Welcome to the big pond of NH. Many different factors to think about when purchasing a boat.
usage?
can you afford it? (new/used)
reliability?
seating arrangement?
capacity?
kids/pets?
elders/parents?
head or port-a-potty?
water system (sink/shower)?
As for marina's, look into Harilla Landing Yacht Club (
www.harilla.org). It is managed by Complete Marine Care (
www.completemarinecare.com) on the tip of Long Island at the end of Moultonborough Neck Rd. Brand new fully enclosed storage building for year round storage/protection from the weather.
Happy Boating, See you on the water.