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Rustic Charm · 18-03-2016, 21:15

Hi all,,

Ive had a new trim tab built for my transome hung rudder. The tab works so easily by hand, but when i put the linier auto pilot on it, the pilot seems to over react and i'm going from one extreem to the other.

Anyone know how to set up the Raymarine so that it doesnt do this?

Alan Mighty · 18-03-2016, 21:50

Hmm ... I'm surprised you are using a Raymarine ST4000 for your trim tab.

It's sort of overkill if your trim tab is working as a servo-rudder or Flettner rudder.

On 'Led Myne', I use an ST4000+ GP to drive the tiller. And an ST1000 to drive the trim tab (i.e. when using the trim tab as a servo-rudder or, if you prefer, as a Flettner rudder).

That quibble aside, I think you need to look at either of both of:

a) changing the automatic trim level of the ST4000 (see page 30 of the manual); or

b) working through the calibration menu, especially rudder gain (see p. 34 of the manual).

Do you have a copy of the Raymarine ST4000 Operation and Installation Manual? You should have a paper copy. I have a scanned electronic copy (about 3 MB) I could attach that in an e-mail to you (try sending me an PM) or break it into sections/pages to send to you.

Al

Alan Mighty · 18-03-2016, 21:55

Quote:

Originally Posted by Alan Mighty

That quibble aside, I think you need to look at either of both of:

a) changing the automatic trim level of the ST4000 (see page 30 of the manual); or

b) working through the calibration menu, especially rudder gain (see p. 34 of the manual).

Do you have a copy of the Raymarine ST4000 Operation and Installation Manual? You should have a paper copy. I have a scanned electronic copy (about 3 MB) I could attach that in an e-mail to you (try sending me an PM) or break it into sections/pages to send to you.

Of course, there are other alternatives.

(1) is to change the effective lever arm of the tiller to which you are attaching the ST4000.

(2) (which I don't necessarily recommend, but is worth mentioning) is to through even more $$ into the hole in the sea and to buy and install a Raymarine rudder reference transducer and link that to the ST4000 control head so the ST4000 control head 'knows' your rudder angle.

Al

Alan Mighty · 18-03-2016, 22:08

Raymarine does still have copies of manuals for ST4000 autopilots on its website. See: https://raymarine.app.box.com/s/nwf2...gu/1/720704863

Alan Mighty · 18-03-2016, 22:27

Quote:

Originally Posted by Alan Mighty

(1) is to change the effective lever arm of the tiller to which you are attaching the ST4000.

The length of the effective lever arm of the trim tab tiller is crucial. Too long an arm leads to oversteer, the phenomenon you are describing.

On Led Myne, I have a truck on the trim tab tiller than I can slide back and forth along the tiller; the ST1000 that I use attaches to that truck. That allows me to adjust the effective lever arm length.

On Led Myne (a transom-hung rudder, fairly large) and a trim tab acting as a servo-rudder, I align the autopilot attachment point so it is in line with the line of the gudgeon/pintle axis. That's the so-called "null point" or "differential". See the diagram on p. 246 of Larry and Lin Pardey "The Self-Sufficient Sailor".

I usually err on the side of understeer, by aligning the autopilot attachment point so it is in line with the line of the forward edge of the transom-hung rudder. Depends on sea conditions. A sliding attachment point allows that.

Alan Mighty · 18-03-2016, 22:55

An ST4000 used as a tiller-pilot is usually calibrated for the boat (see p. 31 of the manual).

That means the "Trim Level" is set to:

1 for a crab crusher (a medium/heavy displacement full keel boat with a transom hung rudder, such a Led Myne);

2 for a moderate/light displacement thing that heels and yaws every which way; or

3 for an ultralight racer that needs a constant hand on the tiller.

If your ST4000 is driving a trim tab operating as a servo-rudder or Flettner rudder, those calibration settings are likely not suitable.

That's because your ST4000 is not helming your boat, it's helming a leveraged version of your boat. The trim tab (and its tiller) is the lever.

On Led Myne, the "Rudder Damping" setting for her ST1000 (which drives the trim tab) and the ST4000 (which drives the rudder tiller directly). The ST1000 has Rudder Damping set to 1. Led Myne's ST4000 has rudder damping set to 9.

I mention those settings only as a guide, not for you to copy.

I think you first need to investigate and adjust the effective length of your trim tab tiller.

And then second to calibrate your ST4000. Calibration is not dry lab work. You need to do it sailing and seeing what works. Or does not work.

Rustic Charm · 18-03-2016, 23:48

wow

Alan a little much for me.

To answer your first questions. I have a 4000GP. But I didn't buy this for the Trim Tab. I already had it on my boat piloting my roughly 10500kg boat with it's rather big transome hung rudder.

Today is the first day I have ever used the trim tab on the back of the rudder. I wasn't about to purchase a down graded one when the GP is more than adequate. I'd assumed I'd just put the GP on it and reverse the head wires and off I'd go, but alas that didn't happen. I hadn't realised I'd have to callibrate again.

The tiller position and auto pilot arm is within the distance (620mm) it has to be according to the set up instructions.

So, you think recallibrating will do the job?

jslayton321 · 19-03-2016, 08:02

Raymarine ST4000 w/wheel pilot on my 32' sail boat does the same thing - back and forth. Even after a professional technician replaced the wheel unit and calibrated it - same thing. Motoring on perfectly smooth water - same thing. Back and forth.
I'm now thinking about fitting it with a remote control in order to get at least some use from it.
My only suggestion is get another make of autopilot!

Rustic Charm · 19-03-2016, 12:01

Quote:

Originally Posted by jslayton321

Raymarine ST4000 w/wheel pilot on my 32' sail boat does the same thing - back and forth. Even after a professional technician replaced the wheel unit and calibrated it - same thing. Motoring on perfectly smooth water - same thing. Back and forth.
I'm now thinking about fitting it with a remote control in order to get at least some use from it.
My only suggestion is get another make of autopilot!

Is that with the auto pilot on a trim tab?

Alan Mighty · 19-03-2016, 14:39

Quote:

Originally Posted by Rustic Charm

I'd assumed I'd just put the GP on it and reverse the head wires and off I'd go, but alas that didn't happen. I hadn't realised I'd have to callibrate again.

You're pulling my leg?

Your pic in post #1 shows you've mounted your ST4000 to starboard to drive the tiller of your trim tab.

If you had previously used you ST4000, mounted to starboard, to drive your rudder tiller, then you have to change the 'Operating Sense' of the ST4000. Raymarine never suggests doing that by swapping wires about.

Page 75 of the ST4000 manual explains how to change the 'Operating Sense', by simultaneously pressing the +1 and -1 buttons on the control head for 5 seconds.

ST4000 units are delivered in 'starboard mount' mode. If mounted on port side to operate a rudder tiller, the operating sense needs to be reversed.

And if mounted to starboard to operate a trim tab, the operating sense needs be reversed.

Check p. 69 of the manual to see how to check that you have the correct operating sense. You do that by pressing +10 so you can see what the ST4000 arm does.

Rustic Charm · 19-03-2016, 14:53

Quote:

Originally Posted by Alan Mighty

You're pulling my leg?

Your pic in post #1 shows you've mounted your ST4000 to starboard to drive the tiller of your trim tab.

If you had previously used you ST4000, mounted to starboard, to drive your rudder tiller, then you have to change the 'Operating Sense' of the ST4000. Raymarine never suggests doing that by swapping wires about.

Page 75 of the ST4000 manual explains how to change the 'Operating Sense', by simultaneously pressing the +1 and -1 buttons on the control head for 5 seconds.

ST4000 units are delivered in 'starboard mount' mode. If mounted on port side to operate a rudder tiller, the operating sense needs to be reversed.

And if mounted to starboard to operate a trim tab, the operating sense needs be reversed.

Check p. 69 of the manual to see how to check that you have the correct operating sense. You do that by pressing +10 so you can see what the ST4000 arm does.

my manual doesnt have an 'operating sense' section? What you have posted is what i was thinking, but if i wanted to change the side then page 75 tells me in the chapter on 'auto pilot direction' to reverse the wires on the back of the unit.

Page 69 on mine has some bracket on a 'wheel' set up thingy.

I have found a pdf of my manual on the Raymarine website on obsolete manuals.

Rustic Charm · 19-03-2016, 15:03

The index at the back of my manual has 'operating sense page 86' but on page 86 it has nothing to do with this.

Alan Mighty · 19-03-2016, 15:38

See operating sense reversal.pdf, about 44 KB

Rustic Charm · 19-03-2016, 18:57

Thank you Alan,

that page is not in my manual at all. When my wife comes back home soon, i might go for a ride on my bike to the marina (hour way) and give it a go. Otherwise i wont get to try it until Easter break. Ill let you kniw how it goes.