Ok....looks like you are correct....much to my surprise....that non-motorized kayaks, canoes, rowboats and sailboats are required by NH statute to have one pfd on-board for each person, and persons 12 and under are required to wear them. Could not determine if a throwable flotation device is also required on-board non-motorized boats as well.
Still, there's a lot to be said for wearing a swimmers belt as opposed to not wearing a pfd when paddling a kayak or canoe.
Last August, I got stopped by an MP in a big defender mp boat at about 8:15-pm out by Buoy 3 for rowing my 17' row-canoe without any nav lights, and he just let me off with a warning after taking my name, so he let me off the hook with no fine to pay. At the time I was wearing a swimmer's belt, and I suspect that had I been not wearing that and not having a pfd on-board either, then he probably would have cited me for no lights-no pfd for a double fine, but instead I got to row off with just a warning.
A very wise and knowledgeable MP officer that there MP officer was there, that there night, you betcha, don't you know!
