These remarks are in two parts and NAUTICAL LOG will have some general remarks in this Part and cover the 'assistance towing' industry to the recreational boats in Part 2 - and that can be fraught with problems.
NAUTICAL LOG has had experience, early in my career, working for tow companies in the areas of Southeastern Alaska, and British Columbia log booms, chip barges and later log carriers, via Juan de Fuca Strait to the Columbia River entrance with rock barges and through the San Juan Islands to Seattle with railroad barges. On the New Zealand coast moving a dredger across Cook Strait and down the East coast of the South Island from Wellington, NI to Littleton, SI a truly terrible experience. In a cruise ship towing another cruise ship, which had lost its power, clear of a Caribbean reef. That was a scary experience as both ships had a full compliment of passengers and we had to run out the towlines by passenger tender.
In the last two decades there has been a great change in the design, powering and operating of tugs but they are still there to move a unpowered barge from one place to another. Also the harbour tugs are there to assist ships in berthing and unberthing in port, they often double as fire boats when fitted with powerful fire-fighting water jets. They move fuel barges around for ships to refuel from particularly the cruise ships, handle garbage barges and do a myriad of similar tasks around a port. A modern tug can go ahead, astern and sideways with equal ease - have a look at those working in your port sometime or visit the link below to YOUTUBE and see the videos.
Well that's a brief introduction to towing and there is so much video on YOUTUBE that a visit there is worth a thousand words here.