Installing an ST1000+ - how to measure "B" with a transom hung rudder?

joe17

joe17

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Installing an ST1000+ - how to measure \"B\" with a transom hung rudder?

I am installing an ST1000+. One of the key dimensions is the "B" which is the distance along the tiller where the tillerpilot pin should be placed.

The manual gives some guidance, but I am unsure how to measure it with a stern hung rudder. The main problem being that the rudder slopes "away" rather than the example that slopes "under".

Anyone any experience of this? Any advice?

I include a picture to show the manual guidance and an example of the rudder of my type of boat.

o75bon.png



Joe
 
Re: Installing an ST1000+ - how to measure \"B\" with a transom hung rudder?

I don't beleive that this is a critical measurement. The fixing just needs to be about 18 inches along the tiller from the place where a line through the pintles intersects the tiller. So the lines on your picture are about right. Just lift the front of the (below) horizontal red line up to the tiller.
 
Re: Installing an ST1000+ - how to measure \"B\" with a transom hung rudder?

I mounted mine a bit further back than was shown in the manual to put the autopilot out of the way of the cockpit and it works ok. SO I don't think it's all that critical.

I've even heard of tiller pilots being attached to selfsteering vanes and they work.
 
Re: Installing an ST1000+ - how to measure \"B\" with a transom hung rudder?

It dosent matter which way the rudder is sloping, point "B" is the optimum point of radius of the tiller to give you the best steerage, the ram only has a set stroke, the further away from the pintel the less amount of steerage youve got likewise the nearer to the pintel gives you more but with extra effort required by the ram.
 
Re: Admittedly

You need to make sure of two things:

1. With the rudder central, the pilot is at 90 degrees to the boat centerline.
2. The throw of the pilot results in the required movement of the rudder. Make sure the pilot does not push the tiller against the end stops. It will stall out, consume huge amounts of power and trigger the alarm. Too far aft will result in this. Too far forward will not use the whole rudder range.

If you can, clamp the pilot to the tiller and the boat and test it before you drill.
 
Re: Installing an ST1000+ - how to measure \"B\" with a transom hung rudder?

I tried to explain in words gave, up deleted the post, and did a diagram instead. The pin goes 460mm from the extended imaginary line through the pintles measured at right angles to that line.

Autopilotfitting.jpg


I hope it's clear in the diagram.

I would not like to comment on how critical the 460 is but I would keep it as close to that as reasonably possible.
 
Re: Installing an ST1000+ - how to measure \"B\" with a transom hung rudder?

How critical the position is is I suspect a factor of how close to the limits for that pilot your boat is. The point on the tiller has to be far enough away from the rudder pivot point to ensure it has sufficient mechanical advantage to be able to move the tiller under the normal maximum load conditions, and close enough to the pivot point to ensure you get enough movement of the rudder, but not so close that you get to the hard over position on the rudder before the pilot is hard over.

I would estimate your fixing point and sit in the cockpit and check the geometry actually works. You may also find out you need some extension tubes, they will probably be a compromise and the rudder will be able to turn more one way than the other but that is not a problem as it works out it's own midships position from boat reaction
 
Re: Installing an ST1000+ - how to measure \"B\" with a transom hung rudder?

[ QUOTE ]
You may also find out you need some extension tubes,

[/ QUOTE ] There is a good range of extensions available for the push rod and they should be chosen in conjunction with the mounting options so that the push rod is as close as possible to the centre of its range of travel when the tiller is centred so that the unit can,
as you say, turn the rudder equally in each direction. Obviously not critical within a few mm or so.

It's all in the manual.
 
Re: Installing an ST1000+ - how to measure \"B\" with a transom hung rudder?

As the smallest tube is 3 inches the mismact can be more than a few mm but the clever little thing sorts that out for itself.
 
Re: Installing an ST1000+ - how to measure \"B\" with a transom hung rudder?

Thanks for the many quick replies. I now know what I am doing.

VicS, thanks for the pic, it now makes perfect sense.

wooslehunter, thanks for the tip on the end stops. My rudder does hit the outboard mounting when pulled to its furtherest extent on one side. I will set it all up and test it to make sure the pilot cant make that happen.

Maxi77, So far I have worked out I will be better with the cantilever mounting. With the tillerpilot mounted inside the cockpit it just needs a few cm of to get it to the optimum position without needing the extensions. I will probably also get the bracket so the pin is below the tiller so the whole installation will be kept lowish and out of the way.

Thanks again for everyones advice!
 
Re: Installing an ST1000+ - how to measure \"B\" with a transom hung rudder?

[ QUOTE ]
As the smallest tube is 3 inches

[/ QUOTE ] According to the manual they should be available in 1 " increments from 1" to 6". (and longer ones can be made by screwing two or more together) (Part nos D003 to D008)
If a cantilever mounting is used that can be cut to the exact length required, which applies in Joe17's case. If a pedestal mounting is used then its position can be adjusted and the same with the basic socket.

A bit of a blow if the rudder can hit the outboard. Fortunately mine does not.
 
Re: Installing an ST1000+ - how to measure \"B\" with a transom hung rudder?

[ QUOTE ]

A bit of a blow if the rudder can hit the outboard. Fortunately mine does not.

[/ QUOTE ]

well it doesnt normally hit when underway, the only time it has hit is when the rudder is left free - especially going astern - and then it slams across.

I am confident the tillerpilot can be set up so this wont happen.

Thanks, again.
Joe
 
Re: Installing an ST1000+ - how to measure \"B\" with a transom hung rudder?

The specified measurement for our (AH800) tillerpilot put it right on the rear cockpit bulkhead so I had to choose between putting it too close to the pivot and having it inside the lazarette or too far and having out in the cockpit. I went for the former so it's a good 75mm too close to the rudder pivot axis. The boat is quite small and the helm is almost always feather-light, so we thought we'd chance it.

It has always worked absolutely fine in that position.
 
Re: Installing an ST1000+ - how to measure \"B\" with a transom hung rudder?

Worth remembering that the tiller doesn't move in a flat plane where the rudder stock is mounted at an angle, and therefore the pin doesn't stay at right angles to the push rod. The angle increases, I think, the further away from the stock you put the pin.

Yes, I did remount mine.
 
Re: Installing an ST1000+ - how to measure \"B\" with a transom hung rudder?

[ QUOTE ]
Worth remembering that the tiller doesn't move in a flat plane where the rudder stock is mounted at an angle, and therefore the pin doesn't stay at right angles to the push rod. The angle increases, I think, the further away from the stock you put the pin.

Yes, I did remount mine.

[/ QUOTE ]

I understand what you mean about the angle, but not completely clear on the warning you are giving me! When you remounted yours then I am assuming you moved it nearer to the rudder stock? Or?
 
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