Drill Baby Drill!
At the end of part 3 I had started the drilling process. The Edson tiller arm can lock to the shaft in one of three ways: key, set screws or through bolt. For a hollow pipe rudder shaft I would think a through bolt is the easiest to deal with. A key will require an existing keyway or some machining work on the shaft (that will need to be removed from the boat). The through bolt is probably easier then set screws which would require drill/tapping two holes. I went with through bolt but your mileage may vary.
After I drilled through the outside in I chucked a 10″ 3/8 bit (Black Oxide) and started going at it. I used tape on the bit to gauge my progress. With lots of pressure I got through it in about 20 minutes. I pulled the bit every few minutes to clean the shavings. I could tell when I crossed from the stainless steel shaft to the bronze arm as the drilling got smoother and quieter. Never had any issues with overheating.
Rudder Stop Modification
After getting the tiller arm attached I started working on rudder stop modification. The rudder travel cannot exceed the drive travel or else the drive can be destroyed. I hooked up the drive to the tiller and and moved it by hand to see where the drive stops are. I then measured the distance to the rudder stops using drill bits as feeler gauges. I then added 1/4″ as shock protection.
The rudder stop on the Sabre 36 is a piece of steel angle with rubber blocks. To move the stops I shimmed up the rubber blocks using King Starboard blocks that ripped on the table saw. I used two 1/2″ pieces to get to 5/8″ and 7/8″ on the rudder stops. I wound needing a second attempt to add another 1/8″ to be sure even under hard shock load that the drive limit would not be tested. Better safe then sorry.