Autopilot installation problem

[trimarannaga]

Hi everyone
Hope someone has advice to help me
I ordered an EV200 Raymarine autopilot with linear drive. Problem is the drive unit is too long for the space I have. Space required is 31 1/2" from center. This gives room for the mounting bracket (4") and the drive unit at center helm position (27 1/2")
I only have 26 1/2". My transom if very narrow where the quadrant is.
So...
Is there a good quality autopilot on the market that will fit in this space? Obviously this one won't, even with a modification of the bracket.
Thanks

[IdoraKeeper]

I am working a similar issue. Perhaps linear drive is not the answer. I am adapting a chain drive to my boat. Actually converting chain to cog belt. In my case I have an existing hydraulic steering installation with a stern hung rudder. I would love to use a wheel pilot but the boat is too heavy for a RayMarine wheel pilot. The key question seems to be the drive computer that needs to power the electric motor. If you size the drive computer correctly you should get decent life from the system. All the rest of the project is mechanical architecture.
Consider also buying a different linear actuator with a shorter throw.Then just vary the arm length to get the desired rudder angles. I assume you want an inside drive system.

[mgh]

Also working on a similar issue. A couple of ideas I am also playing with:

- Angling the tiller arm "forward" may give you some additional distance, although it will reduce the available torque applied to the rudder post, and introduce more side pressure on the rudder bearings.

- Reducing the usable stroke on the drive (move the rudder center to less than the RM 700mm distance) could also reduce the distance requirement, but then will need to be even more careful with rudder stops, and limit the available hard-over angles.

Most of the linear drives I looked at have similar length requirements, even the hydraulic ones. Still exploring options.

One other alternative might be a Jefa DD1 (I am also looking at this), reportedly a good unit. The geometry is more complicated, and will need to watch the vertical distance as well since the base sits a few inches lower than the ram-type drives. But the distance requirement then drops substantially.

Good luck. Will be curious what you end up doing.

[toddedger]

Just go into the software and reduce your hard over angle in the setup menu. Then add some spacers on your rudder stops to prevent loading the actuator when in manual steering mode. The evolution is a great autopilot. You won't be disappointed. You can double check my suggestion with Raymarine on the Raymarine online forum.

[DeepFrz]

You can mount the drive unit so that it is more fore/aft than 90deg. from center line. So long as the center position of the steering arm forms a 90 deg. angle with the drive unit arm at the center position. So long as the geometry is correct it will not increase any pressure on the steering system. It will probably require a custom made rudder steering arm.

[trimarannaga]

Originally Posted by DeepFrz

You can mount the drive unit so that it is more fore/aft than 90deg. from center line. So long as the center position of the steering arm forms a 90 deg. angle with the drive unit arm at the center position. So long as the geometry is correct it will not increase any pressure on the steering system. It will probably require a custom made rudder steering arm.

DeepFrz this sounds like the solution but I can't envision it, don't understand. Can you please make a drawing for me and attach it? Thank you. Chrissi

[UNCIVILIZED]

Originally Posted by trimarannaga

DeepFrz this sounds like the solution but I can't envision it, don't understand. Can you please make a drawing for me and attach it? Thank you. Chrissi

I'm fairly sure that he's thinking what I'm thinking. Which is that instead of mounting the AP ram on an axis at 90 deg to the boat's centerline, so that it acts on what's essentially a shortened tiller arm (or the quadrant). That you have a short tiller arm made which attaches to the rudder shaft, so that the new tiller arm (or quadrant) is perpendicular to the boat's centerline. And that you connect the AP to this arm, with the AP ram oriented on the same axis as the boat's centerline.

Such setups are quite common in some circles. And it was how servos were sometimes connected to the rudders on remote controlled aircraft when I was a kid. Possibly called a bellcrank connection? That was a long time ago. But the principle is still more than valid.
Edit: Yep, it's Bellcrank, I just looked. Bing it for some more pics & info. https://en.wikipedia.org/wiki/Bellcrank

Also, don't brand me a heretic. But might the shaft on the AP ram be shortened by a small amount? Though this might entail having it's connecting hardware remachined I would think? I don't know the unit in question, sorry.

[DeepFrz]

Originally Posted by UNCIVILIZED

I'm fairly sure that he's thinking what I'm thinking. Which is that instead of mounting the AP ram on an axis at 90 deg to the boat's centerline, so that it acts on what's essentially a shortened tiller arm (or the quadrant). That you have a short tiller arm made which attaches to the rudder shaft, so that the new tiller arm (or quadrant) is perpendicular to the boat's centerline. And that you connect the AP to this arm, with the AP ram oriented on the same axis as the boat's centerline.

Such setups are quite common in some circles. And it was how servos were sometimes connected to the rudders on remote controlled aircraft when I was a kid. Possibly called a bellcrank connection? That was a long time ago. But the principle is still more than valid.
Edit: Yep, it's Bellcrank, I just looked. Bing it for some more pics & info. https://en.wikipedia.org/wiki/Bellcrank

Also, don't brand me a heretic. But might the shaft on the AP ram be shortened by a small amount? Though this might entail having it's connecting hardware remachined I would think? I don't know the unit in question, sorry.

Exactly. However the ram doesn't have to be positioned parallel to the center line of the boat. What matters is that when the rudder is at it's center position the steering arm/connection to quadrant is at 90 deg. to the ram.

[Time2Go]

Originally Posted by UNCIVILIZED

.

Such setups are quite common in some circles. And it was how servos were sometimes connected to the rudders on remote controlled aircraft when I was a kid. Possibly called a bellcrank connection? That was a long time ago. But the principle is still more than valid.
Edit: Yep, it's Bellcrank, I just looked. Bing it for some more pics & info. https://en.wikipedia.org/wiki/Bellcrank

.

Being an active RC pilot for 45 years I can say that bell ranks were
rarely used for rudder. There most common use was in the wings
where the servo was positioned in the center of the wing and pushrods
went through the wing, then attached to 90* bellcranks
the resulting pushrods coming off the 90 then were connected
to the airelons. One servo then controlled two surfaces.
Left and right airelons,
With radios and servos getting much cheaper
and with radios now having all sorts of digital programming,
It's now usually one servo for each movable service or control.
The servos are mounted as close as possible to the
surface being controlled. Eliminates a tremodous amount of
slop and flutter.
Makes set up and trimming a breeze.
I also fly control line and here bellcranks are used to convert
relative pull on the flight wires to elevator control.

To the OP question
A few years ago I was crew on a boat that had a Jaffa unit
(Sorry don't remember model)
That looked and behaved just like a
Giant RC servo, could be just the ticket
Cheers
Neil
Wikipedia is incorrect
In there example what they are calling a bellcrank
Is actually two "control horns" connected to a
Pull Pull Sytem
System

[JohnT]

Can you install a trim-tab on the trailing edge of your rudder (but your rudder needs to be transom mounted)? If so, you can mount the ram parallel to the tiller and let the AP steer via the trim tab, which will in turn steer the rudder. It uses far less energy. You may need to reverse the compass wiring if the ram is located in the same housing. I delivered a 34' mono with this setup from Namibia (Africa) to FortLauderdale with the AP set up like this with no troubles.

[fallingeggs]

Originally Posted by Time2Go

To the OP question
A few years ago I was crew on a boat that had a Jaffa unit
(Sorry don't remember model)
That looked and behaved just like a
Giant RC servo, could be just the ticket
Cheers
Neil

Yep, check out Jefa...

Jefa Steering Systems

[antoha]

How strong does it need to be? Would the octopus mechanical drive work for you? Simrad branded sd10 if you google, looks like a push-pull cable that you can route with reasonably small curvature:
http://www.defender.com/product.jsp?...715&id=1156029

If you need stronger, check out lecomble & schmitt; pyi in the U.S. and others sell them (pricey units). Looks like their smallest linear drive would almost fit your 26.5" constraint (it's 27", so if you drive at a slight angle it may work). They are split systems so the pump is not hanging off the back of the drive itself:
http://www.ls-france.com/en/power-pa...-f60f9b65-e758

[alctel]

I've got the simrad branded version of the jefa DD1 (DD15)

It's way smaller than standard ram drives

[IdoraKeeper]

Love the tab idea, actually a "servo tab" in this case. Not sure how the autopilot software would react to the lag in reaching a desired rudder angle as the tab is deflected. There would also be issues at low speeds created by the smaller area of the tab. The mechanical advantage created by the tab would certainly reduce power consumption as compared with directly driving the rudder. There is also the problem of stalling the tab in weather helm situations.

[Celestialsailor]

Glad I found this thread. I have hydraulic steering on my HR. I see Defender has the EV 200 for a hydraulic set-up. for around $1500 minus $200 for a rebate. I think I could plug and play but might want to add 2, inline check valves. Anyone tried this?