Local Records Offices sometimes have some useful stuff. One of my ancestors was a Master Mariner who sailed from Littlehampton, Sussex (interestingly he sailed to and from Sunderland regularly)
The Sussex Record Office had some ships records, quarterly returns, crew lists etc for ships he sailed - very patchy as to what has survived so could never piece together his whole career or anytihng, but very interesting all the same.
I dont know if you would, therefore, find anything at the appropiate records office for Sunderland.