depending where you're staying, you may be in luck...a lot of the places have rowboats and/or kayaks available to guests...if not, check out lake george kayak company in bolton for rentals; they are right by the sagamore and pretty close to some of my favorite spots on LG
there are also some smaller mom and pop type places that may have yaks and maybe even rowboats for rental, but I can't think of any off the top of my head

( I know of 2 places, bonnie view and northward ho,both in Bolton that have row boats and kayaks for guests; may even be cheaper to rent a room for the 'day' and grab a rowboat from them, depending on rates?)