Hi Jim,
Thanks for your note.
I have briefly looked at your research problem and I think you are dealing with a corrupted spelling of the name. I’m finding it used interchangeably with “Drudy”, “Droody”, and “Dardy”.
Most notably, it seems to be centered in the Roscommon County area.
It is not unreasonable that James would sail from Dublin, but not actually be from Dublin.
There are a number of entries for a James Durdy in Roscommon – he obviously isn’t yours since yours immigrated, but the name is fairly uncommon and you would want to focus on the areas where you find the surname.
There is a Catholic baptismal entry in St. Paul’s Dublin in 1838 for a child Alicia Durdy, daughter of Andrew Durdy and Mary Wheelihan.
So it does at least put the Durdy surname in Dublin.
If you are to hire a professional there, I would suggest
John Grenham or
Eileen O’Duill.
John Grenham https://www.johngrenham.com/mail/ or
Eileen O’Duill HeirsIreland Research Director nelie@heirsireland.com
Best, David RencherDE@familysearch.org