Incidents with lifeboat lowering devices
MARS report on recent lifeboat incidents in fleet
Incidents with lifeboat lowering devices
MARS Report 201126
Recently, several incidents involving trouble with the lifeboat lowering device have been reported by our fleet vessels.
Case 1: Breakdown of lifeboat brake unit
During a routine drill, the lifeboat could not be controlled by the brake unit. The brake unit was dismantled and the thrust bearing was found to have completely broken, with the thrust shaft worn out and bent. The cause of this brake failure could not be positively identified, but the manufacturer advised that this type of damage could occur if excessive (> 15 kgf) downward force is applied on the brake counterweight by the operator, usually in a panic response to the lifeboat lowering out of control, often caused by a poorly adjusted or maintained brake system.
During the last annual inspection, which took place 5 months earlier, a dynamic winch brake test could not be undertaken, because, at that time the vessel was alongside at berth, preventing the full requirements of the test being carried out.
Case 2: Parting of lifeboat self-lowering control wire
An attempt was made to swing out the lifeboat, but the remote control wire suddenly parted just after starting the swing out. The remote control wire had recently been renewed but wound the wrong way round the auxiliary drum by a person trained and certified by the manufacturer at the last inspection.
Recommendations
When tests cannot be completed during an annual inspection due to circumstances such as those described above, the outstanding tests must be completed at the earliest opportunity without fail;
In addition to authorised service personnel, crew have equal responsibility for ensuring lifeboats are in good working order and are maintained and operated properly. Therefore ship's crew should take the utmost care to check and ensure lifeboat equipment remains fit for proper operation at all times;
An arrowed line on the drum is a simple and effective measure for ensuring it is wound in the correct direction.
Manufacturers have reminded us of the following operational safety information:
General
Do not apply a downward force of more than 15 kgf to the counterweight of the brake lever, as this may damage the thrust bearings. If properly maintained and adjusted, the brake is designed to operate solely by the force applied by the counterweight.
Confirm the home position of the brake lever is in the horizontal position. The ideal position for the lever is in slight contact with the stopper pin. The allowable clearance between the stopper pin and brake lever is 10 mm.
Before operation
Check braking efficiency by slightly lifting the suspension block (sling block) from the davit by davit handle without releasing the davit arm stopper (cradle stopper).
Adjust the limit switch so that the davit arm (cradle) stops just 50 to 100 mm from the stowing position. Check that the brake holds the boat in the position. If the winch is wound with the davit arm (cradle) touching the upper stopper because the limit switch is incorrectly set, the davit will become overloaded.
During operation
When stowing the boat, it is important to equalise the length of the fore and aft boat falls. Stop hoisting just before the wire guide comes into contact with the suspension block (sling block), and check clearance between the fore and aft. If clearance balance is uneven, adjust the end turnbuckles to make the clearance uniform.
After operation
After setting the davit arm stopper (cradle stopper), raise the brake lever of the winch slowly and unwind the boat fall wire to allow the boat to lower slightly. Mount the suspension block (sling block) onto the horn of the davit in order to release the load from the boat fall wire.
