Heave compensated dual hoist crane

A dual hoist crane, comprising:

• a crane structure;
• a boom, the boom having an inner end, a midsection and an outer end, the boom being pivotable supported by the crane structure such that the boom can be pivoted about a horizontal boom axis;
• a main hoisting assembly, for lifting and lowering a load, the main hoisting assembly comprising a main hoisting winch and an associated main hoisting cable, and a main load suspension device;
• an auxiliary hoisting assembly for lifting and lowering a load, the auxiliary hoisting assembly comprising an auxiliary hoisting winch and an associated auxiliary hoisting cable, and an auxiliary load suspension device;
• and
• a dual hoist heave motion compensation system, the heave motion compensation system comprising:
• a support frame;
• a heave compensation cylinder, having a cylinder body mounted on the support frame and a cylinder rod, the heave compensation cylinder being connected to a gas buffer to enable passive heave compensation;
• a sheave head, wherein the sheave head is supported by the cylinder rod for movement along a heave compensation trajectory;
• a sheave dock, mounted on the support frame at an end of the heave compensation trajectory;
• a first set of sheaves guiding the main hoisting cable of the main hoisting assembly;
• and
• a second set of sheaves guiding the auxiliary hoisting cable of the auxiliary hoisting assembly,
• wherein the main hoisting cable extends from the main hoisting winch along the heave compensation trajectory, via the first set of sheaves, and via at least one main hoisting sheave at the outer end of the boom to the main load suspension device,
• wherein the auxiliary hoisting cable extends from the auxiliary hoisting winch along the heave compensation trajectory, via the second set of sheaves, and via at least one auxiliary hoisting sheave at the outer end of the boom to the auxiliary load suspension device, and
• wherein the dual hoist heave motion compensation system is configured to individually lock the first set of sheaves and the second set of sheaves to the sheave head, for respectively providing the main hoisting assembly and the auxiliary hoisting assembly with heave compensation, and to individually lock the first set of sheaves and the second set of sheaves to the sheave dock, for respectively not providing the main hoisting assembly and the auxiliary hoisting assembly with heave compensation, and the dual hoist heave motion compensation system thus enables for providing only the main hoisting assembly with heave compensation and for providing only the auxiliary hoisting assembly with heave compensation.