These are two simple, active stretching techniques that you can use to help increase the rotation in your thoracic, or upper spine. Add them to your daily warm up and see if your “set up” or your “reach” improves.
If you have any issues with side to side board movements, or having to change sides more often than desired while paddling, then chances are you have an issue with not getting your paddle shaft vertical when the blade enters the water. Not only does this help you paddle straighter, but it also helps to get a nice, clean “catch” of water to set the blade. If you have very tight lats and intercostal (rib cage) muscles then you might be restricted in your reach on one or both sides. As an experiment, try both sides of this stretch and see which arm can reach higher/open more. Do you have a “tight” side? Most of us do. Over time Yoga can help correct imbalances in your body. 🙂