inspection hole in base of mast

[woodysca]

Looks like I need to cut an inspection hole in the base of the deck stepped mast on my 1986 Catalina 34.
I am asking for guidance from those with more experience.
What size should the hole be?
How far above the deck?
On which face of the mast (fore,aft, port,starboard)?

I've found advice on starting with 4 drill holes, and then cutting between them with a Dremel cutting wheel. This seems logical to me.
The round corners will help prevent stress cracks.

Thanks in advance.
Woody
San Diego

[KWKloeber]

location/size, kinda depends on why/what you need to inspect, eh? 
More info?
sabre saw works also. 
Also there a reciprocating power saw about the size of a Dremel tool that takes a thin metal blade (very cool man tool.)
I have a B&D battery-powered recip saw that takes a standard saber saw blade.
A roto-zip cutter or a roto-zip cotter in a Dremel chuck also works very neatly, unsure about on aluminum tho?