Method of upgrading a knuckle-boom crane and a heave-compensating crane

A heave-compensating crane comprising:

• a crane base;
• a main boom having a near end pivotably mounted to the crane base and a far end spaced apart from the near end, the main boom extending in a single linear direction along the entire length of the main boom;
• a heave-compensating boom pivotably mounted at a far end of the main boom and having a first end pivotably coupled to the far end of the main boom and a second end coupled to a rotatable head, the length between the far end of the main boom and the second end of the heave-compensating boom being fixed, wherein the heave-compensating boom extends in a downward vertical direction (Z) in operational use of the heave-compensating crane, wherein the heave-compensating boom is configured to be pivotable with respect to the main boom in both horizontal directions (X, Y) defined with respect to the downward vertical direction (Z),
• a first heave-compensation system comprising a plurality of actuators, the rotatable head, and the heave-compensating boom which is pivotable by at least one of the plurality of actuators, and wherein the first heave-compensation system is configured for compensating for horizontal deviations by controlling the orientation of the heave-compensating boom relative to the main boom, and
• a second heave-compensation system comprising a winch system configured for manipulating a hoisting cable to compensate vertical deviations.

A heave-compensating crane comprising:

• a crane base;
• a main boom having a near end pivotably mounted to the crane base and a far end spaced apart from the near end, the main boom extending in a single linear direction along the entire length of the main boom;
• and
• a first heave-compensation system comprising a plurality of actuators and a first heave-compensating boom pivotably mounted at a far end of the main boom and having a first end pivotably coupled to the far end of the main boom and a second end coupled to a rotatable head, the length between the far end of the main boom and the second end of the heave-compensating boom being fixed, wherein the first heave-compensating boom is pivotable by at least one of the plurality of actuators and extends in a downward vertical direction (Z) in operational use of the heave-compensating crane, wherein the first heave-compensating boom is configured to be pivotable with respect to the main boom in both horizontal directions (X, Y) defined with respect to the downward vertical direction (Z);
• wherein the first heave-compensating boom comprises a first arm that is pivotably mounted to the main boom for allowing a rotation in a first horizontal direction (X), the first heave-compensating boom further comprising a second arm that is pivotably mounted to the first arm for allowing a rotation in a second horizontal direction (Y) orthogonal to the first horizontal direction (X);
• wherein the crane base comprises a second heave-compensation system comprising a winch system configured for manipulating a hoisting cable to compensate vertical deviations.