i'm a novice at sailboat maintenance but quickly becoming quite adept. ref: i have a c-22 with a oblong 25-ft mast. scenario: i want to put in a 24-ft schedule 20-40 pvc 'conduit' so i can rewire the mast light and use it also for my vhf radio cable, etc. question: is the mast mostly 'hollow'? i don't have any internal halyard schemes set up (yet).... any/all info/data considered. thanx.