CASE 33
Definitions, Clear Astern and Clear Ahead; Overlap
Rule 19.2(b), Room to Pass an Obstruction: Giving Room at an Obstruction
Rule 19.2(c), Poskytnutie miesta pri prekážke
Rule 20.2 , Room to Tack at an Obstruction: Hailing
Rule 20.2 , Room to Tack at an Obstruction: Responding
When a boat approaching an obstruction hails for room to
tack, but does so before the time when she needs to begin the
process described in rule 20 to avoid the obstruction safely,
she breaks rule 20.1(a). However, even if the hail breaks rule
20.1(a), the hailed boat must respond. An inside overlapped
boat is entitled to room between the outside boat and an
obstruction under rule 19.2(b) even though she has tacked
into the inside overlapping position.
Facts for Question 1
There are breakwaters projecting from the shore at fairly regular intervals
with a reasonable amount and depth of water between them. To be
competitive when beating against a contrary current, it is advantageous to
tack into and out of the area between adjacent breakwaters. SL and SW,
small keel boats, enter one such area overlapped, close-hauled on starboard
tack. In the absence of SW, SL would tack at a point where, on port tack
and close-hauled, she would just clear the end of the next breakwater.
Question 1
If SL were to hail for room to tack at position 2, would SW be required to
respond as required by rule 20.2(c)?
Answer 1
Yes. SW is required to respond by rules 20.2(b) and 20.2(c), even if at
position 2 SL was not yet in danger of running aground and her hail would
therefore break rule 20.1(a). To avoid breaking rule 20.1(a), SL must not
hail before the time when she needs to begin the process described in rule
20 to avoid the obstruction safely.
Additional Facts for Question 2
SL does not hail for room to tack. However, SW tacks between positions 2
and 3 at a point where, after she completes her tack, her close-hauled course
passes just to leeward of the end of the next breakwater. Seeing SW begin
to tack, SL immediately begins to tack as well.
Question 2
After position 3, is PL (formerly SW), required to give PW (formerly SL)
room between her and the breakwater?
Answer 2
Yes. When SW tacks, SL is able to tack without breaking a rule. When SW
turns past head to wind, the overlap between her and SL ceases to exist,
because they are then on opposite tacks and sailing at less than 90 degrees
to the true wind (see the definition Clear Astern and Clear Ahead; Overlap).
A new overlap begins when SL passes head to wind, at which time the boats
are once again on the same tack. After the new overlap begins PL, by
bearing off, can easily give PW room between her and the breakwater.
Therefore, rule 19.2(b) applies and, provided that PL and PW remain
overlapped, it requires PL to give PW that room.
GBR 1975/8