Now that we've ....
...dealt with the pole fore and aft position, it's time to deal with pole height. There are a few misconceptions that we need to deal with. 1. The pole position largely affects sail shape - True.2. The height of the pole is strictly determined by the height of the leeward clew - False.3. The pole height controls the break of the leech, which helps induce the correct, designed sail shape when set right - True. Let's analyze some different pole height settings. With the pole too low, you'll be trying to pull that curve too straight. Instead of billowing away from the boat, the shoulders will curl over, causing the top of the spinnaker to break early, which causes the trimmer to tighten the sheet prematurely. The end result is an over-trimmed (and over-flattened) spinnaker, which is choking off flow of air around the main as well - all bad things.As you raise the outboard end of the pole, you see the break change - instead of the breaking at the top, it moves down and evens out along the luff, as the top of the sail opens up. The break becomes even, indicating a properly shaped sail - at least in the front. The easy way to remember this is "move the pole to the break." If the sail breaks high, raise the pole. What about the inboard end? Well, that's easy. One of the pole's jobs is to extend the sail as far away from the rig as possible. The inboard end is adjusted to match the outboard end, strictly to keep the pole perpendicular to the rig, therefore keeping it as extended as much as possible.