When it comes to boat soap for the overall washdown, I’ve always sworn by OrPine Wash & Wax, a cleaner and wax mix. Buy a gallon jug and leave it in the lazarette for when you need it. I tend to mix a capful or two (depending on how dirty the boat you’re cleaning is, but no more than that is needed) with a gallon of water.
After I’ve scrubbed and hosed down the boat, I dry everything with a chamois and the boat glistens. People used to ask me if I’d waxed their boats. No sir, just a wash. If you go with OrPine Wash & Wax don’t be surprised if someone on the docks asks you the same thing.