Jim, the CR's usually state when they apply.  The CR's often state that they apply when boats race in a class OD event.

For instance, in the J105 Class, our CR 1.3 states:

Def: rule(d) specifically includes Class Rules as a rule

So, as you can see in our CR 1.3, any time J/105's are competing in an OD event, the CR's automatically apply.  Now, we had a thread which opened a rabbit-hole regarding handicap systems.  Many racers think that if they are racing handicap that they don't need to pay attention to the CR's, but that is not necessarily the case.  In that thread we discovered several handicap systems that base their ratings of OD-class boats assuming FULL CR compliance.  So an OD boat racing in handicap systems might also be under the CR's for their class of boat.

If the rrs applies class rules apply as they are in the definition of rule in the rrs.

RRS J1.1(4) requires the NOR to include 'the classes to race'.

The class rules of whatever classes are identified in the NOR apply in accordance with the  Definition Rules.

It is superfluous, and contrary to  NOTICE OF RACE GUIDE Principle 4 to say in the NOR that class rules apply. 

Jim this is a very good topic and one that I became intimately familiar with in my former role as the J105 Fleet Measurer for the Annapolis fleet (over 30 J/105's in our local fleet) and being on the Nat'l Class TC for 10 years (I have since retired from both of those positions).

Many local OD fleets do not pay close attention to some of their CR's for local non-championship events.  Over time, this can train people to think that the CR's don't apply unless stated in the NOR or that the CR's only apply for "serious" events.

The first one of these rules to go by the wayside is crew/weight limits.  There are few fleets that have a system to weigh crew for each event or for the season (the season is a tough one as skippers find subs to compete).  Eventually the local fleet stops paying attention to crew weight all together.

Some CR's (like the J/105) have limits on who can drive the boat.  That's another one that people fudge in the spirit of "getting boats on the line".

Some CR's have the ability to tailor which rules apply based on the "level" of the event.  Again, using the J/105 CR's as an example, we have a system of letters and numbers within the CR's to tailor which rules apply in an event.

The letters A/B/C designate who can be on board:

The numbers 1/2/3 designate who can drive:

The trick here is that unless the NOR states the level of the event, the CR's state it defaults to Level 1A (the most limited).

Now, I'll climb on my soapbox for a moment .. 

I've always thought that it's the fairest to everyone that the local OD fleet decide:

For instance, our local fleet wanted to waive the crew-weight limit for 6 crew as long as there were 2 women on board.  Another was that for Level C events, we wanted to have no crew/weight limits (reserved for our weekly Wed-night races and other family-fun events).  We have that Rule 87 approval and incorporated that into our local fleet rules.

For instance, here is the NOR for Annapolis YC's Wed Night Series (it's the same NOR for the winter Frostbite Series as well).

Notice above we designate the Level "3C" and provide notice that the rules are changed by our local rules (for which we have a Rule 87 letter).  The result is anyone can drive and there are no crew limits on Wed nights.


Each local event we compete in has the same NOR wording, except we change the level.  Most weekend events are designated Level 1A, but we customize some weekend charity events with a lower designation.

All this is to say that the CR's apply when there is a OD start.  Some CR's have the ability to turn on/off rules based on the level of the event and all local fleets have the ability to request a Rule 87 letter from their Class to customize the CR's to suit their needs for local "non-serious" events.

It's something I've studied too. Wasn't there a recent thread?

78.1 requires conformity with class rules, so as said above, no need for any separate mention in N O R.

I also received an RYA opinion a few years ago that if a craft does not conform to class rules it ceased to be a member of the class.

So if a boat is entered as an XYZ her class rules apply. Even, I am confident , if it's a handicap event.If it's not entered as an XYZ, well that's another matter.

In most cases there's no need for a Rule 87 letter. If a club chooses to list in the NOR class XYZ *and* similar craft not conforming to XYZ class rules then they may. But if they want the event approved by the CA they need the letter

Many years ago I used to use the words "Class Type" in the NoR, with a caveat that any deviation from type could result in the boat having their handicap changed or being moved to a different "Cass Type". We were dealing with sailing centre boats many of which would be modified by the centre or never measured.
I don't think anyone really noticed.

Thanks all, great comments. I'm think of the Melges 15 class. I'll review the document again but it's not clear the rules are clear on when they apply. But I'll read them again with these comments in mind. 

Jim Archer,  It's pretty clear under what circumstances class rules apply.  Are you asking

Just to muddy the waters, in Dublin Bay we have fleets such as the J109 that sail one race scored 3 times: Scratch (One Design), IRC and ECHO (our local handicap system). Which technically means that 3 sets of class rules apply.