Thyssen-Waas-Bug

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The Thyssen Waas bow is an icebreaking bow that significantly improves the previous concept: As before, the ship drives onto the ice, but now the ice is sheared out as a whole by the special bow to a defined width . The ice breaks in half under the keel and slides sideways under the remaining ice.

concept

Max Waldeck with Thyssen-Waas-Bug

The bow resembles a pontoon from the front : the waterline shows no curvature, the ship's wall is inclined forward over the ice. The bow has sharp edges on the sides, where the waterline swings backwards at a right angle. The side walls of the ship are vertical here. The edges shear the ice in a leading shear fracture . At the same time the bow hits the ice and pushes it under the ship. There, the bow increasingly takes on a V-profile, which breaks the ice in two halves and allows it to slide to the side.

Advantages and disadvantages

The bug is characterized by two improvements over the previous concept:

  • The ice is now pushed as a whole under the ice on the side, no fragments remain in the channel. This extends the time until the canal is frozen again. At the same time, the friction on the ice is significantly reduced, so that less engine power is required and fuel consumption is reduced.
  • The shear strength of ice is significantly less than its flexural strength . This allows the ice to break more easily along the shear fracture leading to the side than in the case of a bending fracture under a conventional icebreaker bow. The remaining bending fractures in front of the ship also require less force, as this acts via a longer lever. This reduces the demands on bow weight and engine power as well as fuel consumption.

Various model and practical tests have shown power savings of over 50%, depending on the ice thickness and speed. Ice masses pushed one on top of the other could also be mastered in tests of suitability for ice.

On the negative side, seaworthiness in open waters continues to decrease compared to corresponding restrictions on other icebreakers. Particular attention should be paid to the increase in the frequency and extent of slamming (hitting the bow hard on the surface of the water or ice), which is a heavy burden on the ship's structure, personnel and cargo. There is still no work to be done on a further restriction: Normally, vertical side walls are avoided with icebreakers in order to avoid the destruction of the ship by press ice . The Thyssen-Waas-Bug, however, requires at least partially vertical side wall elements. However, previous plans are more aimed at efficient and fast travel than suitability in difficult ice situations.

term

The part of the name "Waas" refers to Heinrich Waas , to whom the concept goes back. The development was carried out by Thyssen Nordseewerke .

See also

  • Max Waldeck , a ship that was fitted with a Thyssen Waas bow in a research project.

literature