British Seagull was a British manufacturer of two-stroke outboard engines from the early 1930s until the mid-1990s. The company went out of business due to the motor design not being able to keep up with more modern boat engines and increasingly tight emissions regulations. British Seagull no longer produces new engines but still operates for parts.
The main engines produced through most of the company's history can be divided into two main types, the Model 102 and the Classic models. The Model 102 was a development of the very early Marston models offered through the 1930s. They featured an all-in-one engine block and cylinder head and a water-injected exhaust. The Model 102 engines were fairly large, with the largest having a 13-inch-diameter (330 mm) propeller and obtained the name of "The Barge Pusher". The other style of engine, known as the classic or square block models, were divided into four main types, the Featherweight or Forty Minus, the Forty Plus, the Century and the Century Plus. The Forty Minus and Plus used identical power units, but the Plus had a larger gearbox and propeller. The Century and Century Plus used a larger 102 cc block with larger gearboxes and propellers. The engines remained in production from the late 1950s right through to the mid-1990s, and many examples of early engines are still in everyday use. The long life span is due to the good quality metals that are used. The Seagull also uses high tensile bolts and studs.
From the early 1980s a new series of British Seagull outboards was made available, called the QB series. These were designed by Queen's University, Belfast (hence QB) and featured quieter engines, water-cooled exhaust and modified cylinders and were painted in black. These were known by some as the Irish Seagull.
In the late 1980s British Seagull introduced two further models to their range; these were called the Model 170 and the Model 125. These had engine covers or cowlings and upgraded carburettors and blocks. They both suffered from poorly designed crankshaft bushings, which caused the company many problems, and inevitably the models were never popular.
One notable feature of a British Seagull is the gearbox and propellor combination: at first glance they seem very primitive, but due to the high gearbox reduction ratio they are capable of propelling much larger boats than might be expected. The silver Century Plus model, for example, is designed to propel a displacement hull of up to 26 feet in length.
Towards the end of production a new model called the "5r" was introduced. The design of this engine was quite different from other models, as it used a conventional outboard gearbox which was from a Yamaha 4HP outboard; this was attached via an adaptor plate to a QB series power unit and was painted blue. Some of the very last engines to leave the factory had gold-painted propellers and recoil starter tops and are called "gold tops" by enthusiasts.
Models manufactured from 1931 to 1945 had a recommended petrol-to-oil mix of either 8:1 or 10:1. From 1942 models specified a 10:1 mix which was specified up to 1979. After that date a 25:1 mix was specified, which was again changed for the introduction of the models 125 and 170, but these engines with the 50:1 mix soon failed, and British Seagull again specified 25:1. This relatively high percentage of oil was necessary due to the way the crankshaft bushings worked. Early engines used short bushings, and later ones used longer bushings, hence the changes in oil requirement. The longer bushings were, in fact, used from 1967 onwards, and the engines from 1967 to 1979 can be used on the 25:1 mix by making carburettor adjustments.
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