Feature Articles - Helical Pier World

^{Birth of the Helical Pier} by Rich Davis, Editor-in-Chief

The inventor of the first known Helical Pier was born April 13th, 1780. It was on this date that Alexander Mitchell was born in Belfast, Ireland. Growing up, Mitchell excelled in mathematics throughout his youth, and after his schooling he went into business as a builder and brickmaker. This story is all the more extraordinary considering he was completely blind by the age of twenty three as a result of a childhood bout with smallpox.

Around 1831, at the age of 52, Mitchell was asked to consider how a dock could be constructed for the repair of moderate sized vessels, and the dock would be neither a dry dock nor a patent slip, would cost little, would occupy little space and could be worked economically. It is not clear why Mitchell was consulted for this job. Perhaps it was through his connections as a builder. Mitchell suggested a dock that would sit atop never before used “screwpiles.” Mitchell described his invention as “a bar of iron having on its lower extremity a broad plate or disk of metal in a spiral"…on the principle of a screw. Mitchell maintained that the screwpile should enter the ground [sea bed] with [ease], pushing aside any obstacles to its descent without materially disturbing the texture of the strata while descending. As the result of embedding the plate or disk into firm strata, Mitchell suggested the screwpile would then provide resistance against a downward pressure or an upward strain.

Two years later his patent application was accepted as one of the very first civil engineering patents ever to be awarded. At first the major market for his screwpile was in marine moorings. By 1838, Mitchell’s screwpile found its way under the Maplin Sands Lighthouse, and thus began an explosion of lighthouses built on screwpiles all over the world.

Brandywine Shoals Lighthouse Sombrero Key Lighthouse American Shoals Lighthouse

In May 1851 Mitchell moved to Cove to lay the foundation for that lighthouse. The success of these p The first pier built with screwpiles in 1855 rojects led to the use of his invention on the breakwater at Portland, the viaduct and bridges on the Baroda and Bombay railway, and the entire system of Indian telegraphs. The adjacent photograph shows the very first pier constructed with helical piers in 1855.

The news of Alexander Mitchell’s successes with his screwpile spread far and wide, as the predecessor to today’s helical pier became an integral component of lighthouse and marine pier construction.