I used to do whitewater paddling and helmets were required at all times. However, it's not needed on the CT river where it's flatwater (which is most of it). I've been paddling the CT River in many places north to south (flatwater sections only) for nearly 30 years and I've never seen one paddler wear a helmet. Where you have class 2 or 3 rapids in the northernmost sections, yes, wear a helmet, as capsizes among rocks are possible.