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Lyme Regis Harbour (1825)
Lyme Regis, Dorset
associated engineer
William Jessop
date  circa 1300, 1819 - 1825
era  Georgian  |  category  Harbour  |  reference  SY338916
ICE reference number  HEW 414
In its original form, Lyme Regis Harbour dates from around 1300 and was one of the earliest harbours constructed in Britain. Extensive works were undertaken in the 1820s, including the rebuilding of the Cobb, now a Grade I listed structure and well known for its appearance in the opening scene of The French Lieutenant's Woman.
Lyme Regis lies 40km west of Dorchester on the Dorset coast. It is exposed to south westerly gales and the Cobb was built as both breakwater and harbour, using oak piles infilled with large boulders. However, it was prone to storm damage and was indeed destroyed by a storm in 1377, after which it was rebuilt in lias limestone. The Cobb is U shaped in plan, with the base of the curve to the south.
Lyme Regis was once a major port — at its most prosperous between 1500 and 1700 when vessels plied their trade with the Mediterranean, the West Indies and the Americas. Quay facilities were built during this period.
Until 1756 the Cobb was detached from the shore at high tide, which allowed natural longshore drift and the accretion of shingle. In 1793, a southern arm was added, giving the Cobb's western half a 'forked tongue' outline.
The local geology consists of alternating layers of limestone and clay, which by 1805 had led to severe erosion and receding of the cliff face by some 82m. The Board of Ordnance, who were responsible for maintenance of the harbour, engaged renowned engineer William Jessop to address the problem.
The High Wall was built 1819-20 but an 1824 storm caused extensive damage to the harbour, including the wall. Major repairs to the High Wall and the complete reconstruction of the Cobb took place between 1820 and 1825. The works were carried out by army engineers using Portland stone.
The south west arm of the Cobb is 274m long and approximately 12m wide, with a parapet some 3.7m high and almost half full width. The eastern breakwater is 5.8m high and 3.7m wide, with a low parapet. It has become detached from the shore as a result of land regression, although the gap was closed by haphazard blockwork — an easy task as the harbour dries at low tide owing to local accretion.
The harbour acquired rock armouring in the 1970s and additional strengthening works took place in the 1980s. Coastal protection works along the entire Lyme Regis and harbour frontage, including new sewerage provision, have been ongoing since the 1990s. In February 2005, as part of a 16m programme of sea defence works, contractor Mowlem began removing the existing rock armouring around the Cobb and replacing it with granite boulders delivered by barge from Norway. The blocks make up a random pattern mass structure. GPS equipment was used to position them. The entire scheme was opened by HRH Princess Anne on 4th April 2007.
Lyme Regis Harbour is owned and operated by West Dorset District Council. It is no longer a trading port but provides fishing and leisure activities, supported by moorings, stores, boat storage and a public slipway. There are 23 permanent moorings for commercial vessels and around 133 letting moorings for private use, with additional space for visiting boats.
Supervising engineer (2005): High-Point Rendel
Main contractor (2005): Mowlem
Piling (2005): Systems Geotechnique
Research: ECPK
reference sources   CEH South

Lyme Regis Harbour (1825)