Totally-Enclosed Lifeboat and Rescue Boat Stability

Existing lifeboat stability regulations in the International Maritime Organization’s Life-Saving Appliance Code consider a range of worst-case passenger loading scenarios, but not scenarios where persons are able or required to stand and/or crowd off-center or longitudinally. This can be important for lifeboats in general, but particularly for those operating as rescue boats. An accident onboard a totally-enclosed lifeboat/rescue boat conducting training as a rescue boat was the genesis for this study, in which hydrostatic stability analysis was performed on a representative 26-person totally-enclosed intact lifeboat. This study was undertaken to inform possible regulatory reform on the stability of totally-enclosed lifeboats, particularly those acting as rescue boats with standing persons onboard. Conditions studied were for a driver plus 6, 13, or 26 persons. Person locations were systematically varied in the fore-aft direction and the athwartship position and varied vertically based upon sitting versus standing. Data analysis was focused on international regulations that require positive GM for 50% personnel complement and also the ability of a lifeboat to self-right with partial or full complement. The lifeboat met these criteria in many conditions, but some results suggest that personnel crowding and/or personnel standing may cause a lifeboat to lack compliance with these criteria. New stability standards may be required for conditions where people are standing and for lifeboats operating as rescue boats. Consideration should be given to optional substitution or addition of hydrostatic analysis for the proof tests as an effective means of assessing totally-enclosed lifeboat and rescue boat stability.