A Comparative Analysis of the Stability of Open-Deck River Boats Using Righting Moment and GM0 Based Criteria

Abstract

The Musi River is a crucial water transportation route in Indonesia, used by traditional boats such as Jukungs and Keteks, which are open-deck boats, making the stability of these boats a vital aspect of ensuring safety and operational feasibility. This study aims to analyze and compare the stability of a Jukung and a Ketek and to provide insights into developing a more stable and safe traditional boat design. The research methodology includes calculating the stability moment (M_GZ) at a specific heel angle and the heeling moment (M_KR) of turning and passenger based on the Rules for Small Vessels up to 24 m - Section 5C.1.2.1.1 as established by the BKI, and the GM₀ value as specified by the IS Code 2008 IMO. In addition to these empirical calculations, the stability analysis is also conducted using numerical simulation methods based on the hull geometry of the vessels to obtain a more detailed and accurate assessment of the vessel's stability. Although both boats have similar sizes, the Jukung has a larger displacement due to its relatively flat hull shape, which extends from top to bottom. Load reductions from full load to lower passenger loads lower the vessel’s centre of gravity and increase the height of the stability arm. Both boats meet the stability arm criteria across these load conditions; however, the Jukung consistently exhibits a higher stability moment (M_GZ), which increases further as the load decreases. These results demonstrate that both boats maintain overall stability with M_GZ greater than M_KR. The Jukung consistently meets stability requirements with a positive GM₀ when fully loaded with passengers and at lower loads. The Ketek fails to meet stability requirements at higher loads but is safe at reduced passenger loads. Therefore, the Jukung is more stable and safer compared to the Ketek. However, the Jukung’s flat U hull shape provides a significantly larger righting arm and greater stability margin compared to the Ketek’s V-shaped hull that widens toward the top. Consequently, the Jukung’s hull design contributes to higher stability levels and a wider safety margin than the Ketek, emphasizing the critical role of hull form in traditional boat safety on the Musi River.