Who is in the right?
So in the diagram, which boat is going to end up "toast"
in the protest room? The green boat on port, but clear ahead? Or
perhaps the red boat on starboard, but clear astern?
And the answer is ....
The red starboard boat is in the right. This is a straight
port/starboard incident covered by Rule 10.
"Clear Astern" does not apply in this case because if
you have a read of Rule 12 (the clear astern rule) you will see
that it only applies "When boats are on the same tack",
which in this case they are not.
The one thing you have to keep in mind is if you are both on
port tack, then the boat clear astern gybes and becomes the right
of way boat, they must "initially give the other boat room to
keep clear", so you can't gybe just before you hit the other
boat and try to get out of it on a port/starboard.
This situation usually comes up when you are getting close to
the leeward mark, so you also need to be careful as the mark
rounding rules will apply.