Tiller auto pilots

[newuser]

My old Tillerpilot went the way it should have travelled long ago, and I amlooking to purchase a new tiller autopilot. My problem is the conflicting information put out by the chandleries as to what size and displacement each unit is designed for.
Of course, I want to have a reasonable cost,but I can''t see spending money for any particular unit when the next smaller unit would have been perfectly satisfactory.
I sail a 1966 Pearson Coaster, 30 ft LOA, displacement of 9500 lbs. She has a slightly modified full keel and can have quite a bit of weather helm in a strong breeze.
Can anyone point me toward a source of good comparative information on tiller auto pilots?

[RichardElliott]

I chose the Autohelm ST2000+ for an Islander 28 of about 8,00lbs displacement, which is likely an overkill but the ST1000 is marginal. The 2000 also offers better features. I can''t see compromising for a couple of hundred bucks. Ours has been in service for more than two years with very ggod performance.If you are concerned about the ability of a unit to perform,pounds thrust is a published number which you can estimate as to the thrust to hold your tiller under strong weather helm.

[newuser]

Richard,
Thanks for the response. This was exactly the type of information I was looking for.

Anyone else have experienced opinions on this?

Mikey

[cghbrook]

I recently went through the research stage of comparing tillerpilots for my Cheoy Lee Offshore 27. The Raytheon ST1000 should probably be considered only for small daysailer types and powerboats. The additional features and power of the ST2000 are well worth the extra money for a boat your size. Practical Sailor did a comparison of the ST2000 with the Simrad TP30(used to be Navico). They are very similar, and PS conclusion was basically a tie with a nod to the Simrad unit for slightly less amperage used. As far as size of the unit vs your boat size, opt for a unit that is more powerful than the minimum recommendation. You will want a unit that will hold a course in nasty conditions while you go forward to change a jib or whatever. If you can find a factory reconditioned unit you will save good money.

[BeneteauMark]

I have had a Navico tillerpilot on my Beneteau 23 since 1996. Unfortunately, I don''t recall the exact model number, but this unit was the "second from the bottom" of their product line. Here''s a few things I remember thinking about as I bought the unit and some of my experience with it. This is a long post, but I hope this info will help you avoid reinventing a couple of the wheels that I had to...

The lowest model was marginal on thrust and had no interface capability. The model I bought has more thrust that my boat should ever need, and has performed beautifully in any conditions that I have used it in. Interface capability has had unexpected benefits. Here''s more on both subjects.

Thrust -- the pin that connects the tillerpilot pushrod to the tiller is located much closer to the rudder than the point where a human helmsman holds the tiller. Consequently, the tillerpilot has much less leverage on the rudder than you do with your arm and has to have more "strength" than a human helmsman to do the same job. While you might read tillerpilot specs on thrust and say "my boat would never put that load on an autopilot", think about what it would be like to hold the helm with a tiller only about a third as long as what you''re used to -- that''s what my Navico has to do.

Interfacing -- my tillerpilot has a "nav lock" mode, where it alters set course as necessary to stay on the track programmed into the GPS. While this offers the possibility of automatically correcting for set and drift, I refuse to run an autopilot in "nav lock" mode, because I consider it hazardous for a sailboat to potentially change course on its own initiative.

However, if my pilot is connected to the NMEA bus, it will use the speed info coming off the GPS to help it determine how much helm to apply, much as a person would. It steers the course I set, but can handle the helm more intelligently if it knows how fast the boat is moving.

Also, interface capable pilots usually can be used with a remote control. I use my remote a lot when motoring as a way to dodge obstacles and such. I can steer the boat from the bow this way for better visibility, from the companionway to get out of the sun, etc.

Hope this helps....

[geohan]

BeneteauMark:
You make some good points, thanks. However I''m confused between "heading" and "course" in your remarks about NMEA interface and why the usual range of boat speed matters in making heading corrections.
Cheers, George

[geohan]

Mikey:
IMHO,it might be better to try to balance the boat with sail trim to reduce the weather helm rather than to provide excessive capacity in either an autopilot or helmsman. Our 30-ft Mercator of 9700-lbs has a cutaway forefoot and attached rudder. Since the rudder is only about 8-ft aft of the axis of rotation it is large, about 27 by 38-inches and while effective,causes considerable drag when angulated more than a couple degrees. Under these circumstances we try to keep the boat fairly well balanced by flattening and/or reefing the main. For short periods or puffs we will ease the traveller and carry a 3 to 4-ft long bubble in its luff just behind the mast. In the extreme we will temporarily let the entire full-battened main luff. Even so our AutoHelm 2000 is much more useful under power than sail.
Cheers, George

[walt123]

Geohan hit the "Nail" on the head when he told you it is sail balance that makes the difference in wether any autopilot will work on your boat. No matter how good or strong or dependable etc a tiller pilot is, the boat it is on Must be balanced for the course sea and wind conditions. This means proper sail trim and the right sail for the conditions. Any boat that is properly set up for the wind, course and wave conditions should almost sail herself prior to the use of an auto-pilot. Your boat will sail easier with less electric consumption and less work this way. I do favor the larger pilot for the boat most boats..Good luck

[thefantasea]

You write:

"Interfacing -- my tillerpilot has a "nav lock" mode, where it alters set course as necessary to stay on the track programmed into the GPS. While this offers the possibility of automatically correcting for set and drift, I refuse to run an autopilot in "nav lock" mode, because I consider it hazardous for a sailboat to potentially change course on its own initiative."

I, too, have a Navico Tiller Pilot. When I use it I plot my course between two points on a chart. This establishes a straight line compass course to be sailed and becomes the initial heading. Various forces acting on the boat combine to push it from this line. This introduces cross track error which, depending on the severity of the forces, can mount quickly. Although the pilot maintains the original heading, Loran or GPS readings show the cross track error at a given time. (Cross track error can be thought of as the accumulated leeway the boat has made.)

Plotting the boat''s L&L coordinates on the chart and drawing a heading line from it would show that the boat was sailing a course that is parallel to but separated from the original plotted line by the distance of the reported cross track error.

To reach the target a new course has to be plotted and the compass heading of the pilot adjusted accordingly. As soon as the pilot is set to the new course, the cross track error commences anew. Ang again, and again.

If one was sailing parallel to the shore a mile off in conditions of poor visibility, uncorrected cross track error of one mile could result in a beached boat.

The pilot maintains the compass heading by making a great number of small but frequent course corrections. Coupling the pilot to a Loran or GPS constantly feeds the information needed to compensate for cross track error thereby keeping the boat precisely on the chart line first drawn. The course changes remain undetectable, as before.

I believe that coupling the pilot to a Loran or GPS enhances the level of safety. Of course, a prudent sailor makes frequent chart position plots to verify his progress along a route.