Mark,

I ran into the same issue when installing a new tiller arm for a new
autopilot. On our rudder shaft there is about an inch or slightly more
of the key extending above the quadrant. This should be enough to secure
the tiller arm from moving. With past autopilots there has never been a
problem with the key shearing or showing any signs of stress. If you are
not comfortable with using only the extended key from the quadrant you
can drill a hole in the aft part of the rudder shaft and pin the tiller
arm from the back. this is perfectly acceptable as the force is in shear
with the set screw and should do the job of keeping the tiller arm in
place. If the bore for the new tiller arm is exactly machined, there
should be enough clamping compression to hold the tiller arm to the
rudder all by its self leaving the pin or key as basic insurance. Edson
offers securing their tiller arm with either a key way or a pin. when
you order a new tiller arm from them you must specify which you will need.

This autopilot stuff is very interesting and complex as I have found
out. I learned a lot in the past six months while planning and
installing a ComNav, ComPilot in our Tashiba 40. It was not easy and
there are many considerations in the planning stages that will effect
current draw and reliability. In my opinion, the drive system, (in my
case a hydraulic system) is the most critical to get right. The
electronics part of the autopilot is easy but you must get the
hydraulics perfect or you will pay the price forever.

Let me know if you have any question and I will try to help. I have lots
of pictures and a project log I will post to the Baba site when finished.

Rich Cassano
S/V Gray Eagle, Tashiba 40
Oyster Bay, NY USA

Mark Bergin wrote:
> I've just run into a big problem in trying to fit a tiller arm on the
> rudder shaft to support a hydraulic autopilot ram. The existing keyway
> in the rudder shaft is only about 3.5 inches long - about enough to
> accomodate the quadrant with an inch or so of excess. I have been
> attempting to get the keyway extended a few inches to allow an autopilot
> tiller to be added to the shaft.
>
> The rudder is out and has been taken to a marine machine shop
> specializing in shafts. They are unable to lengthen the keyway due to
> the rudder blade preventing them from being able to set up the cutting
> machine (a Bridgeport). Other machine shops have also been unable to do
> the job.
>
> Has anyone out there had this type of work done and if so did you have
> similar problems - or know of a machine type that is capable of doing
> the job? Otherwise what other means of securing the tiller arm are you
> aware of? I've thought about trying to use the remnant key - although
> it is pretty short - or drilling the arm and shaft to allow a pin to
> secure the arm. Any experience or thoughts?
>
> Maybe I should just get a windvane and drive it with a small tiller
> pilot - sure would like to use the hydraulic a.p. though since I already
> have it.
>
> --
> Mark Bergin

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Received on Wed Jun 28 11:47:18 2006