If you want a seatbelt, here is my idea..... Install a 1 inch thick rope that is secured to the boat on one side of you then bring it across your body through a ring that is secured to the boat. bring rope back across your body again and hold the now 2 ropes with your hand. The pressure of the 2 ropes being squeezed together will hold you in. If you flip the boat all you have to do is let go of the rope and it will release allowing you to float up to the surface with your PFD on.
OR
2 grab handles to hold on to.
