rafter n.1

"transport or float on a raft," 1680s, from raft (n.1). Related: Rafted; rafting.

late 15c., "floating platform of timber lashed or fastened together," from earlier meaning "rafter, beam" (c. 1300), from a Scandinavian source such as Old Norse raptr "log" (Old Norse -pt- pronounced as -ft-), Old Danish raft, related to Middle Low German rafter, rachter "rafter" (see rafter (n.1)).

In North America, rafts are constructed of immense size, and comprise timber, boards, staves, etc. They are floated down from the interior to the tide-waters, being propelled by the force of the current, assisted by large oars and sails, to their place of destination. The men employed on these rafts construct rude huts upon them, in which they often dwell for several weeks before arriving at the places where they are taken to pieces for shipping to foreign parts. [Bartlett, "Dictionary of Americanisms," 2nd ed., 1859]