RRS 21.3 states that a boat moving sideways through the water shall keep clear of one that is not. This maneuver, often called crabbing, is very common at high levels of ILCA racing, and sailors are coached on how to do it. (See this video:
https://www.youtube.com/watch?v=avH7S9ayFrI)
But what if two boats are crabbing, i.e., moving sideways through the water. This is very common on the starting lines of major ILCA regattas.
In those situations, my guess is that Rules 10-13 come into play; specifically, Rules 10-12 if the boats don't cross
head to wind, and Rule 13 if they do.
But here's here's the rub: is "head to wind" based on
true wind direction (the wind a boat sees when luffing, net of current) or the
apparent wind direction? This matters because crabbing is most often done in light air, and moving sideways adds an apparent wind vector that pulls a boat's wind direction 10-20 degrees to the right (assuming they're starting their crab on a starboard close-hauled course and push their boom to the port side).
Here's the edge case that is especially challenging: both crabbing boats are pointed 10 degrees right of true wind, but are 10 degrees left of apparent wind. (This comes up all the time as boats attempt to increase their hole to leeward, while reducing the hole of the boat to windward of them.) If head-to-wind is based on true wind direction, the boat on the right is right of way per Rule 13; if apparent wind, the boat on the left is right of way per Rule 11. The HTW definition switches the right-of-way boats.
Thanks in advance for your clarification.
It is extremely interesting to watch the video Al has provided. Do take a look while thinking about Al's question.
I have no doubt that he'd get a yellow flag from me. My only doubt is which breach I'd write down in my notebook.
The head to wind question: the phrase apparent wind does not occur in the rules. the phrase true wind appears in the clear astern/ahead definition and a number of appendices. None of the occurences involve head to wind. I suppose one could interpret it two ways, one being that if true wind must be specified in specific rules then it must otherwise mean apparent wind, and the other that apparent wind isn't a concept in RRS so may never be meant.
Seems to me that its probably best to apply last point of certainty. If its unclear whether a boat changed tack then she did not. In the video he does in fact pass head to wind, and then sculls forcefully back.
A defence, I suppose, for the windward of two boats crabbing, is to stop crabbing, at which point leeward must keep clear. However I suppose if windward stops crabbing then RRS 15 applies. Its a bit of a mess isn't it?
The matters to consider are, principally, the boom push has no associated sculling so it is not in breach of the interpretations.
On the rock, if it propels the boat it is always a breach, we cannot usualy see this, so it does not get penalised.
As to the roll, i think there were at separate times, so not linked, so i go back to whether you are sure it propelled the boat if so penalise
The above depends on where you are viewing from, if behind, you cannot be sure, if alongside, then you can be sure.
Can be ok therfore, but always a risk of a penalty.
On true or apoarant wind.
Not easy and a contradictory answer.
I go for apparant wind caused by outside factors affecting all boats such as tide.
Wind generated by the boat does not count as it compromises wjen to an outside observer you are such as tacking.
(1) body movement
Repeated means more than one in the same area on a leg, this definition is found in the Interpretations of Rule 42. I sent a question to the US Sailing Appeals Committee concerning "the same area on a leg":
Question 2
If a boat behind the starting line rocks once 5 seconds after prep down and then rocks again 2 seconds before go, is that repeated?
Answer 2
Your questions reveal an issue with the WS Interpretations of Rule 42, Propulsion definition of the term “repeated” in that it is only relevant when a boat is on a leg. That definition does not address boats in the starting area before or shortly after their starting signal.
We will be informing the WS Rule 14 Working Group of this situation. With regards to boats in the starting area before their starting signal and shortly after they have started, until such time that World Sailing updates its Interpretations of Rule 42, Propulsion, we think it is typical and reasonable that Appendix P observers, umpires and judges interpret the term “repeated” in rule 42.2 to mean the action was performed more than once in the same area of the starting area in a relatively short period of time. It will be up to the observers, umpires or judges to determine if an action has been “repeated,” based on the type of boats, the wind and wave conditions, and what the actions of the boats were.
If I observed the the actions of the boat in the video during the pre-start while the boats were racing, I would penalize the boat for rocking, 42.2(b)(1).