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Crew ascend Prince William's ratlines in order to work aloft.
See Ratlines (history) for escape routes of WWII war criminals.

Ratlines, pronounced "rattlin's", are lengths of thin line tied between the shrouds of a sailing ship to form a ladder. They are found almost invariably on square rigged ships whose crews must go aloft to stow the square sails, but may also be present on larger fore-and-aft rigged vessels in order to make repairs or conduct a lookout from a higher position.

Sometimes, especially on the lower shrouds, they are made of wood rather than rope, in which case they are occasionally known as "ratbars", or battens instead. Wooden ratlines can have holes bored through them to guide and organise lines between the deck and the rig; these would usually be clewlines and buntlines that are not under much load.

pl:Wyblinka de:Webleinen