Wednesday, April 25, 2012

Project ST5000: Initial Sea Trials

We took the boat out this weekend for the first time this year.  And the occasion served as the ideal time for the first trials of the ST5000 under actual operating conditions.

The installation instructions advise that the first task should be to swing the autopilot compass.  The is an easy task - after working yourself thru the menus to the right spot in the autopilot's software, you turn the boat 360° taking at least 3 minutes to do so.  Apparently all is well with the compass location if the maximum deviation discovered is less than 30° - ours was 8°.  At least from the effects of nearby iron (and magnets), the compass location is apparently good.  OK!

So, the Moment Of Truth. Get the boat on a steady heading and... (as Jean Luc Picard says) Engage!

That picture does not give an adequate description of the behavior.  The first time a course correction was needed, the autopilot turned the wheel a little.  And then, apparently not satisfied with the boat's progress in the new direction, it turned it again, a LOT.  The boat immediately overshot and the autopilot then turned the wheel in the other direction, all the way until the limit switches stopped it.  I disengaged it.

I used the rest of the trip to fool with the internal settings, trying to find a way to tone things down a bit.  No joy.

Then I said to myself, "Self, I wonder if the rudder transducer is really a required part of the system?"  So I plugged it in to the back of the ST5000 and, holding it in my hands, I tried to make it do what I thought it would be doing if it were properly installed and hooked up to the rudder.  What did I learn?  That the autopilot is exquisitely sensitive to the rudder position.  So much so in fact, that I believe that the autopilot is actually commanding a rudder angle directly.

Guess I'm going to have to swallow my impatience and go ahead and install the rudder transducer.

The necessary three-conductor shielded wire is now on order.


1 comment:

Chuck and Jackie on SV Aria said...

The ST4000+ does not need the rudder transducer. But it will approximate your exaggerated path if a strong wind is exactly on the nose so that the wind blows the bow around farther than the pilot thinks it should.

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