i agree on all, even if it go, it seems, against Q&A 2018-006
i agree 
- because boats should know who's their opponents, and their score cannot change at the end of the event  (and that happened to a friend of mine in Spain; after 9 races, he was 2nd, but then 2 boats were taken out of the score, because duly registered, but never started and never paid the fee; 2 points less to the  DSQs, that included his main opponent, and he lost the podium. Rather unfair. Those 2 boats has been scored DNC for 8 races, then disappeared.)
- because I believe if a boat races, she is under the RRS, and if she breaks a rule, shall  be penalized accordingly (w or /o hearing). Not complying with 75.1 is just that: breaking a rule.
- because if RRS 78.2 already takes care of something very similar ( fail to present a valid certificate = boat is IN the event, but then DSQ) so same concept can be applied to other faults
- because if a boat should not be in the event, she must be denied the entry before the first race (RRS 76.1). If she has been warned,  and she's racing anyway, she is  IN, but then RRS 2 and possibly 69, to be presented to her Club for any deemed actions. If not warned, by OA mistake, the boat is IN, and she can be protested for RRS 75;  I would exclude RRS 2 and 69. And I would not DSQ without a hearing. 

well, i might not be right, but that's how i'd act,  if it happen to me,  as PC

Aldo, I do not think this SI goes against the Q&A, which pertains to calculating A5.2.  A5.2 already differentiates between entered and not-entered boats by stating ...

The above SI’s applies to A5.1. It’s purpose is to allow RC’s to DSQ boats that are not entered without the need for a hearing .... which is what most of them are probably doing now anyway.  

What am I missing here? If a boat has not entered a race or series she surely cannot be given a score, be it 1st or DSQ.  Nor should she - as Aldo illustrates above with his tale of retrospective scoring actions applied to boats that should never have been given scores in the first place.  It is the fundamental way in which we keep control of our events. 

Malcom, I laid it out in the reason section.  

Like I said, YC’s are functioning now as if the rules said what this SI allows. This is just putting those words in place.  

PS: Paul (on the Zombie thread) brought up a good example.  

His YC had COVID contact tracing documentation requirements as part of entry.   Though this might seem “ancillary” to the core functions of sailing and racing to a competitor (and therefore might come out and race though their entry is deficient thinking the requirement is trivial), if the RC has added this as an entry requirement ... that boat is not entered if it is not done. 

Now this boat comes out and starts and finishes.  A4 says she must be scored.  If the SI’s required this doc before racing, the boat can’t sheepishly cure this after the race.  Now the RC wants to DSQ this scored boat without a hearing. That’s what this SI allows. 

Aldo re: “- because if a boat should not be in the event, she must be denied the entry before the first race (RRS 76.1). If she has been warned,  and she's racing anyway, she is  IN, but then RRS 2 and possibly 69, to be presented to her Club for any deemed actions. If not warned, by OA mistake, the boat is IN, and she can be protested for RRS 75;  I would exclude RRS 2 and 69. And I would not DSQ without a hearing. ”

That question is what I was getting at in Facts 3 of the Zombie thread here: 
https://www.racingrulesofsailing.org/posts/803-what-is-rule-76-1s-entry-of-a-boat

I'm afraid that if a boat sails across my finish line but is not entered in my race or series she does not get listed in the results because she is not part of that race or series because she has not entered. The requirement to enter is specified in the Notice of Race (or at least it is in my NoRs, usually under Paragraph 3 Eligibilty and Entry).  What's she going to do? Claim Redress?

Malcom, I get what you are saying.  Certainly, RC’s all over are proceeding as you suggest. 

My point is only that it is a simple SI which codifies that RC action in the rules. Since I started this thread, I added an option to simply modify A4 as an alternate (maybe more simple) approach (above in OP).  

Angelo: I take your point.  Certainly it is worth clarifying somewhere in the documentation that to be properly accounted for in the race or series a boat must be properly entered. You have assuredly alerted me to that requirement..

Malcolm .. maybe something as short and simple as this ticks the box ?...  

"A boat lacking an entry under RRS's 75.1 or 76.1 will not be scored.  This changes RRS A4."

We use:

To be registered and scored in the event each boat owner must complete all registration steps and pay all fees on-line on the regatta website.

Sue .. did you mean "entered" instead of "registered" in its first use?  Also, that chances A4, so might want to add that at the end. - Ang

"To be registered [entered] and scored in the event each boat owner must complete all registration steps and pay all fees on-line on the regatta website."

Haven't had a problem using registered.  And not sure how this changes A4 as they don't get a score and are not even on the results 

re: " And not sure how this changes A4 "

RRS A4 says that an RC shall score boats that start and finish.  Start and finish do not require entry or registration in the event. Therefore, I'm suggesting that by not scoring them if not entered or registered, it changes A4.

re: "registration" in the first use ..

oh .. OK .. I thought it might have been a typo that's why I asked. FWIW, using "entered" in the first use might be tighter as "enter" is the term used in RRS 75.1.

Angelo, I think Q&A 2021.003 provides some clarification that a boat which has not complied with all of the entry requirements specified by the OA is not entered and does not exist for the purposes of the event. She can't be DSQd and can't be scored in any form including "NOE". I think a boat that did not enter the event did not race and did not intend to race. The RC erroneously putting her on a "list of entries" doesn't change that status.

I still think the best solution to this is for the OA to keep "entry" requirements to a minimum (sign up and pay fee). Any other requirements regarding measurement, contact tracing (hopefully that will become irrelevant soon) or anything else can be required by the NOR or SI and thus sanctionable either with or without a hearing.

I'd say that the recourse against a racing boat that doesn't enter but comes out and sails around the racing area anyway interfering with racing boats would be a rule 69 report for a breach of good manners and sportsmanship.

Thanks for sharing that Q&A.  It’s interesting how they answered the following Q’s. Like you said, it’s like the competitor is completely non-existent.