The March mystery ship is Mona’s Queen, built in 1885 by the Barrow Shipbuilding Co for the Isle of Man Steam Packet Co. She is leaving Douglas harbour and, judging by the east light on her funnels, it is a morning sailing, probably at 0830 for Fleetwood, the route on which she spent much of her life. She returned to IoMSP after World War I service as a troopship and continued in service until broken up after the 1929 summer season.
I would date the view between June 1905 and August 1914, as those are the dates of entry into service and last sailings of the fourth steamer (right, on the far side of Victoria Pier), Manxman. Theother two steamers pictured are also IoMSPCo vessels: the steamer waiting off the pier is the 1871-built King Orry and the steamer at the pier to her right is the rather larger Empress Queen.
David Rowe, London