The tiller Al tubing is an oddball size.
I sourced the closest possible I could find at my local specialist Al shop. It was slightly too big for the castings, so I had to machine the castings out enough to get it in.
I only did one initially (the broken one, naturally). It has held up well so far.
The other one let go a few years later, when I was about 2km off the coast of Torquay, out in Bass Strait. That could have been a bit exciting, except that it was my upwind rudder on a ~15km reach along the coastline, so I didn't really need it that day anyway 😄 .
Incidentally, if