[cwa]

Ben,

The splices are sleeved and plug welded.
Easy to make the sleeve by reducing a piece of pipe to the required dia. and inserting inside the joining pieces.
As for getting stiffness, I believe that the .275" wall thickness would really help there.
Actually I'm having a fellow at Beecher Bay on Vancouver Island make my mast.
He has done a number of masts (I've seen two examples so far) using this technique but haven't asked about ones for a gaffer.

I just talked to Ken (the fellow making my mast) and he has made 2 masts for gaffers using this technique.

Carl