It is the dream of every tug and barge operator, to find a trade where one can build less tugs and more barges. Obviously, as my friend Mr. Yamaguchi often reminded me – the barge is the “Earning part” – the tug is the “Expense-part”.
We have investigated more than a few possibilities where we had more barges than tugs. However, it is important to remember that even the best-built tug can have unexpected downtime. If you run a 3-barge, one tug system, you’re golden – until the tug breaks down. For one project we investigated, we suggested the Owner build 6 barges, and three tugs. One pair of tugs was always working the 3-barge/1-tug trade. The third tug was a swing tug, able to step in if one of the other boats went down. It also allowed other tugs to be taken out of service and cycled for routine maintenance.
The counter-argument is that by the very flexibility of having a barge notch another tug can fit into – even a conventional one – the lack of need for a “swing-tug” is part of the very attraction of an AT/B system.