OK, what about the original America? Was it the fastest sail boat around set course.
What about the Js and the boats the led up to the J's?
Why are you characterising the AC by relatively recent restrictive class rules intended to get more challengers involved, when the real rules produce the fastest course racing sail boats of all time?
America was NOT the fastest racing boat of her day. She was easily beaten by John Stevens' Maria in trials before she left NY. As the renowned writer/historian/leading-edge designer of the day (WP Stephens) wrote in his "History of American yachting", "that Maria won very easily was but natural" because Maria was a larger boat and an inshore racer. Lawson claimed that Maria sailed around America three times in a short period during the trials.
So from her very trials, America was NOT the fastest boat and NOT a radical boat.
Some people, including LF Herreshoff, say that she was actually quite lucky to win the race around the Wight; there were issues about the course and faster boats fouling out and going to assist others. Be that as it may, America had 13 wins in 53 races in her career (LF Herreshoff, Golden Age of Yachting) and people like Herreshoff refer to her superiority as a "myth" despite the fact that Nat held her up as a model of the type he loved to create himself.
WP Stephens wrote that the fleet America met was NOT representative of the best British boats, but merely of the boats owned by prominent yachtsmen who did regular races. He does believe (unlike others) that America was superior but notes "the
victory of the America had no effect whatever
on the progress of yacht design in her native
country" because most owners and designers ignored her "pilot schooner" hull and went for faster, more radical "skimming dish" centreboarders. So America was NOT "bleeding edge" herself in the USA.
Schuyler himself wrote that if the AC was not a test of sea-going qualities as well as speed, then it would "essentially detract" from the interest in the Cup. So an owner of America herself was NOT calling for bleeding-edge inshore boats, but for seaworthy yachts. Note that Schuyler himself referred to DoG challenge arrangements being there "in case" mutual consent could not be arrived at - he did NOT see DoG challenges as the norm!
The early schooners were NOT leading-edge boats, either. Nor, were the early "L x SA" rule cutters anything outstanding. For example, look at the 1893 AC boats. In UK waters, Valkyrie rated 153 - much lower than Satanita, only 1 higher than Britannia. The US defender Vigilant went to the UK after the AC and rated 169. There she was beaten over the line by Britannia (Valkyrie's near sister) 11 times out of 17 races. Vigilant was also rated slower than the Soper-designed Satanita. So the AC winner was NOT the fastest boat on the water, and neither was the challenger.
Britannia and Valkyrie were near sisters, which is yet another indication that the AC boats were NOT anything very different from the normal mainsteam non-AC big boats of the day. Let's not even get into the big cutter Germania, which was a bigger, faster version of Valkyrie....
As noted, the excesses oft he L x SA boats like Reliance were cured by Nat Herreshoff's rating rule - he of all men should have known what the AC was about and as is clear from his letters on the Mystic Seaport site, he believed that sense should rule over speed.
In the 1930s, the AC Challenger Shamrock V was rated equal with Astra and Candida (23 Metres), all of which were rated 1.2 seconds per mile SLOWER than Britannia. Later AC challengers were rated only about 3 seconds per mile faster than the majority of the "Big Class'. As late as 1934, the J Class era, the schooner Westward was the scratch boat in the UK Big Class, even up against the America's Cup Js.
As late as the 1930s there were racing schooners that could beat all the AC-type cutters in the right weather and had a higher top speed; the top speed recorded for a boat of the "America's Cup cutter" style was the 13.73 knots of Satanita, known as the fastest reacher of the Big Class, whereas in the schooners Rainbow hit 16 knots, Germania hit 15 knots, and Atlantic averaged 14.2 knots for over 24 hours. So in peak speeds, the AC boats were inferior to the schooners.
All of these boats were basically big and conservative versions of smaller Metre, Universal, and Linear rule boats. For lots of detail about this, see for example John Irvings 1930s book "The Racing Yacht Brittania".
Some idea of how the AC development leaned on info from smaller conventional class-racing boats comes from the fact that when the first post WW12 challenge was received, according to the man who would know best, "Because of
their light construction the committee decided to bar both Resolute
and Vanitie, built to defend the Cup in 19 14, from consideration as
cup-defense candidates. While these yachts were eligible under the
Racing Rules (they had been constructed prior to the adoption by
the Club of Lloyd's scantling rules), the committee deemed it for
the best interests of the sport to bar them, as the Challenger would
have to be of heavier construction to comply with Lloyd's rules. As
a result of this action, the Challenger could suffer no handicap in re-
spect to weight of hull construction."
That is from Harold S Vanderbilt, most successful owner of Js. So we have one of the greats of the AC pointing out that the lighter boats were PREVENTED FROM DEFENDING by the NYYC. That is hardly the stance of a club intending that the AC be raced in bleeding-edge technology.
The Js that were adopted for the challenge were simply one of a range of cutters and sloops under the Universal Rule that ran down to the 25'-ish "S Class", just as the Metre boats ran from 23 Metres to 5 Metres. They were NOT something unusual in basic design. See, for example, Uffa Fox's writings about how design practice in smaller Universal Rule and Metre boats, which lead the larger boats in development for reasons that Uffa explained, could be used to predict the future development of 23 Metres and Js.
As an example of how closely linked the AC boats were to smaller boats, Vanderbilt was so impressed by his smaller Universal Rule M Class Prestige (54' LWL) that he "suggested
that (designer Burgess) make the model of the (succcessful cup-defending J Class Enterprise) resemble that of Prestige
as nearly as possible."
The experience of the smaller Universal boats was used directly to ascertain the LOA of Enterprise, and choosing the correct LOA was seen by Vanderbilt as one of the two critical reasons she won the AC. "Comparative data were obtainable from ex-
isting boats only up to and including the M class 50 to 54 feet
waterline. The arguments in favor of the large boat were that in
yachts up to and including the M class, those with the maximum
waterline length and with the limit of displacement had proven to
be the fastest".
The facts are clear - almost all of the AC races have been under restrictive rules creating "normal" boats, because that is what people like the NYYC, Schuyler and others wanted. Those events were sailed in boats that were NOT bleeding edge, but refined and large versions of the standard inshore boats of their day.
It is these events that created the AC legend and made the AC what it is today, not the couple of DoG matches.