If you are looking for speed, put the seats out on racks off the ama's. There is/was a cross altantic f18 attempt that had racks with molded seats, looked comfy.
My question is, are you going to locate all the controls in the "****" so you can sail it from there (like a Rave) or are the seats for passengers? If you have the controls going to the ****, then hiking and driving or triming might be an problem.
I say lose the seats in the ****, make them benches that go fore and aft. Make the controls easily controlled from the amas.
If its a nice sunny day, I'd rather be relaxing on the tramp or the ama, and if its an all out speed run on a windy day, you are going to want to be on the ama's or hiked out.
Bill
I agree - it gives you all the flexibility in the world for any weather and an array of passengers. Use for example, any of the Farrier/Corsair tris.
