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 farther breakwater.

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)?

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.

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 farther breakwater. Seeing SW begin to tack, SL immediately begins to tack as well.

After position 3, is PL (formerly SW), required to give PW (formerly SL) room between her and the breakwater?

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 remains overlapped, it requires PL to give PW that room.

GBR 1975/8