Answer
What is GBS?
Mandated under SOLAS Regulation II-1/3-10, Goal-Based Standards represent a high-level safety philosophy for ship construction. Instead of prescribing the exact thickness of a steel plate, GBS establishes the overarching safety goals and functional requirements that a ship must meet (e.g., the ship must be designed to have a design life of 25 years under North Atlantic wave conditions). The Classification Societies then design specific rules to fulfill those goals.
What was before GBS?
Before GBS, the industry relied entirely on Prescriptive Regulations.
The Difference: Prescriptive regulations were reactive ("design-by-rule"). They dictated exact dimensions, formulas, and structural layouts based purely on historical accidents (e.g., "the plate must be exactly 12mm thick"). The problem was that prescriptive rules could not keep pace with rapid technological advancements, alternative designs, or complex novel vessels (like modern ultra-large gas carriers). GBS allows for innovative engineering designs, provided the safety goals are fully validated.