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William Denny and Brothers Limited, often referred to simply as Denny, were a British shipbuilding company based in Dumbarton, Scotland, on the River Clyde.
Denny's had the highest output of any Clyde shipbuilder in terms of numbers of vessels built (a total in excess of 22,000). Denny built all types of ships but were particularly well known as producers of fine cross-channel steamships and ferries. Peter Denny developed the company's interests in ship owning and operation with principal interests in the British and Burmese Steam Navigation Co, Glasgow, the Irrawaddy Flotilla Company and La Platense Flotilla. Denny were pioneers in development of the ship's stabiliser in conjunction with Edinburgh-based Brown Brothers and Co. Denny also undertook pioneering experimental work in hovercraft and helicopter-type aircraft.
Although the Denny yard was situated near the junction of the River Clyde and the River Leven, the yard was on the Leven. Denny’s were always innovators and were one of the first commercial shipyards in the world to have their own experimental testing tank. This is now open to the public as a museum.
1856 Subscribed £100 to the Smith Testimonial Fund, commemorating the work of F. P. Smith in promoting the screw propeller.
1814 William Denny (1779-1833) formed a partnership for steamship construction, located in Dumbarton, West Dunbartonshire, Scotland, with Archibald McLachlan.
1844 After William senior's death, three of his six sons, William, Alexander and Peter (1821-1895), set up a partnership, known as Denny Brothers, marine architects, to design iron steamers. William had been chief draughtsman in the Belfast, Northern Ireland, yard of Coats & Young before he was appointed yard manager at Robert Napier's Govan yard in 1842. Alexander had been in business independently as a marine architect in Paisley, Renfrewshire, Scotland, and Peter had worked as a clerk before becoming assistant to, first, William in Govan, Glasgow, Scotland, and then Alexander in Paisley.
1845 Within a year of establishing their new company, the brothers moved back to Dumbarton and were in business as shipbuilders, taking up the lease of a small yard known as Kirk Yard situated on the banks of the River Leven.
1845 The brothers they leased the Wood Yard, which had been their father's old premises, and they fitted this out for the building of iron steamers. At this point, the firm employed 14 men and had a capital of £800. The business prospered.
1846 James Denny returned from America and joined his brothers
1849 the firm of Denny Brothers was dissolved by mutual consent - William, James, and Peter paid out Alexander and started afresh under the name of William Denny and Brothers.
1849 The company moved from the Wood yard to a new Leven shipyard on its East Bank. William Denny, Junior came to work in the company at this point, and it is he who was behind the first ocean-going steam ship along with many other technical innovations that established the Denny name.
1850 Peter Denny went into partnership with two engineers, John McAusland and John Tulloch, to form the marine engineering business of Tulloch and Denny, to operate in parallel with, but independently of, the shipyard.
1851 Employing 350 men. Brothers William, Peter, Alexander, Archibald involved with the business
1859 a new shipyard, the North yard, was acquired
1865 See 1865 Clyde Shipbuilders for detail of the tonnage produced.
1868 William Denny (1847-1887) became a partner at the yard
1870 The hull of the Cutty Sark was built by Scott and Linton who went bankrupt due to the low contract price. The hull was towed across the river Leven to William Denny and Brothers, and was rigged ready to sail in 12 weeks.
1873 Walter Brock joined the shipyard and later became a senior partner in the company
1870s Various designs were prototyped and tested in Denny's private test tank and this stood it in good stead when avoiding penalty clauses in various contracts with the Belgian Government to build Cross-Channel Steamers. The Leven yard went on to build iron steamers including the first ocean-going steel steamers in the world. The yard also had a virtual monopoly on building ships for the British India Line and the British and Burmese Steam Navigation Co Ltd.
1879 Peter Denny became a partner at the engine works in 1879 and at the yard in 1883.
1881 William Denny persuaded his father to build the first commercial test tank in the world at Dumbarton, with assistance from William Froude's son, superintendent of the Admiralty test tank in Torquay. This investment was part of a massive extension of the yard, which included a new wet dock, longer berths, and heavier cranes.
1885 John Ward became a partner at the yard
1888 Glasgow Exhibition. Description of products in The Engineer. 
1888 Built, for the Belgium Government, the luxury, high speed channel steamers Princess Henrietta and Princess Josephine. They had paddle engines and developed 21 knots. Then came the PS Leopold II for the same company, a 22-knot ship.
1889 See 1889 Shipbuilding Statistics for detail of the tonnage produced.
1890 Built the 'PS Duchess of Hamilton'. Details in 'The Engineer'. 
1890 The Princess Victoria was built for the Larne and Stranraer Service.
1892 Henry W. Brock became partner in the engine works in 1892, and at the yard in 1895. He died in 1906.
1892 The Princess May was built for the Larne and Stranraer Service. Around this time, the Duchess of Hamilton was also built, an 18 knot boat for the Clyde service of the Caledonian Railway.
1893 Firms in connection with William Denny and Brothers:
1894 Twin screw engines for SS Duke of York, built for the Lancashire and Yorkshire and London and North-Western Joint Railway Company, on service between Fleetwood and Belfast. 
1894 the Seaford was built for the London, Brighton and South Coast Railway, but sunk a year later.
1895 The death took place of the last of the founders of the firm, Peter Denny.
1895 Colonel Leslie Denny was admitted a partner at the yard in 1895, Mr Daniel Jackson in 1907, and were subsequently assumed into the engine works.
1896 The sunken Seaford was replaced by the Sussex. Around this time the company was commissioned to build the Dover and Calais, top quality steamers for the cross channel service. These were followed by the Lord Hamilton and many others including the paddle boat "Lord Warden" (See right for image.)
1896 James Denny became a partner
1899 See 1899 Shipbuilding Statistics for detail of the tonnage produced. Second highest output.
1900s Denny's established and built upon its reputation for building the best cross-Channel steamers, it maintained this reputation until the yard closed in 1963. The yard also built large refrigerated steamers for New Zealand and Spanish companies. In 1905 the yard began to reposition itself with an eye on the Admiralty market. It was successful in tendering for a number of torpedo boats, destroyers, submarines and river hospital ships along with 150 fighter aircraft. Following the War, the yard also built four large ferries.
The turn of the century saw the revolution of the turbine engine, invented by Sir Charles Algernon Parsons.
The Lystistrata was a hansome yacht built in 1900 for Mr Gordon Bennett of New York. She could achieve 19.5 knots, and was fitted to the highest specifications regardless of the expense.
The two Shamrocks were built for Sir Thomas Lipton as challengers for the American Cup. The first was constructed of manganese bronze, a first in ship contruction.
1907 Walter Brock, junior, was assumed at the engine works in 1907, along with Mr Edward Griffith, who died within the year.
1909 saw the arrival of the Sir Trevredyn Wynne, a train ferry for the Bengal-Nagpur Railway.
The Lady Inchcape was a powerful screw tug for India.
1911 The Cross-channel Turbine Steamer 'Riviera' 
1911 Maurice Edward Denny became a partner at age 24.
1911 George Ward, son of the the late John Ward was made a partner; as was J. McA. Denny, son of James Denny.
On the Clyde The King Edward turbine ship was built followed by the Quenn Alexandra, for the South Eastern and Chatham Railway Co.
1913 Messrs. Denny delivered the TS "Paris" to the London, Brighton and South Coast Railway for their service, conducted jointly with the State Railways of France, between Newhaven and Dieppe. This ship was fitted with Yarrow water-tube boilers and geared turbines on Sir Charles Parsons' principle. It attained great speed of upwards of 25 knots.
1913 the notable big ships produced by the company were the Rotomahana, the first liner of mild steel. Followed by the Buenos Ayres. There was also the Bavarian built in 1899 for the Allan Line, which proved to be one of the best troopships of the South African Government. The Scot was made for the Union Castle Line, one of the first 20 knotters. The troopship Reva was a steamer built for the British India Co. Then there was the Otaki for the London Shipping Co of New Zealand; the first merchant ship fitted with turbines and reciprocating engines. The Chinduin built for the Patrick Henderson Co of Glasgow. The Infanta Isobel de Barton, was a triple screw combination ship capale of 18.6 knots, built for the Compania Transatlantica, Barcelona.
The Union Co of New Zealand built ships at Clyde and were naturally interested in the turbine engine and built the Loongana there.
1914 Shipbuilders of steamships of every type up to the largest dimensions. The shipyard was capable of producing about 45,000 tons of shipping per annum represented by 1001 vessels of all classes, from ocean liners to yachts. Vessels were built for most of the leading British shipowning firms and companies and for most foreign countries and British colonies. Specialities: high-speed vessels; turbine machinery; closely associated with the application of the steam turbine to navigation. Were the first firm to fit turbines to a ship intended for the mercantile marine, viz. the "King Edward", well known as a pleasure steamer on the Clyde. Constructed a considerable number of turbine steamers, embodying notable improvements, among them being the South Eastern and Chatham Railway Company's SS. "Queen" (the first cross-Channel turbine steamer), and the "Onward", "Invicta" "Victoria", "Empress" built for the same company's Dover-Calais service. The three-screw steamer "Otaki" belonging to the New Zealand Shipping Co Ltd., and built by Messrs. Denny, was the first vessel fitted with the combined engines invented by Sir Charles Parsons, having two triple-expanding reciprocating engines driving the wing screws and a turbine driving the centre screw. Employees 2,150. 
1917 Private company.
1918 The Leven shipyard and the marine engine works of Denny and Co were combined in a single limited liability company William Denny and Brothers Ltd.
1920s Denny’s built over 14 cargo-liners during the difficult early 1920s and cannily used speculation builds as a way of generating interest and business. However, from late 1920 -1923 the yard closed with no construction being completed. In the latter half of the 20s the yard made a number of ferries and cross- Channel packets. This along with orders from the Admiralty and a large turbine ferry for Canadian Pacific, meant that the yard was able to ride out The Depression without too much difficulty.
1925 See Aberconway for information on shipbuilding h.p produced in 1904 and 1925
1930s Merchant orders kept the yard operating, along with an order for a drive-on car ferry which was later converted into an auxiliary minelayer.
1934 Built the first all-welded ship in Scotland, the Robert the Bruce, which was in addition the first diesel–electric powered paddle wheel vessel constructed in Britain.
WWII The main output of the yard was warships and merchant ships; twelve destroyers, twelve sloops, two minesweepers, two steam gunboats and a large tank transport ferry. In addition, six cargo-liners, one cross-Channel packet and four paddle steamers were built for India with two standard tramps and two merchant aircraft carriers and an aircraft transport ship completed for Britain.
1950s In the post war period the yard stopped making shallow-draft river craft. It also reduced the number of berths down to five. The work now consisted of deep sea merchant ships, short sea ferries, excursion craft, Scottish fishery protection cruisers and a frigate. From 1947 to 1961 the yard made ten large ferries in response to the nationalisation of the railway system. Other ferries were made for the Isle of Wight and Channel Islands along with other companies in and around the UK. The yard manufactured some of the early roll-on/roll off ferries in the late 50s.
1959 The yard was modernised in 1959 but remained unable to compete for bulk carrier orders.
1961 Shipbuilders, designers and marine engineers. Specialists in the construction of Cross Channel steamers. 1,800 employees. 
1963 The company went into liquidation in 1963. Later, the Denny yard was demolished and a sawmill company used the old fitting-out basin.
Assembled aircraft in WW1.