Anthony, we also had our "Zombie" thread which explored ideas of "Entry" and scoring here: Enter” the Zombies? - Ang

We have this problem in spades in our Friday Night and Midwinter regattas.  Net net, we amend the RRS. DNF = finishers plus one. DNS/C/SQ = Starters plus one.  Sometimes we allow single-race entries which, again, we amend not to count in the point assignments.

If the NoR makes no mention of scoring: Number of entries = 10, therefore a DNF scores one more than the number of entries, so both the DNC boats and the guy who turned up but DNF get 11 points. The answer in the old rules used to be A9 which was always in force but with the current rules the answer is to state in the NoR or SIs that Appendix A5.3 applies to the series.  If this had been done then the DNC boats still get 11 but the DNF, DNS, NSC, DNF RET, DSQ or UFD or BFD get one more than the number that came to the starting area for that race i.e. they get 8 points.  It could be seen as an incentive to turn up.  As mentioned above A5.3 must be invoked by the NoR ir SIs.

If your NoR didn't invoke A5.3 then you score DNC, DNF, DNS the same. A boat is entered if they correctly fill in and submit to the OA as per the OA's NoR. If they don't show up DNC - because, well they didn't compete. :)

It seems to me that a customized application of A5.3 has much more impact when scoring series that span a season, such as a Wed Night racing series that might span months.   In those instances, I think it’s very important to have that provision.  Often, boats will sign-up for the entire season though they know at the beginning that they might only make a few races, and those entries can add up to have a dramatic impact on DNC/DNF scores. Also, you might have a large number of boats decide to stay ashore due to weather on a particular race or for other circumstances, which would give a huge scoring advantage to those who decided to race that particular day. 

In the case of weather, I think it helps prevent the sailboat race changing to a “game of chicken” in the face of questionable conditions.

PS:  scoring for season-long awards that accumulate results from independent regattas can  have scoring rules that are independent of the scoring for the event.  For instance here in the Chesapeake Bay (Annapolis, MD) we have season-long awards called “High Point”, which disregards the scores of the events and aggregates a score based upon the number of boats beaten .. tossed into a formula.   Therefore, it does not matter whether the individual regatta referenced A5.3 or not. 

PS#2: personally I like a customized version of A5.3 which gives DNF=F+1 and DNC=F+2

So, in a single day race, not a series, the OA authorities NOR should be clear on what constitutes an entry? 

At the end of the day Rule 75 applies - if the OA has described how to enter, thereby constituting what qualifies a boat for entry, and the boat meets these requirements, the boat is entered. This SHALL be included in the event's Notice of Race (J1.1 (3)). Doesn't matter if it's a series or single race day. If the boat completed the entry process correctly, the boat is considered entered. How the DNC is scored can be different between a series over a period of days and a single event but it needs to be defined or declared in your race documents.

... in support of what RBYC-SO replied, there is a Q&A from our "Zombie" discussion: Q&A 2021.003 which underlines their point. -  Ang