Lax regulation allowed a ship the size of the Dunbrody to carry anywhere from 160 passengers to over 300. In 1847 she is recorded as carrying 313 passengers to Quebec. Many of her passengers were tenant farmers from the estates of Lord Fitzwilliam in Co. Wicklow, and Viscount de Vesci in Portlaoise.
Only two classes of passengers were carried by he Dunbrody; cabin passengers, paying between £5 and £8; and steerage passengers, paying between £3 and £4. As the average farm labourer could expect to make little more than £1 per month, even a steerage ticket was beyond the means of many people. Cabin passengers had substantial food and services provided. Steerage passengers, though, largely had to fend for themselves.
By 1847 the potato crop had failed for 3 years in a row, and mass emigration was underway. Within the first open months of spring, 40 ships were waiting to disembark at the quarantine station at Grosse Ile in Quebec. With the facility utterly overwhelmed by the numbers arriving, many people were forced to wait for weeks before they could even leave their ships. In May 1847 after finally disembarking his passengers, Captain Baldwin wrote to William Graves reporting, “the Dunbrody was detained in quarantine for five days because there were too many ships queuing in the St. Lawrence River. Doctor Douglas is nearly single-handed… everyday, dozens of corpses are thrown overboard from many ships… I have heard that some of them have no fresh water left and the passengers and crew have to drink the water from the river. God help them!”
Although the Dunbrody was detained at Grosse Ile on a number of occasions, her onboard mortality rate was very low. This was, without doubt due to her good and humane captains, Captain Baldwin and his successor Captain John W. Williams. On more than one occasion, emigrants writing back home praised their care and dedication to both crew and passengers. Thanks to a well-organised overseas mail service, the Captains were also able to remain in regular contact with William Graves.
The Graves Family continued to operate the Dunbrody until 1869, when she was sold to another company. In 1874, while en route to Quebec from Cardiff, her captain chose not to wait for a pilot to assist him in navigating the St. Lawrence. He paid for his impatience when she promptly ran aground. She was fortunate to bought by a salvage company, who repaired and resold her. Unfortunately, in 1875 she suffered a second and fatal grounding. Sailing for Liverpool with a cargo of timber worth £12,500, a fierce gale blew her off course and onto the shore of Labrador. While the exact details are not known, having run aground fully laden with a heavy timber cargo it is assumed that her aging hull was damaged beyond economical repair. She was abandoned at last, left to break up over time and rot away to nothing.