37' boat...how much?
Can't speak to prices in the Chesapeake, but here in the Bay Area, we charge $2.25/foot for hull cleaning and $10.00/zinc for installation (plus the zincs). So, for a hull cleaning and a couple of 1" shaft zincs, I'd charge you about $138.00.
Lots cheaper than a haulout. And you didn't even have to go down to the boat.