TS King Edward was an excursion steamer built at Dumbarton for service down the River Clyde to the Firth of Clyde and associated sea lochs on the west coast of Scotland, as far as Campbeltown. The first commercial vessel to be driven by steam turbines, King Edward operated as a Clyde steamer for half a century from 1901 until 1951, interrupted only by service in the two world wars. The success of the vessel quickly led to the adoption of turbine propulsion for all manner of merchant vessels, from channel ferries and coastal steamers to transatlantic liners.
Background In 1803, showed the practicality of steam power for marine use, and in 1812 Henry Bell's began the first commercially successful steamboat service in Europe, sailing on the River Clyde between Glasgow and Helensburgh. Others soon followed, and by mid century a large fleet of Clyde steamers competed for holiday and excursion traffic down the River and Firth of Clyde. By the end of the century paddle steamers had reached a peak of design, with a maximum economic operating speed of around , but speed was at a premium, particularly on the longer routes such as sailings from Glasgow to Inveraray and Campbeltown. Up to this time, vessels had been powered by reciprocating steam engines. Steam was generated by boilers, and piped to cylinders wherein it drove pistons, the back-and-forth motion of which was converted to rotary motion by connecting rods. Early vessels were driven by paddle wheels, but at mid-century screws became more prevalent. Although increased boiler pressures and the reuse of partially expanded steam in compound engines greatly increased efficiency, the continual creation and destruction of momentum of their heavy reciprocating parts each turn of the crankshaft put great strain on the engines, which required constant maintenance.Baker & Tryckare, p. 98: "[W]ith reciprocating engines there was a limit to the speeds attainable within given weight and strength limitations. The breaking of connecting rods when operating at full power had caused severe damage."
The modern steam turbine, invented by Charles A. Parsons in 1884, overcomes these problems by having only rotating parts, and no reciprocating parts. In 1894 he formed a syndicate to build a small experimental steam launch, . In a famous publicity stunt, Parson's steam launch sped uninvited past warships in the Solent at the 1897 Review of the Fleet held on the Diamond Jubilee of Queen Victoria's accession to the throne. Turbinia raced past them at the unheard-of speed of , far outstripping the ships of the Royal Navy sent to intercept.Woodman, pp. 199–200.Baker & Tryckare, pp. 98–99. In January 1898 the Admiralty ordered a turbine-powered destroyer, , and later that year a typical lightly built destroyer being built as a private venture was fitted with turbines. The Admiralty purchased this ship after requiring strengthening of the hull, and named the vessel . Both destroyers were launched in 1899, and both were soon lost for reasons unrelated to their machinery, and before the Admiralty could obtain substantial experience with turbine propulsion.
Such experience was needed before the turbine could obtain wide acceptance, as there had been problems in its development. The reciprocating steam engine, for all its theoretical faults, had been perfected over eight decades of development. Its manufacturing and operating characteristics were widely known; it had attained a high degree of fuel efficiency, and functioned economically across a range of speeds. In contrast, the turbine was new; the seagoing prototype Turbinia experienced engine problems in its expensive development; and its theoretical advantage in low vibrations had not been realised, as turbine blades had failed due to vibrations, as well as contacting the casing, leading to catastrophic destruction within the turbines. In short, it was an expensive and unproven technology.
From a records of a later discussion, it appears that Archibald Denny, a partner in the shipbuilders William Denny and Brothers, had already been impressed by a technical paper by Parsons and had approached him with the suggestion of using steam turbines to power a merchant vessel. Denny apparently invited Clyde railway steamboat owners to sponsor the venture, but nothing came of these exploratory informal approaches. It was left to one of the owners of private steamer fleets to take on this challenge.
Turbine syndicate Captain John Williamson had followed his father Captain James Williamson in owning and running Clyde Steamers, purchasing his first ship in 1893 and buying and selling ships to build up a fleet. These included the PS Strathmore, built to order in 1897, which took over the service running from Fairlie Pier railway station to Campbeltown, and proved reliable. He seems to have given independent consideration to introducing a turbine steamer, and agreed to take this on. Towards the end of 1900 a syndicate was formed in which he agreed to personally operate the proposed ship for its first season without pay, William Denny and Brothers would build the hull and boilers, and the Parsons Marine Steam Turbine Company was to provide the machinery. Each member of the syndicate provided one third of the cost of the vessel, estimated at £33,000 (), plus £267 () towards initial working and running expenses. On 22 January 1901 the Glasgow and South Western Railway minuted an agreement in its official records, backing this improvement to a service from its railway terminal into areas which its act of Parliament prohibited its own vessels from serving:
Design
The hull design of King Edward was closely based by Denny on its successful steamer, PS Duchess of Hamilton, and shared the main dimensions. The hull was long and in breadth. Depth was about and the vessel drew about of water.Gardiner, p. 96. Tonnage was measured at 502 gross and 182 net.Lloyd's Register (1945–46), p. KIM-KIN. Republished by Plimsoll Ship Data. The register for other years measures gross at 551 and net at 222. E.g., Lloyd's Register (1930–31) p. KIN. The ship accommodated 1,966 passengers.
The machinery was amidships down in the hull, with a lower deck fore and aft, the crew's quarters being located towards the bow.Baker & Tryckare, p. 111. A full-length main deck was above, enclosed almost to the stern, with circular portholes over much of the length and larger rectangular windows aft.Baker & Tryckare, p. 121 (image). First-class accommodations were aft, and second-class fore, with dining saloons for each class on the lower deck. The superstructure or promenade deck was open, save for a pilothouse and bridge, a house around the uptakes, and a small house just aft of amidships. The promenade deck planking showed provision for conversion to paddle propulsion, in case the turbines proved a failure. Uniquely at that time, a short flying deck supported the two funnels, and a lifeboat on each side of the funnels.
The power plant consisted of Scotch marine boilers providing steam at to Parsons turbines. Steam first drove a high-pressure turbine, which turned a propeller shaft with a screw at up to 700 revolutions per minute. Exhaust steam from the centre turbine drove two low-pressure turbines, one on either side, turning wing shafts each with two propellers, at up to 1,000 rpm. (In 1905, the fore propellers were removed from the outboard shafts,Maber, pp. 33–34. which actually improved performance). The drives were ungeared, and the speeds of the turbines were the speeds of the shafts. After final use in the lower-pressure outboard turbines, the steam, now expanded 125-fold, exhausted into condensers.Baker & Tryckare, p. 112. Astern turbines operated on the two wing shafts, with the central shaft idling when the ship was backing. The aim was for a speed of , outpacing other Clyde steamers while providing economy in fuel, rather than the high speeds of the navy vessels. The propulsion system differed from that of the lightly built destroyers, which operated under higher steam pressure and drove four propeller shafts. Denny gave the new ship the yard number 651.
Launch and trials, performance
On 16 May 1901 the vessel was launched by Mrs. Parsons, who named the ship King Edward by royal permission. The ship's colours were those of Captain John Williamson – black hull, white saloons and white funnels with a black top, flying the well remembered "star and crescent" pennant of the old "Turkish fleet" of Clyde steamers.
The builders had tested the hull form in their own tank, and hoped to attain a speed of with the turbine machinery. On 14 June the first steam trial was supervised personally by C. A. Parsons and John Williamson, then on 17 June during manoeuvring trials in calm weather the mean speed of two runs over the measured mile at Skelmorlie was . After full hull cleaning at Scott's of Greenock a further series of trials took place on 24 June: in seven return runs over the mile, the best mean speed attained was . On the next day at the Pointhouse yard of A. & J. Inglis the central propeller of diameter was exchanged for one of diameter, and the outer propellers of diameter were exchanged for propellers diameter. Trials on 26 June with smooth sea conditions and a light breeze achieved a mean of and a fastest single run at . At the official trial on 28 June, invited guests came aboard off Craigendoran, and the ship then sailed to Campbeltown with intermediate visits to Dunoon, Rothesay, Largs, Fairlie and Lochranza, where Duchess of Hamilton waited with a special party of members of the Institute of Naval Architects. The two ships raced down Kilbrannan Sound and King Edward passed the paddle steamer without difficulty. A dinner in the after saloon was presided over by Peter Denny, who with other speakers commented on the speed and smoothness of the turbine steamer, in contrast to the rhythmic surging motion and vibration associated with all paddle steamers.
The machinery developed 3,500 indicated horsepower and 399 nominal horsepower. King Edwards performance was compared with that of Duchess of Hamilton, the similar vessel built by Denny at about the same time, but with reciprocating machinery driving paddle wheels. In actual service on the Firth the turbine vessel averaged , about faster than Duchess of Hamilton. In 1902 James Denny compared the achieved on trial with an estimated maximum using the most modern triple expansion reciprocating engines of 19.7 knots, which would have involved considerably increased initial and fuel costs, and said that this showed the turbines giving a 20% increase in power. He said that fuel efficiency of King Edward had been found to increase in proportion to speed, and was best when the turbines were worked at full capacity. The ship burned more coal per knot of speed than reciprocating-engined steamers only when operating at a lower speed range of between , corresponding to around 50% of maximum power output.
Career