Whats the deal? If we are sailing at 90 degrees apparent downwind then why ever go farther than 90? The sail should be as full as it's ever going to get at 90 degrees too so it's doesn't seem like this would make it any fuller either..

Keep in mind that 90 degrees apparent is down at the bridle fly which is only a couple feet off the water. As you go up higher, the wind speed increases (wind gradient) and so the apparent wind shifts aft meaning higher up, you are actually at something greater than 90 degrees apparent.

sm

Why didn't they just make a mast that rotates more at the top then....