On Lilliana the mast wiring is almost exactly as Ron described. At the base of the mast is an inverted J that leads the wires through the roof and into the aft end of a teak tube. They then go forward into a soffit at the forward end of the saloon.
i recently installed a new furuno radar that only requires a power cable going up the mast. The radar image is sent by WiFi to an iPad.
In hindsight I would not have purchased this WiFi radar. I would instead use a conventional radar cable and run it on the outside of the mast.
for my more detailed comments see my posts on the trawler archive site.
Willard 40 -Lilliana-Sea of Cortez, Mexico
Willard 30- Puffin- SE Alaska
Tiffany Jayne 34-sailboat- Dancer- SF Bay