My halyards are all external, so that's not a problem. And, the foam is soft enough and remains attached to the pull line so you can remove it at any time to install another wire if needed.
One of the reasons the conduit would be quite expensive is first all wiring must be disconnected, then the mast must be removed and placed on support stands, which in many instances are nothing more than saw horses. Next, all wiring must be removed from the mast interior, then the conduit is measured, exit ports for spreader and mast light must be drilled at the correct locations, then the conduit is positioned outside the mast and pop-rivet holes are drilled in both the conduit and mast--all of this prior to inserting inside the mast. Once all the holes are drilled, then the wiring is installed inside the conduit and anchored at 18-inch intervals. Naturally, the original wires would be replaced with NEW, tinned, marine grade wire, which adds tremendously to the expense.
The next step is to insert the entire assembly into the mast, which requires 3 to 4 people to pick up and walk the conduit to the end of the mast so it can be inserted. Once the conduit is inside the mast, someone holds each end in place while another person pop-rivets the conduit in place. The person doing the riveting is usually laying on the ground beneath the mast.
Finally, the wiring is reconnected to the mast lights, antenna, etc..., then the crane lifts the mast, reinserts it through the cabin top, the rigging is reattached, the mast boot and seals are reinstalled, then the wires exiting the base of the mast are reconnected to their appropriate connectors and resealed with silicone cement.
Now you have an idea why the cost of installing a PVC electrical conduit inside a mast is cost prohibitive. Most of the marinas I talked with said they would not even quote a price for this, saying the only way they would undertake the task would be on a time and materials basis. Some facilities said they would not consider doing the job at all.
After considering all the options, the foam rubber blocks strung inside the mast seem to be the most economical and logical solution.
Thanks for all the replies and suggestions everyone,