Keep the hull clean
An encrusted boat hull increases fuel consumption and adversely affects top speed and acceleration. A number of cleaners and methods to avoid this are being developed. Many hull paints contain toxic substances. Your local environmental authorities can provide information about what is permitted.
Always use the amount of paint recommended by the paint manufacturer. Always clean the hull, drive and propeller several times during the season - both you and the environment benefit.
Naturally, all refuse must be returned to land and deposited in garbage cans or other waste containers, or at recycling stations. The boat toilet must be emptied at the proper facilities in the harbor.