Need help with painting bottom of wood boat

[68/67 chris craft cavalie]

I have a 1968 Chris Craft Cavalier and need to paint the bottom of the boat. The boat has been on dry dock since the fall of 2007. It is a fresh water boat, I am unsure of what type of paint is one the boat at present. It is a plywood hull. I know I need to sand it and make sure to give extra care to areas that are peeling other than that is there anything else I need to do to pre the hull? 2. What type of paint do you suggest I get to paint the hull considering I am not sure what type of paint is on it currently? How long does it take to paint a boat hull (33' x 10') Thanks for your help