Your Marine Parts Source Professionals Know How Important It Is to Remove the Confusion

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Raritan Engineering Company your marine parts source analysts would like to share with you these topics we thought would be of interest to you this month regarding how to decipher multiple boat rules

Your marine parts source experts know that when two boats meet, the rules are often clear, but when more boats pile up, things can get confusing.

Let’s consider what, at first glance, seems to be a very simple three-boat incident. The diagram shows Luke, Molly and Willie on starboard tack on a downwind leg. The boats are lightweight one-design boats, each sailing the course that maximizes its Velocity Made Good to the leeward mark. 

We’ll examine how the rules apply at each position shown. Because the boats are on the same tack, either Rule 11 or Rule 12 always applies to each of the three possible pairs of boats (Luke-Molly, Luke-Willie and Molly-Willie). The boats don’t change course during the incident, so Rule 16.1 does not apply. 

At Position 1, Molly and Luke are overlapped, and each of them is clear astern of Willie. So, Rule 12 gives Willie right of way over Molly and Luke, and Rule 11 gives Luke right of way over Molly. 

At that moment, several changes occur: (1) When Molly becomes overlapped with Willie, she is between Luke and Willie and overlapped with each of them. Thus, according to the definition of “overlap,” Luke also becomes overlapped with Willie.

(2) Willie is then a windward boat to both Molly and Luke, so Rule 11 is “on,” Rule 12 is “off,” and Willie must now keep clear of both Molly and Luke.

(3) When Molly and Luke acquired right of way over Willie, Rule 15 applied. It applied “initially” — i.e., for only a few seconds, during which time it required both of them to give Willie room to fulfill his new obligation to keep clear of them.

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(4) The distances between Willie and Molly and between Willie and Luke are both less than two hull lengths, and therefore Rule 17 applies to both Molly and Luke with respect to Willie.

(5) Finally, because it’s now Luke who has right of way over both Molly and Willie, Willie is no longer an obstruction, and Luke has become an obstruction to Molly and Willie. 

OK, moving on again, consider Position 3. The relative positions of the boats have not changed. However, Luke has just reached the jibe line to the leeward mark. If Luke continues on starboard tack across the jibe line, he will break Rule 17. 

One might ask whether Molly also broke Rule 17, about a length before Position 3, when she sailed across the jibe line. The answer is no. The reasoning is as follows: At that time, Rule 17, as it applied to Molly and Willie, required Molly not to sail above her proper course, which was the course she would sail to finish as soon as possible in the absence of Willie.

Finally, let’s change things a bit and assume Luke didn’t become overlapped to leeward of Molly while within two lengths of her. If that had happened, Rule 17 would not have applied to Luke and Molly at any time during the incident. Would that change how the rules apply at Positions 2 and 3? Again, the answer is no. 

The complexity of four- and five-boat incidents shows why it is very important for race committees to set starting lines and courses so the chances of boats concentrating in a small patch of water are minimized in the first place.

So don’t forget these helpful tips in how to decipher multiple boat rules. 1) At Position 1, Rule 12 gives Willie right of way over Molly and Luke, and Rule 11 gives Luke right of way over Molly;  2) Willie is then a windward boat to both Molly and Luke, so Rule 11 is “on,” Rule 12 is “off,” and Willie must now keep clear of both Molly and Luke; and 3) When Molly and Luke acquired right of way over Willie, Rule 15 applied. It applied “initially” — i.e., for only a few seconds, during which time it required both of them to give Willie room to fulfill his new obligation to keep clear of them.

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via Clarifying Rules with Multiple Boats