Here's a link to some runs through Horn at med/low water, I'm guessing somewhere around what you'll see. All 6 rafts run right of both horns and all of them take a piece of the wave/hole 3/4 of the way through.
I'm probably going to get flamed for the following comments but here you go...
The yellow raft has by far the smoothest run. He is calm and tries to move left behind the river right horn. When it's clear he's not going to miss the holes (he figures this out way before anyone else) he simply spins the boat forward and pushes downstream through the left side of the big stuff. This is a classic right side run at this level. Better to spin and be facing in the right direction than to keep fighting a losing battle to get left.
So, if you want to get some action, this is a great way to run it. Note that he spins early so he's set up to take on the downstream stuff pointing directly into it. Most of the following boats don't straighten out in time to be set up correctly for the runout past the horns. No offense to any of you out there that might be in this video!
All of the boats seem to be attempting to run right to left but none of them make it. (They could be planning on hitting the big stuff so maybe I'm wrong and they went exactly where they wanted.) None of them have any real right to left momemtum going down the tongue however. If you really want to get left from the right, you have to have massive right to left momentum
going for you. That means starting farther right at the very top and rowing hard
(backwards and downstream!) towards the left (always with downstream angle). You'll want to drop your stern into the eddy behind the river right horn earler than they do, so you slide across the eddy as you begin your counter clockwise spin to get your boat straight. The sharper your angle (closer to straight downstream that to the river left) the better chance you have of using the eddy behind the horn. If you hit the eddy line without much right to left momentum and with too shallow and angle, say 45 degrees, you'll simply get rejected back into the tongue, even as you're spinning.
But, I would suggest an arguably better line if you want to miss the bottom stuff: Simply drop between
the horns backwards and, as soon as you clear the V-wave just downstream in the tongue between them (you can see it clearly in every run on the video - none of them get close to it) you point your stern about 45 degrees towards the left shore, take a couple of big strokes and spin your boat around. You'll miss the stuff on the right completely and likely won't even get wet. You'll be facing downstream now and can set up a right ferry angle if you're heading too close to the left wall in the runout. I think this is a super clean and classy run personally.
While I'm at it, here's a tip for Granite, which is the next rapid downstream: Start right and stay right, just off the wall by about 20 feet. If you try to get left the river will keep tugging you back to the wall. If you're already there you can take advantage of the lateral compression waves that come off the wall to keep you on the tongue. It's one of my absolute favorite rapids!
Have a great trip!