The history of Dún Laoghaire Harbour – construction and compromise
09 January 2018
The West Pier lighthouse
On 31 May 2017, President Higgins took part in a ceremony to commemorate the 200th anniversary of the laying of the first stone for the construction of Dún Laoghaire harbour. Many other events took place in the bicentenary year, commemorating a construction project that was one of the largest of its day in Ireland.
There has been a harbour at Dún Laoghaire, then called Dunleary, since medieval times, though this would have been used only by small fishing boats. In later years, from at least as early as the 17th century, some passenger boats called in at the harbour to avoid the difficulties of accessing Dublin port. By the 18th century, some forty coal boats were trading with ports in England and to facilitate this a new pier was built in the 1760s, supervised by the military engineer, Charles Vallancey.
The pier that commenced in 1817 had no connection with the old harbour at Dunleary, however, but was designed solely as a means of providing shelter for the safety of shipping during major storms.
The port of Dublin was difficult to access due to a sand bar that ran across the mouth of the Liffey and as there was nowhere else in Dublin Bay capable of sheltering ships there were hundreds of wrecks in the bay over the centuries. Various ideas were put forward over the years for means of reducing or eliminating the losses, including several concepts for ship canals and some for building piers.
Following a double tragedy in 1807, in which about 400 people lost their lives, Dublin-based ship-broker, Richard Toutcher, began a one-man campaign to have a pier built near Dunleary to provide shelter to shipping in storms. His pier would have been located close to where Traders’ Wharf is in Dun Laoghaire today and would have extended 300 metres to the north before turning to the north-west and running for a further 150 metres.
His campaign led to the passing of an act of parliament in 1815 to establish the Dunleary Harbour Commissioners, charged with the responsibility for selecting a site for this pier and providing a design.
John Rennie’s design for Dún Laoghaire
The commissioners engaged the well-known Scottish engineer, John Rennie, who had carried out a number of projects in the Dublin area, including the harbour at Howth, which was nearing completion in 1815. Rennie’s plan envisaged a site significantly further to the east, to avail of deeper water, while avoiding the rocks of Scotsman’s Bay.
His design also proposed a longer pier, extending 450 metres out from the shore, followed by three further stretches of 150 metres, 150 metres and 60 metres respectively – though these dimensions were later amended. The intention was to create a substantial area of water that would be sheltered from the ferocity of the easterly and north-easterly storms, so ships could lie at anchor until the storm abated. Significantly, it was not intended to act in any way as a port.
With a site selected and a design prepared, a second act of parliament in 1816 gave the Dunleary Harbour Commissioners the responsibility to construct the pier. Prior to this, Richard Toutcher had secured land at Dalkey for quarrying to provide the stone, though two other sites also provided small, but significant amounts of stone – these are now occupied by the People’s Park and the Lexicon library in Dún Laoghaire.
Before the commissioners could begin the construction of the pier, extensive preparatory work was required, including access to the coast, for which the commissioners laid out Marine Road. To carry the stone from the quarries, a railway was built along a route that still survives today as a footpath and cycle path between Dún Laoghaire and Dalkey, known as ‘The Metals’ – this being an old term for an iron railway.
The team involved in the construction included John Rennie as consultant engineer, until his death in 1821, following which his son, also John Rennie, and later Sir John Rennie, took over. The resident engineer was John Aird, another Scot, who had worked on various projects with Rennie over the years, the most recent of which was the construction of Howth Harbour.
The assistant resident engineer was Richard Thomas, from Halifax in Yorkshire. Richard Toutcher also came to work on the construction, as store-master, though with wide-ranging duties.
Just before the laying of the first stone in May 1817, Rennie decided to opt for a revised location, slightly further to the east than his earlier proposal and this was the site on which Dún Laoghaire’s East Pier was built. More than a year after this, Rennie began to be concerned about how the pier would perform when constructed, particularly as it was becoming evident that the clockwise flow of the sand-bearing currents in the bay were resulting in a build-up of sand to the north of the mouth of the Liffey, arising from the construction of the South Wall.
To prevent this process from silting up the anchorage in the lee of the new pier, Rennie proposed the construction of a second pier, which would also provide shelter from the prevailing westerly winds. John Aird produced alternative sites and designs for this second pier in October 1818 and, in 1821, a fresh act of parliament authorised its construction.
Construction of the Dún Laoghaire piers
The construction of the piers involved trundling wagons of stone along the tramway from Dalkey to the pier, where the contents were deposited in the sea by means of a timber tipping frame. A diving bell was used to help guide the stones into the right positions and experience soon showed that the action of waves during storms helped to settle the stones down onto the sea bed.
While diving bells had a long history, John Rennie had extensive experience in their use for civil engineering works, having taken over construction of Ramsgate Harbour from Alexander Smeaton, who had pioneered their use in engineering. Rennie had used diving bells at Howth and these were transferred to Dún Laoghaire, along with a mortar mill for preparing lime-based mortars.
Once the rubble core of the piers was in place the finishing of the outer surfaces could begin, though this was not undertaken until the 1830s. The glacis on the outer face was to have a slope of 1 in 5, except for the lowest part, where it increased to between 1 in 1 and 1 in 2.
When added to the width taken up by the two roadways on the top of the pier, the total width of the piers at the base was as much as 80 metres. The glacis was paved with roughly-squared stones, about 1.2 metres long, set perpendicular to the slope and packed closely together. The inner face was built with a batter, and again roughly-squared stones were used to construct the face. This was in contrast with the design at Howth, where Rennie used granite ashlar as the facing.
Rennie’s original design proposed a gap of 130 metres between the ends of the piers, though the Admiralty was convinced that this was not wide enough and would result in collisions. In 1829, work on the two piers was brought to a halt until the final design of the mouth of the harbour could be debated and determined.
Rennie and Aird believed that any gap wider than 130 metres would result in swells from northerly winds entering the harbour, while others were concerned that unless it was significantly wider, sailing ships would have difficulty entering during storms.
Some compromises were suggested, including keeping a wider harbour opening, but constructing a breakwater in the bay beyond the harbour mouth. In the end, the mouth was kept more or less as it was when construction was halted in 1829, but with rounded pier heads constructed with substantial blocks of granite ashlar. This ashlar had a foundation of sandstone blocks, each of 1.1 cubic metres and sourced from Runcorn in Cheshire.
Completion of the piers
The two piers were completed in the 1840s, though other works were undertaken to facilitate use as a port, including Victoria Wharf in 1837 – now the site of the former ferry terminal – Traders’ Wharf in the 1840s and Carlisle Pier in 1859.
The harbour has been a centre for recreational sailing almost since its inception, the base for Irish Lights since the 1870s and, most famously, was the principal port for the mail boats throughout most of its history.
Rob Goodbody BA (mod), Dip. Environmental Planning, Dip.ABRC, MA, MUBC, MIPI is a historic building consultant. He has researched the history of Dùn Laoghaire harbour over many years and has written several books including ‘The Metals – from Dalkey to Dún Laoghaire’. He has co-authored a number of others, most recently ‘Dublin Bay – Nature and History’, which was recently published by Collins Press. Email: email@example.com://www.engineersjournal.ie/2018/01/09/history-dun-laoghaire-harbour-construction-compromise/http://www.engineersjournal.ie/wp-content/uploads/2018/01/dun-laoghire-lighthouse-2.jpg.pnghttp://www.engineersjournal.ie/wp-content/uploads/2018/01/dun-laoghire-lighthouse-2.jpg-300x300.pngCivilDublin,Dun Laoghaire-Rathdown Co Co