Reading the following details is optional:

On a Sunday, the meters are free!

but if no if no street parking is available you might want to consider the following:
So you are at the bottom of College St. (you either crossed Battery or turn off it) and just before (50 feet from) the RR crossing there is a parking lot on the right hand side (Kiosk payment, - click for instructions). If this parking lot is small and if full there is another lot on the other side of College. If that if that one is full too, the next best bet would be to get back to the parking lot at the bottom of Maple St. AKA Perkins Pier (3 blocks south (it is about 10 minutes walk)). In a really busy weekend the next option is to park at the parking garage on Cherry St. (Near Macy's).

Finding the dock/pier/slip#55. At the absolute end of College St, pass the RR crossing there is a round about; take any of it's sides and continue walking west towards the red roof boathouse. Walk throught the boathouse and turn right twice. The marking "55" is written on a small pad on the dock. It is easier to identify the boat with its name "LET'S GO SAILING" written on the side towards stern. If the boat is not there, we are probably on our way in from another cruise.
We are looking forward to sail with you soon.