ISO 12217-2:2022

Overview

ISO 12217-2:2022 - "Small craft - Stability and buoyancy assessment and categorization - Part 2" defines methods to evaluate the stability and buoyancy of intact sailing boats with hull length ≥ 6 m (applicable up to 24 m). The standard covers flotation characteristics, susceptibility to swamping and, for habitable multihulls, assessment of inversion and requirements for inverted flotation and means of escape. The outcome of the evaluations is assignment to a design category (A, B, C or D) appropriate to the craft’s design and maximum load.

Key topics and technical requirements

• Scope and applicability: Primarily for sail‑propelled boats 6–24 m; can be applied to some craft <6 m (habitable multihulls or certain decked boats). Excludes inflatable/RIBs covered by ISO 6185, gondolas, pedalos, surfboards, and hydrofoils not operating in displacement mode.
• Stability assessment methods: Tests and calculations for righting moments and stability curves, including normative procedures in annexes for determining righting moments and reserve buoyancy after inversion.
• Downflooding and recesses: Identification and measurement of downflooding openings, downflooding height and angle, and requirements for recess size and retention.
• Energy and angle criteria: Minimum righting energy and angle of vanishing stability requirements to evaluate capsize resistance.
• Stability index (STIX): Calculation methodology and component factors such as dynamic stability (FDS), inversion recovery (FIR), knockdown recovery (FKR), displacement‑length (FDL), beam‑displacement (FBD), wind moment (FWM) and downflooding (FDF).
• Practical tests: Knockdown‑recovery, wind stiffness, capsize‑recovery tests and buoyancy/inversion tests, plus detection and removal of water.
• Habitable multihulls: Additional checks for susceptibility to inversion, inverted flotation, and definition of viable escape routes.
• Documentation & markings: Requirements for safety signs and information to be provided in the owner’s manual.

Applications and users

ISO 12217-2:2022 is used by:

• Naval architects and yacht designers - to design and certify hulls and buoyancy systems.
• Boat manufacturers - to demonstrate compliance and assign design category.
• Certification bodies and flag authorities - for conformity assessment and regulatory approval.
• Surveyors and marine insurers - for risk assessment and condition surveys.
• Owners/operators - for understanding safe wind speed limits, stability information and emergency provisions.

Related standards

• ISO 12217 series (other parts for powerboats, small craft <6 m, additional methods)
• ISO 6185 series (inflatable and rigid‑inflatable boats) - cited as exclusion/related reference
• ISO 11812 (quick‑draining recesses) - referenced for some small craft applications

ISO 12217-2:2022 provides the technical framework to evaluate intact stability and buoyancy of sailing craft, enabling consistent safety categorization and practical guidance for design, testing and operation.