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Double Hull Construction

The most significant and original engineering feature of the Great Eastern was the concept of the double hull - essentially the application of the cellular system of girder construction to the structure of a ship. The Great Eastern had two hulls, one inside the other, 2ft 10in apart and heavily braced.

Each hull plate was shaped by means of hand operated rolls and was cut by steam operated shears, all in accordance with wooden patterns taken from lines that in their turn were taken from a wooden model of the hull. Every plate was marked and numbered on the model.

A boy painted the positions of the rivet holes, using another template, and the holes were made by a steam punch. Each plate was then transported on a bogie to the site, where it had to be lifted by primitive block and tackle to its position, clamped or bolted in place, then hand riveted. Each hull plate was fixed alternately overlapping the adjacent plate. This innovation was known as 'in and out' strakes.

The transverse bulkheads and inner skin were fitted first, then the longitudinal ones, and the webs to which the outer skin was riveted. The ship was built entirely with single riveting and double riveting, with two sizes of angle iron and two thicknesses of plate.