The Deed of Gift governs the America's Cup. There were so many court cases filed on behalf of this particular race
that I assumed everyone knew that.
The Deed of Gift is a registered Trust document in the Supreme Court of the State of New York
in Albany, New York
The Deed of Gift mentions nothing about what kind of boat you have other than what's below this paragraph, as well as engines or lack of them. Obviously challengers must believe their boat is the fastest and it could not be the loser of a previous America's Cup match. The Cup has a 'tradition' of changing it's rules.
I quote from original the Deed of Gift which was donated through a Deed of Gift to the New York Yacht Club after a loss to the schooner America on July 8, 1857.:...." ....certificate of the name, rig and following dimensions of the challenging vessel, namely, length on load water-line; beam at load water-line and extreme beam; and draught of water; which dimensions shall not be exceeded;......"
A change was made to the rules in 1881, when the deed was rewritten to discourage inland-based yacht clubs from challenging the Cup. Boats were supposed to arrive at the start line on their own bottoms, as previously mentioned, but this rule
was eliminated in 1944 to allow the use of 12 meter boats, which only have a 44' LWL,(and fit very nicely on a 60' 18 wheeler trailer) as opposed to the 100' LWL monster America's Cup "J" boats of the 1930s.
I'm paraphrasing what can be found here:
The actual original Deed of Gift is here: