ISO DIS 12215-7

Description / Abstract: This part of ISO 12215 applies to the determination of local design pressures, and to the determination of the global loads acting on connected structural members of multihull craft constructed from fibrereinforced plastics, aluminium or steel alloys, glued wood or other suitable boat building material with a hull length LH up to and including 24m according to ISO 8666.

It only applies to craft in the intact condition and with a maximum speed ≤ 50 knots in mLDC conditions.

It is not applicable to Hydrofoils, Small Waterplane Area Twin-Hull Ships (SWATHS) or surface effect multihulls.

The assessment shall generally include all structural parts of the craft that are assumed watertight or weathertight when assessing stability, freeboard and buoyancy according to ISO 12217 and are essential to the safety of the craft and of persons on board.

For the complete scantlings of the craft, this part of ISO 12215 shall be used in conjunction with Part 5 for detail local scantlings; Part 6, for construction details, Part 8 for rudders and Part 9 for appendages, and Part 10 for rig loads and rig attachment, with eventual changes coming from this document.

The scantling determination of windows, portlights, deadlights, hatches and doors shall be assessed using either ISO 12216 which is a simplified scantlings standard, or using the pressures determined in this document and/or ISO/DIS 12215-5, particularly for panels other that non stiffened plates and their supporting structures, then using the equations, safety factors, mechanical properties and detailed requirements of ISO 12216.

The scope of ISO 12215 was initially developed for up to 24 m hull length LH, but it may be applied for craft up to 24 m load line length and beyond, (see Note) with the necessary critical mind.

Scantlings derived from this document are primarily intended to apply to recreational craft including recreational charter vessels. They are considered to correspond to the minimum strength requirements of motor and sailing craft which are operated in a safe and responsible manner, having due cognisance of the prevailing conditions. It primarily applies to boats designed to be available to open public, and used by non-professional crews, it is not suitable to racing craft that are only performance oriented and excludes boats designed only for professional racing. However Clause 14 considers the usage of a multihull as a workboats, with professional crew, provided Annex I of ISO/DIS 12215-5 is complied with.

Throughout this document, and unless otherwise specified, dimensions are in (m), Areas in (m²), masses in kg, forces in (N), moments in (Nm), Pressures in kN/m² (1kN/m²=1 kPa), stresses and elastic modulus in N/mm² (1N/mm²=1 Mpa).

NOTE The load line length is defined in the OMI "International Load Lines Convention 1966/2005", it may be larger than LH for craft with overhangs. This length also sets up, at 24 m, the lower limit of several IMO conventions.