I agree with the last comment. I'm not sure how many men it would have taken to row a wherry. My grandfather was a wherryman on the Tyne. His wherry was simply a large, unpowered barge which would be towed by a tug boat from and to wherever it was needed. During World War II, one of his tasks was to take ammunition from damaged ships, which had come into the Tyne for repair, up to the ammunition dump near Lemington. When the ships were ready to put to sea again, they would take the ammuition back down river.
John