Auto pilot tiller arm position clarifaction

[wiekeith]

Originally Posted by Mg451

Yes im with you the cou will stop it from hitting the end stops as long as they are set to stop prior..so i assume i dont need the (physical)stops at then?

Correct, I wouldn’t anticipate that you’d need to actually add any physical end-stops. Whatever mechanism is in place to limit the movement, is already in place.

[goboatingnow]

Just to be clear. The requirement is the arm when extended hits the existing mechanical rudder endstops and never hits its own internal full travel stops. In practice the calibration procedure then sets the limits less then the max allowed rudder travel.

Where this is an issue is where the tiller arm that the linear drive is connected to is made too long and the linear drive hits its own endstops first.

This is to ensure that the arm does not become the replacement mechanical end stop under any circumstance

[ShineOn]

Originally Posted by Mg451

Im reading steve de antonios booklet on systems steering part 1 me hanical systems. He says;

Additionally, the geometry between
the tiller arm and the ram must be cor-
rect to derive the greatest mechanical
advantage when it’s needed most—
when the rudder is moved away from
amidships; while it’s dead ahead, the
least effort is required. Ideally, and
contrary to popular belief, the ram
should not be positioned at 90° to the
tiller arm and vessel centerline (assum-
ing, in this example, that the tiller is
fore-and-aft when the rudder is fore-
and-aft) when the rudder is straight
ahead; rather, it should be at 90° when
the rudder is over to some degree
(steering and autopilot manufacturers
typically specify the degree) in either
direction, thereby enabling the ram to
impart greater force when it’s needed
most. This often means the ram, if
installed athwartships, must be posi-
tioned farther aft.

That is a very long-winded way of making the correct installation sound complicated... and I'll probably come up with another long-winded way...

Usually drive units are installed so the angle to the tiller arm at amidships is slightly *less* than 90 degrees.

This gives more effective use of travel (requires less travel from the drive unit, which naturally gives more push for a given angle) and provides a more efficient angle at limits of travel (doesn't get too close to being in-line at one end of travel).

I'm probably going to have to find a diagram as it isn't easy to describe - and here I am assuming a transverse drive unit installation (nothing to stop the tiller arm and drive being at any angle relative to boat, just easiest to explain it if straight).

The "correct" geometry is so that the drive unit attachment is at roughly at 90 degrees to the *boat* (not tiller arm/quadrant) when the travel is at maximum either side. That means that at amidships the angle to is lower than 90 degrees due to the arc in travel.

On our installation (IIRC...) this meant that with a 10" tiller arm, drive unit stroke of 12" and max angles of +/- 35 the drive unit was positioned 8" forward of the rudder stock (vs. the 10" is would have been at 90 degrees).

Trying to think of the math, but suspect it is something like sin(rudder angle max [e.g. 35]) x tiller arm length would give the right number.

Or, just mk.1 eyeball it at about 85% of the tiller arm length and be happy?

[ShineOn]

Originally Posted by ShineOn

Or, just mk.1 eyeball it at about 85% of the tiller arm length and be happy?

Got bored, did the sums. 80% for our installation.

[ShineOn]

Originally Posted by goboatingnow

Just to be clear. The requirement is the arm when extended hits the existing mechanical rudder endstops and never hits its own internal full travel stops. In practice the calibration procedure then sets the limits less then the max allowed rudder travel.

Spot on.

[Shaneesprit]

Hi
How big is your boat?
Not sure on the EV200, but the EV100 states at 90 and I am sure it’s the same, having fitted an EV100 Tiller version last year and found the angle the rudder can achieve with it fitted is no more than 12 degree in either direction. Install at 90 as anything else just won’t be worthwhile thinking about.
The only issue I had is I wish I went against the Raymarine manual and fitted the linear drive closer to the tiller pivot, I have a 2500kg CAT and 6000Kg drive so don’t feel like loading should be an issue and that would achieve a greater angle for steering (but then my boat could eat a Raymarine ST2000+)

Make sure you update the Firmware! That means you need a Raymarine MFD to do that.
I posted some issues that in the end were just Firmware that I had no intention of updating at the start. It even seem to confuse Raymarine as to why the pilot had a mind of its own, it would suddenly turn to port or starboard sometimes both even while on the hard.

[Shaneesprit]

Originally Posted by ShineOn

Spot on.

There is no point calibration on a tiller pilot as the angle is fixed. By the installation manual distances - not even sure you can calibrate the actual angle anymore as it’s 12 degree there is no other possibility
Sorry applies to EV100 - I haven’t looked up the EV200

[Mg451]

Im 32ft 17000 lbs displacement. Cutaway keel. Well balanced under sail. Been reading about the raymarine downside is limiting steerage. I have a raymarine mfd that can also plot and control the ev 200. So thats what im really liking..been also looking at the cpt autopiliot because it wont limit steerage. Gotta get under there and see if 35degrees is gonna hamper me or not.

[Shaneesprit]

Where did the 35 degree come from?
If it’s a tiller pilot you can draw the angles from the installation manual + & - the drive length

[Mg451]

Cant do more then +/- 35 degrees

[Mg451]

Blurry for some reason try this;

[Mg451]

Well any how page 12 of tbe evoloution ev 200 install....

[Shaneesprit]

https://www.cruisersforum.com/forums...le-248633.html

In this thread you can see that the EV100 can achieve 12 degrees in either direction.
If I get time I will review the above EV200 information, to see - the attached was not readable