Analysis Seakeeping Akibat Penambahan Bilge Keel Pada Kapal Tugboat

The Tugboat Chilean Dolphin operates from Tanjung Balai Karimun to Singapore. The vessel experienced uncomfortable conditions during its dock trial, causing motion sickness for some crew members due to extreme ship movements. To address this, the researcher added a V-shaped bilge keel with a 15° angle, aiming to reduce the ship's extreme motions. This study analyzes the influence and effectiveness of adding a bilge keel on the vessel's seakeeping performance. The ship was modeled using numerical simulation software. Simulations were conducted under two conditions—the existing ship and the ship with a V-shaped bilge keel—both tested across six wave variations based on heights of 0.2 m, 0.5 m, and 1.25 m, and incoming wave directions of beamsea and headsea. The results show that adding a bilge keel effectively reduces heave, roll, and pitch motions, thus improving the vessel's comfort in the Malacca Strait. The effectiveness is calculated at 20.00% for heave motion (beamsea), 43.69% for roll motion (beamsea), and 15.63% for pitch motion (headsea). Additionally, the bilge keel successfully lowered the RMS vertical acceleration, upgrading the comfort level from "slightly uncomfortable" to "comfortable" according to the ISO 2631 standard. Significant changes were observed at a wave height of 1.25 m, while the effect was not as pronounced for waves of 0.5 m and 0.2 m due to relatively calm conditions.