Autopilot/rudder position

[Woodpile]

Many thanks to all who answered my earlier autopilot query. One point that appears to have divided opinion is whether a rudder position indicator is necessary when installing a self-steering system that works directly on the steering wheel itself. Won't such a system just turn the wheel to keep the boat on course irrespective of rudder position - and if so, why would a rudder position indicator be necessary?

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[Koeketiene]

A pilot fixed to the wheel will always assume that it's being engaged with the rudder midship, and takes it from there.
I've got a Simrad WP30 - if I engage it with the rudder not midship, I end up all over the place.

<hr width=100% size=1>Experience is a good teacher, but she sends in terrific bills.

 

[boatmike]

It's not necessary. It's a nice to have. On autopilots that bolt on the wheel the autopilot will read from a fluxgate compass and turn the wheel P or S depending upon the difference between the present course and that set regardless of the position of the rudder. Only problem being that when the rudder reaches limit of travel you need some form of clutch (usually inbuilt) to stop the motor from overloading or trying to turn the rudder further than is possible and busting something.
On permanently installed pilots (usually attached to the rudder quadrant directly) you need to calibrate centre position and tell it maximum travel P&S. This requires rudder position readout which is available regardless of pilot engagement and is very handy with wheel systems when moving in marinas manually.

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[Rohorn]

Hi....I'm quite sure it isn't necessary, assuming your steering wheel is mounted directly on the pump shaft, as per the usual small boat systems like Vetus and several others. You turn the wheel one way or the other, oil is directed to one end of the actuating cylinder(s) or the other, and the system works.
After a while, particularly on a long tack where pressure is maintained in one direction for a long time, (or one forces the steering up against the endstop), there will be a bit of leakage past the piston, so the wheel position will change slightly, relative to the piston position.
So what? The Autohelm is driving to a compass course, and will take up this slippage in doing so. There's no limit to the number of turns the pump/wheel can make, independent of the cylinder hook-up. The last thing one wants is a steering wheel position indicator.
If you have a much more complex (and expensive) servo system, where a motor pump and servo-valves are used, and the system drives to a selected wheel position, then clearly a wheel centering reference would be necessary.
But that's not the case in most small boats. We want to follow a heading, be it compass or true.
Hope that's useful....cheers...R

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[Guest]

When you switch off auto-helm

It would be nice to know if you are going to take a sudden swing one way or another ...... having done just that on a friends boat ! (ok so his baot was badly trimmed meaning the helm was kept over to compensate - not my trimming - was his !!)


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Posts personal opinions and maybe controversial

 

[Woodpile]

Re: When you switch off auto-helm

Thanks for the feedback - most helpful.

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