Just curious if anyone knows the background of why the maximum luff on the blade is a full 6" shorter than the max luff on the genoa. Seems odd since most if not all competitive boats have done away with the #2, why the class rules would limit the potential size of the #3 creating a larger span in sail area from the #1 to #3.
The #3 sail plan was intended to depower the boat in big air. Going to full hoist height adds sail area at the top and provides more heel which is undesirable. Some use a #2 for a transition between the #1 and #3, but is has a very narrow effective wind range. Fully crewed, the #1 / #3 sail combination works for most boats that can swap headsails.
Ironically, the older boats such as the J/30 were designed with big overlapping headsails. Many of the newer boats (e.g. my J/109) were designed with non-overlapping headsails. For PHRF, I get trounced if I use the OD rating and the wind is less than 10 kts. I have a rating with a 145% genoa that keeps the boat competitive in light air at a cost of 3 seconds per mile.
Past president John McArthur had the same idea several years ago and it was discussed during a BOG meeting. If I recall correctly, Rod Johnstone advised against a longer luff on the #3 from a design perspective and similar point of view to that expressed above by Bill.