Job is done. Thanks for the suggestions. Here's what I did:
- decided I didn't want to put in a new conduit at this point.
- decided to use the existing skinny RG8X cable for new AIS antenna
and not try to use the fat RG 213
- because of connectors realized the new CAT5 wire had to be pulled in from the top, and the wind vane
wire from the bottom. So one pull was out of the question.
- removed both old wires and pulled in an electrician's snake that is made of a skinny nylon material.
- Could not pull new wire in very far this way.
Here's the trick:
- pulled the whole bundle of wires, including the snake with the new wire on the end, as far as the excess slack wire at the base of the mast would allow, about 5 feet. Put lube on the wires before each pull. Then pulled all the bundle back again except the new wire. Repeated countless times moving the new wire through the mast in 5 foot increments. Was working alone so made the 65' trip many times back and forth to do this!
- did this all again to get the second wire in from the other direction.