I have a radar pole supported by the swim platform, stern rail and two struts extending from the top of the cockpit coaming up to about 4' above the coaming .
The pole is fabricated from 2" aluminum electrical conduit. I had a welder add some aluminum blocks near the top of the pole so that I could fasten a gimbaled radar mount. The pole also supports a GPS antenna, a hailing speaker and a flag halyard.
At the swim platform there is a socket flange bolted to the platform. This is a commercially available railing fitting. The socket and pole are drilled for a 3/8" clevis pin to secure the pole in the socket.
At the stern rail there is a bracket that I made. The bracket spaces the pole out an appropriate distance so the pole is plumb.
On top of the coaming I bolted two rail fitting base plates for two struts that attach to the pole with clamps I purchased from Garhauer.
I did bend the pole early in its life during an accidental jibe. At that time the cables for the radar and GPS antenna were tied to the exterior of the pole. The cables produced enough friction so that the sheet did not easily unwrap from the pole as the boom continued around. The fix was to cut out the bent section and add a new piece with threaded pipe couplings top and bottom of the new section. I also ran the cables up inside the pole. We have had a few less than controlled jibes since (mostly at racing marks). The sheet appears to slip off easily now.
In IMG_6327 you can see the bracket on the stern rail. If you zoom in you can see some detail on all of the 4 photos.
This setup is aft of the stern rail. If you do not have a swim platform, you will need to deck step the pole inside the stern rail.
The boat also has a vertical windlass.
I can provide more detailed photos in a couple of weeks if you desire.
We can host you in Niantic (Eastern Long Island Sound between the CT River and New London) on your way through if that makes sense.
Ward Woodruff
N33 #8 Margery
Niantic Bay, CT