Hip snap
From KayakWiki
The hip snap is a sideways rolling motion of your hips that brings a boat under your butt. It is a fundamental part of bracing, rolling and the eskimo rescue. It's a simple rolling motion of your hips. The best way to visualize it is to try and 'snap' your hip into your armpit. At the same time, try and bring your armpit to your hip. The hardest part is to keep your upperbody low to the water until the hip snap has a chance to "do its thing".
You should regularly work on the hip snap to keep your flexibility up and to make sure the involved muscles reflexively know what to do. This is easy to do.
Find a fixed anchor to work with -- a dock, the side of a pool or even a partner's bow will do fine. Grab the fixed anchor and push your knees and thighs into solid contact with your boat. Now feel the boat rotate along its long axis as you roll your hips side to side. With a firm grasp of your anchor, lay down on your side in the water. Keep your head and lower body low to the water and roll the boat upright underneath you. Keep working on this until you can bring the boat up while maintaining little pressure on the fixed anchor.
You should repeat this exercise often to maintain a fluid, reflexive hip snap.

