"Lakers" is correct as they are built in the Great Lakes for use only in the fresh water of the lakes and do not travel beyond as they are built too wide/long to go around Niagara Falls thru the narrow Welland Canal and its locks. Incidentally, the famous Edmund Fitzgerald was a Laker.

I bet Loon got Lakers from the 2 cities where the pro basketball Lakers played. Good job Loon, however you got it.

For Art, those are correct types of freighters under the broader category of "Lakers" or the other broad category.

The other group are those built anywhere for carrying ocean borne freight. When these ships are in the Great Lakes they have their own nickname which is .......? If no answer to the second group by tomorrow evening, I'll post the answer.