Abstract
To clarify the characteristics of NOx emission and optimum speed for environment on a small fishing boat,
concentration of NOx and O2, Ship's speed and fuel oil consumption were examined by using 12 GT size fishing
boat equipped with 265kW/2200 rpm 4-CyCle marine diesel engine. Two comparative examinations, Sailing and
trawling conditions, were carried out in order to study the relationship between the ship's speed and NOxemission.
The results obtained from the examinations are as follows : (1)At the sailing condition of a sIow speed,
NOx emission [kg/h] increased proportionally to the approximate square of the ship's speed, but the condition of
a high speed, the NOx emission practically keeps constant value ; (2) Both conditions of sailing and trawling,
NOx emission [kg/h] correlates with fuel oil consumption ; (3) Total NOx emission [kg] per unit sailing distance
increased with the ship's speed unti1 13 knot, then decreased gradually ; (4) To sail at the high speed that actual
fuel oil consumption become smaller than theoretical fuel oil consumption based on propeller low is effective for
reduction of NOx emission and improvement of fisherboat’s function.
