Go alongside the outer section of the N harbour wall.  Further in you risk taking a fishing boat's space, but water & elec seem to be available there.

A great harbour with tavernas supermarkets and access to a very interesting island.  We hired a car and spent some time at the Sanctuary of the Great Gods (very evocative and well preserved/restored) as well as the swimmable pools & waterfalls further E on the N coast.