Four funnel liner

A four funnel liner, four funnelled liner or four stacker is an ocean liner with four funnels. The SS Great Eastern, launched on 31 January 1858 (a full 40 years ahead of any comparable ships), was the only ocean liner to sport five funnels. As one funnel was later removed, the Great Eastern, by default, became the first ocean liner to have four funnels. However, after the Great Eastern became a four funnel ship she never carried passengers so really should not be considered the first four funnel liner. The SS Kaiser Wilhelm der Grosse, launched on 4 May 1897, was properly the first ocean liner to have four funnels and was one of the first of the golden era of ocean liners that became prominent in the early- to mid-20th century. The most famous four funnel liners are the RMS Titanic, which sank after striking an iceberg on her maiden voyage on 14 April 1912, and the RMS Lusitania, which was torpedoed on 7 May 1915 during the First World War.

In all, fifteen four funnel liners were built (five were built and owned by Germany, nine by the UK, and one by France): the Great Eastern in 1858 and the remaining fourteen between 1897 and 1922. Four of these were sunk during the World Wars, and apart from the Titanic, the remainder were scrapped.RMS Mauretania was the fastest of all four funnelled liners. The last four funnelled liner ever built was the SS Windsor Castle but two funnels were removed making RMS Aquitania the last four funnel liner in service and the only one to survive service during both World Wars.

The primary purpose of funnels on steamships were 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, so shipping companies sometimes added false funnels (like the one sported by the Olympic-class ocean liner) to give an impression of power.

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. As for the number of funnels in some cases the reason for sporting four was a matter of necessity in other cases it was more 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 sporting 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 'dummy' fourth funnels in order to rival the two Cunard ships. The ideology of four funnels representing size and power rapidly diminished soon after the First World War, later larger flagships including the SS Imperator, SS Normandie and the RMS Queen Mary all sported 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 all built with only a single funnel and many military vessels no longer sport them at all.

...
Wikipedia