Overview
ISO 5780:1987 - "Shipbuilding - Side scuttles - Positioning" specifies allowable positioning of side scuttles (portholes/windows) that comply with ISO 1751 for passenger and cargo ships on international voyages. The standard sets location limits relative to the Summer load line and freeboard deck, prescribes strength limits tied to calculated design pressure, and includes two integral annexes: Annex A (formula for design pressure) and Annex B (simplified graphs for positioning).
Key topics and requirements
- Scope: Applies to side scuttles manufactured to ISO 1751 on ships intended for international voyages (passenger and cargo).
- Positioning rules:
- Minimum sill height measured from the Summer load line (or Summer timber load line) - specific exclusion zones are defined (see clause 3.3).
- No side scuttle sill may be below a line parallel to the freeboard deck with its lowest point at 2.5% of ship breadth (B) above the Summer load line, or 500 mm above that load line, whichever is greater.
- Certain longitudinal zones (defined by ship length and station ordinates) restrict installation; some positions require non-opening scuttles.
- Strength and pressure limits:
- Side scuttles must withstand external design pressure calculated per Annex A. If the local design pressure exceeds the product’s allowable pressure, installation is not permitted.
- Annex A provides the formula and factors (height factor a, length-distribution factor b, probability factor f, breadth factor c) used to compute design pressure.
- Annex B provides simplified graphs and tabulated allowable pressure values for ISO 1751 types (A, B, C) to determine minimum sill heights.
- Deadlights and safety:
- Permanently attached deadlights (ISO 1751 type A or B) are required where side scuttles open into spaces below the freeboard deck or into first-tier superstructures that access below-freeboard spaces.
- For vessels with damage-stability requirements, side scuttles whose sills would be below the damaged final waterline must be non-opening.
Applications and users
ISO 5780 is used when designing and arranging hull and superstructure openings on seagoing ships. Typical users:
- Naval architects and ship designers laying out hull openings and specifying sill heights
- Classification societies and flag administrations assessing compliance
- Shipbuilders and outfitting engineers selecting window types and glass thickness per ISO 1751
- Surveyors and safety assessors verifying damage-stability and load-line compliance
Related standards and references
- ISO 1751 - Shipbuilding - Ships’ side scuttles (detailed product requirements)
- International Convention on Load Lines, 1966 (IMO)
- IACS Requirement S3 (strength of end bulkheads)
- Relevant IMO conventions (SOLAS, MARPOL) cited in the ISO 5780 bibliography
Using ISO 5780 together with ISO 1751 and the IMO load-line rules ensures safe, compliant positioning of side scuttles based on calculated design pressure and operational safety requirements.
