National Physical Laboratory

Ship Tanks

Ship tank

The National Physical Laboratory (NPL) opened its first ship tank on 5 July 1911. It was 150 m by 9 m wide and held 5000 tonnes of water with a centre depth of 3.75 m. A marine engineer and shipbuilder, Alfred Yarrow, provided £20,000 for the tank's construction to enable the testing of ship models.

It was originally known as 'The National Experimental Tank'; later the 'William Froude National Tank' after the engineer and naval architect; and finally 'No 1 Tank'.

The work of the Ship Division was broadly divided into two: investigations commissioned by shipbuilders, ship owners and other external organisations; and the Division's own programme of research.

Commissioned investigations were mostly design studies for new ships and unusual hydrodynamic problems related to existing ships; while the result of the Division's programme of research led to improvements in ship design.

Ship Tank 2 ConstructionThe ship models were made of paraffin wax, first moulded to approximately the form required, and then shaped by a special cutting machine to reproduce exactly the lines of the ship. The use of wax not only enabled the quick and rapid construction of the ship but also allowed the form to be altered to test the effect of modifications.

The tanks included apparatus for producing 1 m high waves so that models could be tested in rough or shallow water.

Read a brief guide to NPL's Ship Tanks

As a result of increasing demands from industry, the Government provided funds for the construction of a second tank (right), which was completed in 1932. The record number of models tested at NPL in any one year was 190 in 1944.

A water tunnel (pictured below) to test propeller designs for cavitation (the formation of bubbles by a propeller in water) was provided by Sir James Lithgow in 1938.

Water tunnel

Full-scale observations on board ships supplemented the experiments in the tanks. Scientists at NPL went on voyages to obtain data about the motion of ships in rough weather and to study the conditions affecting the steering and manoeuvring power of ships for comparison with data from the tanks.

The ship tanks were made famous by the 1950s 'Dambusters' film , which immortalised the role of NPL in the development of Barnes Wallis' bouncing bomb: NPL's No 2 Ship Tank had been used to test the bomb that the RAF launched at the dams of the Ruhr in Germany in 1943.

Find out more about NPL's role with Barnes Wallis' bouncing bomb

The Ship Division grew steadily until the opening of the ship hydrodynamics laboratory at Feltham in 1959, which then became its headquarters.



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