I am surprised that the spinnaker would lift the leeward hulls
It doesn't, but that is not the point. The point is that the spi DOES calm down the boat alot WHICH feels just as if the bows are lifted. Mathematically and physically speaking the feeling is very much correct but the explanation isn't. However, reality only adheres to what truly happens (feels) and not whether our human explanation for the phenomenon is correct or not.
It will be far to complex to get into this in detail and unless you are science junky it would be pointless trying to explain it as well.
Wouter, it's not complex at all. If the aerodynamic center is lowered, the boat will be more stable. If (by moving the tack well forward) the the aerodynamic center is moved forward
and an upward component is added to the lift vector, the boat will be more stable. An extreme yet logical extrapolation of this is the Kiteship kite. Attach that to the bow and it will be lifting the bow, because it's awfully hard to push a rope.
