Use sailboats in preference to motorboats, when feasible. Record fuel consumption data and swap information with fellow operators to identify fuel-efficient options.
Diesel engines are more fuel-efficient than petrol ones, and diesel fuel has a lower fire risk.
Collect comparative information when buying a new boat. Issues Fuel consumption of most boats increases dramatically at high speed. Reduce speed by a few kilometres per hour and save fuel. Ensure engines and drives are properly maintained, and that hulls are kept clean to minimise drag. Leaving an engine idling for long periods wastes fuel.