The phrase "aboard a steamer" is correct and usable in written English.
It can be used when referring to being on or inside a steam-powered boat or ship.
Example: "We spent the afternoon aboard a steamer, enjoying the scenic views of the river."
Alternatives: "on a steamer" or "in a steamer."
Reporter remembered Floyd Gibbons, correspondent for the Chicago Tribune in WW I. Gibbons crossed the Atlantic aboard a steamer that he knew would pass through the German U-boat zone, in the hope that the steamer would be torpedoed.
On a winter day in 1883, aboard a steamer that was returning him from Marseilles to the Arabian port city of Aden, a French coffee trader named Alfred Bardey struck up a conversation with a countryman he'd met on board, a young journalist named Paul Bourde.
His Regiment then sent a troop of soldiers to arrest him for desertion, though just as Macphee was about to be taken handcuffed aboard a steamer at Corpach, he managed to escape and fled his captors.
On 19 January, Leonard Hussey accompanied the body aboard a steamer bound for Montevideo, but on arrival there he found a message from Lady Shackleton, requesting that the body be returned to South Georgia for burial.
Sailors recently arrived in Liverpool aboard a British steamer claimed to have been members of the Sea King's crew who had been rescued at sea.
Mountain railways have since replaced anything horse-drawn, but I was still able, once I had caught the train down to Lake Thun, to make the crossing to Interlaken aboard a graceful steamer with an old-fashioned ambience, even though it no doubt had something modern under the bonnet.
Hussey accompanied the body aboard a British steamer, and returned to Grytviken.
Scotland Yard detectives soon discovered that Webster had fled back to Ireland aboard a coal steamer in the company of her young son.
By the time he had been placed aboard railroad cars and then a steamer for Washington, his leg was "swollen as large as the skin would allow".
By the eighteen-nineties, three or four thousand tons of coal could push a steamer across the Atlantic in just six days, and a ticket aboard cost only thirty dollars.
