Model LHR3.5M2, variant 3, on-load/off-load release mechanism, for use with single-point suspension lifeboats and rescue boats; maximum approved working load is 3500 kg per hook.

Common issues

• Hydraulic release mechanism sticking or requiring excessive force to reset after a test
• Corrosion or wear at the hook/keeper pin interface, reducing margin against premature release
• Interlock (hydrostatic or mechanical) misalignment that could allow release before the boat is waterborne
• Hydraulic hose or seal leaks in the release actuation circuit
• Fall wire or davit arm corrosion where paint has broken down at sheave contact points
• Winch brake slipping under load during a lowering test
• Release handle/labelling worn or illegible, risking incorrect operation under pressure

Inspection checklist

• Weekly visual/operational check per SOLAS drill and inspection routine
• Monthly lowering with crew, per drill schedule where practicable
• Annual thorough examination by a competent person per MSC.1/Circ.1206 as amended
• 5-yearly dynamic winch brake test and load test of the on-load release gear
• Check hydraulic fluid level and condition in the release actuator
• Check hook, keeper, and interlock pins for wear, corrosion, deformation
• Confirm the release handle moves through its full range and resets correctly
• Check fall wire condition along its length - broken wires, corrosion, lubrication
• Verify the interlock prevents on-load release when the boat is not waterborne, during the test sequence

Service intervals

Typical intervals for this design class, not the manufacturer’s figures for your model. The manufacturer’s manual is binding.

Critical spares

• Hydraulic seal kit for the release actuator
• Hook and keeper pin set
• Interlock spring/linkage components
• Fall wire of correct diameter and construction for this davit
• Hydraulic hose assembly for the release circuit

Safety

• Premature release of on-load release gear under load has historically been a major cause of lifeboat launching fatalities worldwide - this is the single most safety-critical function on the davit
• Personnel must never be inside the boat during a release/lowering test unless the procedure specifically requires it with all precautions in place
• Stored hydraulic pressure in the actuator can cause injury if worked on without isolating and depressurising first
• Crush hazard between the boat and davit structure or ship's side during lowering/recovery

Class survey

Class looks specifically for up-to-date thorough examination and 5-year test records for the on-load release gear, not just the davit generally; a lapsed 5-year test or a component change without matching documentation is a common source of a class remark or condition of class.