True, though note that very little play at the radial wheel keyway is required. If your rudder swings 80 degrees and that takes 3 turns lock to lock ( no idea, just an example ), then 1 degree on the rudder is 13.5 degrees on the wheel. If your rudder post is 2.5" diameter then 1 degree is less than 1/32" of play.
Other than taking everything apart on Windburn I have only looked at two other drives systems. Both had been damaged and had some play in them. On one it was a similar observation, the center mark on the wheel was no longer straight ahead. My guess is while in full reverse the wheel was let go and slammed over against the stop hard enough to shift the radial on the shaft. The key was brass or bronze and was damaged. On the other one the keyways were not the same size, maybe out by 0.02" or so. It is not always easy to get in and make good measurements. That allowed the radial to move, polished the fit a bit and the drive system slipped down enough to cause alignment problems. I take it from your advise that everything was engineered to be a very tight or interference fit. The ones I looked at were not but I couldn't tell by hand. Still, 20 degrees is a lot. I did take the plate and idlers off of Windburn, had them sandblasted and coated them with POR-15. Came up as hard as rock and looks to be a good solution for rusting steel. Michael Brown Windburn C&C 30-1 From: "Chuck Gilchrest" <csgilchr...@comcast.net> Michael, A 20 degree deviation on wheel centering is an AWFUL lot of wheel travel with no explanation. I suspect Bruce?s boat has a 44? diameter wheel which means at 20 degrees of travel, the Turk?s head knot would have moved roughly 7 ?? to one side or the other. Generally speaking, if my hand moves the wheel that much, the boat changes course dramatically, even with a big wheel. Most C&C Yachts had radial drives that are held in place on the rudder shaft by an interference fit of the two halves of the radial, machined undersized by .003? for a machinist clamping tolerance and then a keyway is cut in the radial drive to accommodate a stainless key that locks the drive wheel in place on the rudder. Generally, even if the boat is run aground on the rudder, the radial drive wheel or rudder post may bend, but it won?t slip on the post unless it is not clamped tightly at the hub of the wheel. I too suspect a weakened idler assembly that is allowing the idlers to pivot after tensioning. The next step is the idler wheel letting go and dropping various bits into to the bilge whilst the cable goes completely slack. Boat handling suffers when this happens.. Chuck Gilchrest Half Magic 1983 Landfall 35 Padanaram, MA
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