Starboard hole. Vessel sunk. Rule 14 says they both are, key word "shall":
SECTION B
GENERAL LIMITATIONS
14 AVOIDING CONTACT
A boat shall avoid contact with another boat if reasonably possible.
However, a right-of-way boat or one entitled to room or mark-room
(a) need not act to avoid contact until it is clear that the other boat
is not keeping clear or giving room or mark-room, and
(b) shall be exonerated if she breaks this rule and the contact does
not cause damage or injury.