An outboard motor is a propulsion system for smaller boats. Mercury Marine, founded in 1939 is a division of Brunswick Corporation of Lake Forest, Illinois, in the United States. Marine propulsion is the act of moving a floating object over or through water A boat is a Watercraft of modest size designed to float or plane on water and provide transport over it
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General uses
Outboard motors for a boat are developed as a self-contained unit with engine, subsidiary systems, and propeller, designed to be mounted at the stern (rear) of the craft. A boat is a Watercraft of modest size designed to float or plane on water and provide transport over it An engine is a mechanical device that produces some form of output from a given input A propeller is essentially a type of fan which transmits power by converting Rotational motion into Thrust for propulsion of a vehicle such as an They are the most common motorized method of propelling small watercraft.
As well as providing propulsion, outboards provide steering control, as they are designed to pivot over their mountings and thus control the orientation of the propeller. The transmission leg in the water also acts as a rudder even when the propeller is not providing power. A rudder is a device used to steer a Ship, Boat, Submarine, Hovercraft, or other conveyance that move through a fluid (generally air or
When boats are out of service or being drawn through shallow waters, outboard motors can also be tipped forward trimmed up over their mounts to elevate the propeller and transmission shaft out of the water to avoid accumulation of seaweed or hitting underwater hazards such as rocks. Seaweed is a loose colloquial term encompassing macroscopic Multicellular, benthic marine Algae.
Types of motors
The smallest of outboard motors are truly self-contained, with integral fuel tanks and controls mounted on the body of the motor and steered by a "tiller" directly connected to the motor. Such small motors can weigh as little as 12 kilograms (approximately 26 pounds) and provide sufficient power to move a small dinghy at around 15 km/h (9 mph), far faster than possible with oars. An oar is an implement used for water-borne propulsion. Oars have a flat blade at one end They are highly portable, able to be removed by simply loosening their mounting clamps. Small outboards typically use a manual pull start ignition system while larger models often have electric start similar to a car.
Manufacturers have produced large outboard designs, with sufficient power to be used on boats with lengths of 38 feet or longer. The most powerful are V-6 and V-8 cylinder blocks rated 350 hp. Manufacturers also produce electric outboards, commonly referred to as "trolling motors", which are used on very small craft or on small lakes where gasoline motors are prohibited, as a secondary means of propulsion on larger craft, and as repositioning thrusters while fishing for bass and other freshwater species in the US, where their quietness and zero emissions outweigh the range deficiencies shared with electric cars. For other uses see troll. Trolling is a method of Fishing where one or more Fishing lines baited with lures or Bass (ˈbæs is a name shared by many different species of popular Gamefish. Zero emission refers to an Engine, Motor, or other energy source that emits no waste products that pollutes the environment or disrupts the climate Diesel outboards are also available, but their weight and cost make them impractical for most purposes. Diesel or Diesel fuel (ˈdiːzəl in general is any Fuel used in Diesel engines The most common is a specific fractional distillate of petroleum An additional issue with diesel outboards is toxic exhaust emissions.
Pump-jet propulsion (replacing the conventional propeller) is available as an option on most outboard motors. A pump-jet or water jet is a marine system that creates a jet of Water for propulsion. Like other types of pump-jet propulsion systems, they offer virtually no cavitation, giving the boat more maneuverability and the ability to operate in very shallow water. Cavitation is defined as the phenomenon of formation of vapour bubbles of a flowing liquid in a region where the pressure of the liquid falls below its vapour pressure However, the low efficiency compared to propellers has seen them restricted to specialized applications.
History and developments
The first practical outboard motor was created by Norwegian-American inventor Ole Evinrude in 1909. Norwegian Americans (norskamerikanere are Americans of Norwegian descent Ole Evinrude, born Ole Evenrudstuen ( April 19, 1877 — July 12, 1934) was a Norwegian-American inventor famous for the Year 1909 ( MCMIX) was a Common year starting on Friday (link will display full calendar of the Gregorian calendar (or a Common year starting
Historically, most outboards have used two-stroke engines fitted with a carburetor due to their simplicity (and consequent reliability), low cost, and high power-to-weight ratios - weight issues being particularly important as too much weight over the stern of boats tends to impede their handling. The two-stroke Internal combustion engine differs from the more common Four-stroke engine by completing the same four processes (intake compression combustion exhaust Power-to-weight ratio (specific power is a calculation commonly applied to Engines and other mobile power sources to enable the comparison of one unit or design to another However, the high specific fuel consumption and high emissions associated with traditional carburated two-stroke engines has led to the development of more sophisticated engines. Most manufacturers have marketed four-stroke engines, often with computer controls, fuel injection, variable camshaft timing, multiple valves per cylinder, and supercharging. Today Internal combustion engines in cars, Trucks motorcycles aircraft construction machinery and many others most commonly use a four-stroke cycle. Others have focused on developing computer controlled direct-injected two stroke engines. Either of these designs can reduce fuel consumption and emissions markedly, especially at low engine speeds, albeit at the expense of greater cost and complexity.
Marine engines also benefit from the ability to draw an unlimited supply of cooling water from the environment; this eliminates the need for radiators and cooling fans, lowering complexity and weight. Radiators and convectors are types of Heat exchangers designed to transfer Thermal energy from one medium to another for the purpose of cooling A mechanical fan is an electrically powered device used to produce an airflow for the purpose of creature comfort (particularly in the heat ventilation, exhaust
Manufacturers
- British Anzani
- British Seagull
- Briggs & Stratton
- Evinrude/Johnson, a division of Bombardier Recreational Products
- Honda
- Mercury/Mariner
- Nissan Marine
- Selva Marine
- Suzuki
- Tohatsu
- Yamaha Motor Corporation
- Yanmar Diesel Power
- Ul'yanovsk Motor Plant
See also
External links
- The Super-Elto Outboard Motor (1927) Smithsonian Institution Libraries
Patents
- U.S. Patent 1,001,260 - Marine propulsion mechanism
- U.S. Patent 1,011,930 - Canoe and other small craft
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