Fishing boats have to travel and work in rough and bumpy environment, so the working environment of marine diesel engine is very different from that of land diesel engine.
The most basic requirements for fishing boat diesel engines should be reliable work, good economy and convenient maintenance and management. In addition, marine diesel engines also have the following characteristics:
(1)Determination of rated power of marine diesel engine: For marine diesel engines used in unlimited navigation areas, the rated power shall be the maximum continuous power measured on the output shaft of the diesel engine under the reference environmental conditions of engine room ambient air temperature of 45℃, absolute atmospheric pressure of 0.1MPa, relative humidity of 60% and seawater temperature of 32℃.
(2) Fishing vessel diesel engine shall be able to work reliably under the following conditions:
1) Diesel engines above 300kw: 15° for heel,5°for trim, 22.5° for roll and 7.5° for pitch.
2) diesel engines not exceeding 300kw: 15° for heel, 7° for trim, 22.5° for roll and 10.5° for pitch.
(3) In order to ensure sufficient maneuverability of fishing boats, the propulsion system should be able to reverse the vehicle.
(4) The main diesel engine should have good low speed performance.
(5) Marine diesel engines shall be equipped with reliable speed regulators and overspeed protection devices.
(6) The starting of marine diesel engine shall be rapid and reliable.
(7) Requirements for torsional vibration. Torsional vibration calculation shall be conducted for the propulsion and front-end output power transmission system of the main diesel engine and auxiliary diesel engine systems with rated power equal to or greater than 10kW for important purposes, and shall be reviewed by the ship inspection department.
(8) The front end of the fishing vessel’s main diesel engine needs to drive a variety of auxiliary engines, so it requires a large front-end output capacity. In addition, the Code has special provisions on the strength calculation of the crankshaft of marine diesel engines, the physical and chemical properties of the crankshaft and other important components, material tests, nondestructive testing tests, hydraulic tests, etc., which will not be described in detail here.
Photo: (Cummins Marine Generator)