IN THE FIRST PART of this article, published in the spring issue of THE LIFEBOAT, we recalled the righting after capsize on service of four of the Institution's lifeboats and looked at the designer's work which had made possible the snatching of success from disaster in this way. The four lifeboats are all built to different designs and their righting capabilities are provided by different design factors.

For Kilmore's 37ft Oakley lifeboat Lady Murphy, which was capsized and righted twice in the strong gales and wild seas of December 24,1977, a water transference system is employed to give her a righting capability. Barra Island's 52ft Barnett lifeboat R. A. Colby Cubbin No 3, which was capsized and righted in a hurricane on November 18, 1979, and Salcombe's 47ft Watson The Baltic Exchange, which was capsized and righted in a violent storm on April 10, 1983, are both fitted with an emergency air bag to give them a righting capability. Islay's 50ft Thames lifeboat Helmut Schroder of Dunlossit, which was capsized and righted on the same day and in the same area as R. A.

Colby Cubbin No 3, is designed with a substantial watertight deckhouse to give her a righting capability. All these lifeboats were able to return to station safely after righting; Salcombe's The Baltic Exchange, however, was the first lifeboat to continue on service after a complete capsize.

From the designer's point of view, getting the boat upright again after capsizing is only part of the job. Consider the likely results of turning an ordinary motor launch upside down in rough water and righting her again. Crew members on deck would have been thrown into the sea; those down below would have been rattled around like dice in a box with consequent injuries.

The engines would have stopped with water in the intakes and up the exhausts, possibly in the cylinders with dire consequences. The engine room bilges would be awash with spilt sump oil, fuel and battery acid. The electronics would be swamped and dead, the radar scanner flooded and useless. The boat might just remain afloat but she would be in no state to do a job of work, even if the surviving crew were so disposed.

It is now RNLI policy that lifeboats should be designed and built not only to survive capsize, but also to remain operational so that they are able to carry on with their job after the event.

However, staying in business means that a great deal of attention must be given to details of machinery and equipment, as well as to the main hull itself.

The crew Consider first the facilities provided for the crew. While at sea all crew members wear regulation life jackets and personal lifelines with which they can secure themselves to fixed jackstays running along the upperworks when on deck (see fig. 1). One of the Salcombe crew was not so secured at the moment the sea struck; he was washed overboard and later rescued. Wherever possible crew and passengers inboard are furnished with seats and safety belts, the belts specially designed so that they can be released under load; if belts are properly fastened all should be able to survive complete inversion without physical injury. There is a simple rule for anyone aboard a lifeboat facing risk of capsize: be inboard if you can, sit down if you have a seat and fasten your belt.

Even if it is possible for everyone on board to be seated and strapped in while on passage, at the time of a rescue the crew will inevitably have to be moving about the boat. Bump caps are provided for the crew to protect their heads, should they be thrown about by the seas or should gear in use or which has broken free fly around. New lifeboats, being faster, are more rapid and severe in their movement than older boats, so in their building care is taken to avoid sharp edges or hard corners; any which cannot be bevelled or rounded are protected with soft plastic pads specially made for the RNLI.

Stowages Not only can familiar objects become lethal missiles in an environment which is suddenly turned upside down, but a lifeboatman has to be able to put his hand on any piece of equipment he needs without hesitation. Everything on board has, therefore, to be provided with its own place and with fastenings to keep it secure in the face of not just severe heeling but of total inversion—or of a crew member, being thrown around by wild seas, holding on. It is easy to think of the deck as a safe place to put things, but during a capsize the deck is overhead. Fastenings must not only be strong and reliable, they must be simple to release so that a crew member can quickly get whatever equipment he needs whatever the movement of the boat, however dark the night, however cold and wet he may be himself. Shaped wooden stowages, shock cord, straps, lanyards spliced in place, drop-nose pins, firm but easily opened catches for lockers all play their part in any well found boat, and most certainly in lifeboats (see figs. 2 and 3).

Engines Once a lifeboat rights, her engines are essential, perhaps to get her out of immediate danger or make it possible for her to continue on service, certainly to get her safely home. There are good reasons for slowing them down or stopping them in the event of a capsize. In lifeboats capsize switches are fitted which will stop the engines, or bring them to idling speed, if the boat rolls beyond 90 degrees. The heart of the capsize switch unit is a glass tube closed at both ends and mounted vertically.

The tube has a small amount of mercury resting in the bottom end and two metal contacts at the top end. When the glass tube is turned more than 90 degrees the mercury runs down the tube and bridges the contacts. With the electrical circuit thus closed a solenoid is energised which in turn pulls the fuel pump racks on the engine either to the 'idling' or the 'stop' position.

Checking the engines is just part of the story. Preparation has also to be made to forestall many other hazards— in particular the penetration of sea water into the machinery. Exhaust gases must have an escape route to the open air, but the system is so designed that ingress of sea water can be cut off or limited on inversion. In some lifeboats the engine exhaust pipes are fitted with spring loaded valves, specially designed by the RNLI (see fig. 4), which are kept open by the pressure of the exhaust gas as long as the engine is running; once the engine stops the valves close and keep the sea water from running up the exhaust pipes.

More modern lifeboats rely on the engine exhaust pressure when engines are idling keeping the exhaust system clear of sea water. Crankcase and fuel tank breather openings are fitted with automatically-closing valves; the fuel fillers and sounding tubes are fitted with captive caps; batteries are of a nonspilling type housed for extra safety in acid-tight boxes. These and similar measures, such as the provision for ventilation (see below), taken all together mean that, when a capsized lifeboat comes upright, the motor mechanic only has to re-start the engines or cancel the 'idle' instruction imposed by the capsize switch and the coxswain once again has his engines at his command.

Ventilation While free passage of air is important for the lifeboat crew, it is vital for the engines. If the ventilation to the engine room were sealed off for more than a few seconds and the engines were still running, air would be sucked from the engine compartment and the suction might collapse the boat's structure.

There must be intakes for the combustion air, but where air can pass, so can water. It follows that, for a lifeboat which depends on the integrity of her hull and deckhouse for her reserve buoyancy and for the protection of her engines, her electrics and her electronic equipment from sea water, very careful provision by her designers must be made for her ventilation. The detail varies from boat to boat, but in most the air intake openings, through which the engines draw their combustion air, are situated in the superstructure, one each side. An interruption of ventilation should not occur because the trunks leading from the air intake openings are crossed. This means that, except perhaps for a second or two during which a lifeboat which has been capsized is close to the 180 degrees, whatever the heel of the boat, the intake on one side or the other will be above the water and operative. Say the boat is heeled right over to starboard. Air is still free to pass through the port intake and along the trunk to an opening into the hull on the starboard side. Meanwhile, the starboard intake may be under water, but at the other end of its crossed trunk, the outlet on the port side is raised up above static sea water level; water would therefore not enter the hull that way.

The Arun lifeboat is so designed that even when she is completely upside down the air intake louvred openings, on the after end of her deckhouse, will still be above water level so that the sea cannot get in; they, and the engine room outlets at the other end of the trunking, are within a limited area in the centre of the boat, known as the 'envelope', which will always be clear of the static water level, whatever the aspect of the intact boat (see fig. 5).

Deckhouse and cabin ventilation systems need similar protection, and the RNLI design office has produced a combined capsize or anti-flooding air intake valve with a minimum of moving parts; it is also used in some designs of lifeboat for the engine supply. With all the virtues of simplicity, this valve ensures not only that the sea is excluded as the boat goes over, but also that ventilation is interrupted for as short a time as possible. The valves are sited to port and starboard in the boat's deckhouse.

Should the boat be rolled to starboard, while the starboard valve is closed by a heavy ball responding to gravity (see fig. 6), the port valve, still clear of the water, remains open and allows the continued supply of air. It is not until the angle of heel approaches 100 degrees that both valves close, and it is then only a matter of seconds before, as the boat rights herself, the water drains away and the valves open once again. Even when the boat is upright and under way, green water may come aboard and could wash into the ventilation system; to prevent that from happening, there is also a lightweight float which will rise up on the incoming water and close the valve.

Radio and radar The radio and radar installations in any boat face hazards of two kinds. The first and most obvious is through water getting into the works. This is countered by fitting the sets in watertight enclosures in open deckhouse boats, and by putting as much gear as possible inboard in closed deckhouse boats.

'Watertighting' anyway is a worthwhile precaution for coping with normal lifeboat conditions; there can be a lot of salt water splashing around the equipment at roll angles considerably less than half of 180 degrees! The second hazard is the risk of mechanical damage to masts and upperworks caused by rolling over. In shallow water the impact with the sea bed could carry a mast away completely. A heavy blow to the mast could endanger the boat's safety if the mast structure were to be torn out bodily leaving a hole in the deck or deckhouse roof. To avoid this risk the mast is deliberately built with joints at the base which are weaker than the supporting hull structure, so that if the mast carries away it will part at the joints leaving the hull and deckhouse with watertightness intact. When Lady Murphy, Kilmore's Oakley lifeboat, capsized in 1977, the foremast broke as intended. That mast carried the VHP dipole aerial and also supported the MF twin wire aerial, and communication was lost. This situation had been foreseen and a programme of replacing mast supported MF aerials with whips had already begun. The VHF aerial is now backed up with an emergency low profile solid slot aerial (fig. 7). The slot aerial gives rather less range than the main aerial but is physically less vulnerable and so it forms a valuable stand by.

While a radar display unit can be fitted with a watertight cover or sited in a watertight wheelhouse, the rotating scanner aloft is in a much more vulnerable position. 37ft Oakley and 37ft 6in Rother class lifeboats have specially modified sealed radomes encasing the scanners, so they should have no problem, but it can easily be seen that an open and free turning scanner unit which continues to rotate in the water when a boat is capsized is likely to be badly damaged. When the Barra and Islay lifeboats righted, in 1979, both scanners were full of water and their radars out of action.

Work began to find a solution to this problem and in 1981 a 52ft Arun was fitted with the first watertight radar scanner. This radar automatically switches off before the scanner enters the water; then after the boat has righted herself, the radar is switched on again manually and a picture is once again obtained on the display. Harbour capsize and righting trials have shown that radars can remain operational after total inversion. It is to be hoped, but is yet to be seen, that they will do as well if ditched on service in rough weather. Summing up Capsizing is and always will be an alarming and dangerous experience, and coxswains will always navigate and handle their boats to avoid it if they possibly can. But no one can ever guarantee that a lifeboat will never find herself facing overwhelming seas. The risk of being turned over, though small, is one which the Institution's crews have always faced, and will continue to face.

The designers are doing their best to furnish these men with boats which will survive capsize, which will protect their crews, and which will be usable after the event—not just to limp home, but to continue with the service in hand before turning for shelter.

Coxswain Griffiths of Salcombe lifeboat, finding his lifeboat upright again, was able to get under way at once and to turn at full power to recover his colleague from the sea, and then to resume his original course; he and his crew have shown that it can be done..