First, the catamaran does not have AMAS...the AMAS are the smaller outrigger hulls on a TRIMARAN or PROA. A Catamaran has two HULLS.
Sorry about my bad Englhish. In all other languages that I speack there are not a different name for the hulls of a multihull (tri or cat), so I have assumed that the amas where the hulls of a multihull. Thanks for the correction.
When you're in a cruising size catamaran, you really should never be flying a hull. IF you are flying a hull in a cruising sized catamaran, regardless of LOA, you're being an idiot and deserve what you get.
Not all trimarans are designed to fly an ama. Many cruising designs, including my Telstar 28, are designed to sail with all three hulls in the water normally. In fact, depending on what the design is, flying an ama may be a warning sign of the boat being overpowered.
I believe you have misunderstood me. I have said:
"There is a significant difference between a stability curve of a tri and the one of a cat.
Basically when a small cat (less than 50ft) starts to lift its amas, there is very little stability left and you can capsize really fast. In a tri it is normal to sail with an ama out of the water and when the central body starts to lift you have much more time to let go the sails."
And I believe that this is correct. It is out of the scope of this thread but if you want to discuss the differences in a stability curve between a cat and a tri you can open a thread about it and I will post some stability curves.
What I mean is that when a cruising cat lifts a hull, you are in trouble. I am not talking about doing it purposely, but sometimes it happens (as in the recent Australian accident). When it starts to happen you have little time to correrct the situation.
About the trimarans, when I have said that it is normal to sail with an hull out of the water, I mean that in the generality of the trimarans, that is not a dangerous situation (unlike the cruising cats) because you still have plenty of reserve stability.
Even huge and heavy trimarsns can sail safely with an ama out of the water. Here you have some pictures, including one from a Telestar:
But I was referring mostly to fast cruising trimarans (why sailors would want a boat that has less interior space than a monohull and is more expensive if it is not faster?) and for those it is normal to raise a ama even without much wind, some with weak wind.
Here you have photos of most of the cruising trimarans on the market, at least the ones I know