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-   -   any bad experiances with wheel autopilots? (http://www.sailnet.com/forums/gear-maintenance/5733-any-bad-experiances-wheel-autopilots.html)

pmills42255 12-06-2002 01:21 PM

any bad experiances with wheel autopilots?
 
I am considering a wheel autopilot. They are rated to boats of 40'' but the displacement is way lower then my boat. My steering is very light, can be done with just a gentle touch. Why do the manufacturers have a maximum displacement limit? It seems to me the equipment would work with what I have? Used self-steering gear is about the same cost, maybe thats the answer?
thanks Paul

WHOOSH 12-06-2002 03:19 PM

any bad experiances with wheel autopilots?
 
Paul, one finite limit on what a wheel pilot can take is the building weather helm aboard many boats as the winds build. But as you point out, semi-balanced rudders don''t load up as much and present less force opposing steering control by the pilot. But another source of opposing force is the sea itself as swells roll past the underbody, torque the hull in one direction or another, and also directly impact on the rudder. This becomes especially noticeable in heavy seas on and aft of the beam, and doubly so in cross swell conditions. Rudders are sized to control the hull form, seas act on the larger hull form and its rudder, and lots of force can be generated at the helm.

You asked about experiences with wheel pilots: I found my Navico (now Simrad) wheel pilot to be a big disappointment as multiple copies of the same molded parts didn''t fit and there were contact wiring problems in the push buttons which I finally gave up repairing ''in the field'' and returned to the mfgr. It now sits under the V-berth. I currently use a CPT sold these days by Scanmar, which needed a motor change to operate properly on both tacks, also done by the mfgr. My conclusion from these two experiences is to buy from a source where returns aren''t a problem, work the pilot very thoroughly immediately after purchase, and don''t expect it to handle all conditons. That''s one reason why we also sail using a wind vane.

Jack

Jeff_H 12-06-2002 05:53 PM

any bad experiances with wheel autopilots?
 
I have some experience with a number of wheel pilots. There seems to be a lot of factors at play. The primary seems to be the proposed use of the autopilot. They are fine for 35 or so footers under about 12000 lbs (The manufacturer''s weight ratings seem a little optomistic when things get bouncy) They seem happiest when motoring. They seem to work best on boats with fin keel and counterbalanced spade rudders. They seem to work worst on boats with high lateral (yaw) stability as the forces seem to prevent the small quick trim that is necessary in a following sea. I was very disappointed in wheel pilots on boats much over 15,000 or so as the momentum of the boat seems to cause pretty wide swings and use a lot of juice.

I am using an Autohelm 4000 on a 10,500 lb 38 footer for coastal cruising. It works fine in most of the lighter conditions that I have encountered but really was not up to handling the boat in heavier going. Its funny because the helm loads were pretty low and adjustments were minimal yet every so often there would be a large wave in the wave train that would confuse the logic of the autopilot.

I think that I would opt for the heavier duty, more sophisticated below decks 5000 or 6000 series if I were going offshore or putting the unit on a heavier boat.

Jeff

Sailmc 12-09-2002 03:42 AM

any bad experiances with wheel autopilots?
 
I agree with Jeff on the wheel pilot computer issue. I have used 4000''s for about 13 years starting with the first model. I now have a 6000. I think the main differece is not the strength but the sophistication of the computer. In a sloppy following sea the boat would sometime start to oscillate with the 4000 since it did not anticipate or learn as well. The new 6000 seems to due a hugely better job of this. With the addition of a gyro, course keeping becomes near perfect in challenging conditions.


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