Don't Apply Part-2 Rules to the Wrong Boat

 

I’ve had a series of rules discussions with various people in the last few weeks, in which I’ve heard a common theme: They think that wording in a rule that applies to one boat in an incident somehow applies to the other boat, as well. The fact is, except for rule 14, Avoiding Contact, each numbered rule of Part 2, When Boats Meet, speaks to only one boat -- there is nothing the other boat can do, that breaks that rule.

This misunderstanding seems to happen mainly when it comes to the rules about giving room, in Sections B and C of Part 2.  For example, consider rule 18.2:

18.2 Giving Mark-Room

        (a) When boats are overlapped the outside boat shall give the inside boat mark-room, unless rule 18.2(b) applies.

        (b)  If boats are overlapped when the first of them reaches the zone, the outside boat at that moment shall
               thereafter give the inside boat mark-room. If a boat is clear ahead when she reaches the zone, the boat
               clear astern at that moment shall thereafter give her mark-room.

        (c) When a boat is required to give mark-room by rule 18.2(b),

            (1) she shall continue to do so even if later an overlap is broken or a new overlap begins;

            (2) if she becomes overlapped inside the boat entitled to mark-room, she shall also give that boat room to sail
                 her proper course while they remain overlapped.

The rule goes on from there, but (a)-(c) are the salient parts, for the purpose of this discussion.  Note that this entire rule restricts the behavior of only one boat -- the one required to give mark-room.  It does not restrict the behavior of the other boat.

Consider the following scenario (see the animation below).  Boat IW enters the zone of a leeward mark to be left to port overlapped inside boat OL.  As they approach the mark, IW sails an approach for a “wide then tight” rounding, rather than sailing directly to the mark, which is what she is entitled to room to do (see the definition Mark-Room).  OL sails alongside her while hailing “Hey!  You’re taking too much room!”  OL protests, alleging that IW broke rule 18.2(b); but the protest committee denies the protest.   

 

What was the protest committee thinking?  Well, according to rule 18.2(b), OL must give mark-room to IW; the rule says nothing about what IW might or might not do.  Put another way, there’s no rule against “taking too much room”.  So in order to be disqualified, IW would have  to break some other rule, and since she was the keep-clear boat, that means she would have to fail to keep clear under rule 11, Overlapped on the Same Tack.

This takes us to the definition of Keep Clear, which says, “A boat keeps clear of a right-of-way boat (a) if the right-of-way boat can sail her course with no need to take avoiding action, and, (b) when the boats are overlapped, if the right-of-way boat can also change course in both directions without immediately making contact.”  Did OL ever have to take avoiding action?  No; she simply sailed her course alongside IW.  Did the boats ever come close enough that OL could not change course without immediate contact?  Again, no.  So IW broke no rule.

This is sometimes referred to as “room freely given”, using the words of World Sailing Case 114, but, with apologies to the Casebook writers, I think it’s a mistake to use that expression.  I think that, to the extent possible, we should not create concepts that aren’t in the rules themselves.  The same Case could have come to the same conclusion by simply stating that the boat required to give room did so and the other boat broke no rule.

If OL wants to protest IW, she must force the issue by luffing slowly, giving IW room to keep clear of her.  If IW does not respond by changing course to sail directly to the mark, and OL has to bear off to avoid hitting her, then OL can protest IW for breaking rule 11 -- OL had to take avoiding action.  IL is not exonerated under rule 43 because she didn’t begin sailing a course directly to the mark until after position 3, when she had already broken rule 11. 

Note that if one boat's behavior is restricted under one rule and the other boat must keep clear under another rule, both rules still apply.  In particular, the keep-clear boat is not freed from her obligation to keep clear (though she will be exonerated if she sails within the room to which she is entitled).  A good example of this is rule 17, On the Same Tack; Proper Course.  That rule says that under certain conditions, when a boat establishes an overlap to leeward of another boat from clear astern she shall not sail above her proper course.  Rule 17 only refers to the proper course of the leeward boat – it says nothing about the course of the windward boat, and it does not free the windward boat of her obligation under rule 11, Overlapped on the Same Tack, to keep clear.  So, for example, if the leeward boat carries an asymmetrical spinnaker and the windward boat carries a symmetrical one, the course the windward boat will have to sail to keep clear under rule 11, Overlapped on the Same Tack, is usually going to be much higher than her proper course, even if the leeward boat obeys rule 17.  In the scenario below, Yellow could not change course to windward at position 3 without making immediate contact, so Blue breaks rule 11.

Here’s another example, from an incident a couple of weeks ago, in which a boat thought wrongly that a rule applying to her also limited the other boat.  WS and LP were sailing downwind on port tack, with WS overlapped to windward of LP (see scenario, below).  WS jibed onto starboard and the boats converged.  LP held her course until WS had to bear off to avoid contact.  Then LP jibed away and there was no further incident. 

 

LP protested WS under rule 15, Acquiring Right of Way, which says, “When a boat acquires right of way, she shall initially give the other boat room to keep clear, unless she acquires right of way because of the other boat’s actions.” 

The first issue here is whether WS initially gave LP room to keep clear.  In the discussion, I asked LP whether she had kept clear after WS jibed, and she replied “Yes.”  I asked her whether she had done anything unseamanlike, and she said she hadn’t.  So I asked her how she could claim WS hadn’t given her room to keep clear, when she had kept clear and in a seamanlike manner.  She said, “When WS jibed, she had to let me sail my course without taking avoiding action.  That’s what the definition of Keep Clear says.  And because I had to jibe away, she broke that rule.” 

I think she got that definition backwards.  As we saw earlier, the definition Keep Clear speaks only about the right-of-way boat taking avoiding action.  LP was, from position 3, the keep-clear boat, so the definition doesn’t say anything about whether she was needed to take avoiding action; she needed to do whatever it took, in a seamanlike way, to keep clear.

The second issue is whether LP herself broke any rules.  In my opinion, LP broke rule 11.  It’s true that LP didn’t have to begin to take action until position 2 to keep clear – there’s no requirement in the rules to anticipate a change in right of way – but she does have to begin to take action immediately when WS's mainsail crosses her center-line, just before position 2.  These particular boats were about 21’ long and traveling at about 6 knots, so they would sail a boatlength every 6 seconds or so;  that means LP sailed something like 20 seconds before she jibed.  20 seconds seems to me to be a very delayed reaction. (If you don’t believe that, imagine the skipper of LP saying "Jibing!" at position 2 and count out 20 seconds while visualizing the action aboard LP as they prepared to jibe.)  So, to my mind, LP broke rule 10, On Opposite Tacks.   

There’s one additional fact in this scenario that would, I believe, have helped a protest committee decide to penalize LP: the boats were only 5 or 6 boatlengths from the finish line and WS was on the layline to the starboard end of that line (see diagram below).  One of the things judges must do in considering the evidence is to understand the tactical significance of the boats' actions; this is one reason why it’s so important for judges to have extensive racing experience.  In this case, there’s an easy explanation for LP’s failure to respond to WS’s jibe: she wanted to get to the finish line without having to jibe twice.  That’s not conclusive evidence, of course, that she didn’t respond promptly to WS’s jibe; but it would help the protest committee determine the credibility of LP’s claim that she needed all that time to prepare to jibe.

 

Changes to the Racing Rules of Sailing for 2017

The 2017-2020 Racing Rules of Sailing (RRS) have been finalized and published on the internet. These rules come into effect on January 1, 2017 and can be found at http://www.sailing.org/documents/racingrules/. The printed version, with US Prescriptions, will be available to members of US Sailing this month.

As in previous rulebooks, all changes from the previous version of the rules are indicated by change bars in the margins. But, unless you have your old rulebook in your hand or (God forbid) have memorized the rules, the change bars won't do you much good, as they don't indicate what change was made.  And even if you do a word-by-word comparison, you still generally won't know why the change was made.

For detailed answers to those questions, go to the same page as above and click on “Racing Rules of Sailing 2017-2020 Study Version”. That document, compiled by Dick Rose, shows all the changes in red; but also, if you click on the last word of the change (in blue), you can read the submission that led to the change. The submission shows what wording was originally proposed and, more importantly, the reasons given to the World Sailing Racing Rules Committee that caused that committee to adopt the change.

If you do look at Dick's study version, you'll see a lot of red, especially near the beginning of the rulebook and at rule 69. From this, you might conclude that the new rules are a huge revision of the 2013-2016 rules; but for most sailors, the changes are extremely minor. Below, I summarize the changes to the rules we're most interested in: Part 2, When Boats Meet. But first, a word about the massive red ink.

Much of that red ink is legalese, addressing how to discipline coaches, medics, and other support personnel (including a new definition of “support person”, which says nothing not already in the ordinary meaning of the expression), as well as a new rule against betting (as if our sport should be so lucky as to attract the attention of bookies!) and yet another new rule, about the World Sailing Disciplinary Code (which I admit I haven't read). Additionally, rule 3, Acceptance of the Rules, now reads like an insurance contract. These rules are, incidentally, “Fundamental Rules” of Part 1.

To my mind, these legalistic changes make it clear how detached the top people at World Sailing are from the thousands of us who actually participate in this sport. I, personally, have never had my own sailing coach, let alone my own medic. Are these people really a problem? Maybe at some top events, but not for the vast majority of event organizers and sailors like me. All the people who will never run or attend an Olympic event will just have to leaf past the Fundamental Rules, I guess. I hope they don't miss rules 1 and 2, which are the only Fundamental Rules that are actually fundamental.

The rules we really need to read and know are the rules of Part 2, When Boats Meet, and the corresponding definitions.There have been seven changes in Part 2, none of which is likely to affect any of us much. These are summarized below.

Change 1: The preamble to Part 2 has been changed to permit penalties for boats that break rule 14, Avoiding Contact, in an incident when the boats are not racing, if there is injury or serious damage.

The rules of Part 2 apply to boats that are “sailing in or near the racing area and intend to race, are racing, or have been racing”, but until 2017, a boat not racing could not be penalized except for breaking rule 24.1, which says, “If reasonably possible, a boat not racing shall not interfere with a boat that is racing.” Starting in 2017, if a boat not racing breaks rule 14 and causes serious damage or injury, she can be penalized. Note that if the other boat's score in a race was seriously affected by such an incident she has always been entitled to request redress, and that won't change in 2017.

Change 2:  Rule 18.2(d), which deals with when a boat is no longer entitled to mark-room under rules 18.2(b) and (c), adds the statement "[Those rules] cease to apply when the boat entitled to mark-room has been given that mark-room." This addition incorporates into the RRS the conclusion of an excellent Q&A published in 2013 (since renamed B 005), so in some sense it's not a change in how rule 18 works; but it's always good to have basic principles in the rules themselves rather than in other documents.  For a full explanation of the reasoning behind this change and its implications, see my earlier blog, "When does rule 18 turn off?".

Change 3: Rule 18.3, Tacking in the Zone, has been extensively rewritten. This rule is more complicated than the 2013-2016 rule, but actually it now says what most sailors thought it said before – in particular, that rule 18.3 applies only at port-hand windward marks and only between a boat that tacks in the zone and one that doesn't.

The first change, making rule 18.3 only apply at marks to be left to port, is of little interest to most sailors because we commonly only encounter port-hand windward marks. In fact, rule 18.3 was really written for port roundings. Its basic purpose was to solve a problem that had become common in large fleets before rule 18.3 existed, where boats tacking in at a port-hand mark caused boats on the layline to luff up and stall, thus creating a cluster of boats nearly stopped at the mark, preventing all boats behind them from rounding the mark. When teaching rule 18.3, I emphasize that its purpose is to encourage boats coming in on port tack to find their way through the boats on the starboard layline and tack above them, rather than crash-tacking at the mark.

But in the case of a mark to be left to starboard, the situation is reversed. The boats on the layline are on port tack, and the boats that have to tack to round the mark are on starboard, with right of way. In that situation, we want to encourage the starboard-tack boats to tack at the mark (as long as they can do so without tacking too close). If they continue on starboard tack past the layline, they may cause havoc as the port-tack boats are forced to tack away to avoid them. So current rule 18.3 is counter-productive at starboard-hand marks. The 2017-2020 rule solves that problem.

The second change in rule 18.3 stems from a question that was raised some years ago about what happens when two boats both tack in the zone. Suppose PL and PW are on port tack inside the zone of a port-rounding mark and they meet S coming in just above the layline on starboard tack. Both port-tack boats tack ahead and to leeward of S. It's clear that they both have to obey rule 18.3 with respect to S, i.e., they cannot cause S to sail above close hauled or prevent her from leaving the mark to port, and that hasn't changed in the new rule. But under the 2013-2016 rule, which of PL and PW has to obey rule 18.3 with respect to the other?

The answer depends on which boat passes head to wind first. Normally, I'd say, “So what?” One or the other tacks first, and current rule 18.3 applies to the other boat. But the problem here is that  commonly both boats wait until the last possible moment and tack together. So it's very hard for even the crews of the two boats, let alone a protest committee, to know which boat passed head to wind first.

The solution is to only make rule 18.3 apply between a boat that tacks in the zone and a boat that sails into the zone on the opposite tack and is fetching the mark, which fortunately is exactly what most sailors thought the rule said, anyway.

Change 4: Rule 19, Room to Pass an Obstruction, has been changed so that when three boats are overlapped going into a mark and rule 18.2, Mark-Room, applies, rule 19 does not. To see why this change is necessary, consider the following very simple scenario: Three boats, W, M and L are approaching a leeward mark to be left to port, all on port tack and all overlapped when they enter the zone. As everybody knows, the outside boat L owes mark-room to the middle boat M, and M owes mark-room to the inside boat W. So far, so good. But L has right of way over both M and W and hence is an obstruction to them. According to rule 19.1, W owes M room to pass the obstruction (L) on the same side. Now suppose there is contact between L, M, W and the mark; what then? Most protest committees would penalize only L, the outside boat, for not giving M and W mark-room. But under the current rules, that's wrong – W should also be disqualified under rule 19.1 for not giving M room to pass the obstruction L!

There are a lot of words in new rule 19.1(b) about overlaps. Why not simply say that when rule 18.2 applies, rule 19 does not? To answer that question, consider two port-tack boats, PW and PL, inside the zone of a windward mark to be left to port, and a starboard-tack boat S, also approaching the same mark. If PL decides to duck S, she has to give PW room to duck S, too – and the rule that says so is rule 19. So we clearly need rule 19 to apply in this situation, even though rule 18.2 also applies between PL and PW.

Change 5: Rule 20 has been changed for 2017-2020 in order to make it illegal to hail for room to tack unless there's an obstruction that the hailing boat must change course to avoid. The 2013-2016 rule is not clear on that point. It begins, “When approaching an obstruction, a boat may hail for room to tack and avoid a boat on the same tack. However, she shall not hail if ...” The rule goes on to list the reasons a hail might be invalid. If there is in fact no obstruction at all, the hailing boat does not break this rule because the rule doesn't apply. So under the 2013-2016 RRS, the hailed boat has to decide whether there really is an obstruction. If there is no obstruction, then she need not tack. But if there is an obstruction and it's a right-of-way boat the hailed boat can't see, or a person in the water, or some other object visible to the hailing boat but not to the hailed boat, that could be a catastrophic decision.

What we'd like to have is a rule that says the hailed boat has to tack, obstruction or not, and if she thinks there was no obstruction, protest. The 2017 wording accomplishes that by moving the lack of an obstruction into the list of reasons the hail is illegal.  The 2013-2016 rule begins,

“A boat may hail for room to tack and avoid a boat on the same tack. However, she shall not hail unless
(a) she is approaching an obstruction and will soon need to make a substantial course change to avoid it safely, and … “

The new wording doesn't set the scene as well as the 2013 wording, but it does solve the problem.

In case you think this is about angels dancing on the head of a pin, this exact situation came up in a race in which I was participating a few weeks ago on the San Francisco city front (where there can be a ferocious current and rule 20 is used a lot). A boat several boats to leeward of us hailed, the hail was passed up through the intervening boats, we all tacked, and later it was determined that there was no obstruction the hailing boat needed to change course to avoid. It would have been fruitless to protest under the current rule – but next year, it will be a different story.

Change 6: Rule 21, Exoneration, has been moved and extended. In the 2013-2016 RRS it is the last rule in Section C, Marks and Obstructions, and says that if a boat is taking room at an obstruction or mark-room to which she is entitled under a rule of Section C, Marks and Obstructions, she is exonerated from breaking a right-of-way rule or rules 15, 16  or 31 (Obtaining Right of Way, Changing Course and Touching a Mark, respectively). Rule 21 will now be the first rule in Section D, Other Rules [that apply when boats meet], and the words about rules of Section C are deleted. This means that no matter what rule entitles a boat to room or mark-room, if she breaks any right-of-way rule or rule 15, 16 or 31 while sailing within the room to which she was entitled, she is exonerated.

The effect of this change is that rule 21 will apply to situations where a boat is entitled to room to keep clear, as well as situations where she is entitled to mark-room or room to pass an obstruction. For example, if boat B establishes an overlap to leeward of A from clear astern, and A immediately tries to keep clear but is unable to do so because B didn't give her enough room, A breaks rule 11, On the Same Tack, Overlapped. But the reason this happened was because B didn't give her room to keep clear, and she will be exonerated under rule 21 for breaking rule 11.

Until now, this has been covered by rule 64.1(a), which says that a protest committee shall exonerate a boat if she was “compelled” to break a rule by another boat that was already breaking a rule. Putting the concept into rule 21 is a cleaner solution and removes the issue of whether the boat entitled to room was compelled to break a rule. Overall, though, there is no practical impact on sailors of the change to rule 21.

Change 7: Rule 22.3, which currently says, “A boat moving astern through the water by backing a sail shall keep clear of one that is not,” has been expanded to deal with boats that are moving sideways through the water by backing a sail. From 2017 on, boats crabbing sideways by backing a sail must keep clear of boats that are not doing so.

This apparently tiny change has the biggest repercussion of all the Part 2 changes for 2017, at least for small dinghies. I recently judged an Optimist Dinghy event where at every start, sailors were coming up to the starting line, pushing their booms out to leeward and pulling their helms up to windward at the same time. The net effect is for the boats to crab to windward, opening the gap with the boat to leeward and closing the gap with the boat to windward. Under the 2013-2016 RRS, the windward boat (that was not crabbing) was required to keep clear, even if that meant tacking away or sheeting in and crossing the starting line early. (In Optis and many other dinghies, she cannot separate from the boat to leeward by imitating the crabbing maneuver unless she has way on, without sculling and breaking rule 42.) Under the 2017-2020 RRS, the crabbing maneuver is still legal, but the boat crabbing to windward by backing her sail must keep clear of the boat to windward of her.

IRPCAS? I think not.

The Preamble to Part 2 of the Racing Rules of Sailing (RRS) contains an interesting provision: “If the sailing instructions so state, the rules of Part 2 are replaced by the right-of-way rules of the IRPCAS or by government right-of-way rules.” (IRPCAS stands for International Regulations for Preventing Collisions at Sea, usually called the COLREGS. The US Coast Guard publication containing these rules can be found here.)

The rules of Part 2 govern the conduct of racing sailboats when they meet, including right of way, mark-room, and room at obstructions. In theory, regatta organizers could throw out those rules and substitute the IRPCAS rules of the road for their entire regatta, but I've never heard of this being done. The only situation I've heard of in which IRPCAS rules replace the rules of Part 2 is for long-distance races, and even then, only during hours of darkness. But even in that limited application, IRPCAS rules of the road don't really work for sailboats racing each other.  

The idea behind invoking IRPCAS rules in long-distance races is that those rules rules don't allow close maneuvering, so the boats would be safer than they are under the rules of Part 2. But I have the feeling that many of the folks who write sailing instructions replacing RRS Part 2 with IRPCAS rules of the road really don't understand what they're doing. Here are a few facts about the IRPCAS rules as they would apply to sailboats racing:

1. IRPCAS rules apply to any pair of sailing boats in sight of each other (IRPCAS Rule 11). That's a long way apart – at least 5 miles in most cases. Technically, the RRS also apply to boats far from each other, but the rules of Part 2 only require boats to take action when they are in close proximity.  IRPCAS rules require boats to take action as soon as it appears that, on their current courses, the boats might collide; at that time they could be miles apart.

2. Under IRPCAS all vessels are required to maintain lookouts, “by sight and hearing”, and vessels equipped with radar must use it (IRPCAS Rules 5, 7(b)). In fog or other reduced visibility, vessels must slow down to “a safe speed adapted to the prevailing circumstances and conditions of reduced visibility” (IRPCAS Rule 19). Such conditions include background lights ashore at night, as well as fog and rain (IRPCAS Rule 6(a)).

3. In terms of maneuvering, a give-way vessel must “take early and substantial action to keep well clear” (IRPCAS Rule 16), and a stand-on vessel must maintain her course and speed (IRPCAS Rule 17(a)) except to avoid imminent collision (IRPCAS Rule 17(b)). If there is any possibility of danger of collision, give-way vessels must act as if there is such danger, and take appropriate action (IRPCAS Rule 7(a)).

4. IRPCAS does not assign right of way between two boats under sail the same way as do the RRS. Under both sets of rules, port-tack boats must keep clear of starboard-tack boats and windward boats must keep clear of leeward boats, but there is one big difference: RRS 11 only requires a boat clear astern to keep clear of a boat clear ahead if the two boats are on the same tack, while IRPCAS requires the boat astern (the “overtaking boat”) to keep clear regardless of what tacks the boats are on. Further, in that situation if the boat ahead changes course, the overtaking boat must continue to keep clear even if the boats are now in a crossing situation (IRPCAS Rule 13(d)). For example, if both boats are on starboard tack to begin with, and the boat ahead tacks onto port and crosses the other boat, the boat that was clear astern must continue to keep clear even though she is on starboard tack and the other boat is now on port tack!

5. Of course, the IRPCAS have no rules equivalent to the rules of Sections B and C of Part 2, because the IRPCAS rules do not envision that vessels will come close enough to require “room” or “mark-room”.  (There is also no equivalent to the rules of Section D, but those rules are not likely to apply to boats racing offshore at night.)

The fact that IRPCAS and RRS assign right of way differently should make us wonder how much safer boats will be, racing under IRPCAS.  Racing sailors may or may not know the racing rules by heart, but most of them know and understand the game defined by those rules. On the other hand, most are totally unfamiliar with the game defined by IRPCAS. How much safer can it be to suddenly drop a fleet of racing sailors into that new brier patch?

As a full-time cruiser with tens of thousands of miles of passages under my keel, I'm pretty familiar with IRPCAS, and in my opinion there's no way anybody could reasonably race sailboats under the IRPCAS rules. On our cruising boat, if we see a vessel approaching on a nearly constant bearing, we hail her on VHF Channel 16 when she's at least a mile away. If she responds, we negotiate the crossing (“Request permission to cross ahead of you,” or “We will slow and pass astern of you,” etc.). If she doesn't respond and we are the give-way vessel, we immediately take avoiding action – even though the other vessel is still almost a mile away! IRPCAS requires that such action be substantial enough so that it is “readily apparent” from the other boat (IRPCAS Rule 8(b)), so slowing from 6 knots to 5.8 knots or changing course by 5 degrees won't satisfy the requirement, even if such an action is all that's needed to avoid the danger of collision.

If we are racing against each other with you on port tack and me on starboard, would you negotiate with me on VHF radio regarding which of us should change course or (gasp!) reduce speed? If you're the keep-clear boat, would you change course substantially (basically, tack or bear off by 20 degrees or so) while we're still, say, a mile apart, as required by IRPCAS? I think not; but if the sailing instructions mandate IRPCAS, I can protest you if you don't.

While the IRPCAS requirements on give-way vessels seem extreme, the limitations imposed on stand-on vessels are even more onerous. IRPCAS Rule 17 says that a stand-on vessel “shall keep her course and speed” when another vessel is keeping out of her way. Suppose X and Y, both 50-foot boats, are beating to windward on the same tack with X ahead and to leeward of Y. Because Y is the “overtaking vessel”, she is required to keep out of X's way, which she is easily doing. Now suppose X discovers that she's entering an adverse current or big header and decides to tack. That means changing course toward Y, and if X's new course puts her on a more or less constant bearing from Y's point of view, then when X tacked she broke IRPCAS Rule 17. If the boats are racing under IRPCAS, Y may protest and get X disqualified, even if it takes little effort for Y to avoid X on her new course, or X tacks back when she is still several boatlengths away from Y.

Of course, if boats will round a mark or cross a finish line at night, all bets are off. IRPCAS is simply not set up to handle situations where vessels purposely put themselves in danger at full speed. It's hard to imagine a mark rounding or finishing scenario in which all boats within sight of each other don't break IRPCAS, one way or another. Protests galore!

So, if IRPCAS rules aren't the solution, what can be done to make night racing safe? My idea is to keep the RRS, including Part 2, but establish an understanding of what it means to keep clear, that ensures greater distances between boats.

The first part of the definition “Keep Clear” in the RRS says, “A boat keeps clear of a right-of-way boat … if the right-of-way boat can sail her course with no need to take avoiding action ...”. Organizers can't change that definition (see RRS 86.1) but the expression “need to take avoiding action” is not a defined term in the RRS and depends on the prevailing conditions. In daylight, even maxi yachts are accustomed to sailing within a boatlength or less of each other at full speed, but at night in the open ocean, surely a crossing at speed with only a length or less between the boats will have both crews terrified, and the right-of-way boat might well think she needs to take avoiding action.

So I suggest a provision in the Notice of Race and Sailing Instructions, saying something like:

“In the case of a protest, the jury will make the following rebuttable presumption: Between sunset and sunrise, if boats come within two of the longer boat's overall length of each other, the right-of-way boat needs to take avoiding action.”

Obviously the organizers could take an even stronger position and drop the word “rebuttable”, but I think that's unwise. “Rebuttable presumption” means that the jury makes that presumption but upon strong enough evidence that it is not true they may drop the presumption. For example, if a port-tack boat crosses a length and a half behind a starboard-tack boat, the starboard-tack boat wouldn't feel she needs to take any action to avoid the other boat because the boats are, at that point, sailing away from each other.  In that case, the jury is free to drop the presumption.

Note that if the jury keeps the presumption, rules requiring the right-of-way boat to give the other boat “room to keep clear” are broken if the actions of the right-of-way boat brings her within two lengths of the other boat. For example, if the right-of-way boat changes course so as to bring the boats within two lengths of each other, she breaks RRS 16.1 because the other boat needs to take avoiding action, under the presumption in the sailing instructions. By the same reasoning, an overtaking boat on the same tack breaks rule 15 if she establishes a leeward overlap at night within two of the longer boat's lengths. This puts more of a burden on such a boat than the “proper course” restriction of rule 17.

Overall, my advice to organizers of long offshore races is, stay away from IRPCAS as a replacement for the rules of Part 2, and be sure to communicate clearly to competitors that the distance needed to keep clear at night is substantially greater than the distance needed during daylight.