金枪鱼延绳钓渔业是远洋渔业的重要组成部分。金枪鱼延绳钓作业过程包括航行、作业两种完全不同的工况。航行工况时要求航速较高，作业工况时要求航速较低。为了满足两种工况，采用柴电独立运行（PTH）方式机电混合动力系统。机电混合动力系统由柴油机推进系统与电力推进系统两部分组成。高航速时使用大功率的柴油机模式，低航速时使用小功率的电力推进模式。近两年，上海远洋渔业有限公司先后两批次建造了5条装备了PTH方式机电混合动力系统金枪鱼延绳钓船。根据实船测试，在作业期间，不同船型起钩阶段节油25%和8%，航行节油均达14%。通过计算分析，使用柴电独立运行（PTH）方式机电混合动力系统增加的初始投资成本可通过节油方式在四年内回收。综合节油效果显示，使用电力推进比使用柴油机推进可以节油15%~20%，达到了良好的节能减排、降低运营成本的效果。

Tuna longliner fishing is an important part of the pelagic fishery. The process of tuna fishing consists of  two completely different working conditions: navigation and operation. The speed is high with the condition of navigation, and the speed is low with the condition of operation. In order to meet the requirenents of the two conditions, the electromechanical hybrid power system through the diesel electric independent operation (PTH) mode is used. Electromechanical hybrid power system is composed of two parts, which are the diesel engine propulsion system and electric propulsion system. The high power diesel engine model is used when the speed is high, and the small power electric propulsion mode is used when the speed is low. In the past two years, Shanghai Ocean Fishing Company has built five tuna longliners which are equipped with electromechanical hybrid system. According to the real ship test, fuel saving was 25% and 8% with different types in the hooking stage in the operation period, and fuel saving of voyage reached to 14% in the navigation period. Through calculation and analysis, the initial investment cost of using electromechanical power hybrid system throgh the diesel electric independent operation (PTH) mode could be recovered by way of fuel saving within four years. The fuel saving effects showed that using electric propulsion could save 15% - 20% of the fuel compared with the diesel engine propulsion, which could achieve the effects of good energy-saving, emission reduction and cost reduction.