They are mostly riveted on. Use aluminium rivets of the most appropriate size and length. If the mast steps are cast alluminium (most likely) then you wont have a problem with electrolysis
. If you are doing it with the mast up, then do it step by step and slowly. Start by measuring and marking . Have a shoulder bag for your tools and little lanyards. I promise that the only tool dropped from the mast that dosnt go over the side, does so because it has smashed through a hatch
! The bigger rivets take a fair bit of force with a squeeze type rivet gun. If you have access to a consortina type use that. Test the rivet size and depth
by using a piece of material of equal thickness to your mast wall and one of your mast steps. Follow the drill size on the rivet box. Hold the mast step firmly against the material insert rivet into the end of the rivetor, through step and material. Squeeze up till it goes bang, and the shank pulls through.
Now check on the other side of your material that you have a good solid (bulb) swelling and that the whole lot is rock solid. Even if you only have one rivet in , it should pull up very tight. If successful drill the head
of the rivet off using a slightly larger drill bit. remove the mast step. Tap the remains of the rivet through your scrap material until it drops out using a pin punch. You can now put them in AND take them out.....
You are ready to go !!
(Dont forget to put a side by side pair at the mast head)