SIST EN ISO 12215-7:2021 PDF

Overview

EN ISO 12215-7:2020 - "Small craft - Hull construction and scantlings - Part 7" specifies how to determine local design pressures and global loads for multihull craft (catamarans, trimarans) with hull length or load line length up to 24 m. It defines dimensions, load cases and pressure‑distribution rules used to size local structural elements (panels, stiffeners, supports for windows/portlights/hatches) and to assess overall structural loads. Scantlings corresponding to these local design pressures are then assessed using ISO 12215-5.

Key Topics and Requirements

• Scope & applicability: Applies to recreational and commercial multihulls (including charter vessels and workboats) built from materials covered in ISO 12215-5; excludes professional racing multihulls. Load line length per IMO may be smaller than LH; 24 m upper limit is significant for several conventions.
• Local design pressures: Tables and methods for defining local pressures on hull panels, wet decks and floats; includes pressure‑adjusting factors and area limits.
• Panels and stiffeners: Procedures to determine panel dimensions and stiffener arrangements under local loads, including the constant averaged pressure method and alternative assessment methods.
• Global loads & load cases: Definitions and procedures for global load cases (GLC1–GLC6), e.g. diagonal quartering‑sea loads, rig loads, asymmetric broaching, pitchpoling/longitudinal broaching, longitudinal force on one hull, and crossbeam bending for motor catamarans.
• Assessment methods: Both a simplified method and an enhanced method are provided; Annexes give established practice for FEM analysis and reporting.
• Structural details: Guidance for structures supporting windows/portlights/hatches/deadlights/doors, crossbeams, and attachment points; units and conventions for dimensions, forces, pressures and stresses are specified.
• Documentation & operations: Requirements for owner’s manual information (e.g., respect of maximum loaded displacement, operational guidance, sandwich plating care), and additional provisions for commercial craft.

Applications

Who uses EN ISO 12215-7:2020 and why:

• Naval architects & structural engineers - to size local scantlings and to evaluate multihull global loads during design.
• Boat builders & fitters - for specifying panel/stiffener layouts, window and hatch supports, and crossbeam attachments.
• Surveyors & classification societies - for compliance checks, certification and inspection of recreational and commercial multihulls.
• Regulators & owners - to ensure safe operational limits and prepare owner’s manuals consistent with structural capabilities. Practical outcomes include safer hull designs, validated scantlings per ISO 12215-5, and documented load cases for structural analyses (including FEM).

Related Standards

• ISO 12215-5 - assessment of scantlings from local design pressures (required companion document)
• ISO 12215-6 - additional structural details
• ISO 12215-8 / -9 / -10 - rudders, appendages, rig loads and attachments (used together for complete scantlings)
• ISO 12217 - stability, freeboard and buoyancy considerations referenced for watertight/weathertight parts

Keywords: EN ISO 12215-7:2020, small craft, multihull, hull construction, scantlings, local design pressures, global loads, ISO 12215-5, multihull load cases, crossbeam bending, FEM analysis.