Wave pants
The wave trousers are used to describe the guidance of the propeller shaft of a ship, which encloses this shaft between the exit from the hull and the propeller . The word is made up of the German "Welle" for "propeller shaft" and the English "hose" for "tube".
use
Wave pants are often found on ships with more than one propeller. They enable the hydrodynamic profile of the hull to be optimized independently of the drive system, in that the propeller is attached far behind the exit of the shaft from the ( tapering aft ) hull. In this way, the rudder can develop the best leverage on the ship's pivot point and the propeller has a good flow against the rudder blade even when moving slowly (e.g. maneuvering in port). This also enables a sensible arrangement with several rudder blades, one behind each propeller. However, it is disadvantageous that such an excessively long wave (sometimes measuring several meters) has to be intercepted to prevent vibrations from occurring. This is usually achieved by bracing against the hull and keel or a fin-shaped housing that is connected to the hull over the entire length. In the shaft pants there are grease channels to supply the shaft bearing located outside the fuselage. The Simmerring is located directly in front of the propeller .
effect
The configuration of a propeller with wave pants gives the propeller a good flow of water, and, as mentioned above, the rudder can also work ideally. At the same time, the suction of air and the resulting cavitation are reduced. The disadvantage is that the motor shaft is very heavy and the starting and reversing are thus delayed. In addition, vibrations can arise and a propeller with an odd-numbered propeller blade arrangement becomes necessary. In warships , damage to one (or more) wave pants repeatedly led to total losses, e.g. B. that of the HMS Prince-of-Wales .
literature
- Jakob Chi Hsi: Influence of the wave pants on propulsion and resistance in double screwdrivers , 1941
- Max Bohnstedt: Practical shipbuilding. Jänecke, Hannover 1907 (Reprint: Salzwasser, Bremen 2009, ISBN 978-3-941842-08-3 ), p. 150 f. ( limited preview in Google Book search).