Four minors were tubing.  One was operating and the other three were on the tube.  It was the operator's 2nd time operating this vessel.  The tube hit a wave and one of the boys fell off.  The operator shut off the boat to see where the boy was who fell in the water.  He started the vessel up and cut the wheel over to one side and applied forward throttle while turning.  The motor revved too high and after the vessel turned around it motored directly at the two boys on the tube.  The two boys on the tube jumped off when they realized the vessel was coming right at them.  When operator realized he was going to strike one of the boys in the water he cut the wheel to the left while he shut off the motor by pulling out the key.    It is not clear whether the motor was still running or in the propeller was spinning when this collision took place.  
Hingham