Following severe increases fuel oil price, the Fisheries Agency and the National Federation of Fisheries Co-operation Associations (JF-zengyoren) issued a booklet on fishing vessel fuel conservation. In this booklet, the writers stressed that fishing vessel operators should maintain optimum vessel trim and reduce payloads to minimize fuel consumption. However, concrete fuel consumption measurements were not provided. In this study, experiments aimed at measuring the fuel consumption of a semi-planing hull type fishing vessel were conducted to evaluate the fuel-conservation effects resulting from variations in payload and vessel trim. Results showed that 1) a 1.5L/h per 100kg payload relationship existed between payload and fuel consumption at vessel speeds above 7knots, whereas under 6knots no such correlation existed, and fuel consumption was dependent only on speed; 2) varying vessel trim by lowering the bow increased fuel consumption, while varying the trim by lowering the stern deceased fuel consumption.
