Chain ferry

A cable ferry (including the terms chain ferry, swing ferry, floating bridge, or punt) is a ferry that is guided (and in many cases propelled) across a river or large body of water by cables connected to both shores. Early cable ferries often used either rope or steel chains, with the latter resulting in the alternate name of chain ferry. Both of these were largely replaced by wire cable by the late 19th century.

There are three types of cable ferry: the reaction ferry, which uses the power of the river to tack across the current; the powered cable ferry, which uses an engine or electric motors (e.g., the Canby Ferry) to wind itself across; and the fast-disappearing hand-operated type, such as the Stratford-upon-Avon Chain Ferry in the UK and the Saugatuck Chain Ferry in Michigan, USA.

Powered cable ferries use powered cogs or drums on board the vessel to pull itself along by the cables. The cables or chains have a considerable amount of slack built into them, in order to sink below the surface as the ferry moves away, allowing other vessels to pass without becoming grounded, snared or trapped. Where a ferry carries both passengers and vehicles the car deck occupies the centre (helping to balance the vessel) and two passenger areas are at the sides, over the tunnels for the chains and the engines. As the ferry cannot steer a ramp is built at both ends, and there is usually a set of controls facing in either direction.

Cable ferries are common where there is little other water-borne traffic that could get snagged in the cable or chains, where the water may be too shallow for other options, or where the river current is too strong to permit the safe crossing of a ferry not attached to the shore. Alignment of the platform at each end of the journey is automatic and, especially for vehicle ferries, safer than a free-moving ferry might be in bad conditions.

A special type are electrically powered overhead-wire ferries like Straussee Ferry, which have an onboard propulsion unit and can float free, but are connected to the overhead wire for power supply, using an electrical cable that slides along the wire as the ferry moves.

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Wikipedia