The safe launching of a lifeboat in adverse weather conditions from a ship making way requires an expertise which few mariners possess. Training colleges cannot hope to simulate realistic conditions and few masters are prepared to risk lives and lifeboats in heavy weather to facilitate the acquisition of a skill which may never be required in earnest.

The inability to practise such a manoeuvre is compounded by the difficulty of ensuring that both falls are released simultaneously in a lifeboat fitted with the conventional suspension chain and open hook arrangement. This requires local release of the falls by two crew members working at opposite ends of the boat. Experience has shown that, all too often, the boat's crew has managed to release only one hook, leaving the boat suspended from the other fall. In the next wave trough, the boat is upended, tipping its occupants into the water with potentially serious consequences. Recognition of this problem by lifeboat manufacturers and maritime authorities, together with the introduction of partially and totally enclosed lifeboats, has led to the development of more sophisticated lifeboat release systems to enable simultaneous release of both falls from a single control position.

Initially, an 'off-load' release system was developed. The design of this system ensured that the lifeboat could not be released unless it was fully waterborne, with no load on the falls. This did not fully address the problem and with further research the 'on-load' release system was developed. This system is designed to release the lifeboat, whether or not the falls are under load, due to the movement of the ship or prevailing sea conditions.

Under the SOLAS Convention, it is now mandatory for all lifeboats installed on ships, constructed after 1st July 1986, to be equipped with a release mechanism capable of operating both off-load and on-load which is adequately protected against accidental or premature release.

Systems currently in use

There are a number of different types of on-load release systems available, although all are similar in operation and with common elements. Each system comprises a single control unit with control cables linking the unit to two release hooks and a hydrostatic interlock. The control unit locks the hooks in the closed position and the operation of the release mechanism requires a deliberate and sustained action. Each hook is fitted with a hinged guard plate to prevent the fall link from dropping out of the hook until the release mechanism is operated. The hydraulic interlock is operated by a diaphragm installed in the bottom of the boat and prevents premature or accidental release of the falls by locking the control unit unless the lifeboat is waterborne. A manual override, requiring a deliberate action, is provided in the event that the hydrostatic interlock fails to operate.

Unlike the static hooks in the usual lifeboat suspension arrangement, the hooks in on-load release mechanisms are designed to trip when the system is operated, releasing the lifeboat falls. There are two principal methods of operation: the cam system and the open-topped cone system.

Cam system. The operating lever of a half-round cam is connected to a push/pull control cable from the control unit, which locks the cam when the hook is in the closed position. The hook is prevented from opening by the overlap between the tail of the hook and the upper segment of the cam. When the release system is operated, the cam is rotated through 90° by the control cable, allowing the hook to trip and release the falls.

Open-topped cone system. This has a vertical spindle, the upper part of which is conical and has a u-shaped open sector. The tail of the hook is located in the conical section and is locked by rotating the cone so that the closed sector is against the tail of the hook. The cone is locked in the closed position by a spring-tensioned control cable linking the release mechanism of the two hooks. When the release system is operated, the spindle is rotated through 110°, aligning the open sector of the cone with the hook tail, allowing the hook to trip and release the falls.

Regardless of the type of on-load release system, it is important that the hooks are correctly reset prior to the recovery of a lifeboat from the water. With the cam system, care should be taken to ensure that the face flats of the hook tail and the cam are tight up against each other. In all cases, the correct positioning of all safety devices, including the hydrostatic interlock and hook guard plates, should be ascertained. Failure to do so may result in the system being incorrectly set, which could lead to premature release the next time the lifeboat is lowered.

Experience in service

Since their introduction, on-load release systems have been involved in a number of serious accidents during lifeboat drills, including one on board a ship entered in the Club. The accidents have often resulted in death or serious injury to the lifeboat's crew and extensive damage to the boat, and have invariably been initiated by the premature release of one fall. The full weight of the lifeboat coming on to the remaining fall, combined with the shock loading, has damaged the hook assembly and control system to the extent that it has also released, allowing the lifeboat to free-fall. Subsequent investigations have concluded that the premature release was caused by a failure to ensure that the release mechanism had been correctly reset on the last occasion that the lifeboat had been used. In some cases, this has been up to three months prior to the accident. In some instances, warning signs that the system had not been reset correctly had been ignored.

There have also been a number of incidents, during lifeboat drills, when hooks have failed to release after a lifeboat is waterborne and the release system has been operated. The implications should such a failure occur in a genuine emergency require no elaboration.

Human error has been identified as the main cause of incidents involving on-load release systems with systems either being incorrectly operated, inadequately maintained or improperly adjusted. No design or manufacture fault has been the principal cause of an incident. Properly adjusted, maintained and operated, lifeboat on-load release systems are safe and enhance safety when launching lifeboats.

There is little doubt that the number of accidents involving on-load release systems has led to a lack of confidence among mariners. This is of concern to the Club as a lack of confidence may lead to a reluctance to carry out the lifeboat drills prescribed by SOLAS. The mandatory requirement to fit on-load release systems to all ships constructed after 1st July 1986 will also result in a proliferation of these systems in the future. This will increase the potential for accidents unless the root cause of the problem, i.e. human error, is addressed and confidence restored.

Recommendations

Members whose ships are equipped with lifeboats fitted with on-load release are urged to note the following recommendations:

• Prior to commencing any drill involving lowering of a lifeboat, the release system should be checked to ensure that the release hooks are properly set with the guard plates closed and the hydraulic interlock in the locked position.
• All crew members should be familiar with the manufacturer's operating instructions and be given detailed and regular training in the correct operation of the on-load release system. Training should be directed towards improving both confidence and competence in operating the system.
• The manufacturer's operating instructions should be strictly observed, with particular regard to the correct resetting of the system, the consequential checks prior to effecting recovery of a lifeboat from the water, and the correct operation of the hydrostatic interlock once the lifeboat is clear of the water.
• The on-load release system should be maintained strictly in accordance with the manufacturer's instructions insofar as is practicable. Most manufacturers recommend operation of the on-load release system on a monthly basis. This will not be practicable for many ships unless appropriate arrangements are provided to enable the lifeboat to be hung-off on a maintenance pendant and the main hooks to be released.
• Members, and their masters, should ensure that each lifeboat is waterborne at least once every three months and that the on-load release system is tested and proven fully functional at that time. Any deficiencies in operation should be rectified immediately.
• The officer-in-charge should satisfy himself that the release system has been correctly reset prior to recovering a lifeboat from the water. If any doubt exists, a thorough check should be carried out before attempting to lift the lifeboat.

Future legislation

Members may be aware that the revised Chapter III of SOLAS, which comes into force on 1st July 1998, contains three important requirements in respect of the maintenance of on-load release systems as follows:

(a) On-load release systems should be subjected to a thorough examination and test by properly trained personnel familiar with the system at every safety equipment survey.

(b) On-load release systems should be operationally tested under a load 1.1 times the total mass of lifeboat when loaded with its full complement of persons and equipment whenever the release system is overhauled. This overhaul and test should be carried out at least once every five years.

(c) On each lifeboat launching appliance there should be provision for hanging-off the lifeboat to free the release system for maintenance.

These requirements are mandatory for all ships constructed on or after 1st July 1998. However, the Managers strongly recommend that any member with existing ships fitted with on-load release systems to consider implementing the above requirements on a voluntary basis.

With regard to the hanging-off arrangements, fatal accidents have also occurred as a consequence of wrongly attaching the hanging-off or maintenance pendant to the on-load release system.

One inquiry recommended that the manufacturers of on-load release systems should...'remove the possibility of human error by devising a system which prevents the (maintenance) pendant from being attached to anything other than the pendant (maintenance) lug'. A number of such systems now exist and any member contemplating the retrofit of hanging-off arrangements to an existing ship is strongly recommended to contact the manufacturer of the original on-load release mechanism for guidance.

The attention of members requiring more detailed guidance on the correct operation of on-load release systems is drawn to a video training programme entitled ‘Lifeboat On-Load Release Gear-Safe Inspection and Maintenance,’ produced by the UK’s Health and Safety Executive.

The video may be obtained from:

CFL Vision
P.O. Box 35
Wetherby
West Yorkshire
LS23 7EX
Tel: 01937 541010
Fax: 01937 541083

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