Stroke distance of auto drive

[sabray]

I measured the distance on my old but rebuilt linear drive. It measures 18 inches. I have a back up octo hydraulic drive that was free. In open area it would be fine. But its throw is 12 inches. I can find drives that have throws of 9 and 12 inches but nothing that matches the old autohelm linear drive. Suggestions are sought for a good value drive with the proper throw. Guess i could replace the rudder post mount but seems counter intuitive given it has better leverage then a smaller attachment would have.
Hoping i made sense on my question.

[Paul L]

The stroke on the Raymarine long shaft is 18 in. I just replaced one with an L&S linear hydraulic that has a 12 in stroke. It required working out the geometry of where to mount the drive and how far along tbe rudder arm to attach it so that you can keep a 70* turning range. I bought the drive from PYI Inc and they were helpful in making up a drawing. The L&S drive seems pretty bullet proof so far.

[sabray]

Originally Posted by Paul L

The stroke on the Raymarine long shaft is 18 in. I just replaced one with an L&S linear hydraulic that has a 12 in stroke. It required working out the geometry of where to mount the drive and how far along tbe rudder arm to attach it so that you can keep a 70* turning range. I bought the drive from PYI Inc and they were helpful in making up a drawing. The L&S drive seems pretty bullet proof so far.

Thanks PYI is a good outfit. I think my current arm is fixed pin so no adjustment. Could mean i need a new arm so that i can get away from the linear drive.

[Paul L]

The arms are not tbat hard to drill and install a new connector pin. In my install I used the old position of the pin on the arm, but I had to carefully install the drive unit base offset from the old one.

[colemj]

Originally Posted by Paul L

The arms are not tbat hard to drill and install a new connector pin.

That is what I did when I installed our new (longer) drive. We have a bronze Edson arm that has pilot holes drilled every 1" along it, so I just drilled out a new pin hole at the appropriate distance.

Mark