Overview
ISO 13742:2020 - Ships and marine technology - Ship's mooring and towing fittings - Universal fairleads without upper roller - specifies types, nominal sizes, dimensions, materials, construction, manufacturing, inspection and marking requirements for universal fairleads installed to lead a ship’s mooring rope. The standard covers fairleads without upper roller(s) (used where the mooring deck level is higher than the quay) and includes dimension tables, assembly figures and a normative annex on strength assessment.
Key topics and technical requirements
- Types and classification
- Four types are defined: 3R, 4RL, 4RR, 5R (single or double rope-pass openings, with optional side guide rollers).
- Nominal sizes
- Specified nominal roller diameters: 140, 160, 180, 200, 250, 300A, 300B, 400A, 400B, 400C (dimensions and SWL referenced in tabulated data).
- Materials and mechanical properties
- Frame/plates: weldable steel (yield ≥ 235 N/mm²; for 400A/B/C frames ≥ 315 N/mm²).
- Rollers: weldable steel plates or equivalent tubes (same yield point rules).
- Axles: carbon steel (yield ≥ 345 N/mm²).
- Bushes: brass, bronze or equivalent.
- Construction
- Rollers from steel tubes or plate; foundation and welding details to ensure load transmission to hull without plastic deformation or cracks.
- Guidance on D/d ratio (roller diameter D vs rope diameter d) to reduce strength loss by bend radius; tensile strength reduction per rope manufacturer guidelines.
- Manufacturing and inspection
- All surfaces (including welded surfaces) free of visible flaws; rope-contact surfaces free of roughness that could abrade ropes.
- External anti‑corrosion coating required; rotating parts greased.
- Marking and documentation
- Safe working load (SWL) must be recorded in the ship’s towing and mooring plan (IMO MSC/Circ.1175) and marked on the fitting (weld bead or equivalent), expressed in tonnes. SWL values in the standard’s tables are for reference and may be adjusted based on actual foundation/reinforcement.
Practical applications and users
- Intended for shipbuilders, marine equipment manufacturers, naval architects, ship outfitters, classification societies and ship operators.
- Used for design, procurement, fabrication, inspection, installation and maintenance of ship mooring and towing fittings (universal fairleads without upper roller).
- Supports specification of fittings for new-builds, retrofits and in-service replacement to ensure compatibility with mooring plans and rope manufacturer guidance.
Related standards and references
- Normative reference: IMO Circular MSC/Circ.1175 (Guidance on shipboard towing and mooring equipment).
- Developed by ISO/TC 8 (Ships and marine technology), Subcommittee SC 4 (Outfitting and deck machinery).
Keywords: ISO 13742:2020, universal fairleads, mooring fittings, ship mooring, SWL, D/d ratio, marine hardware standard, ship outfitting.