Why does a gennaker/kite lift the bow?

Part of the story is that with the kite up, you go faster, moving the apparent wind forward, where it isn't pushing the rig forward over the hull like a main in 'blow along mode'.

On a yacht, a kite can give lift without increasing the speed that much, on a much broader reach (apparent wind) by raising the clews, the top of the kite is nowhere near vertical, it gives lift, pulling up on the guy and sheet much more than it's pulling down on the halyard, which is pulling more forward than down.

I most noticed the upward lift on an asymmetric twin trapeze boat when you come of a big bit of swell. Without the spinnaker you nose dive and pitch pole, with it you seem to almost parachute down making the jumps far less dramatic.

J im C gave us a nice diagram last time this was discussed which explained things well, and which, in anticipation of a reprise of the topic, I saved!:

Edited by Medway Maniac - 12 Mar 12 at 10:08pm

Originally posted by Peaky Pretty sure I drew that picture

Oh good, because I was pretty sure I hadn't.

Its a lovely picture, but shouldnt the wind hitting the genny be coming from much further forward (ie in front of the boat)? Or are those arrows forces rather than wind?

Edited by r2d2 - 13 Mar 12 at 7:27am