In this postcard, the wooden structure you see on T-Wharf is the coal pocket where coal was once stored there. Just to the right of the wharf, a shuttle boat is approaching with a uniformed sailor standing in the bow, probably carrying crew from one of the U.S. Navy warships that regularly visited Rockport in those days. On the left side of the picture, you can see the three smokestacks of one of the battleships.
This photograph appears to have been taken at the same time as the one you see in this postcard from the same publisher. You can see the same shuttle boat tied up to the pier and the same small sailboat to the right of it.
The postcard was published by The Rotograph Co. of New York City. It is undated. The company was in business only from 1904 to 1911.