The term "fret" is used to describe the steady build-up of play from very small clearances to noticeable play. It is normaly a problem for splined shafts delivering power where the lubrication cannot be assured all the time. The clearance gradually enlarges with time. I heard the term to describe the build-up of play in a BMW motorcycle final drive shaft, so I used it. It is not dissimilar.
I trust that a new key will help. It cannot worsen it, for sure.
A stepped key, properly radiused is a possibility. They are not universally popular as the step is a weakness. Still, if it avoids dropping the rudder post, it will be welcome.
I wonder is the shaft solid section? I trust it is? If so, if I have to, I will grind two flats on the shaft (slowly), change the steering head to thick walled steel, and put two of the most enormous bolts in there to lock it, and fit a new key. I am not dropping that rudder post unless I have to, and I will over-engineer a steel (or stainless) rudder head before I have to drop the post. I simply cannot face that one, as yet.
I will measure up for the fitting of a big torque arm on the rudder shaft too. I really need to have some aux steering capability. I can send a man below to operate it, using a pitch-fork handle and shaft or something similar....just enough to be able to control the ship. I plan to cut a wee aperture for the handle and a wee inspection hatch to be able to connect it quickly. It sounds a reasonable project.
Last edited by Rockter; 06-03-2008 at 06:40 AM.