Analysis of Stability Condition Improvement and Ship Maneuvering Performance on a Tugboat

Analisa Perbaikan Kondisi Stabilitas dan Olah Gerak Kapal pada Tugboat

Abstract

A Tugboat plays an important role in assisting the berthing process of large vessels in ports, requiring optimal stability and seakeeping performance. This study was motivated by the relatively high distance between the keel and the ship’s center of gravity (KG), which results in a short rolling period and may reduce operational comfort and safety. The study aims to analyze and compare the stability and seakeeping conditions of a tugboat before and after design improvements, focusing on the application of bilge keel variations. The methods employed include stability and seakeeping simulations on the existing model and seven modified bilge keel models. The evaluation criteria refer to the International Maritime Organization (IMO) Resolution A.749 – Chapter 3: Design Criteria Applicable to All Ships and the NORDFORSK Seakeeping Criteria (1987). The results indicate that the 15° bilge keel variation provides the most significant performance improvement compared to the other models. This configuration demonstrates a greater stability margin than the existing vessel, effectively reduces rolling motion under 2-meter wave height conditions with a 14-second wave period to 3.43°, decreases heave acceleration to 2.486 m/s², and produces an average rolling period of 3.4342 seconds. These findings suggest that a 15° bilge keel modification is effective in improving the stability and seakeeping performance of the tugboat, thereby supporting operational safety and efficiency under various sea conditions.