Go to Maryland and get the records. I went to Michigan a few years back, to the court house in the county my g-g-grandparents lived. I ended up with not just their information (when they arrived, etc), but the marriage certificates of all of their children and a few other documents. I was able to use the date of arrival to find the ship they sailed on. I then got help finding the town they lived in England. Now I am trying to find the time. Point being, go to the source. You might find more than you need, but get a copy anyway. You never know when you might need it too.