Inverted bow

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M/Y A cruising at Sorrento, Italy in 2012.
SMS Viribus Unitis, a dreadnought type ship with inverted bow, flagship of Austro-Hungarian navy in 1912.
Well intervention vessel Sarah with X-bow.
Bourbon Orca anchor tug shown in 2012, was first ship built with an Ulstein X-bow in 2006.
USS Zumwalt (DDG-1000), lead ship of her class, after floating out of drydock in 2013.

In ship design, an inverted bow is a ship's or large boat's bow whose farthest forward point is not at the top. The result may somewhat resemble a submarine's bow. Inverted bow maximizes the length of waterline and hence the hull speed.

Inverted bows were popular on battleships and large cruisers in the early 20th century. They fell out of favour as they were very wet on high speeds and heavy seas, but have made a comeback on modern ship design.


Motor Yacht 'A'[edit]

The 390 ft luxury motor yacht M/Y "A" has an inverted bow, along with a tumblehome hull design.

Ulstein X-bow[edit]

The Ulstein X-bow [1] is an inverted ship's bow designed by Ulstein Group to improve handling in rough sea, and to lower fuel consumption by causing less hydrodynamic drag.[2] It is shaped somewhat like a submarine's bow.

As of 2015, more than 100 X-Bow vessels have been ordered,[3] of which close to 50 were in operation in 2011.[4] The yard is constructing the X-stern, a similar shape for the stern, some as offshore wind power service vessels for Siemens Wind Power.[3]

The MV Bourbon Orca, design AX104, is an Ulstein A-Series Anchor Handling Tug Supply vessel (AHTS) built for Bourbon Offshore Norway (the Norwegian division of the French Groupe Bourbon),[5] and was the first ship built with the Ulstein X-bow[6] in 2006. She was awarded Ship of the Year 2006, both by Skipsrevyen and Offshore Support Journal. In 2007, the Bourbon Orca design model was included in the London Science Museum's display of innovative technology. The vessel's operator claims that the design achieves higher speed and a calmer motion in rough seas.[7]

Zumwalt-class destroyer[edit]

The bow of the new Zumwalt-class stealth guided missile destroyer for the US Navy is also inverted. It has a wave-piercing tumblehome hull form whose sides slope inward above the waterline.

See also[edit]


  1. ^ Dagens Næringsliv, November 15, 2008,p.24
  2. ^ Five (TV channel) television program Megastructures, 12.45 to 1.45 pm Friday 29 January 2010
  3. ^ a b Stensvold, Tore. "Ulstein verft feirer 100 skip med X-Bow" Teknisk Ukeblad, 19 January 2015. Accessed: 22 January 2015.
  4. ^ Ulstein X-BOW® five years – overwhelming response from users ShipPedia, 22 December 2010. Accessed: 11 March 2011.
  5. ^ Ship Of The Year 2006. Accessed: 24 January 2015.
  6. ^ Naval architect Royal Institution of Naval Architects 2003
  7. ^ A series of four Ulstein designed inverted bow PSV vessels page 16-17 Bourbon (company), 24 June 2010. Accessed: 11 March 2011.

External links[edit]