Wire tube in mast
To instal a conduit tube up mast:
Use at least 1" PVC tube. I ran large vhf radio wire, and two, three stranded cables up to masthead. This almost maxed the 1" tube out. Electrical conduit with "shouldered" connections work best instead of "sprinkler" PVC with connections, because the junctions lye closer to the mast. This may be important if you happen to need a rivet at that particular point. Measure where these joints are and try not to rivet there. You may put the conduit on whatever corner of the mast you need. Leave about a foot from the top and bottom, don''t run it too far up. To secure the conduit to mast drill two holes side bye side, about and inch an a half apart. One hole is for the rivet, the other for a stiff wire, such as welding rod, to hook under the conduit and pull it to the other hole for riveting. Plug the extra hole with a rivet when done. Also figure out what length rivet best suits the purpose. I used too long of rivets and it reduced the volume of the tube.
This job on my 42 foot mast took me 3 hours with another person to help. It is well worth doing especially if you intend on internal halyards in the future. Good luck and e-mail me direct if you need more details.