Having searched In vain for clues how to hide the wiring for navigation lights Inside a mast I came up with a simple router jig to do the job (all my previous models were unlit).
Basically very simple - hold the mast dowel rigid, rout a groove about 3mm wide and penetrating about 2mm beyond the centre line of the dowel and between the various lamp locations. I left an overhang at the base of the mast to allow for later handling when tapering the dowel and the dowel was left overlong so I didn't need to rout to the masthead. A second run with a 5mm (or so) cutter about 2mm deep gives a ledge to glue pieces of timber to close the slot. Once the timber Is planed down to the dowel It Is a simple matter to process the mast as normal. Wiring can then be fed down the mast and steps for the lights fitted to finish the work off. The photos show the process.