Doing an engine triple test is one thing but being able to pit the Volvo Penta D6 370, Yanmar 8LV 370hp ZT and Mercury Verado 300hp against each other on exactly the same boat really is a rare slice of fortune.

Thanks to the good chaps at Wessex Marine our technical contributor Dave Marsh was given access to three XO 270s, all identical aside from what powered them through the water.

How would the petrol-powered outboard boat compare to the torquey diesels and what differences would we see between two of the best diesel engines that Volvo Penta and Yanmar produce?

We measured top speed, fuel consumption at various speeds, cost per mile and cost per annum to give you a clear idea of where the savings may lie.

You can read the in-depth report in the June 2015 issue of Motor Boat & Yachting.