![]() ![]() The transport Doncaster was fitted with Shorter’s propeller. The inclined shaft carrying the propeller was driven through a universal joint by a second shaft on the ship above the water- line. This consisted of a two- bladed propeller on an inclined shaft supported by a buoy at the stern of the vessel. A boat fitted with this device was tried in Greenland Dock, London, but a speed of only two miles an hour was attained.Ī similar device was invented by Edward Shorter in 1800. It was to have been driven by manually- operated winches through a system of ropes and pulleys. This propeller was designed for mounting in a frame attached to the ship’s hull. In 1794 a triple- threaded screw was patented by William Lyttleton. As early as 1729 an inventor named Du Quet suggested a screw for propelling ships, and similar proposals were made by Daniel Bernoulli in 1752 and by Bramah in 1785. But for many years propulsion by screws had been suggested from time to time by various inventors. It was not until the paddle steamer had reached a high standard of efficiency that the screw propeller was generally adopted by the marine engineer. The screw propeller, however, has been universally adopted for all ships except those used for pleasure excursions and for navigation on shallow rivers and lakes. ![]() WE have traced in earlier chapters the story of the marine engine as applied to paddle steamers. Rattler succeeded in towing her rival at a speed of nearly three knots. Although the vessels were of equal size and nominal horse- power, H.M.S. Alecto, fitted with paddles, were tried against one another in a spectacular tug- of- war. TUG- OF- WAR between a paddle steamer and a screw- propelled steamer to decide the more effective method of propulsion. In the UK paddle steamers dominated the coastal excursion and ferry trades until just after the second world war, when they began to be replaced by motor vessels, and many routes were truncated or lost altogether as air travel made foreign holidays a more affordable proposition and the excursion ships became unprofitable.Steamships had been propelled by paddle wheels from the earliest days until the middle of the last century, when experiments with screw propellers were successfully carried out and the screw- type marine engine was gradually evolved In general, screw powered ships had been found to be more efficient and the paddles of paddle steamers were vulnerable to damage, especially in the case of warships, but the paddlers held on in some markets. These trials finally sealed the fate of the paddle for naval and other large vessels, but did not, however, stop the admiralty constructing 32 paddle minesweepers during WWI, taking advantage of their relatively shallow draft - a significant advantage when sweeping contact mines. In 1849 similar results were seen from the screw sloop, Niger, over her paddle-equipped sister, Basilisk. ![]() The trials ended with a tug of war, in April 1845, between the ships, resulting in Rattler towing Alecto stern first at 2.5 knots. The resulting HMS Rattler competed in a series of trials with Alecto including speed and manoeuvrability of the two vessels. This was used in trials with a paddle driven member of the same class HMS Alecto. In 1842 the Admiralty ordered a paddle sloop to be fitted with a screw propeller. With a replacement propeller, the Francis Smith steamed around the South of England coast and, as a result, the Admiralty commissioned a larger ship, the Archimedes (200 tons), launched in 1838 at Blackwall on the River Thames. During the trials the propeller hit an obstruction which "shortened" the blades, the vessel’s speed actually increased. Sir Francis built a six-ton launch, the Francis Smith, fitted with a 30-inch, two-bladed wooden screw and a single-cylinder engine to demonstrate its advantages to the Admiralty. One of the inventors of the screw propeller was Sir Francis Pettit Smith who patented his idea in 1836.
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