The Earl St. Vincent was a merchant ship built at Topsham, England in 1800.
This was the last of three voyages bringing convicts to New South Wales, the others being in 1818 and 1820.
The convicts came from counties in Ireland - Cork, Limerick, Tipperary, Donegal, Dublin, Kerry, Westmeath, Armagh, Louth, Roscommon , Sligo, Kilkenny, Antrim, Meath, Tyrone, Longford, Down, Fermanagh, Derry, Kildare, Wexford, Clare, Mayo, Waterford, Monaghan, Cavan, Kings, Queens and Wicklow.
Their crimes included various forms of stealing and robbery, administering unlawful oaths, vagrancy, passing base coin and forged notes, being idle and disorderly, coining, insurrection, perjury, murder, rape, pike making and sending a threatening letter.
Surgeon Robert Tainsh
Robert Tainsh kept a Medical Journal from 25th January 1823 to 16 September 1823
The Guard was received on Board the ship 25th January at Cove, consisting of one Ensign (Bute), one corporal and twenty nine privates with eight women and seven children of the 1st Royals. On their arrival on board one half complained, some the first hour, and a number the next morning. (They were) labouring under severe colds, caught on their march from Waterford, to join the St. Vincent. The weather was wet with snow and intense cold easterly winds. Private John McKerry and Private John Mullen, were apparently in the second stage of phthisis - coughs very troublesome, pain of the breast and oppressed breathing, cold chills and considerable prostration of strength with loss of appetite. The pulse fuller than from their wretched appearance I could possibly have expected. I was satisfied these two men should not have been sent as a guard over convicts, however I determined to attempt their care first and then make my representation afterwards. 
On the arrival of the convicts at Cove from Dublin in a small brig, to the number of two hundred and thirty five, the weather was wet, cold and stormy, with snow. On the 5th March, we received on board the St. Vincent eighty men of various ages; above one half were complaining from exposure to the above causes. Some with pneumonia but in its early stage. The others with severe catarrhal symptom. In the first place after bathing particular cases with soap and warm water I filled every bed in the hospital, gave them clean shirts and well aired sheets and for the rest having plenty of room in the main prison, I appropriated a sufficient space as an additional hospital and as others became ill, I invariably separated them from those in health. I had also a number of cases of dysentery but by the above arrangements and devoted attention to their every comfort, I am happy to say that in a few weeks I had not a sick man in the list. I also cured about thirty ulcers.
I am satisfied that the depressing passions had a very considerable influence in producing debility in both accelerating the disease and retarding its cure. Many had parted with their relatives, fathers, mothers, sisters and brothers, and a great proportion perfectly persuaded from the energies of their friends that they would be discharged, being mostly whiteboys; but that unfortunate and outrageous attack in the Playhouse against the Laws seemed to determine their fate - at least I am of that opinion. However the mode of treatment in all was successful.
The Earl St. Vincent was the next convict ship to leave Ireland after the departure of the Recovery on 5th April 1823. She departed Cork on 29 April 1823
By the 15th May scurvy had appeared. Robert Tainsh at first treated the men with lemon juice and preserved meat, however by 20th June many were afflicted and he directed the captain to sail via Rio de Janeiro to procure fresh beef, vegetables and fruit for both convicts and Guard.
The Earl St. Vincent arrived at Port Jackson on 9 September 1823.
On 15th September His Excellency Sir Thomas Brisbane came to Town early and in the forenoon, the male convicts that were landed that morning were inspected by His Excellency and afterwards sent to their various assignments.
Notes and Links
1). Robert Tainsh was also surgeon on the Hooghley in 1825
2). Prisoners and passengers of the Earl St. Vincent identified in the Hunter Valley region
3). Return of Convicts of the Earl St. Vincent assigned between 1st January 1832 and 31st March 1832 (Sydney Gazette 14 June 1832; 21 June 1832)-
Bryan Friar - cooper assigned to Dr. Wardell at Petersham
4). National Archives. Reference: ADM 101/21/8 Description: Medical journal of convict ship Earl St Vincent. : Diary of Earl St Vincent: 25 January - 16 September 1823: ADM 101/21/8A. Medical journal of Earl St Vincent: 25 January-16 September 1823: ADM 101/21/8B.
 Bateson, Charles Library of Australian History (1983). The convict ships, 1787-1868 (Australian ed). Library of Australian History, Sydney : pp.344-345, 384
 Ancestry.com. UK, Royal Navy Medical Journals, 1817-1857. Medical Journal of Robert Tainsh on the voyage of the Earl St. Vincent in 1823. The National Archives. Kew, Richmond, Surrey.