JumbleDuck
Well-Known Member
The Colregs refer to the side the wind is on. They qualify this by saying for the purpose of the regs that is deemed to be the side opposite the mainsail. This does not help greatly in the situation under discussion where the main is not set.
Don;t they somewhere define "mainsail" as something along the lines of "principal fore-and-aft sail", in which case it might be the genoa if there is no other in use.
I suppose all this confusion is why the rules used to separate port tack, starboard tack and running free before the wind vessels.