Stability Assessments of RoPax Open Car Deck on Longitudinal Wave

This paper discusses RoPax Open Car Deck (OCD) without side casings (wing tanks) on longitudinal wave water. The purpose is to know the critical intact stability of RoPax OCD on the longitudinal wave so that the other ship can avoid the condition. A case study takes a RoPax OCD, which capsized on Halmahera seawater. The stability calculation uses the energy balance method on calm water and longitudinal waves with various amplitude, phases, and lengths of waves. Survival stability assessments use the lever righting arm (GZ) of intact stability criteria IMO (IS Code 2008). Results show RoPax OCD full load on calm water has failed to fulfil several of the stability criteria of IS Code 2008, especially on area 30^o-40^o of GZ curve 1.221 meter-degree ≤ 1.7189 meter-degree, and GZ maximum 15^o ≤ 25^o. Hogging and sagging waves reduce the GZ height compared to calm water, but the length of the GZ range on calm water increases 0^o~29^o increase becomes 0^o~32^o on the sagging wave and decreases 0^o~13^o on the hogging wave. With varying wave phases 0-0.8, the highest GZ curve occurs in phase 0.2, and the lowest GZ curve occurs in phase 0.6. With varying wavelength, 10-50 meter, shows highest GZ curve occur on wavelength 10 m, and the lowest GZ curve occurs on wavelength 40 m, the same as the ship length (Lpp). All GZ stability curves have positive values, but the longitudinal wave reduces the GZ heigh and causes the water to ingress onto the car deck. Hence, the effect on the water-free surface influences ship capsizes. The authors suggest that RoPax with opened car deck without side casings should not be operated in the open sea or the strait bordered by the open sea to avoid the same accident.