NH Saf-C403.16(a) states:
"Boats propelled by oars, paddles or other human or natural device except sails, operated on any public water, shall, between sunset and sunrise, display one white light in a conspicuous position, so placed as to show all around the horizon."
This means a white light that can been seen without obstruction for 360 deg for 2 miles. Most flashlights do not meet this requirement.
http://www.gencourt.state.nh.us/rule.../saf-c400.html