The Countess of Erne was built in Dublin in 1868 and started out as an 830 grt iron hulled paddle steamer. She carried two engines delivering about 270hp to the two side paddles.The original owners Walpole Webb & Bewley sold her in 1869 to London & North Western Railway, who used her as a ferry for Holyhead to Ireland (Dublin 69-73, 73-89: Greenore) run carrying a 100 first-class passengers, 600 2nd and 3rd class passengers and also an additional 700 tons of cargo.
In July 1873 she collidied with SS Dodder in Carlilngford Lough. The SS Dodder sank, but the Countess surived it with only minor damage and continued her service as a ferry until 1889, when she was auctioned off in Liverpool and bought by the Bristol Steam Navigation Company who used her for another 2 years and sold for scrap.In late 1890, early 1891 she was converted into a coal hulk, when most of superstructure, cabins would have been removed. She was used in several harbours before being finally moored in Portland Harbour.
During the night of September 16th 1935, she broke free of her moorings and drifted across the port. Considering that Portland was an extremely busy harbour in the 1930s, it is very fascinating that she didn't hit anything while drifting across the harbour. She drifted onto the north-east breakwater within Portland Harbour, holed herself on the rocks and sank quickly to the bottom.