Joseph Hoy OR Hay

Hello folks,
I am trying to trace details of my paternal great grandfather, Joseph Hoy (or maybe Hay) who was born in Norwich, England in 1827 and transported to the Swan River Colony (WA), Australia, as a convict, aboard the "William Hammond" in 1856.

Joseph married Fanny Charlotte Corrigan, born in Dublin, Ireland in 1837, in Guildford, Western Australia, on 1st March, 1863.

His convict record gives his surname as HAY but I would assume that he was possibly HOY because that is our name today. If he wasn't Hay, then we aren't truly who we think we are!!!