Auto Pilots??

[Dale Tanski]

I have a very good customer that is looking for an autopilot.  His wife has laid down the law because he sails alone most of the time and she is concerned bad things could happen to him without a helping hand.  He admits that he indeed sails alone and tries to sail 20 or so miles or so each time he goes out.  His work schedule leaves little time for sailing so day, night or sloppy weather out he goes. 

He doesn't want to spend a fortune so he is looking at wheel pilots but is disillusioned with regards to the robustness/reliability of the Raymarine EV 100 wheel pilot. He knows several people that have them and have had problems with them.  With no other choices out there for wheel pilots, the default position is now becoming under deck pilots.

So... If you were starting over regarding under deck pilots what unit would you purchase and why?  In addition, my customer is also ready to upgrade his instrumentation package so keep that in the mix. 

Thanks in advance for the information and your valued opinion.

Dale Tanski
Maruska
Obersheimer Sailor Supply

[Jim Cozy]

Dale,

Caveat, this is 25 year old info but may provide some insight. We installed an Autohelm 6000 in our 33000 # steel cutter and travelled about 5000 miles with it steering most of the way. Nary a hiccup!!! I am not sure how that translates to today's market but it was an electrically operated ram on a rudder arm. The rudder was unbalanced. It never lacked for power or responsiveness. Hope this is of some use.

Jim

[Jim S]

Anyone have any information or experience with the CPT cockpit autopilot?

[SailingSeaDragon]

Dale,

If had it to do all over again I would do the same thing - below deck with a remote. As my children have gotten older, I sail more and more singlehand and without a doubt a good autopilot is one the most important pieces of safety gear on the boat. My Raymarine setup has served me well for 9+ seasons (knock on wood). You are correct the below deck unit will run 4-5 times the price of a wheel pilot but it works in all types conditions when you need it - important!

Garner

[Sailorlou]

I used to have a Navico Wheel Pilot and even though it was very reliable I found that it could not steer the boat in rough conditions.  I upgraded to an underdeck Raymarine autopilot and after three years of constant cruising it is still working perfectly and steers the boat exceptionally well in all conditions.  Just made a passage across the Sea of Cortez in 30 plus winds with 8 to 12 foot seas 6 seconds apart and on the nose.  My Ray underdeck was a godsend.

[PeteW]

Every sailboat cruiser I know and myself included consider the servo pendulum self steering wind vane such as a Monitor or the Airies to be the only reliable autopilot system. That said, there is a place for electronic Autopilots which includes motoring and in some conditions of downwind sailing.

Here is a write-up comparing Servo Pendulum to Electronic Autopilot system. http://www.selfsteer.com/windvaneVAutopilot/

The biggest problem with the electronic autopilots other than battery drain is in the choice of motor drive. Its clear that drives like the ST4000 Autohelm Wheel drive draw 2.5 Amps average are not capable of steering the Pearson 365. I've have an St4000 wheel drive and even though I've increased the control loop gain it is not capable of maintaining course. The linear type 2 Raymarine M81132 seems to work but will draw 5 amps on the average with peaks up to 30 amps. Most modern boats are being equipped with the electric hydraulic linear drives which draw even more current.

A Monitor Windvane  system will generated steering power proportional to the apparent wind and speed of the boat. So the harder it blows the better it works. Once set it will maintain a course to the wind. This is a much safer mode of operation.

I have seen a small tiller autopilot (very low current) steer the Servo Pendulum self Steering Vane as a very clever adaptation of new and old technology. A servo motor connected to the steering ring of a Monitor Windvane would actually replace the wind van paddle and provide the steering system with tremendous mechanical advantage over a purely electrical steering system. The advanced electronics that incorporates wind, magnetic and inertial guidance  sensors found on the Raymarine EV autopilot could control this in heavy air with very light current draw.

Pete

[Sailorlou]

You are correct Pete.  Along with having my Ray under deck autopilot (AP), I also have a Monitor Windvane and a Ray 1000 Tillerpilot. 
My Monitor does a very good job of steering the boat by the wind in anything above 12 or so knots and the tillerpilot, attached where the vane attaches, will steer you by the compass in light and following winds, when the vane doesn't work so well.  The tillerpilot will also steer the boat (through the Monitor) in any conditions and draw very little power.  I typically use the Monitor on longer then 3 or 4 day passages. 
However the under deck AP is extremely convenient, but does use a bit of power.  But in windy conditions, when you are beating or on a reach, my wind generator handles the load by itself and during a sunny day the solar panels handle the load without any problem.
If you are going to do some long distance cruising, like me, I recommend having both the under deck AP and a wind vane.  If you are only doing local water or Sea of Cortez type cruising I would go with just the under deck AP.

[Sailorlou]

I forgot to mention that both my Ray under deck AP and tillerpilot will steer the boat by the wind as well as by the compass, utilizing the wind transducer at the top of my mast through the SeaTalk ng network (NMEA 2000).

[Della and Dave]

I'm enjoying reading what you guys have to say, even though I don't have much to offer.  There is a good article in Practical Sailer on it.  http://www.practical-sailor.com/issues/37_40/features/Rotary-Drive-Autopilot-for-Worm-Gear-Steering_11374-1.html?page=2

[PeteW]

I like what Lou is saying.  Since I don't think any Raymarine Autopilot system allows for switching between dual drive systems, in this case linear drive on the rudder quadrant and a wheel drive on the Windvane Servo pendulum steering system. I think its more complicated than an electrically switching the 2 servo motors because the calibrations are different. So at the end of the day you end up running  separate autopilot computers. But it is appealing to have a modern autopilot course computer controlling the windvane directly. I think its worth trying.

But to provide Dale with some feedback I'm going to explain why I think the St4000+ Autohelm system just will not cut it on the Pearson 365 and in the process describe what is needed in any autopilot system. I don't know what Simrad offers but it has to be the same technology.

The Wheel drive can't deliver enough tourque to sail a 18,000 lb boat. The Type 1 and Type 2 linear drives can deliver 650 lbs and 1500 lbs of thrust respectively.  The ST4000+ can be  configured as an ST5000+ and fitted with a Type 1 linear drive. But may still underperform because it lacks a rate gyro. The gyro stabilized course computers on modern Autopilot systems respond by steering into the heeling motion of the boat. Non gyro stabilized autopilots must heel, and go off course before the motion can be corrected.

Raymarine has several models of legacy gyro stabilized course computers as well as the current Raymarine EV linear drive systems ($3300). When choosing a Course computer you must match it to the type of linear drive you are using. For type 1 linear drive systems an SPX-10 or S1G course computer can be used. For type 2 linear drives you need an SPX-30 or S2G or S3G computer.  For a control head, the ST6002 will work on either. The ST6001 will only work with the S1 course computer. If you have an ST7001 or ST8001 by all means use it.

If you get an S1 or S2 computer without a rate gyro you can wire in an external gyro. The Ray part# E12101 will cost $500. There is an aftermarket part for $200. Other feedback sensors you will need are the rudder sensor. The newer smart pilot course computers (SPX-10,30) have a rudder position estimator algorithm and I believe they do not require as much calibration as the S1, S2 course computer. From what I've read I'm not recommending the type 100/300 course computer as they do not have rate gyros built in.

You will also need all the NMEA sentences for GPS and apparent wind from other systems on your boat.

So in summary if I can get a Type 1 or 2 linear drive and an S1G or S2G course computer, and an ST6001, I can upgrade to a modern autopilot for under $2K. The only piece of equipment I can repurpose is the flux gate compass.  

In regards to the EV-100 Wheel system. They spec it for boats up to 16,000 lbs. Unfortunately you cannot upgrade to a type 1 linear drive ($2k by itself) without also buying an ACU-200 computer. The ACU-100 is not compatible.  


Pete

[PeteW]

Garner,

Your write up is the best I've seen but you do not say if your Type 1 linear drive is long or short. 

I was at a boat show and it seems that hydraulic electric linear drives are now standard in new boats. Perhaps the advantage is no more electric clutch to wear out and solenoid valves draw less current.

Does your Smart Pilot (S1) have the rate gyro installed? Raymarine seems to think this is a critically important sensor these days.   Thanks   Pete

[PeteW]

Never mind.  The type 1 linear drive and the Type 2 short both have 12" stroke.   Pete

[SailingSeaDragon]

Pete,

Yes the Type 1 is short and I went with the internal gyro - worth the extra money especially when sailing down wind.

Thank you for the kind words.

Garner

[Della and Dave]

Wow guys, you really know this marine electronics stuff.  Where did you learn it?  Is there a good book or web site that explains the basics of how a NMEA 2000 works and how to figure out what will talk to what?.  I understand basic electronics, and have built computers, but the marine specific stuff is new to me. 

[PeteW]

The Nation Marine Electronic Association or NMEA sets the standards for the protocol.

http://www.nmea.org.

Raymarine obfuscated the hardware (physical) layer with the introduction of seatalk. But the NMEA sentences remain the same. Raymarine has a subset of their own proprietary command structures which are proprietary. Since Raymarine like Apple Computer does not believe in open source, your only solution is to reverse engineer. This fellow has done some of that:

http://www.thomasknauf.de/seatalk.htm

As a EE I designed navigation and timing systems for various autonomous "platforms" , so this stuff was job requirement for me. Snooping into a seatalk data stream to decode NMEA sentences might be how I get my kicks but your best bet is to simply read the legacy manuals that you can download from the Raymarine site. But in typical Raymarine fashion there is no theory of operation on anything. Understanding how an autopilot works on a boat, an airplane or a rocket requires a some knowledge of control theory. Another Engineering course I found to be of significant importance throughout my career.