As a judge in a recent ILCA championship of 30+ boats, in similar conditions you mention, our initial attention was drawn to boats where the extent and frequency of rolling downwind was higher than surrounding boats. We'd then get much closer to that boat to assess whether the boat changed course at all,. If not, then flagged. If there were changes in course and barely any tiller movements, then green light. If there was some course change but the range of rolling movement appeared to excessive and producing more acceleration than simply enough to steer in the wave conditions, then that skipper was bordering on flagging, if not crossing that line.
It's a judgement call.

In these boats, it's difficult as a judge to assess, and equally difficult to establish absolute parameters. It's a combination of motions, but whatever they are, we as judges have to be consistent and make those judgements fairly across the fleet. 

In that 3 day event of 30 boats, we flagged only 3 boats for this infraction.

I like the very practical Finn class approach with a windspeed parameter that gives the option of turning 42 on or off

Hi Al,

This is one of the most commonly misunderstood areas of rule 42.  Many competitors get penalised for this type of action, and the competitor claims that they were changing course.

This misses the whole point of rule 42.

Please refer to and read rule 42.1 Basic Rule.  

Additionally, there is a superb resource produced by Bill O'Hara and Sofia Truchanwicz which looks at common breaches of rule 42 around the race course (different classes are covered and some are translated), link here: https://site-isaf.soticcloud.net/raceofficials/rule42/index.php#:~:text=Rule%2042%20of%20the%20World,maintain%20or%20decrease%20her%20speed

I think you'll find what you need there.

All the best, Ewan

The latest versions of the common breaches documents (now called Rule 42 Judging Guides) referred to by Ewan are found on this page.
https://www.sailing.org/our-sport/race-officals/resource-centre/

Thanks Doug. The Laser link on the Rule 42 Common Breaches by Class page you provided above is broken. Here's a working link to that page. However, that page still doesn't answer my question; it only asks the question:

Is the heeling of the boat consistent with the boat's turn?

That's my question: what amount of turn (in degrees) would be consistent given 15 degrees of heel? As competitors, we're left to guess.

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Thanks Ewan. On the page link you provided, there's this Interpretations of Rule 42 document. It defines ROCK 6 as "Heeling to windward to facilitate bearing away and heeling to leeward to facilitate heading up are permitted. The heeling of the boat has to be consistent with the boat's turn."

Which again begs the question -- what amount of turn is consistent with 15 degrees of heel?

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Thanks Tim. I appreciate your sharing what you're looking for as an umpire. I agree that a massive amount of heel would be inconsistent with the basic rule. However, the situation I'm outlining is 15 degrees of heel -- not a huge amount.

Al, I don't think the amount of heel is the determinant. In itself, the heel angle alone isn't what generates speed. It's more about the frequency and speed of the roll in the prevailing conditions and if that appears to be generating extra boat speed.

Tim, thank you; that's helpful. From what you wrote, it sounds like there are two key factors in determining whether a rock is allowed under Rule 42:

1) Speed of rock. Is it a smooth roll (more likely to be permitted) or an aggressive one (more likely to be prohibited)?

2) Frequency of rock: are the turns linked to waves (more likely to be permitted) -- or are they multiple times per wave (much more likely to be prohibited)?

Since a boat will encounter surfable waves not more than once every few seconds, rocking once per wave will limit the frequency of rocks.

Among Laser Masters, the speed of the rocks is more likely to be smooth, not aggressive -- aggressive rocks tend to be incompatible with old backs. But I can see how the rocks could be very aggressive among the younger sailors.

Getting back to my original question, it sounds like you're saying that a 15-degree rock coupled with a mere five-degree turn can be compliant with Rule 42, so long as it's smooth and is once per wave (and doesn't involve any of the prohibited actions listed in the Rule 42 umpire guide).

Do I have that right?

Al,
The event we recently judged was a Laser Masters and you assume that they play the game sedately. Far from it. It takes minor body movements, subtle helm action and a little, imperceptible trim out/in to set up a result that increases roll rate and acceleration. As judges, you can see some skippers looking around them first, to see who's looking !! These are people who are already, mentally in a borderline mode. As a judge, if it looks like a duck, walks like a duck, it's probably a boat we need to get closer to, to see if it is a duck!

You are looking for some formula. I don't think that's the way to look at it. It's what happens, after whatever the action is, that determines if you broke the rule.
It's a self policing sport. You need to ask yourself: Is what I'm doing with body action, trimming  action, steering action making the boat move artificially faster than it would with just wind and waves alone. If you think you are, then don't do it. Simple as that. Just read the guides for your class of boat. It will give you an idea what the actions and results are that a judge is looking at too. It is a difficult subject to judge as a third party, and short of some indicators in the guides (e.g a flicking leach, certain directions of tiller waggle on the start), there are no absolutes. If you get called, then you must have crossed that line, that in someone else's judgement, was too far. Not all judges can judge equally, but they are using the same rules and guides you have. It's certainly easy to write a rule that's binary e.g. is there an overlap or not... if yes...then. that., but in the case of 42, it's very difficult to be crystal clear. You as the skipper know what your intentions are with every move you make. The policing starts right there. A third party is only looking at signs that APPEAR to be close and perhaps crossing, an already fuzzy line. Frankly, I think there are some classes that have given up on 42 when you see someone on the trapeze humping the boat all the way up a windward leg. Clearly that wasn't the designer's intent to sail the boat in that unnatural way !! 

Tim, thanks, but I think we're getting off track. I'm looking for the minimum number of degrees of turn that enables a rock to be considered a ROCK 6. That's it.

Sure, there are plenty of things that can be done to make a rock illegal, such as an aggressive flatten, leading to a leech flick (PUMP 5). But I'm focusing on ROCK 6, and how to comply with it, since as you say, this is a self-policing sport.

Yes, I've read the guides for the Laser, multiple times. They do not specify the number of degrees that go into a ROCK 6. Hence my question.