Hi:
Fior me it is easy enought. Just got a DUBRO 2139 or similar fitting that has a pivoting ball inside, it will move freeely anyway you want. At main boom I epoxy some pice of balsa or hard wood and the put the link with some cyano drops, thats all, at the mast I bolt on a little pice of rectangular alum,inom cuuten in a “C” chape. The long flat side is bolted up and down, at1,5 (3/4") from the edges with servo screws. In the uper and lower edjes I left a pice of aluminum 10mm long that goes backward. In this little pice of aluminum I drill the hole to fit the dubro pivot link for the main boom at the top and for the gooseneck at the bottom. Then in the lower link you can bol or ubolt the connecting rod to set up your sail.
Tato Lazo