The Mary was built at Calcutta in 1813.
SURGEON JOHN RODMELL
John Rodmell kept a Medical Journal from 26 July 1821 to 28 January 1822 the entries of which highlight the difficulties vessels sometimes encountered getting out to sea.......
John Rodmell first boarded the Mary on 26th July 1821 at Deptford where the carpenters were kept busy fitting up the prison. On the 12th August, the ship dropped down to Gravesend and on the 16th weighed anchor for the Nore. On the 17th August they got underway again but were obliged to anchor again in consequence of very light wind and ebb tide. On the 18th they sailed with a light wind and at 7pm came to in the Queen Channel. On the 19th they made sail for the Downs where they procured Irish beef and vegetables, departing there for Portsmouth which they reached on 21st August. 
The military guard was a detachment of the 67th regiment under command of Lieut. Sutherland of 46th regiment
By 22nd August the ship had arrived at Spithead. A sloop with 176 convicts from the Leviathan and York hulks, a guard, two women and 3 children came alongside once they had anchored. The military guard and passengers Rev. Thomas Hassall, eldest son of Rev. Rowland Hassall; and Captain Brown, owner of the Mary
all embarked at this time.
The convicts were berthed, put into messes and had beds given out to them. On the 28th August, Mr. McIntosh joined the vessel as Second Officer.
On 31st August, still at Portsmouth, they received two boxes from the store keeper of the dock yard, containing 11 bibles, 44 prayer books for the use of convicts and guard. They also received 6 tons of sand and 16 puncheons of water.
On the 5th September 1821, at 4 pm they weighed anchor, but were obliged to anchor again at Cowes.
On 7th September 1821, the ship got under way but found it necessary to come to an anchor in Yarmouth.
On 8th September 1821 at 5.30 they got under way and made sail through the Needles and at noon the pilot left the ship.
On 12th September 1821, the ship was unable to make any progress, but on the contrary was drifting to the Eastward very fast: there being no appearance of the weather moderating nor the wind becoming at all favourable, it was deemed advisable to put into Plymouth, and at noon they came to an anchor in the Sand and found there HMS Hyperion, Lee Cameleon all wind bound. 
On the voyage the prisoners were employed picking oakum and knotting rope yarns.
By the time they sighted the Island of Madeira on 5th October 1821, the prisoners and guard had been on board for about six weeks and John Rodmell commenced doses of lemon juice and sugar to deal with the possibility of scurvy. By the 11th October, they arrived at Porto Praya Island
of St. Jago where they intended to get water. The prisoners had irons replaced on them for the duration of the stay. 
CROSSING THE EQUATOR
They crossed the Equator on the 2nd November and the surgeon remarked that the old custom of shaving and ducking was performed, and the ceremony was carried on in great good humour.
They made the land near Cape Ledo on the Brazil Coast on 7th November 1821 and on 23rd January 1822 arrived in Port Jackson, the voyage having taken 140 days.
There were no deaths of prisoners on the voyage out, however one child belonging to a serjeant of the guard passed away.
On 28th January the prisoners were disembarked and inspected by the Governor Sir Thomas Brisbane who was said to be highly satisfied at their general appearance
A list of 79 men from the Mary
was forwarded to the Magistrate at Parramatta that same day with the names of the settlers they were to be assigned to and the men were forwarded by water that same day.
5 assigned to Captain King
2 assigned to Rev. Samuel Marsden
4 assigned to Rev. Thomas Hassall
5 assigned to Mr. Mrs. Samuel Hassall
6 assigned to George Blaxland
5 assigned to John Blaxland
1 to John Rogan at Castle Hill
3 to Nicholas Bayley
2 assigned to Mr. Noble at Pitt Town Evan:
8 assigned to James McHenry at Penrith
15 assigned to government agricultural establishment at Emu Plains
3 assigned to John Wood
4 assigned to John Lees
3 assigned to Mr. Hovell James Grist assigned to Captain Irvine
4 assigned to William Redfern
Thomas Germany alias Jermyn assigned to Dr. Townson
Stephen Reynolds assigned to Thomas Laycock
3 assigned to J. Campbell
3 assigned to Mrs. Minchin.
Eighteen convicts were sent to various magistrates to be assigned to settlers in other districts.
DEPARTURE FROM THE COLONY
Those advertising their intention to leave on the Mary in February 1822 included Captain Arcott; Mr. Usher, 1st Officer; Mr. McKintosh, 2nd Officer; Mr. Sergeant, 3rd officer; Mr. Brown and Dr. Rodmell.
NOTES AND LINKS
1). John Rodmell was employed as Surgeon Superintenent on convict ship voyages:
to NSW in 1823.
Woodman to VDL in 1826.
2). Charles Arkoll was also captain of the convict ship Minstrel
3). Prisoners and passengers of the Mary identified in the Hunter Valley
4). Another detachment of the 67th regiment arrived on the Daphne
5). Return of Convicts of the Mary assigned between 1st January 1832 and 31st March 1832 (Sydney Gazette 14 June 1832; 21 June 1832).....
Daniel Holland - Salesman assigned to Henry Jupp at Field of Mars
 Bateson, Charles & Library of Australian History (1983). The convict ships, 1787-1868 (Australian ed). Library of Australian History, Sydney : pp.344-345, 383
 Ancestry.com. UK, Royal Navy Medical Journals, 1817-1857. Medical Journal of John Rodmell on the voyage of the Mary in 1822. The National Archives. Kew, Richmond, Surrey.
 National Archives
. Reference: ADM 101/51/2 Description: Medical journal of the Mary, convict ship, from 26 July 1821 to 28 January 1822 by John Rodmell, surgeon and superintendent, during which time the ship has been employed in fitting for the reception and conveyance of convicts from Portsmouth to New South Wales.