Bulbous Bow - Development

Development

The bulbous bow concept is credited to David W. Taylor, a naval architect who served as Chief Constructor of the United States Navy during the First World War. The concept (known as a bulbous forefoot) was first introduced in his design of the USS Delaware, which entered service in 1910. The bow design did not initially enjoy wide acceptance, although it was used in the Lexington class battlecruisers to great success after the two ships of that class which survived the Washington Naval Treaty were converted to aircraft carriers. This lack of acceptance changed in the 1920s, with Germany's launching the Bremen and the Europa. They were referred to as Germany's North Atlantic greyhounds, two large commercial ocean liners that competed for the trans-Atlantic passenger trade. Both ships won the coveted Blue Riband, the Bremen in 1929 with a crossing speed of 27.9 knots (51.7 km/h; 32.1 mph), and the Europa surpassing her in 1930 with a crossing speed of 27.91 knots.

The design began to be incorporated elsewhere, as seen in the U.S. built Malolo, President Hoover and President Coolidge passenger liners launched in the late 1920s and early 1930s. Still the idea was largely viewed as experimental by many ship builders and owners.

In 1935 the French superliner Normandie coupled a bulbous forefoot with massive size and a redesigned hull shape. She was able to achieve speeds in excess of 30 knots (56 km/h). The Normandie was famous for many things, including her clean entry into the water and markedly reduced bow wave. Normandie's great rival, the British liner Queen Mary, achieved equivalent speeds with a non-bulbous traditional stem and hull design. However, a crucial difference was that Normandie achieved these speeds with approximately thirty percent less engine power than Queen Mary and with a corresponding reduction in fuel use.

Bulbous bow designs were also developed and used by the Imperial Japanese Navy. A modest bulbous bow was used in a number of their ship designs, including the light cruiser Ōyodo and the carriers Shōkaku and Taihō. A far more radical bulbous bow design solution was incorporated into their massively large Yamato class battleships, including the Yamato, Musashi and the aircraft carrier Shinano.

The modern bulbous bow was developed by Dr. Takao Inui at the University of Tokyo during the 1950s and 1960s, independently of Japanese naval research. Inui based his research on earlier findings by scientists made after Taylor discovered that ships fitted with a bulbous forefoot exhibited substantially lower drag characteristics than predicted. The bulbous bow concept was first definitively studied by Thomas Havelock, Cyril Wigley and Georg Weinblum, including Wigley's 1936 work "The Theory of the Bulbous Bow and its Practical Application" which examined the issues of wave production and dampening. Inui's initial scientific papers on the effect of bulbous bow on wavemaking resistance were collected into a report published by the University of Michigan in 1960. His work came to widespread attention with his paper "Wavemaking Resistance of Ships" published by the Society of Naval Architects and Marine Engineers in 1962. It was eventually found that drag could be reduced by about five percent. Experimentation and refinement slowly improved the geometry of bulbous bows, but they were not widely exploited until computer modelling techniques enabled researchers at the University of British Columbia to increase their performance to a practical level in the 1980s.