Ok so it's spruce and how old? The quick "get her through the season" fix is dry it out, reef out any crap you can from the cracks and pack them with silicate + suitable coloured sawdust thickened epoxy, then re-varnish and carry on until you are faced with more problems..
The proper thing to do is take the signs for what they are and give the boat
a "rig job". Take all the hardware
off the mast, re-glue it entirely (if it'll pop apart with a bit of persuasion - it might!) or route/skillsaw kerf out the seams and glue in suitable spruce splines with epoxy. At this stage if the mast is down to bare wood I usually paint
a couple coats of penetrating epoxy on, fill all the old holes with titebond-III or epoxy glued wooden "nails" and then re-varnish it before any hardware
goes on. 8+ coats of varnish
every bit of metal in your goop of choice (3m 4200 or sikaflex 291 is pretty common) and pre-drill every hole in it.. You should have a mast for atleast another 30 years.