Rule 12, On the Same Tack, Not Overlapped Rule 18.2(a), Rounding and Passing Marks and Obstructions:
Giving Room; Keeping Clear: Overlapped – Basic Rule
Definitions, Obstruction
If an obstruction can be passed on either side by two overlapped boats,
the right-of-way boat, if she chooses to pass it to leeward, must give room
to the other. If the right-of-way boat chooses to pass it to windward, she is
entitled to room to do so, and the other boat must keep clear. There is no obligation
to hail for room at a mark or obstruction.
Question 1
BW, the windward boat, is subject to rules 11 and 17.2 in her obligations
to BL. Does the proximity of the third, slower boat, A, change the relationship
between BW and BL to one in which rule 18 comes into force when they overhaul
A?
Answer 1
Yes. With respect to A, both boats astern must keep clear of her under
rule 12. However, A also is an obstruction to both, as the last sentence
of the definition Obstruction makes clear. When they are ‘about to pass’
A, still overlapped, rule 18 will come into effect. If BL then chooses
to pass A to leeward, rule 18.2(a) will require her to give room to BW,
as inside boat, to do likewise. BW is not required to take the room provided,
and may pass A to windward, keeping clear of her under rule 12 and then
rule 11. If BL chooses to pass to windward of A, then rule 18.2(a) requires
BW to give BL room to pass A and both rule 18.2(a) and rule 11 require
BW to keep clear of BL. Rule 12, and later rule 11, require BL to keep
clear of A.
Question 2
Does BW have to hail for room to pass to leeward of A, or would BL risk
disqualification by not automatically giving room?
Answer 2
BW is not required to hail for room, although that is a prudent thing
to do to avoid misunderstandings. Rule 18.2(a) requires BL to give room
to BW when they both pass to leeward of the obstruction, whether or not
BW hails for room.