The Great South Wall was built to prevent the shipping lanes leading to Dublin Port from filling up with sand and to provide shelter against the winds
This video is designed as a resource for primary and post-primary students up to Junior Certificate.
The Great South Wall and Poolbeg Lighthouse, Ringsend
For many centuries, ships had problems getting into Dublin port. First of all it had dangerous sandbanks. Then its shipping channels were not deep enough and kept filling up with sand, and finally there was no shelter against winds. In the eighteenth century the merchants of the city needed a better protected harbour for their trade so it was decided to build a wall to keep the sand out and give shelter to the ships.
First they built a barrier made from wood some way out from Ringsend along the sandbank known as the South Bull. Bull is an old word for ‘strand’. At the end of it they put a floating lighthouse. But the barrier was not strong enough so they built a strong longer wall with massive granite blocks. Each block weighed a ton. This is about 1,000 kilograms, or a thousand packets of sugar; all packed into one block!
The blocks were brought across the bay on boats from Dalkey and Dun Laoghaire harbours. It took more than 30 years to build what was to be called the Great South Wall and it was finally finished in 1795. At that time it was one of the longest sea walls in the world.
The floating lighthouse had been replaced with the Poolbeg Lighthouse which is still there today. Lighthouses send out a bright flashing light to guide ships at night or in fog and to warn them about sandbanks or rocks. In the beginning turf or coal were used for the light. Poolbeg Lighthouse was the first to be lit with candle light and then, in 1786, with oil.
While the Great South Wall protected the ships entering the harbour from wind and high waves, it could not stop the sand from filling up the shipping channels. So in 1801 Captain Bligh, the famous captain of the Bounty, suggested the construction of another wall on the northern side of Dublin Bay. The Bull Wall, as it is commonly known, was finished around 1824 and from then on, Dublin Port never filled up with sand again.