The Theresa left Deptford for Woolwich on 28 September 1838. At Woolwich 200 male prisoners were received on board the following day and 66 more on 2nd October.
Many of the prisoners of the Theresa had been held in prison hulks prior to embarkation. Select here to read a Prison Hulk Report describing a typical week in the life of convicts incarcerated in the Hulks in 1838.
Officers of the Guard were Captain Samuel Lettsom and Ensign Cookney of the 80th regiment accompanied by 31 rank and file of the 51st and 30th regiments.
The Theresa departed Portsmouth with 264 male prisoners on 10 October 1838.
Surgeon Edward Hilditch
Edward Hilditch kept a Medical Journal from 8 September 1838 to 7 February 1839. He reported that the convicts were generally healthy but emaciated, especially those from the Fortitude hulk at Chatham. With few exceptions, their health improved on the voyage. There were a few cases of scurvy at the end of the voyage, one of which was severe and accompanied by gastric irritability and febrile action. The others would not have been placed in the sick list only that they might be sent to the hospital on the ship's arrival. 
On the voyage, the prisoners were put into three divisions and sent on deck to wash one division at a time, in the mornings. Breakfast was at 8am followed by cleaning and inspection of the lower deck. Dinner was at 1pm and supper at 5pm. Two divisions of prisoners were always on deck during the day when the weather permitted. They were made to exercise in various ways such as dancing, boxing or running round the deck. At sunset they were sent below and the prison secured. The bedding was aired twice a week and the lower deck fumigated with chloride of lime at the same time. The same measures were used with the soldier's barracks. In wet weather bedding was put under a tarpaulin in the long boat. 
Two convicts died on the passage out, both were worn out, debilitated men.
They arrived at Port Jackson on 31 January 1839. The voyage had taken 112 days.
Notes and Links
1). Edward Hilditch was also surgeon on the convict ship Susan in 1837 (to VDL)
4). National Archives. Reference: ADM 101/71/4 Description: Medical and Surgical Journal of the convict ship Theresa for 8 September 1838 to 7 February 1839 by Edward Hilditch, Surgeon, during which time the said ship was employed in a passage from Deptford, Woolwich and Sheerness to Sydney, New South Wales
Medical Journal of Edward Hilditch on the voyage of the Theresa in 1839, Ancestry.com. UK, Royal Navy Medical Journals, 1817-1857. The National Archives. Kew, Richmond, Surrey.