The history of Port Penrhyn can be traced back as early as 1713 when it was recorded that 14 shipments totalling 415,000 slates had been sent to Dublin. In 1720, another 8 shipments totalling 155,000 slates were sent to Dublin, two to Drogheda (20,000) and one to Belfast (35,000). Two years later, a shipment of 80,000 slates were sent to Dunkirk. After these few shipments only coastal traffic left from Aber-Cegin (Port Penrhyn) until Richard Pennant took over the ownership of Penrhyn Estates and appointed Benjamin Wyatt in 1786 as agent.
Wyatt addressed the problem of bringing slates from the quarry at Bethesda to Port Penrhyn by laying a rail line between the two sites. A stone wharf was built at the mouth of the River Cegin by 1790, it was further extended in 1829-30 and a final extension took place in 1855 with a breakwater on the eastern side, forming an inner basin; Port Penryhn was created.
Slate ships c. 1890 alongside the West Wall (where the River Gegin empties into the Menai Straits), showing the Port House and the railway
Deadweight, or d.w.t., is the carrying capacity of a vessel viz fuel, stores, water, crew, and especially in the case of coasters, tankers and bulk carriers, cargo: i.e. the d.w.t. gives an indication of the total cargo certain types of vessels can carry. The size of vessels worked at that time ranged from 39tons to 87 tons d.w.t., and occasionally vessels of over 100 tons d.w.t. were handled. It is stated that the exports of roofing slate then averaged 250 tons per week, so the numbers of vessels using the port annually would have been considerable.
The vessels then were small sailing craft, fitted with schooner or other simple rigs, worked and crewed by perhaps a couple of men and a boy. The port was designed for such vessels, and manpower was cheap and vessels were inexpensive to buy and run. Competition existed in the coastal trades, but as cargoes were tiny and the market large, everyone managed to make a living. See vessels of the past.
Today's 'coastal' vessels are expensive to build and operate. They have to deal with bureaucracy which was undreamed of a century ago. They have to work and find cargoes for almost every day in the year in order to exist commercially. For examples of some of the more recent visitors to Port Penrhyn, see the Vessels page.