Three seasons ago the diesel engine in the Nathaniel Bowditch was converted to burn Bio-diesel. This is a fuel produced from recycled, waste cooking oil and other renewable vegetable produce.

Bio-diesel burns 75% cleaner than petroleum diesel fuel, it doesn't even leave black soot on the back of the boat, it smells much nicer (burnt or un-burnt), even if spilled in the sea it degrades very quickly and has comparatively no negative impact on marine life.

So, when we are not harnessing the wind for propulsion we are still making very little negative impact on our environment and the planet as a whole.