When first I was exploring rivers, a time ago, it was a daunting feat to plump over a 20' waterfall and survive. Now, the bar has risen to what was once incomprehensible. The current record for paddling over a waterfall, and surviving, is 189'.
Keep a change of clothes easily accessible in your sled. If you fall in the drink, you'll need to get naked and change fast before hypothermia sets in. This is not a time when you want to wonder where you have placed that replacement top!