If you go to McDude's Photopost picture of this, you can click on it and see an enlarged view. Here's the link
http://www.winnipesaukee.com/photopo...6&limit=recent
You can almost see inside the portside shed, and it almost looks like either a bed or bench.
I would also imagine they would have to bring hay and grain for the horses, so one of them (probably portside) would be used to store those supplies.