SCIENTIFIC ADVANCES gathering momentum over the past 30 years have pushed back the horizon of the seafaring man.

High-powered marine diesel engines, allied with modern hull design, have given him speed with reliability undreamt of in the days of sail—or, for that matter, in the early days of power— while sensitive navigational aids, such as radar and direction finding equipment, have made it possible for him to use this growing speed with increasing confidence. If a casualty occurs, improved radio communications mean that a call for help is more likely to be picked up—and pinpointed.

Yet, for all that, the old enemies are still there: storm, ice, fog, rock and shoal. Machines can fail; human judgement can err; storms can still prove overwhelming. The sea is waiting in all its ancient majesty; ultimately it is still the man who meets the wind and waves.

A lifeboat service is needed now as much, or more, than in the past; but, if the lifeboat is to perform her traditional role in a modern world, she must keep pace technically in the maritime field, setting her sights on each new horizon as it is opened up.

So, when in the 1960s, fast motor boats became part of the established scene, and had shown good seakeeping qualities, the RNLI began to explore the potential they offered for lifesaving.

There had been a high speed lifeboat before; in 1930 a 64' fast rescue boat capable of 17 knots had been stationed at Dover, but her engines had been petrol powered. Now speed was introduced into the lifeboat service in two different ways. First came the little inshore inflatable lifeboats; launched from the beach and driven by highpowered outboard engines, they can race at 20 to 25 knots to the help of those in trouble close to the shore.

Then came the fast afloat offshore boats; kept at moorings, capable, with their powerful marine diesel engines, of nearly double the speed of traditional lifeboats and with a righting capability inherent in their design. The 44' Waveney was the first, adapted from a United States Coast Guard design.

Then, as the RNLI staff explored the possibilities of larger fast afloat boats, progress was made on the development, in parallel, of a 50' steel boat, the Thames, and a 52' wooden boat which would be equally suitable for glass fibre construction, the Arun.

As soon as the prototype Arun (52-01, named Arun) was launched in 1971, it was clear that here was the embodiment of new ideas. She looked different— more like a high powered motor yacht than the accepted image of a lifeboat.

Reverse sheer? It gives her clear vision over her stem when, under way at speed, the bow rises. Well flared bow? It protects her deck and wheelhouse from thrown spray when she is driven hard (and she can reach close on 20 knots); it also gives her good working space on her foredeck. Broad beam? It adds great initial stability to a hull whose forward sections are veed tobreast the waves; it also provides wide, well protected side decks. An imposing superstructure? It not only houses all instruments, controls and electronic equipment so that this lifeboat can be navigated from her wheelhouse without any crew member being in any other part of the boat, but, being watertight, it provides the buoyancy to initiate self-righting, should she capsize.

The hull is divided into 26 watertight compartments. Most are filled with expanded polyurethane foam, giving so much buoyancy that, should all these compartments be holed simultaneously, she would still float.

Because of her breaks with tradition, Arun was given most extensive sea trials: 12,000 nautical miles. She circumnavigated Britain and Ireland and sailed the European coast from Spain to Norway, mostly under the command of Captain Roy Harding, RNLI trials officer, and crewed by a large number of both RNLI staff and volunteer lifeboatmen.

By the time she went on station she had steamed as many sea miles as she would normally have covered in the whole of her service life and met most kinds of weather, most kinds of sea. And all was well. She was in her element, riding smoothly, even in the roughest seas at high speed. Her crews recognised her worth, and welcomed her; and the combined observations of such seamen provided a wealth of useful data for the design team.

In those early days, she spent some months on station in Guernsey. She was delivered to St Peter Port at about 1600 on October 12, 1972. At 0330 next morning, Friday October 13, she slipped her moorings to go to the aid of a French trawler aground on the dangerous Roches Douvres, 25 miles off the French coast, in north-easterly gales.

She covered the 25 miles from St Peter Port to arrive just in the nick of time as the trawler began to break up; the crew of the trawler took to two dinghies and were soon picked up by the lifeboat.

Within hours of her first taking up station duty Arun had demonstrated the effectiveness of craft of this type in such waters, where speed and range can prove vital.

As a result of experience gained, some minor alterations were made to the structure of Arun and subsequent boats.

Some alterations were also introduced in hull design in the later boats. In 52-02 the freeboard was cut down on the side decks to allow easier recovery of people from the water; the wheelhouse sides were canted further inboard, too, to reduce vulnerability when rolling alongside a casualty in a seaway. In the third boat the transom was rounded to reduce corner vulnerability: this, incidentally, added almost 2' to the overall length, hence she is designated 54-03.

Apart from proving her seaworthiness and reliability, Arun's extended trials were of the greatest value in the development of the class's working layout ondeck and in future wheelhouses. 52-01 's wheelhouse is open plan. 52-02's wheelhouse, however, is divided by a bulkhead with access door and windows, so that should one half be damaged and take in water, the other half would not be flooded; also, at night a light can be switched on if necessary in the after compartment without affecting the helmsman's night vision.

A great deal of thought was put into the positioning of controls and instruments; maximum efficiency and crew well-being were complementary aims.

A boat travelling fast in rough seas will impose unusual strains on her crew, because, as she moves through waves, the contrary effects of gravity and the motions of the boat can result in the load on a man's legs being greater than they are accustomed to carry; consequently falls and injury are more likely. The vital period is when the lifeboat is on her way out to a casualty and speed is all-important; on the way back, with survivors safely on board, things can be taken more gently and risks are reduced.

So, to protect the crew and ensure maximum preparedness when the casualty is reached, seats with arm rests and safety belts are provided. Arun, the first boat, had such seats for helmsman, navigator and mechanic; later boats have them for all five of the crew.

If a crew member is to work from a seat, his instruments must be to hand.

As experience grew, improvements were gradually refined. In effect, it was a field study in ergonomics. In 52-02, the coxswain's seat was moved from the port side to amidships, and in each successive boat it has been possible for it to be edged further and further forward, closer to the windows, each adjustment improving vision. The seat for the navigator/lookout was moved to the starboard side of the coxswain, and a swivelling radar so positioned that both can use it from their seats. It is most important that such navigational aids, as well as the controls, are within the coxswain's reach because there will be times when all other members of the crew will be needed on deck.

54-03's wheelhouse bulkhead has been moved a little further aft, allowing the chart table and Decca Navigator to be on its forward side, so that the navigator now has all his tools round him and need not move from his seat (52-02 had these items abaft the bulkhead).

The mechanic/radio operator sits aft of the dividing bulkhead, but can see the coxswain through the window and can speak to him on the intercom. When the coxswain is at the upper steering position on the flying bridge he can hear all MF and VHP messages on relay speakers, and he can, in fact, also transmit VHP messages.

All-round vision is as important as forward vision, and in each successive Arun every opportunity has been takento improve vision from the wheelhouse and, if possible, reduce blind areas.

Good all-round vision has also been the over-riding factor in considering the upper conning position, used by the coxswain as a casualty is approached.

From here, in action, it is best if he can see all round the boat and members of his crew working on deck. On 52-01 the upper steering position was aft and the wheelhouse wide and, while workable, the arrangement left room for improvement. On 52-02 vision was improved with the narrowing of the wheelhouse, and the increasing of the width of the flying bridge itself. On 54-03 the conning position was brought right to the forward end of the superstructure and the ultimate has virtually been achieved.

We have looked at progress along just some of the lines of thought that have been pursued, but every aspect of the boat has been under similar scrutiny: handrails, ventilators, stowage of deck equipment and inflatable dinghy— everything has had to stand the test of extended use.

In her concept, her design and her fitting out, the Arun has been breaking new ground. She is also the first British offshore lifeboat to go into regular production in glass reinforced plastic (GRP). The first three Aruns were built of cold moulded wood by William Osbornes, but the hull, deck and superstructure of 54-004, just about to be launched, are of GRP, moulded by Halmatic.

54-004 is not the RNLI's first glass fibre rescue boat. The 40' Keith Nelson boat stationed at Calshot is built of GRP, and in 1968 instrumented stress analysis trials were conducted on her with the co-operation of Halmatic.

Runs were made in the West Solent and Portland Bill areas in seas ranging from calm to sea state 5, and one of the purposes of the trials was to measure the hull panel stress levels to obtain guidance for the determination of scantlings in future GRP boats.

Before laying up of the first GRP Arun hull began, pressure tests were made on representative hull panels. Two sheets of the hull skin lay up, each with four frames (of a lower scantling than is in fact being used on the Arun) and two longitudinals, were bolted together, but with a narrow gap between. Water was pumped into this gap until the pressure was in excess of 50 Ibs per square inch.

Soon the first GRP Arun, 54-004, will be afloat, and more trials, as with every new lifeboat, under way. The Arun class is adding a new, and exciting, chapter to a long, unending story of the pursuit of fitness for purpose.—j. D.Length Overall Beam Load draft aft Load draft forward Displacement 52' 0" and 54' 0" I7'0" 5'0" 3'9" 28-30 tons Engines Twin Caterpillar Diesels Type D343.TA, each developing 460 SHP at 2,000 rpm.

Maximum speed 19 knots Range at full speed 220 nautical miles Cruising speed 17 knots Range at cruising speed 240 nautical miles Crew 5 Builders: wood, cold moulded William Osborne Suppliers of: GRP hull, deck and superstructure Halmatic Fit out of 54-004 William Osborne.