Mercury Marine is a marine engine division of Brunswick Corporation headquartered in Fond du Lac, Wisconsin. The main product line is outboard engines. It also produces the MerCruiser line of sterndrives and inboard engines. Some manufacturing is in Fond du Lac, while 40-60 HP engines are made in China. Smaller engines are Tohatsus that have been rebadged.
History
Founding
The Kiekhaefer Mercury company began in 1939 when engineer Carl Kiekhaefer purchased a small outboard motor company in Cedarburg, Wisconsin. Kiekhaefer's original intention for the Kiekhaefer Corporation was to make magnetic separators for the dairy industry. The purchase included 300 defective outboard motors. Kiekhaefer and a small staff of employees rebuilt the motors and sold them to Montgomery Ward, a mail-order company. The motors were much improved, so the buyer purchased more. Kiekhaefer designed motors that withstood the elements better than his competition and called the motor Mercury (taking advantage of the "Mercury" Motor Car popularity at the time) whilst adopting the logo of the Roman god Mercury.
Kiekhaefer took more than 16,000 orders at the 1940 New York Boat Show.
World War II
World War II changed the corporate climate, and Kiekhaefer sought a government contract to design two-man air-cooled chainsaws. Army engineers had been unable to design a lightweight motor. Kiekhaefer designed a new lightweight chainsaw in 2 months. The Kiekhaefer powered chainsaw was able to cut through a green log in 17 seconds, while it took the nearest competitor 52 seconds. Mercury was awarded the contract, and was the world's largest chainsaw manufacturer by the end of the war.
Post-war 1940s
Kiekhaefer Mercury foresaw that the average American's interest in boating would increase after the war. Kiekhaefer introduced a 19.8 cubic inch, 10 horsepower (hp), two-cylinder alternate firing design engine at the 1947 New York Boat Show called the "Lightning" or KE-7. This engine, also called the "Super 10", actually developed around 14 horsepower. Its designation was updated to KF-7 for 1949. For 1951 the engine block, though still displacing 19.8 cubic inches, was updated a great deal, and given the name "Hurricane". The 1951 kg-7 "Super 10" featured this engine, which developed around 16 horsepower. For 1952, this model was updated with a "forward, neutral, reverse" gearset, and a twist grip throttle. It was renamed "Cruiser" at this point, and no longer called "Super 10". This engine later became the heart of the "Mark 25", of the mid to late fifties. Initially rated at 16 horsepower, this engine was soon beefed up to 20. There was also an "H" version, which produced more power but carried no rating. "H" version Mercurys were mostly used for racing.
In 1949, the company also introduced its first large outboard, the approximately 40 cubic inch, 4 cylinder in line, "Thunderbolt". This engine was rated at 25 horsepower, but actually put out around 28. There was soon an "H" version designed for high rpm use. This version put out nearly 40 horsepower, while being rated at "25+". The Thunderbolt engine benefited from upgrades and updates, eventually becoming the Mark 40, Mark 50, and Mark 55 engines of the mid and late fifties. All of these were rated quite accurately at 40 horsepower. The Mark 55H (high speed) developed more, but carried no rating.
Due to a rather large gap between the Mark 25 (20 hp) and the Mark 55 (40 hp), Mercury brought out the 4 in line, approximately 30 cubic inch "Mark 30" (30 horsepower) engine for 1956, and produced versions of its "TurboFour" engine for several years. It, too, was available as an "H" version, producing much extra horsepower for racing and sporting use.
Why these Mark engines (and other Mark engines) carried number names which were not horsepower ratings, not displacement numbers, and not consistent from one motor to another, is a real mystery. Why was the 20 hp Mercury a Mark 25, and the 40 hp Mercury a Mark 55, while the 30 hp job was the Mark 30? No one really knows.
Of course, there were also smaller Mercs during both the K era and the Mark era, such as the "Super 5" and later, such engines as the "Mark 6" and the "Mark 10".