What difference does the tack hieght of the spi make? Fortunately I'm in a position where I can adjust the hieght of the tack on my spinnaker pole by either tightening or loosening the tension on the rope between the bridle and pole, this makes a significant difference at the end of the pole. Does lowering the tack move the centre of effort up the luff of the kite thus increase heeling movement and vice versa the higher the tack the lower the heeling movement and more forward thrust.
When I used to sail symmetrical kites we used to trim the height of the pole so the luff would break first at the centre. Does this therory still apply to asymmetrical kites.
fist rotation
is just a rule of thumb to get you going. Depending on the cut of the spi and your sailing, you need to fine tune it for your best performance.
At present I have a stopper knot approx 15cm from the halyard turning block which gives me the fist rotation. If I took this knot out and raised the pole accordingly I'm raising the centre of gravity for the whole rig (not by alot) but I am running on narrow beams so the lower I can keep the rig then I should stay more competitive as I'm trading off heeling moment for forward thrust.
According to Charlie Ogletree, having slack aloft allows the spinnaker head to blow around the mast, which is not optimal. You're better off having slack at the tack, or best off raising the pole tip.
I've simply set my spinnaker pole tip as low as I could reasonably get it without a stupid amount of pre-bend. I figuure that you want the CE of the sail as low as possible. I consider this tack position to be fixed and vary the hoist height to get a proper set on the kite.
Me too; except my pole on the 17 does not bend much.