If you are thinking wearing a helmet will protect you from further concussion injuries, you are mistaken. Your brain will forever be more sensitive to impacts.

It may offer a small amount of protection from some very intense impacts from other boards but not a hard slap on the water. In fact, the larger surface area may make a hard slap on the water more damaging.

You would be better learning some ways to break the water surface with your hands or arms. It does not take much to greatly reduce the impact by breaking the surface of the water with your fist or elbow or forearm.