to the data reservoir

Task:Salvage pumping duties on board SS "Great Britain"

Application Report 8

Pump: 4" and 3" SPATE
Power Plant: Lister SR 1 diesel Petter AA 1 diesel
Customer: Risdon Beazley Ulrich Harms Ltd. (Southampton)

The following story and one with which this company is proudly associated concerns the historic salvaging of the 127 years old hulk of the steamship "GREAT BRITAIN" from an isolated cove in the Falkland Islands, and her return to Bristol. It is important to know a little of the history of this once great ship to appreciate the desire to salvage its crumbling rusted remains.

SS Great Britain
The s.s. "Great Britain" at sea

The S.S. "Great Britain" was built by the Great Western Steam Ship Company at a time when America's superior sailing ships monopolised the Atlantic maritime trade. Her launching at Bristol in 1843 marked not only the end of the monopoly and Britain's resurgence as a maritime power, but the greatest leap forward in maritime technology in centuries. The steam powered, screw driven, iron built "Great Britain" designed and constructed under the guidance of the engineering genius, Isambard Kingdom Brunei, was the forerunner of all modern ships. She was not the first steam powered ship, she was not the first iron ship, nor was she the first screw driven ship, but she was the first large, ocean going steam powered, practical screw-driven iron ship, the first ship with remote indicating electric log, the first ship capable of lowering all masts in a head wind, the first with a six bladed propeller, semi-balanced rudder, double bottom, transverse bulk­heads, wire rigging, hollow wrought iron propeller shaft, and the first merchant ship with an overall tonnage of 3,600 tons, and nearly three times the size of any merchant ship then afloat. As with most technical innovations, the "Great Britain" had her troubles, experience showed the need to revise certain aspects of the original design, thus over the first ten years of her career, there were a number of alterations which changed her appearance. Her six masts were reduced first to five, then four and eventually three, a new and much longer bowsprit was fitted. The funnel changed in appearance after new engines and boilers of an advanced design were installed; The six bladed propeller was changed early in her career and was finally fitted with a three-bladed version.

The "Great Britain" was originally designed as an Atlantic liner, carrying 360 passengers in spacious accommodation, but in 1846 on her fifth voyage, she ran aground in Dundrum Bay on the coast of Northern Ireland, the subsequent cost of the recovery and repair was too much for her owners and they were forced to sell.

In 1852, under new ownership, the "Great Britain" was refitted for voyaging to Australia and the accom­modation re-arranged to take up to 1,000 passengers. Over the following 24 years she became a reliable and popular ship, carrying more emigrants to Australia than any other vessel in the nineteenth century. Twice during this period she was requisitioned for trooping duties in connection with the Crimea War and the Indian Mutiny.

In 1876, after 44 voyages, the "Great Britain", then 33 years old, ended her career as a steamship and was laid up. Six years later she was to be seen as a straight forward square-rigged sailing ship, her engines and passenger accom­modation stripped out to make room for the stowage of 3,000 tons of bulk cargo, the iron hull was for some unknown reason sheathed with wood. It was in this new guise that the "Great Britain" ended her active career. In 1866, on her 47th voyage and whilst trying to "Round the Horn" in a fierce gale, a fire broke out in a cargo hold, forcing the ship to return to the Falkland Islands. Attempts to carry out repairs were abandoned through lack of facilities and she was declared a total loss. Still afloat and in a basically sound condition the "Great Britain" became a coal and wood storage hulk and remained in that capacity for 51 years until her decks deteriorated to such a degree that she was no longer required even for that lowly task. Some of the remaining decking was stripped out and used for bridge and jetty building and the hulk was towed to the isolated Sparrow Cove, beached, scuttled and left to the mercy of the battering winds and sea in the South Atlantic.

The first attempt to raise funds to save the storm battered hulk were made back in 1936, but not until 1968 did the business of bringing back the historic ship get off the ground. Sufficient funds and enthusiasm were raised and after a long and intensive study of the hulk, salvage operations were put in hand. It is a tribute to the quality of design, craftmanship and materials that after 43 years of voyaging and 84 years of neglect in one of the world's most violent climates there was anything left to salvage.

The Salvage Operation

Risdon Beazley Ulrich Harms Ltd., of Southampton, accepted the salvage contract following favourable reports as to the condition of the hulk.

In March, 1970, the 724-ton tug "Varius II" towing the 2,667-ton submersible pontoon "Mulus III" had arrived in Port Stanley and the salvage operation began. The salvaging method to be employed was to float the "Great Britain" over the submerged pontoon, which would then be raised, lifting the hulk clear of the water, the pontoon still with its load in position would be towed back to Britain.

The first stage in the salvaging operation was to repair the "Great Britain" sufficiently to refloat her, this entailed patching the holes which were made to scuttle the hulk and repairing and strengthening a gaping 8" wide crack in the starboard which ran from the keel up to an access which had been cut through the main deck stringer, when the ship was used as a wood store. The access not only caused the crack but had also resulted in the stern section being twisted some 13" out of line with the bows. Four divers spent long hours in sub­Antartic water, patching the holes with plywood and leak-stopper, old foam and kapok mattresses were forced into the starboard crack from keel to water line and held in place with plywood. Massive 1" thick still plates were fixed to the top and 'tween decks above the crack to avoid the serious possibility of the ship splitting in two when refloated.

The second stage was to lighten the hulk by removing the three masts and remaining yard. The fore and main­masts, rising some 64 ft. above the deck and weighing over 20 tons each are believed to be the largest sailing ship masts ever made. A crane mounted on the pontoon which was anchored on the port side of the hulk was used to remove the masts and also lift on the pumps.

The third stage was to refloat the hulk by pumping out the thousands of tons of sea-water from inside the hulk. Four pumps were installed for this purpose. At midnight on the 6th April the pumps were started and by 7 a.m. the following morning had discharged over 2,000 tons of water and the "Great Britain" was afloat, pumping continued until 4.30 in the afternoon, by this time the salvors were fighting to control the vessel against a force 11 gale. The shore lines which were installed before the pumping started were light cables and the "Great Britain" was in danger of breaking free. The pumps were stopped, and the ship allowed to settle again, this was made possible by holes which remained undiscovered until the pumping was in progress. For the next three days, winds and storms prevented any further progress, but on the 10th April, the pumps were restarted, the ship refloated and towed towards the already submerged pontoon. The ship's draught which was calculated whilst she was still full of water, was more than estimated and it was necessary to re-position the pontoon in deeper water. The next day, in unsettled weather, the "Great Britain" was floated over the pontoon. All went well until the last 25 ft. when the keel grounded, no amount of pushing by the powerful tug would budge her. Thick mud which had accumulated over the years was washed and pumped out, raising the keel sufficiently to clear obstruction, and the ship to be placed firmly over the pontoon and secured to the dolphins (tubular steel pillars) wh ich had been welded to the deck of the pontoon.

The final stage was the tricky job of raising the pontoon under the hulk, lifting it 10ft. clear of the sea, and the 7,500 mile tow to Britain, the longest tow of its kind ever undertaken. The pumps remained in position during the voyage, ready for use when the ship was floated off the pontoon. SS Great Britain
The s.s. "Great Britain" on the submersible pontoon after its arrival at Avonmouth Docks

The flotilla arrived at Avonmouth docks on 23rd June and the "Great Britain" remained on the pontoon whilst further repairs were carried out on the hull, in preparation for the journey up the River Avon, which would have to be made on her own bottom.

On the 2nd July she was successfully floated off the pontoon and moored. Three additional pumps were added to those already on board as a precaution­ary measure for the 4%-hour journey to come.

On the 5th July the "Great Britian" in the care of three tugs was towed up the River Avon, through Cumberland Basin Lock to Bristol City Docks, watched and cheered by thousands of onlookers. On the 18th July in the presence of the Duke of Edinburgh, the "Great Britain" was finally manoeuvred into Wapping Dry Dock, almost 127 years exactly from the day she was floated out in the presence of The Prince Consort. It is the intention of the "Great Britain" Committee to restore this ship to her original design.

The Pumping Operation

Two 4" SPATE INDUCED FLOW PUMPS powered by lister SR1 air­cooled diesel engines were used in the salvage operation, assisted at times by two centrifugal pumps, when water only was being handled. SS Great Britain
A 3" SPATE amongst the debris and hoses of larger pumps
The only modification to the SPATE pumps, was the removal of the wheels and axles, this enabled the large area of the chassis/fuel tank to be used as a static base, giving greater stability to the pumps which would be considerably tossed about once the "Great Britain" was afloat, and particularly in the heavy seas expected on the long tow to Britain.
The lowest point in the ship that the pumps could be safely used was approx­imately 9 ft. below the main deck at the original promenade deck level which had a headroom of 7 ft. 4in. and was approximately 26 ft. above the keel. As the water would have to be removed right down to the lowest point of the hull it was essential that the pumps employed should have a self­priming lift of at least 28 ft. and preferably more.

The pumps were stowed in position on the promenade deck by lowering them through a cargo hatchway using the pontoon's derrick crane and swinging them manually on to old decking at the side of the cargo well. 40 ft. of Selflex armoured suction hose was connected to each pump and secured with SELCLAMPS. The delivery hose was run out through the hull at the promenade deck level. The water level inside the hull, which was subject to tidal fluctuations, reached up to the original cabin deck level 9 ft. below the pumps, and was approximately 17 ft. deep. It was estimated that 2,000 tons of sea-water would have to be pumped out before the hulk would float, and once afloat the pumps would have to continue pumping until such times that the ship was safely secured on the pontoon. It was therefore important that the pumps performance would remain unimpaired by the corrosive effects of the sea-water, and could be fully relied on to work continuously for long periods without breakdowns and the minimum of maintenance and attention. In fact, it took 7 hours of continuous pumping to float the hulk, this continued for a further 9% hours before it was decided to let the ship resettle because of the dangerous weather conditions.

The operation was repeated three days later but this time it was over 38 hours before the pumps could be stopped. Once the bulk of comparatively clean sea-water was removed, the thick sludge, mud and sand at the bottom of the hulk could possibly affect the centrifugal pumps, should this occur the remaining contaminated water could be comfortably handled by the SPATE PUMPS. Equally they could handle the largp. quantities of seepage through the undiscovered holes and cracks in the hulk, their combined output being some 60 tons per hour even at 28 ft. suction lift. The two portable 3" SPATE INDUCED FLOW PUMPS which were put aboard the "Great Britain" at Avonmouth Docks were placed at the bottom of the ship above the bilges with a 21 ft. delivery head. These pumps more than adequately dealt with the seepage into the hull over the 16 days that the "Great Britain" remained afloat prior to dry docking. A further 3" Spate pump was carried at deck level and fitted for fire fighting duties in case of emergency.

The major roll played by the pumps in this salvage operation was performed without trouble and up to specification, and would appear to have been the least of the salvor's worries.

All content, copyright Bochgoch Limited 2005 & WILLIAM R. SELWOOD LIMITED, Chandlers Ford, HANTS.

bg made

We try our best to keep all your browsers afloat in the reservoir but some may struggle in the currents. We recommend FireFox to keep your head above water. Get Firefox!
bg apple