A lighter, or unpowered freight barge (4)?

Question

A lighter, or unpowered freight barge (4)?

Answer 1

More commonly known as a "butty boat" this was a system used when the canals were main arteries for good traffic. A butty towed by a powered narrow boat  meant that twice the amount of goods could be carried at the same cost as running one. Very often the bargee and his family would also have their very cramped living quarters in the butty this meant that with only space for the engine needed in the powered boat more load could be carried.

Answer 2

SCOW

1. any of various flat-bottomed boats with sloping ends.

2. a barge carrying bulk materials in an open hold.