I use fishing rods - - two at a time !, one glued inside the other to give a really strong mast.
You require two identical rods, buy the rod "blanks" which are rods not made up and ready for use.
Decide on the mast height, cut one of the blanks to the correct length.
The other one needs its outer surface roughened up, with coarse emery or a file.
Slide the rough one into the "Mast" and make very sure that it fits and locks into the taper of the "mast".
Cover the outside of the roughened one with Silicon Sealer, just a nice thin layer will do.
Wait for about 3 minutes for the Sealer to start to go off - - - a vinegar smell will be produced.
Slide the rod inside the Mast with a twisting motion as far as it will go.
Leave over night at least, for the sealant to harden, and you have a Very strong Mast !!