There are 2 definitions in play here...
1. 270:73 V. "Ski craft" means any motorized watercraft or private boat which is less than 13 feet in length as manufactured, is capable of exceeding a speed of 20 miles per hour, and has the capacity to carry not more than the operator and one other person while in operation. The term includes a jet ski, surf ski, fun ski, or other similar device. "Ski craft" does not include any watercraft or boat with twin hulls and which is greater than 11 feet long, greater than 5 feet wide, and powered by an outboard motor.
2. 270:74-C I. In this section, "personal water craft" means a motor boat 16 feet or less in length that is propelled by jet pump, not propellers, where the operator and riders stand, kneel, straddle, or sit on, rather than inside, the craft.
No matter what you drive... If you are over 16 you need a SBC. Under 16 can drive under the supervision of a person with an SBC.
http://www.gencourt.state.nh.us/rsa/...270/270-73.htm
http://www.gencourt.state.nh.us/rsa/...0/270-74-c.htm
Woodsy