ISO 24041:2020

Overview

ISO 24041:2020 - Ships and marine technology - Shark jaws and towing pins - specifies requirements for the design, manufacture, operation, performance and acceptance tests of marine shark jaws and towing pins driven by electric, hydraulic, diesel or steam power. The standard covers definitions, types (fork and triplex), structural forms, material and strength requirements, performance specifications and mandatory acceptance tests for deck machinery used to secure and lead towlines.

Key topics and technical requirements

• Scope and types: Differentiates fork shark jaws and triplex shark jaws, and defines towing pins and support boxes (including left/right/central configurations).
• Materials & stresses: Component permissible stresses shall not exceed 0.67 × yield strength; support structures limited to 0.5 × yield strength.
• Safe Working Load (SWL) and sizing: Tabled values relate nominal rope diameters (examples in the standard range from small to large sizes) to SWL and minimum working times. Typical working-time limits are specified (e.g., shark jaws: ~8–15 s; towing pins: ~10–25 s depending on size).
• Load alarms and monitoring: An alarm must activate at 50% of rope breaking load or 50% of shark jaw SWL. Provision for load measuring devices and overload alarms on the wheelhouse and portable control.
• Emergency release: Defined emergency-release load criteria by SWL band:
  • SWL > 5 000 kN → emergency release load = 40% of SWL
  • 1 200 kN ≤ SWL ≤ 5 000 kN → 20% + 1 000 kN of SWL
  • SWL < 1 200 kN → emergency release load = SWL Emergency release controls must be accessible on main and portable control panels with specified maximum delays.
• Support box & seawater handling: Fork-type support boxes must be watertight; triplex types require drainage and water-prevention features when stowed.
• Auxiliary systems: Requirements for wheelhouse control panel with clear view, portable control box, centring device, safe pin (for fork jaws), lubrication access, audible alarms and documentation.
• Acceptance tests: Include operation without load, operation under load, control-system utility, emergency release, and waterproofing tests.

Applications and users

ISO 24041:2020 is relevant to:

• Shipbuilders, naval architects and deck machinery designers specifying towline handling equipment
• Manufacturers of shark jaws, towing pins and support boxes
• Classification societies, yards and shipowners conducting acceptance tests and sea trials
• Tug, salvage and offshore towage operators seeking compliant, safe towline securing systems
• Procurement teams specifying equipment matched to vessel bollard pull and rope selection

Related standards

• ISO 3828 - Deck machinery vocabulary and symbols (normative reference)
• ISO 7365 - Towing winches for deep sea use (referenced for related deck machinery requirements)

Keywords: ISO 24041:2020, shark jaws, towing pins, deck machinery, ships and marine technology, SWL, emergency release, acceptance tests, towline equipment.