I use Goggle,local library's and news papers,also a local historian may be of help to you,coastgaurd also and insurance co.s
But be warned even if you think your first to a site and spend time and money and your hard work to get a name on a wreck Some one will come along and say 'Oh We found it first,or we dove it! so I just call myself the Great Rediscovererer! this ends all the other stuff!
And make your find public so others can enjoy,a hid wreck serves no value unless your in that secret club of old wreck hunters that love to strip artifacts and stash them in basements or let them rot in back yards.
Last trust no one !wreck hunters And Ship Wreck Researchers can be some of the lowest forms of life on earth,not all but some!They will run public with your find,grab the news,and make self serving lies,stab you in the back and throw you out in the wind to lay and try to cover the facts to protect the looters of the past! As this has been done to me!
Last of all it is the Greatest thing to find or discover a new site! Freakin GREAT! so go too it and be safe, And it looks like we may have a new wreck located on LakeMichigan and just got to get a name on her!
Brad Ingersoll