Model KH6.5 M2 on-load/off-load release mechanism, for use with double-point suspension lifeboats and rescue boats; maximum approved working load of 6,500 kg per hook.

Common issues

• Hook mechanism corrosion or seizure from inadequate lubrication, preventing correct engagement
• Incorrect adjustment of the interlock/safety pin, risking premature release
• Hydrostatic interlock (where fitted) fouled or misaligned, defeating the load-sensing safety feature
• Release cable/rod linkage misalignment causing the two hooks not to release simultaneously
• Wear at the hook bearing pin/bushes leading to excessive free play
• Paint or coating buildup masking cracks or wear on load-bearing hook components
• Release handle mechanism sticking or the guard not preventing accidental operation

Inspection checklist

• Function-test on-load and off-load release under no-load and, per the maker's/SOLAS schedule, under load
• Check that the hook engagement/locking indicator visually matches the actual mechanical state
• Verify simultaneous release of both hooks within the maker's tolerance
• Inspect hook pins, bushes and the load path for wear, cracks and corrosion
• Check the interlock/safety device prevents release unless the boat is waterborne, where fitted
• Verify the release handle guard prevents accidental operation
• Confirm the annual thorough examination and periodic dynamic load test are current
• Check the release control wire/rod for correct tension and free movement, with no binding
• Inspect for correct greasing per the maker's lubrication chart

Service intervals

Critical spares

• Hook pin and bush set
• Release cable/rod assembly
• Interlock/hydrostatic release unit, where fitted
• Return spring for the release lever
• Seal/gasket kit if hydraulically actuated

Safety

• Uncontrolled or premature hook release is a documented cause of fatal lifeboat launching accidents industry-wide - never bypass interlocks or work under a suspended boat without mechanical blocking
• Falls under tension present a crush and cutting hazard at the hook and block
• Never load-test with personnel in the boat unless the specific approved procedure requires and permits it
• A corroded or seized hook must be tagged out of service, not forced

Class survey

Release hooks fall under SOLAS III / LSA Code and are subject to annual thorough examination by a competent person and periodic operational/dynamic testing per MSC.1/Circ.1206 as amended; class checks maintenance records, any manufacturer safety bulletins affecting the hook type, and that crew drills cover the release procedure.