Overview
ISO/TR 9814:2025 - Ships and marine technology provides targeted good practices to prevent capsizing of ships with large profile height during turning maneuvers. As a Technical Report, it synthesizes accident analyses and technical guidance rather than imposing prescriptive rules. The report focuses on the dynamic stability risks caused by turning-induced centrifugal force and resultant heeling, and offers three practical mitigation measures based on investigations of five capsizing accidents.
Key Topics
- Ship turning, centrifugal force and heeling - explanation of how turning generates lateral loads and heeling moments on high-profile vessels.
- Accident case analysis - comparative analysis of five notable capsizing incidents (see Annex A) to extract common causal factors and lessons learned.
- Effect of KG on stability and the GZ curve - discussion of the vertical centre of gravity (KG), its influence on the GZ (stability arm) curve, and hull-form characteristics that can produce critical GZ behavior.
- Three good practices to reduce capsizing risk:
- Semi-automatic inclining tests before loaded departure and procedures for stability screening when full inclining is not performed.
- Setting and managing maximum heeling angles during turning, with special considerations for maritime autonomous surface ships (MASS) and cargo slippage.
- Precise calculation of Free Surface Moment (FSM), including practical points such as FSM at high filling levels (e.g., 98 %), software limitations (noted issues like slack limits in some commercial tools), and recommended improvements to stability calculation software.
- Terms and definitions relevant to large profile-height vessels (profile height, free surface effect, inclining test, FSM, etc.).
Applications
ISO/TR 9814:2025 is intended for professionals involved in the design, operation and regulation of ships with large profile heights, including:
- Naval architects and ship designers - to evaluate hull form, KG management and GZ characteristics during design.
- Ship operators and masters - to implement pre-departure stability checks (inclining tests or screening), operational limits on turning and cargo securing practices to mitigate heeling and cargo shift.
- Classification societies and surveyors - to inform inspections, inclining-test protocols and stability assessments.
- Maritime safety regulators and port authorities - to shape guidance, oversight and safety recommendations for area carriers, PCTCs, car carriers, cruise ships and other volume/area carriers.
- Developers of onboard automation and MASS systems - to integrate maximum heeling and stability constraints into control and alarm systems (IMACS).
Related standards
- SOLAS (International Convention for the Safety of Life at Sea) - overarching safety requirements referenced in industry practice.
- ISC (International Code on Intact Stability) - related intact stability criteria and guidance.
- ISO/TC 8 (Ships and marine technology), SC 8 - technical committee responsible for ship design standards and guidance.
Keywords: ISO/TR 9814:2025, capsizing prevention, ship stability, profile height, KG, GZ curve, free surface moment, inclining test, centrifugal force, maritime safety.
