Glossary — W

10 terms starting with W.

• Weather Criterion
  Stability criterion checking that a ship can withstand a steady beam wind plus a sudden gust while rolling — Part A 2.3 of the IS Code.
• Weather Routing
  A service providing vessel operators with recommended routes based on forecast weather and sea conditions to optimise safety and economy.
• Web Frame
  Heavy transverse frame, larger than ordinary frames, providing structural support typically every 3–5 frame spaces.
• Well Intervention Vessel
  Specialised OSV equipped to perform downhole work on subsea wells without a full drilling rig.
• Whipping
  Transient hull-girder vibration triggered by a slam, decaying over several oscillations.
• WIBON
  'Whether In Berth Or Not' — clause allowing NOR to be tendered before the vessel reaches the berth.
• Williamson turn
  Man-overboard ship-turning manoeuvre — helm hard-over one way, then the opposite, returning the ship to its own wake and the casualty's approximate position.
• Windlass
  A powered deck machine used to heave in or pay out anchor chain and sometimes mooring lines.
• Wing Tank
  Tank running along the side of a vessel, often a ballast tank on bulk carriers or a side cargo tank on tankers.
• Wiper
  The most junior engine room rating who cleans machinery spaces and assists with basic maintenance tasks.