Question 1
Rule 19.1 applies between two boats ‘at’ an obstruction. When are boats ‘at’ an obstruction?

Answer 1
Boats are ‘at’ an obstruction when they are near it and the obstruction is influencing the course of one or both of them.

Facts for Questions 2, 3 and 4
Boat W is running on starboard tack parallel to a breakwater which is about one length away on her starboard side. Boat L is on starboard tack, to leeward and overlapped with W, and approaching the breakwater. Boats W and L are on a collision course.

Question 2
If L is broad reaching and approaching the obstruction as shown in the diagram for Question 2, does rule 19 apply; and if so, which boat is the ‘outside boat’?

Answer 2
Because the wall is influencing W’s course and, therefore, her ability to keep clear of L, the boats are ‘at’ the obstruction as that term is used in rule 19.1. Therefore, rule 19 applies.

Because L, the right-of-way boat under rule 11, is choosing to pass the obstruction on her starboard side, a boat overlapped with her on her starboard side is an ‘inside boat’. Therefore, W is the ‘inside boat’ and L is the ‘outside boat’ and, under rule 19.2(b), W is entitled to room from L to pass between L and the breakwater.

Question 3
Does the answer to Question 2 change if L is close-hauled approaching the breakwater as shown in the diagram for Question 3?

Answer 3
Yes. W and L are overlapped because they are on the same tack and neither of them is clear astern of the other (see the definition Clear Astern and Clear Ahead; Overlap). Because L, the right-of-way boat, is choosing to pass the obstruction on her port side (see rule 19.2(a)), a boat on her port side is an ‘inside boat’ and a boat on her starboard side is an ‘outside boat’. Therefore, W is the outside boat and must give L room between her and the obstruction under rule 19.2(b) as well as keep clear of her under rule 11.

Question 4
Does the answer to Question 2 change if L is approaching the breakwater at a ninety-degree angle to it as shown in the diagram for Question 4?

Answer 4
Yes. Rule 19.2(a) gives L the right to choose to pass the breakwater on her port side or on her starboard side. No rule requires L to inform W of her choice. At the moment shown in the diagram, L’s course is directly at the obstruction (ninety degrees to it), and it is not possible to determine whether she is an ‘inside’ or an ‘outside boat’. Rule 19 applies, but while L continues on that course no part of rule 19 creates any obligations on either boat. Rule 11 still applies and requires W to keep clear of L.

At some time after the moment shown in the diagram it will be necessary for L to either luff or bear away to avoid colliding with the breakwater. If L bears away, then the answer to this question is the same as Answer 2. If L luffs, then the answer to this question is the same as Answer 3.

Facts for Question 5
In all three diagrams, reposition W’s sails so that she is shown sailing downwind on port tack instead of starboard tack. Change W’s label to ‘P’, and L’s label to ‘S’.

Question 5
Do the answers to Questions 2, 3 and 4 change?

Answer 5
Answer 2 does not change, except that the relevant right-of-way rule is rule 10 instead of rule 11.

Answers 3 and 4 change. In each of these two situations, S and P are on opposite tacks and, because S is not sailing more than ninety degrees from the true wind, they are not ‘overlapped’ (see the definition Clear Astern and Clear Ahead; Overlap). Therefore, rule 19.2(b) does not apply between them. Rule 10 applies and requires P to keep clear of S.

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