This is my first post at the forums, so let me introduce myself. I live by the coast of the Pacific in ViÃ±a del Mar, Chile, and I bought the first two AI that arrived to Chile on November 2006, so I have shared with all of you the satisfaction of owning these great fun inventions.
I believe a tandem made with two AI side by side would not improve the sailing experience, since one sail will shadow the other, making it slower than two independent AI.
A succesful tandem must be faster, ride drier on heavier seas and winds than the AI, have plenty of below deck cargo capacity for long expeditions, and still be easy to deploy from car to water and be light to be portaged by its crew of two.
In short, the challenge is not simple, since Hobie has to come out with something better than the existing Windrider 17, whose main draw backs are price and long time needed for assembly, besides not having two mirage drives, of course!
For this goal I would try to design a thin and high wave piercing hull form, sit on top, tandem mirage drive, rotomolded version. Such a high draft plastic hull would sacrifice the possibility of use without amas, since it would not have positive stability by itself, but it would not require a daggerboard either. Another advantage of such a deep V hull is that the mirage drives would work more efficiently in it, since the axis section of the fins would be shadowed and also protected by the keel, and the sweep angle of each blade can be increased much over than the current 180 degrees at the AI.
As we know, with any given sail area, or fixed human power, a longer hull makes a faster boat than a shorter hull, so the over all length must be increased to near or over 19 feet, just short enough to be packed and shipped inside a typical 20 feet container (for export to Chile of course
), and it still would be possible to be car topped by two persons and adequate accesories.
For cost reduction, fast assembly and speed I would power it with two sets of the existing self roller, self standing carbon fiber mast of the AI. This sail arrangement, besides doubling the effective sail area, keeping the same mast length, would require less rudder force, which further improves speed.
Have fun, AndrÃ©s