I'm leaning towards stainless as it will match the rest of shiny stuff above the freeboard, as the aesthetics of the thing is quite important, PVC would be a no no. It's not the cost per se that puts me off
buying off the shelf, but that the
current products seem to be designed for earlier magnetron radar weighing 20lbs + at 3" tube diameter and now the newer solid state radars weigh 12lbs which would allow a slightly more elegant solution?
However the mathematics of how strong a
stainless steel tube needs to be doesn't yield completely to an
internet search by a layman (me). It certainly isn't
wind pressure on the dome that is the deciding factor as the loading at high winds on a 22" x 9" dome are low numbers so it must be the horizontal load of the weight at the end (dome) as it swings through x degrees in y seconds and accelerates/decelerates abruptly in a rough sea. I was hoping that someone could put the numbers up on what the realistic loads are so I can
work backwards and see if a 2" pole or even 1.5" pole 8ft long braced such that the dome is on 5ft max of flexing strut.
(and similarly the OP could also deduce if a spinnaker pole has sufficient margin)
Reading online, gimballing the dome appears to not give much benefit so I'm looking to fix one directly. The cost is such that I may go with trial and error at 2" and see what happens.