The laundromat near me that has a giant machine. They will wash big stuff for a price or let you use it for less. They charge extra for really nasty stuff. It is a lot less work than brushes and buckets on the driveway.

A sailmaker in our area has a sail washing machine. It consists of a 200-300 hundred gallon galvanized tub and a electric pump to make the water flow. You could start your businesses.