Explanation of Raymarine ST1000 autopilot installation on Cape Horn

I wanted to have the autopilot easily accessible but control the Cap Horn with
a minimum of fuss.

After thinking about it for several months I finally had the brainstorm that
perhaps the autopilot did not need to be mounted in a transverse location. I
checked with Raymarine and this was indeed the case. I could calibrate the
compass enough to mount it fore-and-aft. The design then became easy.

Photo 20: Autopilot mounted on shelf in lazarette. Note bicycle brake cables
attached to piston and to a bungee cord which acts as the return line spring.
Note: When underway I control autopilot with remote control so lazarette
remains closed.

Photo 21: Closeup showing cable attachment. I used a wingnut to attach to
piston, but figured out afterwards it never needs to be disconnected. Now I
just store the autopilot in fully extended position when not in use to release
tension on cable.

Photo 22: Hard to see in shadow, but bungee goes over a wood screw. To
disconnect autopilot and use windvane sail, I just place auto in STANDBY,
extend piston fully, then pull the bungee off the screw. Note loops are made
in bungee by using a safety-wire "whipping" since knots always pull out of
bungee materials. Small boat dog is supervising the photo session.

Photo 23: The autopilot is mounted on a piece of scrap wood using sliding
brackets from a computer keyboard tray. It can thus slide totally out of the
way under the bulwark for easy access to the lazarette when not in use. The
autopilot still functions when retracted.

Photo 24: The housing for the brake cables are safety-wired to this little
bracket under the deck for the top cable, and to the rudder quadrant strut on
the bottom cable.

Photo 25: Cables are attached to windvane arm with short piece of line because
I needed a little more range of motion in system and the brake cables were too
short. Original plan had the cables attached directly to arm (see next photo)
but I couldn't buy cables which were long enough for final design. The line
attaches to arm with a small metal tab which allows me to adjust the "center"
more easily anyway. Note the oar quadrant is in "retracted" position, i.e. the
oar is swung up out of the water right now, which is why the control lines
look all cockeyed.

Photo 26: Shows original design. Note how control arm has been "choked up" by
pressing arm farther into delrin block in order to match the maximum throw of
the lever arm to the range of motion available in the autopilot. You can also
note that I safety-wired the block to the control tube so it can't come off.
Simply slacking the wires gives enough freedom for the windvane sail to work
properly. You can also see that I rotated the control arm 90 degrees on its
shaft so that it sticks out to the side when neutral rather than straight up,
so my brake cables could pull up and down rather than side-to-side, making
them shorter and all on the port side of the vessel.

Photo 15: Shows delrin block I made to mount the windvane mast to the pulpit.
Attaches to bracket formerly used for stern nav light.


I hope this helps someone out there.


Charlie Freeman
s/v Kamaloha
T37 #542