Overview
EN ISO 12215-2:2018 (Small craft - Hull construction and scantlings - Part 2) specifies requirements for core materials for sandwich construction and embedded materials (inserts) used in small craft hulls and structures. It applies to small craft with a hull length (LH) up to 24 m (per ISO 8666). This European adoption of ISO 12215-2:2002 sets material selection, compatibility and documentation expectations to ensure long‑term structural performance in a marine environment.
Key topics and technical requirements
- Scope and applicability
- Focused on core materials used structurally in sandwich panels and embedded inserts for small craft (LH ≤ 24 m).
- Core material performance
- Materials must enable the sandwich structure to meet the design loads and service life expectations defined in ISO 12215-5 (design pressures, stresses, scantlings).
- Fatigue performance and stable mechanical properties under marine conditions are required.
- Core materials must be able to transfer shear loads specified in Part 5.
- Material-specific rules
- Expanded foams: must be closed‑cell type; PVC and SAN foams for primary hull/deck use must meet at least Grade I (see Table A.1). Other uses require Grade II properties.
- End‑grain balsa: must be homogenized, free from degrading organisms, and packaged at 12–15% moisture; mechanical properties to comply with Grade I or II (see Table A.2).
- Other cores: permitted if they meet the general structural and durability requirements.
- Embedded materials / inserts
- Thermal expansion/contraction of inserts should be similar to the surrounding laminate.
- Embedded plywood must be waterproof and bondable to resin; solid timber inserts are discouraged.
- Material compatibility and protection
- Resin systems, sheathing or coatings must be compatible with the core surface.
- Core materials should limit water penetration beyond damaged skin areas (exceptions for certain open 3D cores).
- Documentation
- Core manufacturers must supply written properties, temperature limits and application guidance; boatbuilders must retain this data in the technical file.
- Annex A
- Normative tables list mechanical property requirements for common core materials.
Practical applications
- Guidance for boat designers, naval architects, composite engineers, shipyards and composite core suppliers in selecting and specifying core materials for hulls, decks and superstructures.
- Used to evaluate material suitability for sandwich construction, inform laminate design (with ISO 12215-5), and support compliance with EU Directive 2013/53/EU when referenced.
Who should use this standard
- Small craft manufacturers and specifiers
- Composite material suppliers and test labs
- Certification bodies, surveyors and regulatory compliance teams
Related standards
- ISO 12215 series (Parts 1, 3, 4, 5, 6)
- Test standards referenced (e.g., ISO 844, ISO 845, ISO 1922)
- EU Directive 2013/53/EU (relevant for product conformity)
Keywords: EN ISO 12215-2:2018, small craft, sandwich construction, core materials, hull construction, embedded materials, boat building standards.
