Orma 60 was actually an open development class - cats were class legal and at least one was built.
The tri is a unique solution here because the DoG limits the boat based on Load Waterline Length. With the tri, you can mostly float everything on the center hull which nails the load waterline limit. Meanwhile, the amas barely touch the water at their deepest rocker...hence why we see the huge bow and stern overhangs on the amas on DogZilla. Since the center hull should ideally be flying, it's water shape is less important than it's measurement shape. It also allows for the weight of the boat to change significantly without affecting the measured LWL...for instance...changing different rigs and adding crazy things like rigid wings.
The catamaran has a tougher time pulling this off and the loading/weight has to be precise to get the measured LWL right - presuming they're trying to get the same kind of overhangs with the benefit of an extended hull length under sail. Getting LWL and weight right also dictates the hull shape more-so than the tri. The tri's ama rocker / shape can be optimized for sailing without much regard for static measurement since the center hull carries the burden for that.
Thanks Jake, I didnt know that. So, the tri would have a measurement advantage under the DOG rules.
I guess thats why Alinghi has that weird bow too, to keep within the static waterline measurement rules.
I've been fascinated at the thought process behind the designs but I have yet to really understand why Alinghi's bow is so proud of the water. I have a theory that they had intended to have a stern overhang while at rest similar to DogZilla and perhaps even with the top of the rudder airborn. Later, they saw an opportunity to mess with the measurement rule to subversively include the rearmost plane where the rudders enter the water into the LWL measurement and give BMWO a humongous headache. All they had to do was add ballast to the rear of their boat sinking the sterns and lifting the bows. Their water line measurement just moves rearward but remains mostly the same overall. In the case of DogZilla, the amas extend well behind the center hull and the rudders are tens of feet from the stern of the center hull. At rest, the rudder/hull join area is well clear of the water. Inclusion of the rudder plane in the LWL measurement is a big problem for DogZilla.
This starts to have perhaps a little credibility when you also consider that Alinhi's cat has been designed for dumpable ballast from day one (which is still questionable from a legal/rule standpoint)...so they can just adjust their fore/aft trim with ballast as needed.
Then again, maybe they were just terrified of pitchpole and decided to add a little margin of safety with the bow line on the Alinghi cat.
