A tub boat lift is a type of boat lift

Boat lift

A boat lift, ship lift, or lift lock is a machine for transporting boats between water at two different elevations, and is an alternative to the canal lock and the canal inclined plane....

 designed to lift tub boat

Tub boat

A tub boat was a type of unpowered cargo boat used on a number of the early English and German canals. The English boats were typically long and wide and generally carried to of cargo, though some extra deep ones could carry up to . They are also called compartment boats or container boats.The...

s between different elevations of a canal. Tub boats are small boats used to transport coal and other minerals, sometimes working singly, sometimes in long trains. A tub boat lift lifts the boat out of the water. Most other types of boat lift such as locks or inclined planes

Canal inclined plane

An inclined plane is a system used on some canals for raising boats between different water levels. Boats may be conveyed afloat, in caissons, or may be carried in cradles or slings. It can be considered as a specialised type of cable railway....

 are designed to move the boat afloat in some kind of water-filled tank, and, apart from maximum dimensions, are not restricted in the type of craft transported. Tub boat lifts and tub boats are designed to work together as a system. A given lift will only be able to lift boats designed for the lift.

Operation

Tub boat lifts consisted of a moveable hoist travelling on four toothed wheels engaging with two toothed wooden rails, one mounted on each supporting wall. The hoist possessed two drums around which the lifting cables were wound. The lifting ropes passed through pulley blocks before being attached to lifting eyes on the boats to make the lift easier. Four men would wind the hoist when lifting a full 2.5 to 3 tonne tub boat until it was high enough to pass over the dam of the upper canal.

Examples

The remains of two tub boat lifts can still be seen, in the same region of Germany.

• The Halsbrücke
  Halsbrücke
  Halsbrücke is a municipality in the district of Mittelsachsen, in Saxony, Germany....
  
   tub boat lift (also known as Rothenfurther Kahnhebehaus), was built in 1788/89 on the Freiberger Mulde
  Freiberger Mulde
  The Freiberger Mulde is a river in Saxony, Germany. It is a right tributary of the Mulde and 124 km in length.The source of the river is in the Ore Mountains, near Moldava, in the Czech Republic. It runs northwest, crossing the border with Germany after a few km, to Freiberg , and further...
  
  . The remains of the Halsbrücke lift and the connecting section of the upper canal were restored in 1988. The tub boats used in this case were 8.5m long and 1.6m wide and when first used carried 2.5 tonnes, upgraded to 3 tonnes later in the canal and lift's working life. This lift worked until 1868.

• The Großvoigtsberg tub boat lift (also known as Christbescherunger Kahnhebehaus), in the neighbourhood of Freiberg, Saxony
  Freiberg, Saxony
  Freiberg is a city in the Free State of Saxony, Germany, administrative center of the Mittelsachsen district.-History:The city was founded in 1186, and has been a center of the mining industry in the Ore Mountains for centuries...
  
  , was built in 1791 to overcome the difference in elevation between the Mulde
  Mulde
  The Mulde is a river in Saxony and Saxony-Anhalt, Germany. It is a left tributary of the Elbe and 124 km in length.The river is formed by the confluence, near Colditz, of the Zwickauer Mulde and the Freiberger Mulde , both rising from the Ore Mountains...
  
   and the Christbescherung mine canal. This canal was not completed, it is therefore possible that this lift was never used. The engineer in charge of the construction of both of these lifts was the Freiberg Kunstmeister Mechanicus Johann Friedrich Mende (1743–1798).

• A third tub boat lift was planned near Kleinvoigtsberg but was never built.