New video by ramazza: I have seen many paddlers with a low efficiency narrow grip. This mistake comes from the natural beginner stiffness of the hand on the shaft. My advice is to fix the correct distance and then force the hand to relax the angle.
To find the paddle calculator google "Michele Ramazza paddle length" or go to https://www.micheleramazza.com/en/paddle-length-calculator
Tag a friend with a narrow grip!