Abstracts Engineering

Design and development of a hydraulic system for outboard-engine-powered-commercial-fishing boats

by Charles A. Marshall

A hydraulic power-take-off was designed and built for outboard engines typical of those used on small boats and Pacific City-type dories. An associated hydraulic system was developed for use on these boats to provide power for fishing machinery. The power for each system was provided by a hydraulic pump direct-drive coupled to the outboard engine crankshaft at the flywheel. Four 1970 model outboard engines were used during the project for the design and testing of these systems. These engines were: a 40 hp and a 60 hp Johnson, a 50 hp Mercury, and a 55 hp Fisher- Pierce Bear cat. A concurrent effort involved the design and development of light-weight hydraulically-powered salmon gurdies especially configured for use on small boats and dories. Four Pacific City-type dories, each equipped with one of the above engines and its associated hydraulic system, were tested throughout the 1970 summer salmon commercial fishing season on the Oregon Coast. These boats logged a total of 2725 hours of operating time during the season and accumulated gross earning of approximately $27,200. This is an average production of $8.50 per operating hour versus an average production of $5.50 per operating hour for such boats equipped with hand-powered gurdies. Subsequent analysis of operational data, engines, and hydraulic system components support the conclusion that a reliable, efficient, and relatively inexpensive hydraulic power-take-off system for outboard engines to power on-board fishing machinery is definitely practical.