autopilot review

[jimb522]

Hi All,
I have been trying to get a boat to the starting line since the 2008 SHTP, without success. I am now finishing, and have actually raced in a couple of casual races, a 36 foot Trimaran, that is tiller steered, and somewhat performance oriented, although by no means as competitive as any of the Corsairs. It will displace about 6500 to 7000, although I am weighing it in two weeks when I get a bottom job, and may be sorely disappointed at how heavy it is. If I can get it debugged, and get a long qualifying voyage in, in which I don't scare the crap out of myself, and my law partner agrees not to sue me for leaving him for two months, and, and, and, I might be able to do it.
I rate about like the F24 (PHRF 84) here in the Gulf Yachting Association. A windvane is not likely to be able to react quickly enough to steer this boat, and that leaves me with the electric autopilot option. I installed a Ralytheon SPX5 Tiller pilot, and it burned up and quit in its first 5 hours of choppy water. The boat can have a hard helm in a hurry, when on a wave, and I am modifying the rudder to try to help relieve helm pressure. In any case, I think I need a much stronger below deck drive. Raytheon service techs recommended the EV200 Linear Pack. That autopilot uses the same drive that's been around for years. It is roughly $3300, and I have not seen anything much better then that. Still only half an NKE price though. Before I spring for that, does anyone have any opinions, backed by some experience or personal observation, as to any other options that might work on a relatively quick downwind boat? Thanks for your imput.
Jim Bates

 

[brianb]

Do you have any specifics on the rudder load when you are holding the tiller ? Some measurement of this load , or guess and under what kind of conditions ? It sounds to me that you are going to want to go to a hydraulic drive or a very powerful motor drive unit. I believe the later, powerful drives, are available from Jeffa and possibly Alpha. You don't have to use their AP with their drive, nor do you have to use the RM brains with the RM drives. For example, your SPX5 can drive a type 1 hydraulic pump, or with a bit of engineering a type 2. The hydraulics are so powerful and forgiving to shock loads, hence you see it used on so much of the heavy machinery out there. It is less efficient , draws more power per ft lb of output, electrically when compared to an efficient electric drive design. Consider separating your brain's choice from the drive choice. I have used the RM recent brain's and they do a good job of trying to put the boat in the right place given sea state. Their success, like all AP's, depends on the drive's abilities. NKE and BG are true champions for sure, but again no better than the drive.

Good luck with the set up.

Brian

 

[jimb522]

Do you have any specifics on the rudder load when you are holding the tiller ? Some measurement of this load , or guess and under what kind of conditions ? It sounds to me that you are going to want to go to a hydraulic drive or a very powerful motor drive unit. I believe the later, powerful drives, are available from Jeffa and possibly Alpha. You don't have to use their AP with their drive, nor do you have to use the RM brains with the RM drives. For example, your SPX5 can drive a type 1 hydraulic pump, or with a bit of engineering a type 2. The hydraulics are so powerful and forgiving to shock loads, hence you see it used on so much of the heavy machinery out there. It is less efficient , draws more power per ft lb of output, electrically when compared to an efficient electric drive design. Consider separating your brain's choice from the drive choice. I have used the RM recent brain's and they do a good job of trying to put the boat in the right place given sea state. Their success, like all AP's, depends on the drive's abilities. NKE and BG are true champions for sure, but again no better than the drive.

Good luck with the set up.

Brian

Brian,
As I understand what you are saying, I can disconnect the tiller drive, and route those two wires to a hydraulic pump attached to a below decks tiller, but at the cost of more electrical draw?
I did ask the Raymarine tech support if their linear drive could be driven off the SPX5 computer and sensor and fluxgate sensor, and he said absolutely not, and that it would only work with the tiller. I cant think of a reason that it wouldn't work, since the two tiller rams wires simply make it go left or right, as you would presume a hydraulic pilot would. But then my electrical expertise is not very high, so what do I know? It would seem that the risk (purchase of drive expense and installation) would be kind of high unless someone had successfully make this combination. but thanks for the info.
Jim

 

[brianb]

Jim,

Yes. Here is a video of a system I put on my boat: http://www.youtube.com/watch?v=3t--EiL2Q60 This is an above deck hydraulic drive. I used non traditional components, for sail boats anyway, to enable a removable above deck solution that is plug compatible with the X5 linear electric drive. I carry the linear drive along as back up when I have the AP with me.

I completed several offshore events with this setup, including the 2012 SHTP. The hydraulics drove about 3000 miles of the solo loop down to Kauai and back. The RM linear stick covered about 1500 of the trip, finally packing it in on my approach to the Farralon's.

The X5 brain, lacks a "clutch" output, as I recall. If you are going below deck you need a way to disconnect the hydraulics, and that is the clutch function. You could add an above deck switch. If you choose to use something like the Alpha electric drive it has a mechanical, manual, clutch control so the clutch signal is not necessary. I choose to keep my solution above deck as I had a strong fear of finding myself in the stern, below deck, in a large seaway, unbolting a jammed hydraulic cylinder because someones AP controller went south, and it allows completely removing the drag of the hydraulics when hand steering. With my solution one simply raises the tiller an inch and the hydraulics are disconnected.

For the SHTP I made my own electronics. This started as a means to save $$'s on a redundant set of electronics. The silly thing worked well enough that it became my primary AP with the RM being the back up. This short video shows it steering in a good blow near Hunters point: http://www.youtube.com/watch?v=rrqSDrfuvHk&list=UU85HCAreLiiJvgPwvDqdWLQ Here is the advanced version of my AP brain steering an Express 27, getting set up for the SHTP 2014, across the slot (boat is Elise, no hands driver is Serge) : http: http://www.youtube.com/watch?v=EWObyejTb3Ain a typical spring afternoon. In this case this AP is redundant to a top line NKE on board. Either AP can take control with the touch of a button. This is a type 1 hydraulic installation showing, that the mixing and matching of components is trivial.

In the RM line, in my opinion, the control algorithms are the same in any of the gyro enabled designs (pre 2013 products). The differences are the clutch and the drive power. When you move to the Type 2 drive peak currents can get up to about 15 amps so the RM boxes have larger drive components in the brain box, and of course they differentiate on price by a significant margin to gain the added power.

Too much detail ?

Brian

 

[Rainbow]

Jim: The Alpha 3000 served Rainbow well on the 2012 SHTP. I completely lack Brian's technical ability so selected it based on being off-the-shelf resady, fastest advertised lock-to-lock speed, and very low power usage. It steered all the way to Hanalei Bay and back without any problem. Later, it started doing circles on the Bay and I had to send it back to the factory where they discovered the course setting mechanism was loose and was turning in it's mount when I turned the course knob -- easily fixed, but no explanation for why it came loose.

Cliff

 

[WBChristie]

Has anyone on the forum tried one of the new generation Raymarine pilots like the Raymarine T70158 EV-200 Sail Linear Drive Evolution Autopilot? They are very spendy...wondering if its worth it.

 

[JAMcDonald]

Has anyone on the forum tried one of the new generation Raymarine pilots like the Raymarine T70158 EV-200 Sail Linear Drive Evolution Autopilot? They are very spendy...wondering if its worth it.

No, but according to the RM online help forum they are apparently releasing the Evolution Autopilot for the X-5 tiller pilot in Sept, which will may improve steering but not durability of the ram nor the apparent inability of the RM wind instruments to drive the AP.

 

[BobJ]

I'm not sure about that last part. I don't do it racing on the Bay but in the LongPac and both SHTP's, I put the X-5 in (wind) Vane mode and it steers to either apparent or true wind (whichever I choose). That's how I slept with the kite up.

You do need spare drive units (rams), treated with diver's silicone grease as advised by The General. Also spare plastic caps (the holes elongate) and as I found out in 2008, a second SS pin in the tiller in case the first one breaks. If that pin breaks, all the spares in the world do no good.

 

[todd22123]

Bob-

For steering with true wind mode, how does your Raymarine autopilot get the GPS data? The apparent wind is on the Seatalk from the wind direction indicator if I remember correctly.

Thanks,
Todd

 

[BobJ]

The wind instrument computes true wind speed and direction from the apparent wind input (from the wind transducer) and boat speed (from the speed transducer). GPS data is also on my Seatalk bus but the autopilot uses boat speed, not SOG for the true wind calculation.

It is not very accurate - my speed transducer is not on the centerline and reads about 4/10 different from one tack to the other, but for this purpose you just want it to steer to the shifts on one tack/gybe and it does that well enough. It cannot handle a squall however. I doubt even a high-end pilot could sail you through a squall in TW mode.

 

[Harrier]

Re Bob's comment about needing spare ends for the Raymarine rams is good. However, I cured this problem by buying the RayMarine extension fitting (the shortest is enuf) and drilling a new hole in it (to mimic the position of the hole in the plastic end piece which comes with the ram). The extension fittings are aluminum and hold up well for me. I have also had an occasional problem with strippage of the plastic threads on the stock end cap. The aluminum extension cures that rare problem too.
Not having Brian's skill with electronics, I just go merrily along with what's available off the shelf. My sailing instruments are RayMarine and they integrate well with the TP4000 and TP4000GP. I often use the "wind mode" (apparent wind setting) on the SHTP. But that method becomes problematic in lite air...less than 5 knots or so apparent.

 

[Mewes]

Good golly, is this you, Jim Bates? I've been looking for you since Ben and I chaired the TransPac in 2006!

Lucie Mewes

 

[WBChristie]

Bob, do you know which evolution model replaces the X-5 GP? The EV-100 sensor seems to be a much better feedback instrument that the previous fluxgate compass for the X-5 series pilots. It also seems that the only difference between the X-5 and the X-5 GP is the ram. One is more robust than the other.

 

[BobJ]

I don't know - I haven't looked at them yet. That's interesting about the sensor because I've had trouble with a couple of their fluxgates. I now have two installed and can switch between them if necessary. I assume it's still sensitive to sources of deviation? That's been a challenge on the smaller boats as we add gear.

Here's a presser: http://www.raymarine.com/news/mynews.cfm?story=7104

There's also an interesting comparison of the GP vs. non-GP drive motors in this thread, started by our own Slacker:

http://forums.sailinganarchy.com/index.php?showtopic=112693

Scroll down to post #20 for the details about the motor. Apparently the motor in the non-GP unit costs about four bucks and the motor in the GP costs $300!

 

[WBChristie]

Thanks, great information there. Apparently the new sensor is not affected by on board magnetic fields.

At the centre of every Evolution system is the intelligent EV sensor core, a 9-axis sensor that monitors vessel motion in all three dimensions. The innovative EV sensor core combines advanced solid-state sensors with the Evolution autopilot processor into a single easy-to-install housing.

Mount the EV sensor core above or below decks, the rugged enclosure is fully sealed and built to IPX6 and IPX7 waterproofing and submersion standards.
EV Sensor Core Benefits

Precision monitoring of heading, pitch, roll, and yaw allowing the autopilot to evolve instantly as sea conditions and vessel dynamics change.
Flexible installation options. Mount above or below deck.
Simple SeaTalkng connectivity to the control head and ACU.
Solid state sensor technology delivers dynamic accuracy to within 2 degrees in all conditions.
Auto-compensation for on board magnetic fields and reliable heading accuracy in the northern and southern extremes.
Fast and reliable heading data for MARPA, radar overlay, and heading modes on Raymarine multifunction displays.

 

[brianb]

The new sensor is implemented with 6 sensors, 3 magnetometers, and 3 accelerometers. These are used to fully characterize the magnetic field direction while compensating for pitch, yaw, and role of the boat as well as magnetic declination. The method used to compensate for on board fields is not unlike that used for the old sensor, that is several 360 degress turns are taken at set up to measure static, on board, interference. It will not account for changing fields, like those caused by electrical wiring. One downside to the new sensor approach is that the accelerometers are sensitive to vibration. One thing to be careful about is to try and locate the sensor module where engine vibration is minimized. One might notice an effect where under motoring the unit will wander a bit more than while the motor is off. Another rare failure is that the accelerometers, which use solid state micro machines, have been known to "latch up". They are implemented in silicon will micro oscillating pendulums (dimensions measured in nano meters) and on really rare occasions have become contaminated. You can find these same sensors in your new smartphone. If you have a compass application on your phone you can experience both the good and bad of this technique. Align the phone while level to north. Then try tilting and rolling the phone. You will see compass direction changes and also how long it takes for the compass to recover back to the true course. In the AP 3 more sensors, rate gyros, are added to help with these dynamics, but the experiment shows just how slow the compass is and the challenge the AP has in dealing with sea state. The older flux gate sensor does a good job and has similar response times. It is more expensive to produce however. The rate gyros, now on all three axis, allows RM to compensate steering for a wider variety of sea state. How well they use this new set of information in their algorithms is an experience left to the user.

 

[WBChristie]

Brian, I Am interested in the hydraulic ram that you built yourself. In a previous post you mentioned that the RM control box can supply enough "power" to drive a hydraulic setup. Is the hydraulic drive control, for that matter the RM control box simply a "bang bang" output, not an analog output?

 

[brianb]

Brian, I Am interested in the hydraulic ram that you built yourself. In a previous post you mentioned that the RM control box can supply enough "power" to drive a hydraulic setup. Is the hydraulic drive control, for that matter the RM control box simply a "bang bang" output, not an analog output?

Hi, The RM, like all of these implementations, use a PWM (pulse width modulation) or pulsed output. The pulse rates are in the < 1000Hz range. You can hear the RM output pretty well on your SSB or an AM radio. It sounds to be about 300 Hz to me. So it sends pulses of variouse widths that are all on, or all off, and the integration of same by the motor and hydraulics results in what appears to be an analog output. This approach gives the best efficiency from the drive electronics.

Hope that helps.

 

[WBChristie]

Thanks, that does help. Which hydraulic pump did you use? I assume you are using the RM X5 tillerpilot control box to drive the pump?
Thanks for any input

 

[brianb]

Thanks, that does help. Which hydraulic pump did you use? I assume you are using the RM X5 tillerpilot control box to drive the pump?
Thanks for any input

I use a small Type 1 pump from RM that does not include the clutch hydraulic bypass valve, so it is a bit less expensive. Any of the various type 1 pumps will work (Octopus/RM/Furuno/Teleflex).

I drive the hydraulics with two brains, the X5 is my back up and one of my own design is the primary. Both brains also drive the X5 tiller drive. This is another point of redundancy.

Brian