Influence of Jumboizing on Propulsive Performance

This paper is concerned with the influence of hull elongation on engine and propulsive performance. Though propulsive performance is known to relate closely to the principle dimensions of a ship, it is not yet clear how ship length can influence the performance of CPP (controllable pitch propeller) ship and FPP (fixed pitch propeller) ship, both of which have the same breadth and depth. Sailing performance under two different conditions (before and after elongation) was examined using an actual ship equipped with CPP. The results obtained from this examination are as follows : (1) engine output increases after hull elongation at the same ship speed as before elongation, and the tendency becomes stronger at higher speeds ; (2) the total resistance coefficient increases after elongation at the same Froude number Fr as before elongation in Fr ≥ 0.22, but it is the same value at before and after elongation in Fr