Crane, vessel comprising such a crane, and a method for up-ending a longitudinal structure

A method for up-ending a longitudinal structure, said longitudinal structure being one of a foundation of an offshore wind turbine or a wind turbine tower to be installed on top of a previously installed foundation, wherein use is made of a crane comprising:

• a base structure;
• a slew bearing;
• a crane housing moveably mounted to the base structure via the slew bearing to allow the crane housing to rotate relative to the base structure about a substantially vertical slewing axis;
• a boom moveably mounted to the crane housing to allow the boom to pivot relative to the crane housing about a substantially horizontal first pivot axis at one end of the boom, said boom having an opposite end remote from said one end;
• and
• three main hoisting systems,
• wherein each main hoisting system comprises:
• a hoisting cable;
• a sheave block with one or more sheaves that are rotatable about a sheave rotation axis, the sheave block being arranged on the opposite end of the boom;
• a hoisting block suspended from the sheave block by the hoisting cable;
• and
• a hoisting winch to lift and lower the hoisting block by hauling in or paying out the hoisting cable,
• wherein the sheave block of each main hoisting system is pivotable about a substantially horizontal second pivot axis that is perpendicular to the sheave rotation axis of the one or more sheaves of the sheave block,
• wherein the sheave blocks of the three main hoisting systems are arranged side-by-side, and
• wherein the method comprises the following steps:
• a) providing a longitudinal structure with an upper end and a lower end in a substantially horizontal orientation;
• b) connecting the middle hoisting block of the three main hoisting systems and one of the outer hoisting blocks of the three main hoisting systems to the upper end of the longitudinal structure;
• c) connecting the other outer hoisting block of the three main hoisting systems to the lower end of the longitudinal structure;
• and
• d) operating the respective winches of the three main hoisting systems until the longitudinal structure is in a substantially vertical orientation with the upper end above the lower end.