This is a copy and paste from a local bulletin board. As there are a good many tooner's on here I thought it might be of interest. This happened on the Chattahoochee River in the metro Atlanta area about 30 miles south of where I normally fish, although I have been through this exact section. I think what happened was by grabbing the limb he got perpendicular to the current and flipped much as I did last year. You have to keep your pontoons parallel to the flow.

Never, ever, Don't Ever!
Grab a limb across the river while in a pontoon boat in a strong current! I did so at the bottom of the chute just below Holcomb Bridge and almost drowned for my error. I went through the chute just fine but there was a limb I didn't maneuver quickly enough to avoid. So I thought I could grab it and shove the pontoon sideways about 6 inches to get around. As soon is I grabbed the limb and before I knew what was happening, I was upside down in the river with the pontoon boat on top of me and my legs wrapped in the rope from the drag chain which had immediately fallen out of the milk crate on back. Thank God (in all seriousness) there was a limb that allowed me to push my head above water and grab a breath. I was then able to get untangled and drag the pontoon via a side stroke to shallow water and get untangled from my fly line and get back in the boat and paddle over to Garrard's Landing.