Hi Newby7 I make a lot of these fittings, but only use soft soldering as I have found it quite strong enough for the job. I also found I could use hard brass wire in a loop and this soldered up OK with some iron wire holding all in place. I accept that a nicely made silver soldered brass fitting can look very nice all polished up.
I use model aircraft aileron plastic hinges for goosenecks, one end goes into the sail boom and the other is free to rotate in a brass tube soldered to another wider one fitted on the mast. The bottom of the gooseneck is cut to size and a hole drilled in the centre of the hinge i.e. up into the plastic and a screweye inserted. This keeps the hinge in place and a boom vang can be fitted to keep the sail boom down.
I paint them out to hide them, i.e. I paint to match the mast and they go unnoticed.
I have several books by a Mr. Hobbs who was a model yacht 'authority' back in the 30's and 40's. Most fittings are illustrated and could also be bought from the long gone Webbs Fittings company.
I had to use his expertise when restoring a small yacht that used Braine steering, so the old stuff is still useful