Dear Sail7seas - I believe that:
From 2001 - 2004 Appendix A:
A4.2 A boat that did not start, did not finish, retired after finishing or was
disqualified shall be scored points for the finishing place one more than the
number of boats entered in the series.
is for the following reasons - (at least one of the reasons that I understood):
It was for a time, fashionable if you will, to go out, cross the start line, hang out for a while and then retire. This was popular in extremely heavy air. That way you beat the boats that stayed on the beach when the rule was "number of starters plus 1"
They changed it to "number of entries plus 1" for safety reasons. Now there is no benefit to go out if you think you cannot finish the race.
... at least that’s my recollection of one of the reasons it changed.
Rico
Fleet 204 . Com 
