Overview
ISO 7462:1985 - Shipbuilding: Principal ship dimensions - Terminology and definitions for computer applications defines the standard vocabulary for dimensional and derived quantities used in ship design software and hydrostatic analysis. Intended as a reference for data input and output, the standard establishes clear meanings for reference lines and surfaces (baseline, load waterline, perpendiculars, midships, stations), dimensional quantities (breadth, depth, draught, length, displacement) and the non‑dimensional coefficients derived from them that describe hull form and hydrostatic condition. The document is published in English and French and was prepared by ISO/TC 8 (Shipbuilding and marine structures).
Key topics
- Reference lines & surfaces - baseline, designed (Summer) load waterline, perpendiculars, midships, waterplane and maximum section. These define the coordinate axes and datums used in calculations.
- Dimensional quantities - consistent definitions for breadth (moulded vs extreme), depth, draught (moulded vs extreme; forward, amidships, aft), length (between perpendiculars, overall, waterline, submerged overall) and displacement (mass and volume).
- Non‑dimensional coefficients - terminology and definitions for coefficients derived from dimensional data that describe hull shape and hydrostatic behavior (used as inputs/outputs in naval architecture software).
- Computer application guidance - specifies that any additional dimensions or coefficients not covered by ISO 7462 must be defined explicitly in program input forms and output reports to avoid ambiguity.
Practical applications
ISO 7462:1985 is practical for anyone producing, exchanging or interpreting ship hull data between people and computer programs:
- Naval architects and hydrodynamicists - ensure consistent input/output terms when running hydrostatics, resistance, stability or strength analyses.
- Shipbuilders and designers - communicate principal dimensions and derived coefficients unambiguously across teams and suppliers.
- Software developers and data modelers - implement standardized field names and datums for shipbuilding applications, CAD/CAM and analysis tools.
- Classification societies and marine surveyors - reference consistent terminology for statutory, design and survey documentation.
Adopting ISO 7462 reduces data misinterpretation, improves interoperability between software systems, and supports accurate hydrostatic and form‑related calculations.
Related standards
Prepared by ISO/TC 8, ISO 7462 complements other shipbuilding terminology and measurement standards. When exchanging outputs that include terms outside ISO 7462, the standard requires those terms to be defined in the output documentation.