Four-funnel liner

The primary purpose of funnels on steamships was to allow smoke, heat and excess steam to escape from the boiler rooms. As liners became larger, more boilers were used. The number of funnels became symbolic of speed and safety,[1] so shipping companies sometimes added false funnels—like the Olympic-class ocean liners—to give an impression of power.[3]

The trend of competing shipping lines building four-funnel liners encompassed a very short time span ranging from the SS Kaiser Wilhelm der Grosse in 1897 to the SS Windsor Castle in 1922. Four funnels were sometimes a matter of necessity, other times purely symbolic.

The Cunard Line record holders, Lusitania and Mauretania, were both laid out with four boiler rooms with one funnel to each room, other slower ships such as the Olympic, Titanic and Britannic only had three operational funnels. However, four funnels represented power, safety and prestige.

In keeping with the style and fashion of the early-20th century, the White Star Line opted to fit the three Olympic-class ships with a dummy fourth funnel to rival the two Cunard ships. The notion of four funnels representing size and power rapidly diminished soon after the First World War. Later flagships such as SS Imperator, SS Normandie, and RMS Queen Mary, all fitted three funnels to conserve deck space.

Later still as shipbuilding became more efficient the RMS Queen Elizabeth, RMS Mauretania and the SS America reduced this further down to two funnels, today's modern cruise ships are mostly built with only a single funnel and many military vessels no longer have one at all.

The United States never operated any four-funneled ocean liners in commercial service. However, in the late 1910s, William Francis Gibbs began to draft designs for new 1,000-foot liners that could reach a speed of 30 knots. Among the proposals was a pair of four-funneled ships designed in 1919. The funnel/boiler arrangement would have been similar to the German four stackers, with the four funnels grouped in pairs with a wider gap between the second and third funnels. Possible names for the liners were the SS Boston and the SS Independence, but the ships never made it past the design phase.[4]

In the late 1920s the world's main shipping lines were Britain's Cunard Line and White Star Line and France's Compagnie Générale Transatlantique (CGT). Each of these three were operating ageing vessels and required new larger and more modern 1,000 feet (300 m) long superliners to remain competitive. CGT began construction of the SS Normandie while Cunard placed an order for the RMS Queen Mary.

White Star placed an order to their shipbuilders Harland and Wolff for Oceanic, a successor to the line's inaugural 1870-liner, RMS Oceanic. The exact intended design of Oceanic III is unknown, although company concept renderings show it to be a three-funnelled 1,000-foot (300 m) liner. However, early plans from Harland and Wolff's archives show a design from 1927 for a four-funnelled liner almost identical to the Olympic-class, except with a more-modern cruiser stern.[5]

With the onset of the Great Depression the shipping lines were crippled. The completion of Cunard's Queen Mary was delayed for four years and to raise the funds to complete her the British government gave Cunard a loan on the condition that Cunard merge with White Star into a single British shipping line. Upon the merger into the Cunard-White Star Line Oceanic, with only her keel laid, was abandoned.

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