William Wigdell Wignell Convict Van Diemen S Land

I had hit a stumbling block in trying to track my ancestry. The earliest ancestor with my surname I could find in Australia is a William Wignell, who was living in George Town (Tasmania) around 1838. His trail ends there. However, there is a convict, William Wigdell, transported to Van Diemen's Land in 1823. He seems to have been a bit naughty and absconded several times. He was sentenced to 7 years' transportation in 1827. From what I can gather he spent time at Macquarie Harbour. He was freed in 1835. His age is listed as 30 years in a runaway notice in 1825, which would have him being born in or around 1795. William Wignell's occupation is listed as a boatman/fisherman and William Wigdell's occupation is shown as fisherman. My hypothesis is that some time between 1835 and 1838 William Wigdell became William Wignell. William Wignell married Frances French/Hunt/Sherlock in 1841. I have an undated photograph of the two of them. William looks to be in his 40s in the photograph, which would put him in the same age bracket as William Wigdell.