Answer
Goal-Based Ship Construction Standards (GBS) represent a paradigm shift in how international maritime safety regulations are written and implemented by the IMO.
What is GBS? (Explanation)
Traditionally, structural rules were prescriptive—they told designers exactly how thick a plate had to be or where a stiffener must go. GBS, instead, sets the broad safety goals and functional criteria that a ship must fulfill, while leaving the exact engineering method or design open to innovation, provided it meets the safety tier.
IMO’s GBS structure is organized into five tiers:
Tier I – Goals: Broad high-level objectives (e.g., "Ships must remain safe and environmentally friendly for a design life of 25 years").
Tier II – Functional Requirements: Criteria that must be satisfied to meet the goals (e.g., environmental conditions, structural strength, corrosion margins, fatigue life) (Darie, 2026).
Tier III – Verification of Conformity: The mechanism by which the IMO verifies that the detailed rules developed by classification societies (such as the IACS CSR) satisfy the Tier I goals and Tier II requirements.
Tier IV – Rules and Regulations for Ship Design and Construction: The actual detailed structural engineering codes applied by class societies during construction (e.g., CSR).
Tier V – Industry Standards and Practices: Operational guidelines, welding standards, and quality control manuals used on the shipyard floor.
Applicability
GBS is mandatory under SOLAS Regulation II-1/3-10 (which entered into force globally through amendments). It applies specifically to:
Oil Tankers of 150 meters in length (L) and above.
Bulk Carriers of 150 meters in length (L) and above.
For which the building contract was placed on or after 1 July 2016, or in the absence of a contract, the keel was laid on or after 1 January 2017, or delivery took place on or after 1 July 2020.