The Mini-Cruiser requires fuel to go but it is only used when fishing - NOT while traveling between islands. While you can avoid burning fuel while fishing using the any of the other boats, the Mini-Cruiser is less likely to get damaged by larger fish than the Dinghy. The number of gallons that are burnt is a function of the weight of the fish caught (each ten pounds is one more percent of fuel consumed). Keep your eye on your tank and fill up when necessary. More details can be found here.