ノンバラスト船及びバラスト水低減船の初期船型計画( 第1報)

Abstract

This is the first report of preliminary hull form planning for Non-Ballast Water Ship (NOBS) and Minimal Ballast Water Ship(MIBS). Ships having large block coefficient(CB) like crude oil tankers and bulk carriers need huge amount of water ballast to keep proper propeller immersion and forward draught to operate in rough sea condition. Ballast water is necessary and useful for the safety operation, whereas it makes ship heavier and inferior in propulsion performance. And ballast water will need to be cleaned by the ballast water treatment system which is approved in accordance with IMO's guideline in the near future. A reduction of water ballast is also desirable to prevent ocean pollution. NOBS/MIBS has a unique hull form having V-shaped/convex bottom, and can keep sufficient draught to navigate safely on empty cargo condition even in rough sea without/with less water ballast. As a result of unique hull form, NOBS/MIBS has a very small midship coefficient in comparison to that of a conventional ship. Such unique principal particulars bring difficulties to investigate preliminary design of principal particulars for NOBS/MIBS.In this paper, the author proposes some simple procedures to estimate propulsive performance for NOBS/MIBS using neural network and measured data fitting. As the accuracy of these procedures and results are confirmed in the projects of NOBS/MIBS development, it can be the same level as that for conventional ships.