Great questions that would take a few reams of cyber parchment to answer but I have one piece of info to share....

Tug boat service began appearing in Baltimore's harbor sometime in the 1840's and 50's. the first tugs to come here were from Wilmington, Delaware and built on the Christiana River.

Before tug service, any ship leaving the harbour without the aid of winds and currents were required to place an onboard anchor cable or line tethered to it's ship anchors in have it rowed out in a long boat ahead of the vessel and dropped to the bottom. The ship's crew would then man the capstan and move themselves along the channel by reeling in and weighing the anchor up to the waiting long boat. The process would be repeated again and again until the ship was in port or out into the wind. This was called 'kedging' and it could be a long and labourious job on a windless day. The advent of steam power (already at work on the fledgling rail roads), and the application of it on small tow or pusher boats changed all of that forever.

Walt
PS Just posted up on the 'shipyards forum' about a new maritime museum slated to open in Baltimore in two mounts. See you there!