Looked in 1933 History of IoMSPCo - gives photos of Captains appointed after 1890 - no Captain Cork(h)ill amongst them - if he was 31 and still an AB seaman on the Snaefell in 1881 then I suspect he was leaving it a bit late to study for his Masters certificate.
Although the IoMSPCo was the main operator on the Island services with many boats (see http://www.ee.surrey.ac.uk/Contrib/manx/fulltext/sp1904/index.htm for 1903 history) there were ferries on the Barrow Route at around the turn of the century and the Fleetwood route as well. My suspicion is that he wasn't Captain (or more legally Master) but may well have worked on the IoMSPCo boats