Tiller pilot positioning - is it crucial

dylanwinter

dylanwinter

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www.keepturningleft.co.uk
the canoe stern on Katie L has consequences for the postioning of the tiller pilot

the manual

https://www.google.co.uk/search?q=r...s=org.mozilla:en-GB:official&client=firefox-a

says that it should be 18 inches fwd of the rudder pivot point while the but end should be 24 inches away from the centre line of the boat

that puts it outside the boat

so - what are the consequences of keeping the 24inches from the centre line but moving the point where the tiller pilot meets the tiller six inches forwards

Dylan

PS - please make it stop raining
 
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dylanwinter said:
the canoe stern on Katie L has consequences for the postioning of the tiller pilot

the manual

https://www.google.co.uk/search?q=r...s=org.mozilla:en-GB:official&client=firefox-a

says that it should be 18 inches fwd of the rudder pivot point while the but end should be 24 inches away from the centre line of the boat

that puts it outside the boat

so - what are the consequences of keeping the 24inches from the centre line but moving the point where the tiller pilot meets the tiller six inches forwards

Dylan

PS - please make it stop raining
Click to expand...

the further forward the less throw the drive will have
its raining here to when the tide came in it rose 10mts :eek:
 
Pushing it forwards will reduce the lock you can get on the rudder for the same ram movement from centre , so it might run out of stroke to get the helm hard over.
Of course most boats the rudder loses all efficiency anyway on full lock , so maybe nothing is actually lost ?
 
I guess that reason it has to be forwards of the rudder pivot by ascertain amount is so that at it's maximum load it can move the rudder.
Too far back and the load becomes too much for it.
So I guess 24" is the optimum for load versus stroke versus reaction time or ram speed ?
 
i think the upshot of the two posts above is that for a given movement of the push rod on the tiller pilot, the actual movement of the rudder will be less than it should be as you will be moving on an arc of a circle of greater diameter.

I assume you have the same unit as me (ST1000+) as the measurements are the same as in my handbook.

I think if you follow the instructions for commissioning the tiller pilot - which includes the gain setting - you'll soon see if the unit works as intended - or at least as close as you need it to.

If once you've tried it and it doesn't work satisfactorily you could always fit a bracket outside the boat. The benefits of having a working autopilot far outweigh the extra efffort of keeping an eye out astern manouvering to allow for the bit that sticks out.
 
dylanwinter said:
the canoe stern on Katie L has consequences for the postioning of the tiller pilot

the manual

https://www.google.co.uk/search?q=r...s=org.mozilla:en-GB:official&client=firefox-a

says that it should be 18 inches fwd of the rudder pivot point while the but end should be 24 inches away from the centre line of the boat

that puts it outside the boat

so - what are the consequences of keeping the 24inches from the centre line but moving the point where the tiller pilot meets the tiller six inches forwards

Dylan

PS - please make it stop raining
Click to expand...

The mounting point position is specified at 23.2" from the centre line so that when the Tillerpilot is in the centre of it travel the tiller is centred

By using extension pieces you can mount it further away but not closer

If you mount it closer than 23.2" the movement of the tiller to starboard will be restricted.

Can you mount it on a block of wood fixed to the outside of the coaming ??

I am not sure about the consequences of deviating from the 18" dimension along the tiller. More important I would guess with the old analogue ones ( like mine :( ) than the smarter digital ones.

If you increase the measurement much more than the specified 18" the arc of movment of the tiller will become reduced. If the boat steers well with small tiller movements that may not matter. If OTOH it requires big sweeping movemnts of the tiller incresing much beyond 18" may prove to be unsatisfactory. This may affect the use of the autopilot to Auto tack but
by and large when steering a steady course it will only make small movement so should not matter.

Id say getting the mounting reasonably close to the 23.2" from the centre line should be the priority.


Lucky with mine. It's mounted on the top of the coaming and uses a 4" extension to the push rod to get the reach correct. It's exactly the right height to fit onto the tiller without any brackets.

I take it yours will be below the top of the coaming though ... hence the significance of the 24" right to its butt end !
 
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Just another thought

it might not be possible but:-

Fitting the tiller pin on a bracket or block on the opposite side of the tiller ( ie port side) would be a way of increasing the mounting to tiller pin dimension.
 
VicS said:
Just another thought

it might not be possible but:-

Fitting the tiller pin on a bracket or block on the opposite side of the tiller ( ie port side) would be a way of increasing the mounting to tiller pin dimension.
Click to expand...
I considered an option like this - might still do it. I think to preserve the geometry you then have to fit the tiller pilot skewed, so that the rod is working at right angles to the pivot to pin line. Of course the compass is then up a gum tree, but I never really use it. I have even seen an instance where an 18 inch arm was stuck out of the side of the tiller with the pin at its end, and the tiller pilot was mounted fore and aft to on to it.

I saw one boat where the pin to pivot distance was hugely too much. The skipper said his tiller pilot couldn't control the boat in anythng but benign conditions.

I'd try to find a way of sticking to the specified geometry if possible.
 
As VicS says keep the tiller dimension correct at 18 ins.

Fit the pilot as far out board as you can.

Fit an A bracket to the tiller with the legs attached to the tiller and the tiller pin at the head. The hight dimension of the A brkt being the difference required to give you 24 ins.

TOP TIP If your best line up means that you fit the pilot to the tiller from beneath add a bit of bungee cord to hold it on. 1/8th did the trick for me.
 
TQA said:
As VicS says keep the tiller dimension correct at 18 ins.

Fit the pilot as far out board as you can.

Fit an A bracket to the tiller with the legs attached to the tiller and the tiller pin at the head. The hight dimension of the A brkt being the difference required to give you 24 ins.

TOP TIP If your best line up means that you fit the pilot to the tiller from beneath add a bit of bungee cord to hold it on. 1/8th did the trick for me.
Click to expand...


I like the A bracket idea.

Id not think it necessary to mount the tiller pilot at an angle as Amulet suggests .. I'd keep it square to the boat.

Id not worry about increasing the 18" a little if it helps.


A little loop of thin bungee cord to keep the thing on the pin is a good idea even if dropped on from above.
 
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I also seem to remember that they should be horizontal and not inclined as the one in VicS second photograph.

When I installed mine, the base mount was supposed to be about 6 inches above the cockpit seat! I made a right angled bracket in square section ali from an old sunlounger and it now makes an elegant armrest as well as mounting the pilot.

John
 
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I have a plan

Thanks for posting those

The bracket on the tiller I have from the slug goes under it

so that should get it pretty level

My plan is to cheat it forwards along the tiller and put a simple wooden struct between the stanchions

a nice bit of mahogany that is shaped to slip into place when I need the tiller pilot

with any luck I should be able to avoid making any fresh holes in the boat

Dylan
 
Fantasie 19 said:
John... "404 Not Found" error on that link?
Click to expand...

Thats cos he put brackets round it..... it works in my post

Not my picture I hasten to add.

It should be horizontal I suppose but it's going to be a lot less horizontal than in the picture when sailing!
 
VicS said:
Just another thought

it might not be possible but:-

Fitting the tiller pin on a bracket or block on the opposite side of the tiller ( ie port side) would be a way of increasing the mounting to tiller pin dimension.
Click to expand...


+1 this is the way to go . probably only needs moving to one side by an inch or 2 . the pin would have to be offset and lower or higher (shutup bruce)to allow the pilot to go under or over the tiller . It wouldn't have to be permanent could be clamped to the tiller with wing nuts .
 
My view. I agree. Preserve the 24" so that it has equal throw P and S. The 18" isn't crucial.

The system uses negative feedback to keep the boat on course. At which point the tiller will me nearly central. Changing the 18" affects the 'gain' in the feedback loop but as the sensitivity of the boat to the tiller is an unknown to the designer of the autohelm the software must be able to adjust the dynamics of the system to cope with this.

The only downside is that the compass display will be slightly less accurate when the tiller isn't central as (presumably) the reading is compensating for the angle of autohelm body. But they're pretty inaccurate anyway in my experience!

Small variations in height isn't critical either. Mine isn't quite level. But it has little affect on the geometry. The boat's never flat anyway. Unless it starts to lift the tiller!

PS: Make a nice canvas sleeve for it. They tend not to be too waterproof.
 
I found I had this problem when I had to replace the original Autohelm that came with the boat (you know, the one with the compass on the top that you turned) and I was assured by Raymarine that the ST1000 had exactly the same fitting points. WRONG!!

I couldn't extend the pivot point outwards so I made an extra bracket for the tiller that took the attachment point to port by about 2 1/2 inches, checking that when the tiller came fully starboard that the tiller & bracket cleared the unit. This arrangement worked fine. The attachment point for the tiller was underneath the tiller.
 
dylanwinter said:
Thanks for posting those

The bracket on the tiller I have from the slug goes under it

so that should get it pretty level

My plan is to cheat it forwards along the tiller and put a simple wooden struct between the stanchions

a nice bit of mahogany that is shaped to slip into place when I need the tiller pilot

with any luck I should be able to avoid making any fresh holes in the boat

Dylan
Click to expand...

agree all but wood choice. You have teak/tecdeck cockpit? Then a nice piece of teak would match better.
Possibly a donation from some one here who has one spare?!
 
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