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  #1  
Old 02-27-2011
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Autopilots--basic question

Relatively new to sailing, and have a basic question about autopilots.

Do they just control the rudder? Or can you get more sophisticated? From sailing my little sloop, it seems that just like in a plane, you can't change one control without adjusting and compensating the others. If all they do is hold rudder, what is the big advantage of a modern expensive model, over Josh Slocum's rope lashing the tiller?
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Old 02-27-2011
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Modern autopilots control the helm—whether it is a wheel or a tiller, and not much more.

Main advantage over Slocum's lashing a tiller, is that a modern autopilot can hold a compass course, which a lashed tiller could not. They can also be used to sail to an apparent wind angle if they're connected to a wind instrument.
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Old 02-27-2011
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Mine is a fairly basic ST1000. Holds a magnetic compass course so a Little better that lashing the rudder.
It has a input marked vane so I presume it can interact with wind direction but as it came with the boat I,m not sure.
Have sailed on other boats with more modern versions but they also seemed to only hold a compass course.
I switch mine off for long periods when the course has settled to save juice and the play the sails between times when not busy elsewhere. The auto pilot acts as a lashing and hold the rudder steady at this point. Sail mostly single handed so often rely on "Auto" to make life easy.
Safe sailing
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Old 02-27-2011
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As SD says, the AP will continue to correct the helm to put you back on course as waves, etc push you off. They work well and this is very helpful when coastal cruising or navigating in congested waters. However, if the winds shift, your sails will be out of trim. This is to be expected. It is usually corrected by adding or subtracting a few degrees from the AP heading, with the simple tap on a "+" or "-" button. You would retrim if the winds change significantly or the corrected heading is undesirable.

While technically available, I have not seen an autopilot do very well when trying to hold an apparent wind angle, even when equipped.
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Old 02-27-2011
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Quote:
Originally Posted by Minnewaska View Post
While technically available, I have not seen an autopilot do very well when trying to hold an apparent wind angle, even when equipped.
My new (used) boat has an integrated autopilot/plotter that does have the capability to hold a course based on apparent wind angle. I've used it very little with mixed results. Part of the problem is that here in the Salish Sea we rarely have stretches of consistent wind. However, the few times when we had a relatively constant reach, it has worked reasonably well. I imagine it would be nice for long passages, but in that situation I wouldn't want to drain the battery so I'm not sure how useful the feature really is.

Most of the time, I use the autopilot to hold a compass heading and trim sails as needed or use it under power.
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Thanks. That answers my question. I hope I didn't sound snippy with the "lashing the tiller" comment. that was tongue in cheek only.
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Quote:
Originally Posted by dnf777 View Post
Thanks. That answers my question. I hope I didn't sound snippy with the "lashing the tiller" comment. that was tongue in cheek only.

It took Joshua Slocum on the first singlehanded voyage around the world so its perfectly valid.
Safe sailing
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Quote:
Originally Posted by centaursailor View Post
It took Joshua Slocum on the first singlehanded voyage around the world so its perfectly valid.
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Old 02-27-2011
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We've found that if you tune the AP for, say, motoring in calm conditions at hull speed, she's too insensitive to handle the heading under sail in some chop or waves, esp close hauled.

For a long sail, off the wind, I might bother to retune it, but mostly we use it for setting and dousing sail, long windless days, and for short term departures from the wheel..

After all, as coastal cruisers if we're sailing, we prefer to steer anyhow.
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Quote:
Originally Posted by Minnewaska View Post
While technically available, I have not seen an autopilot do very well when trying to hold an apparent wind angle, even when equipped.
A few weeks back it was asked if anyone had experienced how an autopilot performed when coupled with a wind sensor. No one seemed to have direct experience to offer. Can you elaborate on this statement? Did the autopilot get into a disagreement with the wind vane? Was it confused by the wind/water combination? Was it a hull/sails configuration issue? Was it an adjustment problem?

Autopilots are expensive enough for a basic system and can get really expensive for one that talks to other devices. But add in the other devices and it gets so expensive one would really want it to work of advertised.

Your observations will be appreciated.
John
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