Inverted bow

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Well intervention vessel Sarah with X-bow.
Bourbon Orca in 2012.

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.



The luxury motor yacht M/Y "A" has an inverted bow.

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 2013, more than 70 X-Bow vessels have been ordered, of which close to 50 are in operation.[3]

The Bourbon Orca, design AX104 is an Ulstein A-Series Anchor Handling Tug Supply vessel, built for Bourbon Offshore Norway, and was the first ship built with the Ulstein X-bow[4] in 2006. The operator claims that the design achieves higher speed and a calmer motion in rough seas.[5]

Zumwalt-class destroyer[edit]

The bow of the new Zumwalt-class guided missile destroyer for the US Navy is also inverted.

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. ^ Ulstein X-BOW® five years – overwhelming response from users ShipPedia, 22 December 2010. Accessed: 11 March 2011.
  4. ^ Naval architect Royal Institution of Naval Architects 2003
  5. ^ 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]