudder Reference
I can't really comment on the improved performance of the rudder reference unit because I've never tried the autopilot without it. It does seem that having the computer know the rudder position rather than respond to a heading change should improve any calculation the autopilot is performing. I am assuming of course, that the rudder reference transducer does provide some useful and used information to the autopilot. What we noticed relly helped, was the addition of the Smart Heading Sensor (gyro unit). It costs almost as much as the autopilot but it really helped settle down the heading issues. Again makes sense. A stabilized heading source should allow the computer to produce better and quicker inputs to the steering system. I have not had an opportunity to try it in all conditions yet, but the initial tests are a definite improvement. Dan Jonas (S/V Feije II)
I can't really comment on the improved performance of the rudder reference unit because I've never tried the autopilot without it. It does seem that having the computer know the rudder position rather than respond to a heading change should improve any calculation the autopilot is performing. I am assuming of course, that the rudder reference transducer does provide some useful and used information to the autopilot. What we noticed relly helped, was the addition of the Smart Heading Sensor (gyro unit). It costs almost as much as the autopilot but it really helped settle down the heading issues. Again makes sense. A stabilized heading source should allow the computer to produce better and quicker inputs to the steering system. I have not had an opportunity to try it in all conditions yet, but the initial tests are a definite improvement. Dan Jonas (S/V Feije II)
Wolfgram re Autopilot Hunting
Jim - if you're getting as much hunting as you describe there is probably something else at work. There are a number of settings that can be adjusted so I'd recommend calling Autohelm and talk to their Tech Rep as they are really knowledgeable about these things. For what it's worth, I had set-up issues with mine but after a couple calls and tweeks with the input it works perfectly now.
Jim - if you're getting as much hunting as you describe there is probably something else at work. There are a number of settings that can be adjusted so I'd recommend calling Autohelm and talk to their Tech Rep as they are really knowledgeable about these things. For what it's worth, I had set-up issues with mine but after a couple calls and tweeks with the input it works perfectly now.
Confessions of an academic
I'm swearing you all to secrecy. I have spent my whole professional career teaching and researching feedback control theory. I can bamboozle everybody with mathematics, I teach some of the best and brightest graduates and undergraduates. I use sailboat autopilots as an initial case study in my undergraduate course, and I use (simplified) sailboat dynamics as a modeling problem in graduate courses. We write all sorts of differential equations and disappear into hyperspace where we have a grand old time luxuriating and buried in the theory. Hmmm, hmmm, just love it. It's a thing of beauty and a joy forever... Now here's where you come in - you've got to promise me that you won't tell my students that I can't get my ST4000+ to work properly. OK? Promise? *x And Jose Venegas, that applies to you especially! ;D
I'm swearing you all to secrecy. I have spent my whole professional career teaching and researching feedback control theory. I can bamboozle everybody with mathematics, I teach some of the best and brightest graduates and undergraduates. I use sailboat autopilots as an initial case study in my undergraduate course, and I use (simplified) sailboat dynamics as a modeling problem in graduate courses. We write all sorts of differential equations and disappear into hyperspace where we have a grand old time luxuriating and buried in the theory. Hmmm, hmmm, just love it. It's a thing of beauty and a joy forever... Now here's where you come in - you've got to promise me that you won't tell my students that I can't get my ST4000+ to work properly. OK? Promise? *x And Jose Venegas, that applies to you especially! ;D
Poles in the right or wrong plane. ;D
Derek, obviously your ST4000 is having to estimate too many state variables. You need to provide it with some real measurements. I designed automatic control systems for the US Navy for 30 years and would never consider designing a servo/ autopilot without a rudder reference. After 6 years of a ST4000 working fair but thinking it could do better, I have a rudder reference unit on my boat to be installed shortly.
Derek, obviously your ST4000 is having to estimate too many state variables. You need to provide it with some real measurements. I designed automatic control systems for the US Navy for 30 years and would never consider designing a servo/ autopilot without a rudder reference. After 6 years of a ST4000 working fair but thinking it could do better, I have a rudder reference unit on my boat to be installed shortly.
This is NOT an ethnic joke...
... and I'm sure Frank has heard it. It will be understood only by engineers and students who are familiar with control theory. It relates to the findings of the Air Transport Safety Board in Poland, which decided that the airplane had crashed because too many Poles had moved to the right half-plane. It's a bad joke even in techno-geek land. Most normal people will scratch their head and say "What???". A "pole" is a concept in control theory that relates to stability. A feedback system (such as an autopilot) that has any "poles" in the so-called "right half of the s-plane", or "right half-plane", will be physically unstable and will probably self-destruct, or at least do nasty things. (It's all related to Laplace transforms and stuff that only crazy people care about.) So that's why the airplane crashed - get it? Bad, bad, bad.... :{ But it's not an ethnic joke, and Frank's post made me write it. If your autopilot is drifting further and further away from your desired heading, or the boat is hunting back and forth forever, I hate to break this to you - you have one or more poles in the right half-plane. You have to push those little buggers back over where they belong in the left half-plane. Now you know what's wrong you have no excuse. Go fix it!!! Shouldn't take but a couple of minutes. ;D
... and I'm sure Frank has heard it. It will be understood only by engineers and students who are familiar with control theory. It relates to the findings of the Air Transport Safety Board in Poland, which decided that the airplane had crashed because too many Poles had moved to the right half-plane. It's a bad joke even in techno-geek land. Most normal people will scratch their head and say "What???". A "pole" is a concept in control theory that relates to stability. A feedback system (such as an autopilot) that has any "poles" in the so-called "right half of the s-plane", or "right half-plane", will be physically unstable and will probably self-destruct, or at least do nasty things. (It's all related to Laplace transforms and stuff that only crazy people care about.) So that's why the airplane crashed - get it? Bad, bad, bad.... :{ But it's not an ethnic joke, and Frank's post made me write it. If your autopilot is drifting further and further away from your desired heading, or the boat is hunting back and forth forever, I hate to break this to you - you have one or more poles in the right half-plane. You have to push those little buggers back over where they belong in the left half-plane. Now you know what's wrong you have no excuse. Go fix it!!! Shouldn't take but a couple of minutes. ;D
It is a small world
Allen, Are you the Allen S. who responded to me last fall ? ? ? I am anxiously awaiting launch so I can try out your suggestion. Raymarine also offered a rudder reference unit to me, I would like to try your suggestions first. When I queried them on my wandering problem, which can at any point of sail, they said they had 100's of these installed on Cat 30's and never have heard a complaint !?!?!?!? More of us should be complaining to Raymarine directly AND if anyone out there has found the perfect solution, let them know. Yes their service is good but if they had the information required to help troubleshoot it would be great!. Good luck with the transducer Allen, let us all know how well it works. It may be th only solution. JS Mine handles amlmost perfectly under power, which first led me to believe that there might be some strange force at work when the engine is on and this has affected the calibration.
Allen, Are you the Allen S. who responded to me last fall ? ? ? I am anxiously awaiting launch so I can try out your suggestion. Raymarine also offered a rudder reference unit to me, I would like to try your suggestions first. When I queried them on my wandering problem, which can at any point of sail, they said they had 100's of these installed on Cat 30's and never have heard a complaint !?!?!?!? More of us should be complaining to Raymarine directly AND if anyone out there has found the perfect solution, let them know. Yes their service is good but if they had the information required to help troubleshoot it would be great!. Good luck with the transducer Allen, let us all know how well it works. It may be th only solution. JS Mine handles amlmost perfectly under power, which first led me to believe that there might be some strange force at work when the engine is on and this has affected the calibration.
Derek - Archive Search
When you go into the archives, search by ST4000, Any word, in any area of the message and click on a specific year, I clicked on 2002 and got 15 hits, 2003 has a few. Its a very popular topic. Good luck. JS
When you go into the archives, search by ST4000, Any word, in any area of the message and click on a specific year, I clicked on 2002 and got 15 hits, 2003 has a few. Its a very popular topic. Good luck. JS
Under Power
I think the 4000 works well under power because there is little induced yaw into the flux gate compass. When heeled a little movement in the angle of heel probably produces more indicated yaw than exists in actuality. The 4000 is not particularly fast so by the time the flux gate compass settles down, it has sometimes gone far enought in the wrong direction to take ahile to get back in the right direction. Setting the response up helps this situation. For us, installing the flux gate near the back of the boat, where yaw forces are smaller helped. And, as we said earlier, the gyro stabilzed compass helps even more. Dan Jonas (S/V Feije II)
I think the 4000 works well under power because there is little induced yaw into the flux gate compass. When heeled a little movement in the angle of heel probably produces more indicated yaw than exists in actuality. The 4000 is not particularly fast so by the time the flux gate compass settles down, it has sometimes gone far enought in the wrong direction to take ahile to get back in the right direction. Setting the response up helps this situation. For us, installing the flux gate near the back of the boat, where yaw forces are smaller helped. And, as we said earlier, the gyro stabilzed compass helps even more. Dan Jonas (S/V Feije II)
Autopilots
Folks, In response to a recent post that we should offer explanations before saying "search the archives," I offer the following: I simply don't understand how anyone could accept having to buy yet another piece of equipment at the same cost to make the original equipment work! There have been an incredible number of discussions about wandering autopilots, especially the ST4000. Here it comes::::::::::: If you do a forum search on ST4000, you''ll see what I mean. I haven't yet heard of a difference in autopilot operation and control between sailing and motoring. Maybe you could consider the possibility that you'd "accept" a bit more course deviation when sailing than motoring and would simply notice more S curves when motoring. Don't know. Seems, though, that if it happens when motoring, it sure IS happening when your sails are up and your motor's off, unless you have a fluxgate location problem where electrical sources are screwing it up when the motor is ON. Before you spend anymore $$$ on a costly fix, find out what the problem is. You're not alone. Also try the link to the C34 website about autopilots. It picks up on the basics. Some of the settings previously discussed on this board are available in the forum archive search under ST4000. And just to give you more material to absorb, try reviewing the discussions here: http://c34.infopop.cc/6/ubb.x?a=srch&s=329609511&findw=ST+4000 Good luck, Stu
Folks, In response to a recent post that we should offer explanations before saying "search the archives," I offer the following: I simply don't understand how anyone could accept having to buy yet another piece of equipment at the same cost to make the original equipment work!
There have been an incredible number of discussions about wandering autopilots, especially the ST4000. Here it comes::::::::::: If you do a forum search on ST4000, you''ll see what I mean. I haven't yet heard of a difference in autopilot operation and control between sailing and motoring. Maybe you could consider the possibility that you'd "accept" a bit more course deviation when sailing than motoring and would simply notice more S curves when motoring. Don't know. Seems, though, that if it happens when motoring, it sure IS happening when your sails are up and your motor's off, unless you have a fluxgate location problem where electrical sources are screwing it up when the motor is ON. Before you spend anymore $$$ on a costly fix, find out what the problem is. You're not alone. Also try the link to the C34 website about autopilots. It picks up on the basics. Some of the settings previously discussed on this board are available in the forum archive search under ST4000. And just to give you more material to absorb, try reviewing the discussions here: http://c34.infopop.cc/6/ubb.x?a=srch&s=329609511&findw=ST+4000 Good luck, StuI think Dan is close
Putting aside my tongue-in-cheek posts below, like Dan I have concluded that much of the problem lies in the mounting of the flux-gate compass and the response speed of the ST4000 drive. Destiny "loses it" in a decent wind and seaway. I noticed, before I installed it, that the compass rattled when shaken, indicating little if any fluid or mechanical damping in the gimballs. My conjecture is that when the motion increases, the compass swings wildly in its gimballs indicating all sorts of heading errors. The ST4000 simply says "I give up - you're on your own" I intend to move the compass from its current fore-aft mounting, fairly high up on the engine-room wall to an athwartships mount as low as I can find. The other possible problem with the drive is that it becomes "slew-rate limited", that is it is going as fast as it can, but it just ain't fast enough to maintain control in a seaway. Solution, get a bigger, faster motor. Easy to say, not so easy to do. So you end up throwing out the ST4000 and getting a ST6000 or ST7000.
Putting aside my tongue-in-cheek posts below, like Dan I have concluded that much of the problem lies in the mounting of the flux-gate compass and the response speed of the ST4000 drive. Destiny "loses it" in a decent wind and seaway. I noticed, before I installed it, that the compass rattled when shaken, indicating little if any fluid or mechanical damping in the gimballs. My conjecture is that when the motion increases, the compass swings wildly in its gimballs indicating all sorts of heading errors. The ST4000 simply says "I give up - you're on your own" I intend to move the compass from its current fore-aft mounting, fairly high up on the engine-room wall to an athwartships mount as low as I can find. The other possible problem with the drive is that it becomes "slew-rate limited", that is it is going as fast as it can, but it just ain't fast enough to maintain control in a seaway. Solution, get a bigger, faster motor. Easy to say, not so easy to do. So you end up throwing out the ST4000 and getting a ST6000 or ST7000.
This is getting more interesting
As everyone can see there are tons of opinions on this issue. My fluxgate is mounted on the mast support under the forward seat of the dinette. (Mine is U shaped). Has anyone else mounted theirs elsewhere and acheived better results? I have held my handheld compass in the same location and don't think I have any magnetic influences in that area that could be throwing me off. I have recalibrated at least twice and my last resort is to Allen's suggestion of tightening my cables. Lets all convene in a few months and see who has the best solution. JS
As everyone can see there are tons of opinions on this issue. My fluxgate is mounted on the mast support under the forward seat of the dinette. (Mine is U shaped). Has anyone else mounted theirs elsewhere and acheived better results? I have held my handheld compass in the same location and don't think I have any magnetic influences in that area that could be throwing me off. I have recalibrated at least twice and my last resort is to Allen's suggestion of tightening my cables. Lets all convene in a few months and see who has the best solution. JS
St 4000+ observations
Mine has worked flawlessly for many years on my c250 cruising the Great Lakes. This past year, I upgraded rudder to the latest 250 offering which is a shorter, wider, thicker and balanced rudder. Things went to hell for the auto pilot. It did not like the new rudder. Here is what happened though keep in mind that I'm not suggesting that its what is happening for others... I just know it did me in. The old rudder was a high aspect ratio rudder that had a lot of lift... enough to manage the boat. The autopilot would drive the new rudder into considerable attitudes of attack in an attempt to hold course with the rudder sometimes being drug at greater degrees of attack. Thick broad foils generate greater lift at steeper angles of attack whereas the old rudder had lots of lift straight on. What happened is that as the seaway or wind caused the boat to go out of balance a bit, the rudder would go harder over to maintain heading...but then if the wind slackened or the effect of the seaway lessened, with the helm over, the boat would of course lurch to that helm position confusing the hell out of the pilot. At times a constant oscillation was going on with the helm and autopilot which resulted in a snake course. I put the old rudder back on and all was fine again. It may be that a rudder position sensor deals with a rudder that goes into greater angles of attack. Watch the wheel, mark the king spoke and watch the angle of attack of the rudder and see if it holds reasonably to a few degrees or if it goes over to 10-15 in a seaway or breeze. If it goes that far in an attempt to hold the boats course, then your experiencing what I did... a state of rudder stall. I do agree that play in the steering system could play into this and it should be tight. My steering wires offer absolutely no play.
Mine has worked flawlessly for many years on my c250 cruising the Great Lakes. This past year, I upgraded rudder to the latest 250 offering which is a shorter, wider, thicker and balanced rudder. Things went to hell for the auto pilot. It did not like the new rudder. Here is what happened though keep in mind that I'm not suggesting that its what is happening for others... I just know it did me in. The old rudder was a high aspect ratio rudder that had a lot of lift... enough to manage the boat. The autopilot would drive the new rudder into considerable attitudes of attack in an attempt to hold course with the rudder sometimes being drug at greater degrees of attack. Thick broad foils generate greater lift at steeper angles of attack whereas the old rudder had lots of lift straight on. What happened is that as the seaway or wind caused the boat to go out of balance a bit, the rudder would go harder over to maintain heading...but then if the wind slackened or the effect of the seaway lessened, with the helm over, the boat would of course lurch to that helm position confusing the hell out of the pilot. At times a constant oscillation was going on with the helm and autopilot which resulted in a snake course. I put the old rudder back on and all was fine again. It may be that a rudder position sensor deals with a rudder that goes into greater angles of attack. Watch the wheel, mark the king spoke and watch the angle of attack of the rudder and see if it holds reasonably to a few degrees or if it goes over to 10-15 in a seaway or breeze. If it goes that far in an attempt to hold the boats course, then your experiencing what I did... a state of rudder stall. I do agree that play in the steering system could play into this and it should be tight. My steering wires offer absolutely no play.
St-4000
Stu, I appreciate your comments regarding the upgrade. I looked at it a little differently. First, the 356 is not easily converted to a 6000 below decks autopilot, and certainly not for less than the cost of the 4000 plus the gyro unit. The 6000 would utilize that kind of equipment as a matter of course. Also, the gyro plus unit puts out a stabilized heading that is also used by the radar chart overlay and makes that and the marpa function better. All-in-all, it was a good upgrade given my needs and restrictions. Having said all that, I wish that Raymarine would come out with a slightly faster and more powerful wheel pilot. Dan Jonas (S/V Feije II)
Stu, I appreciate your comments regarding the upgrade. I looked at it a little differently. First, the 356 is not easily converted to a 6000 below decks autopilot, and certainly not for less than the cost of the 4000 plus the gyro unit. The 6000 would utilize that kind of equipment as a matter of course. Also, the gyro plus unit puts out a stabilized heading that is also used by the radar chart overlay and makes that and the marpa function better. All-in-all, it was a good upgrade given my needs and restrictions. Having said all that, I wish that Raymarine would come out with a slightly faster and more powerful wheel pilot. Dan Jonas (S/V Feije II)
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