Overview
ISO 4853:2023 - Ships and marine technology - A-frame launch and recovery system - specifies requirements for the design, operation, performance and acceptance testing of A-frame launch and recovery systems (A-frame LARS) used for underwater applications (excluding lifesaving appliances). The standard covers the full lifecycle from design and manufacture through factory and installation acceptance tests, and focuses on operational safety, structural integrity and functional performance of stern- or side-mounted A-frame systems.
Key topics and technical requirements
- Scope & terminology: Defines A-frame LARS, associated winches, safe working load (SWL), duty factor, hoisting factor and minimum hoisting speed. (Normative reference: ISO 3828.)
- Operation & controls:
- Main control panel with visible working status and a portable control box for short-distance operation.
- Emergency recovery and quick-release buttons on control systems; emergency release must require at least two separate actions and the prime mover must not re-start automatically.
- Constant tension setting on winches for towing operations to prevent damage when rope is blocked.
- Load measuring device and overload alarm to record wire rope tension and indicate overloads.
- Wire rope and loose gear:
- Specified wire rope tensile range: nominal strand tensile strength not less than 1 420 MPa and not more than 2 200 MPa.
- Safety-factor rules and hoisting factor (φ) considerations; Annex A provides hoisting factor guidance.
- Proof-test requirements for loose gear (chains, hooks, blocks): typically 200% SWL for most items, with reduced percentages for very large blocks per the table in the standard.
- Structural design & loads:
- Design under conditions without wind and with wind; includes deadweight, working loads, inertia, shock, and wind force calculations.
- Allowable stress based on yield strength and specified safety factors (different values for with/without wind cases).
- Requirements addressing fatigue and fracture toughness for critical/main load-bearing members.
- Cylinder protection: Anti-corrosion coatings for piston rods and retraction when out of service to extend life.
- Acceptance testing: Heavy hoisting tests, factory acceptance tests, and installation testing with prescribed test loads and post-test examinations.
Applications
- Design and manufacture of A-frame LARS for offshore survey, ROV/AUV deployment, subsea intervention and towing operations.
- Shipyards, deck machinery manufacturers, offshore contractors, and marine equipment suppliers needing to meet recognized safety and performance benchmarks.
- Classification societies, inspection bodies and procurement teams specifying performance, testing and acceptance criteria.
Who should use this standard
- Marine engineers, naval architects and structural designers
- Deck machinery manufacturers and winch suppliers
- Offshore operators and survey vessel owners
- Classification societies and inspection/test personnel
Related standards
- ISO 3828 - Shipbuilding and marine structures - Deck machinery - Vocabulary and symbols
- ISO/TC 8 / ISO/SC 4 technical committee context and ISO/IEC Directives referenced for development and maintenance
Keywords: ISO 4853:2023, A-frame LARS, A-frame launch and recovery system, ships and marine technology, wire rope, load measuring device, emergency release, hoisting factor, acceptance tests, offshore deck machinery.
