Autopilot

[pauln]

I am intending to install an autopilot on my 34' twin engined/outdrive sport boat. I am thinking of ST5000. Has anyone any experience of these and do you use a separate 'rudder reference unit' because that does not appear to be included in the kit.

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[byron]

<font color=blue>I think you will find that on the ST5000 the rudder indicator is on the main screen at the bottom in the style of a semi-circle with a pointer showing the position your rudder is in.

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[tcm]

yes, correct.

Though, when using a/pilot, you wdn't need to know rudder position really, would you, cos at any speed (as when using apilot) it will be almost always in dead ahead position?

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[byron]

<font color=blue>I'm not that familiar with the ST5000 but would assume that when the auto-pilot is in stand-by mode then the bottom reading becomes an indicator, similarly when engaged it would show any offset.

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[qsiv]

Ah - but without the reference unit the system can only 'guess' where the rudder is. The rudder reference unit gives an explicit input to the course computer, telling it where the rudder actually is.

My pilots have always had rudder reference units, and no they werent included as part of the standard kit, but I believe they are worth paying for.

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[hlb]

I have a ST6000 Cant remember now. But thats what was recomended for my P35. I have a rudder reference unit and funnily enough was talking to my mechanic a few months ago. We seemed to have different opinoins. But I could not see any wires to the auto pilot when I took the reference unit off for repair. The auto pilot has a reference unit built into screen. I would have thought you would program in where is straight and it would work the rest out from there.

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Haydn

 

[byron]

<font color=blue>I think you are right Haydn. You centre up the steering, 'tell' the unit when its centred and it remembers.

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[Piers]

The rudder reference unit will make all the difference to the tracking. Not just me saying this, but the mnay others who have fitted them, to correct "straight line snaking".

<hr width=100% size=1>Piers du Pré
http://www.dupre.co.uk

 

[qsiv]

... but it soon loses it - all the pilot knows is that it is 'off course', and applies a voltage to the drive motor. It doesnt actually know 'for sure' how far the actuator moves (unless there is a reference unit).

A good example of this would be that, when trickling along at displacement speed a 2 second burst of volts to the actuator might give 10 degrees of helm. If the boat was travelling fast, and had a heavy helm, there would be a small voltage drop (due to the high amps), and the rudder might only move 9.5 degrees - add this up over time and you can easily get the pilot confused.

In one sense it doesnt matter - because all the pilot is trying to do is keep you on course, not keep the helm centred, but it does degrade the system when the pilot wants to apply standing helm due to a crosswind, and as Piers says when the boat is perfectly trimmed to track straight with no helm.

Also - you dont get a rudder position indicator when the pilot is disengaged, which is a feature I find useful.

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[hlb]

Well however it does it, my St6000 seems to keep on track, no matter what. Even on one engine it knows to keep plenty of lock on. It's so good, I never use the wheel, but go right up rivers and to the marina entrance before switching to engines only. Even went from Stourport, to Swansea without wheel steering, cos the hydraulics was bust. Thinking of getting rid of wheels, except there'ed be nothing to hang on to when it's rough.

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Haydn

 

[byron]

<font color=blue>Haydn, what happens if you disengage the A.Pilot? does the display show the rudder position if you move the wheel? My thoughts being the reference unit being on the mechanism rather than on the rudder stock.
Just curious because the on-line sales literature says this about the ST5000
</font color=blue><font color=red>The control head is totally waterproof, and powers the drive unit directly - no separate course computer is required. Installation is therefore simply a matter of installing the control head, belowdecks fluxgate compass, rudder reference unit and the appropriate drive unit, making for lower installation cost and easier maintenance.</font color=red>



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[hlb]

I'll have to have a special look for you Byron and wiggle wheel about. Hardly ever look at the rudder display as I have another one which is far bigger and easier to see. Faily sure it does though. Just a point though. Before fitting the boat had towards 90deg rudder movement, now it only has 30deg or rams come out of hole. And can you please write in a more restfull colour, it's hurting my eyes!!

PS The control unit might be waterproof but dont matter cos its in my leci box. But the pump aint and that sits by the rudders. So it has just cost me £400 plus fitting a new one.

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Haydn