From this site (which also has a picture of said ship, and further info on the sinking):

The Ellan Vannin was originally built as an iron paddle steamer and named Mona's Isle. Constructed in Scotland by Tod & MacGregor at Meadowside, Glasgow in 1860 at a cost of 10,673UKL. She had a gross tonnage on building of 339 tons, top speed of 12 knots and an overall length of 63.09metres. She was launched on 10 April 1860.In 1883 the Mona's Isle was converted to a twin screw steamer by Westray, Copeland and Co. of Barrow and renamed Ellan Vannin on 16 November 1883. Ellan Vannin is the Gaelic for "Isle of Man".

I believe that, as the Manx language was traditionally never written down but only survived orally, any spellings (such as Ellan Vannin, Ellen Vannen etc.) are debatable and variable and not worth losing sleep over.