Dead water (shipping)

The articles Dead Water (Shipping) and Boundary Layer Detachment overlap thematically. Help me to better differentiate or merge the articles (→  instructions ) . To do this, take part in the relevant redundancy discussion . Please remove this module only after the redundancy has been completely processed and do not forget to include the relevant entry on the redundancy discussion page{{ Done | 1 = ~~~~}}to mark. No Einstein ( discussion ) 11:07 am, Jul 26, 2020 (CEST)

In shipping, dead water is stratified water that can slow down a ship.

causes

If light fresh water is stratified on heavy salt water near the mouth of a river, an entering ship can create a wave on the boundary surface that runs behind the ship and seems to be sucked into its stern without being able to identify the cause on the surface (so-called . Nansen wave). In 1893, Fridtjof Nansen registered such waves off the estuaries of the Siberian coast, which slowed his ship Fram from 7 to 1.5 knots without the wave becoming visible on the surface. Such water areas are called dead water ( internal waves ). Especially in narrow canals, there can be a rhythmic delay in which the ship alternates faster and slower. In 1904 the Swedish physicist and oceanographer Vagn Walfrid Ekman presented part of the solution to the problem for the first time. The effect is based on two different phenomena: the Nansen wave resistance and the Ekman wave resistance .

Web links

• Jan Dönges: Mysterious braking power: How water becomes »dead water«. In: Spektrum.de , July 7, 2020.
• Martin Schäfer: How dead water slows ships down. In: Wissenschaft.de , October 23, 2008.
• Julia Köppe: When ships suddenly stall: Researchers explain the dead water effect. In: Spiegel Online . July 13, 2020, accessed July 13, 2020 . 
• Johan Fourdrinoy, Julien Dambrine, Madalina Petcu, Morgan Pierre, Germain Rousseaux: The dual nature of the dead-water phenomenology: Nansen versus Ekman wave-making drags. In: Proceedings of the National Academy of Sciences. July 8, 2020, doi: 10.1073 / pnas.1922584117 .

Individual evidence

1. ^ Vagn Walfrid Ekman: On dead-water. In: Fridtjof Nansen (Ed.): The Norwegian North Polar Expedition 1893-1896: Scientific results. Volume V, No. 15, Dybwad, Christiania 1905, pp. 1–152 ( Textarchiv - Internet Archive ).
2. ↑ Jan Dönges: How water becomes dead water on Spektrum.de, July 7, 2020.
3. ^ Johan Fourdrinoy et al. a .: The dual nature of the dead-water phenomenology: Nansen versus Ekman wave-making drags. In: Proceedings of the National Academy of Sciences.
4. ↑ How dead water brings ships to a standstill . In the online edition of the Standard on July 12, 2020, accessed on July 16, 2020.