In June and August, I looked at two rules in Section B of the right-of-way rules that limit the actions of right-of-way boats. This month I will look at the third rule, the rule that defines “luffing rights” even though it never uses that term, rule 17. To understand rule 17, you first have to understand something that seems to confuse people – most boats are permitted to sail above their proper course. Many people say that a leeward boat cannot sail above her proper course, but most can. Rule 17 defines those that cannot.
In the first diagram, we see three pairs of boats. At position 1, Yellow, Green and Purple are clear astern of Blue, Red and Purple respectively. At position 2, Yellow has established an overlap from clear astern to leeward of Blue within two boat lengths. This is exactly the situation described in rule 17 and Yellow is not allowed to sail above her proper course. She is limited by Rule 17 or as most people would say, “she doesn’t have luffing rights.”
Green establishes her overlap from clear astern to windward, not to leeward. Red is now the leeward boat and Red can luff Green. She is not limited by rule 17 and she has luffing rights.
Purple establishes her overlap to leeward at position 2. A that point, she is more than two boat lengths to leeward of Gray. At position 3, she is now within two boat lengths, but as she was not when she established the overlap, so she is not limited by rule 17 and has luffing rights.
Purple establishes her overlap to leeward at position 2. A that point, she is more than two boat lengths to leeward of Gray. At position 3, she is now within two boat lengths, but as she was not when she established the overlap, so she is not limited by rule 17 and has luffing rights.
In the next diagram, we see two more pairs of boats. In the first one at position 1, Yellow is on port tack and Blue is on starboard tack. According the the definiton of overlap, since they are not on the same tack and not near a mark (so rule 18 does not apply), nor sailing more than ninety degress from the true wind, they are not overlapped. By position 2, Yellow has tacked onto starboard tack. They are now overlapped but Yellow did not get the overlap from clear astern to leeward (which would have “switched on” rule 17; instead, she got it by tacking into an overlapped position (which does not), so rule 17 does not apply and Yellow has luffing rights.
Red is overlapped with Green at position 1. If we assume that she got her overlap from clear astern to leeward, then she would be subject to rule 17 and may not luff. At position 2, she has gybed onto port tack. They are no longer on the same tack so the phrase “while they remain on the same tack” no longer applies. At position 3, she has gybed back to starboard and is now the leeward boat again. She is no longer subject to rule 17. This is a good way to gain back luffing rights whle sailing downwind.
The important part about all of this is that all of the leeward boats shown except the Yellow boat in the first diagram have “luffing rights”; none except yellow are limited to sailing “no higher than their proper course”.
17 ON THE SAME TACK; PROPER COURSE
If a boat clear astern becomes overlapped within two of her hull lengths to leeward of a boat on the same tack, she shall not sail above her proper course while they remain on the same tack and overlapped within that distance, unless in doing so she promptly sails astern of the other boat. This rule does not apply if the overlap begins while the windward boat is required by rule 13 to keep clear.
Clear Astern and Clear Ahead; Overlap One boat is clear astern of another when her hull and equipment in normal position are behind a line abeam from the aftermost point of the other boat’s hull and equipment in normal position. The other boat is clear ahead. They overlap when neither is clear astern. However, they also overlap when a boat between them overlaps both. These terms always apply to boats on the same tack. They do not apply to boats on opposite tacks unless rule 18 applies or both boats are sailing more than ninety degrees from the true wind.
© Copyright 2015 Andrew Alberti