Vessel with a retractable thruster assembly

A vessel with a retractable thruster assembly, the vessel comprising a hull, a vertical thruster well within the hull, said thruster well having a bottom opening in a bottom plane of the hull,

• the vessel further comprising a retractable thruster assembly,
• wherein the thruster assembly comprises:
• a thruster head with a propeller,
• a casing structure vertically guided in the thruster well, the casing structure having a lower end portion to which the thruster head is mounted so as to extend below the casing structure, the casing structure including a watertight compartment, an electric propeller drive motor being housed in said compartment,
• wherein the thruster assembly is vertically displaceable between an operative extended position, in which the thruster head projects downward beyond the bottom plane of the hull, and a retracted position, in which the thruster assembly is raised and the thruster head is received within the thruster well,
• the vessel further comprising a retraction device for vertical displacement of the thruster assembly between said operative extended position and said retracted position,
• wherein an annular gap is present between the lower end portion of the casing structure and a surrounding lower seal face portion of the thruster well that surrounds the lower end portion of the casing structure when the thruster assembly is in its operative extended position,
• wherein a first operable sealing device is provided at the lower end portion of the casing structure of the thruster assembly, said first sealing device comprising one or more operable circumferential sealing members extending around the lower end portion of the casing structure, said one or more sealing members being adapted to seal the annular gap by sealingly engaging the surrounding lower seal face portion of the thruster well when the thruster assembly is in its operative extended position,
• wherein the lower end portion of the casing structure further includes a circumferential seal face below the one or more sealing members of the first sealing device,
• and wherein a second operable sealing device is mounted in the thruster well, spaced a vertical distance above the lower seal face portion of the thruster well, said second sealing device comprising one or more circumferential operable sealing members extending along an inner circumference of the thruster well, said one or more sealing members being adapted to seal the annular gap by sealingly engaging the circumferential seal face portion of the lower end portion of the casing structure when the thruster assembly is in its retracted position, so that
• in its retracted position the thruster assembly is raised with its one or more sealing members of the first sealing device above the level of the second sealing device, thereby allowing access to the one or more sealing members of the first sealing device for inspection and maintenance, and so that with the thruster assembly in its operative extended position the one or more sealing members of the second sealing device are accessible for inspection and maintenance.

A thruster installation to be mounted in a hull of a vessel comprising a vertical thruster well and a retractable thruster assembly, said thruster well having a bottom opening adapted to extend in a bottom plane of the hull,

• wherein the thruster assembly comprises:
• a thruster head with a propeller,
• a casing structure vertically guided in the thruster well, the casing structure having a lower end portion to which the thruster head is mounted so as to extend below the casing structure, the casing structure including a watertight compartment, an electric propeller drive motor being housed in said compartment,
• wherein the thruster assembly is vertically displaceable between an operative extended position, in which the thruster head projects downward beyond the bottom opening, and a retracted position, in which the thruster assembly is raised and the thruster head is received within the thruster well,
• the installation further comprising a retraction device for vertical displacement of the thruster assembly between said operative extended position and a said retracted position,
• wherein an annular gap is present between the lower end portion of the casing structure and a surrounding lower seal face portion of the thruster well that surrounds the lower end portion of the casing structure when the thruster assembly is in its operative extended position,
• wherein a first operable sealing device is provided at the lower end portion of the casing structure of the thruster assembly, said first sealing device comprising one or more operable circumferential sealing members extending around the lower end portion of the casing structure, said one or more sealing members being adapted to seal the annular gap by sealingly engaging the surrounding lower seal face portion of the thruster well when the thruster assembly is in its operative extended position,
• wherein the lower end portion of the casing structure further includes a circumferential seal face below the one or more sealing members of the first sealing device,
• and wherein a second operable sealing device is mounted in the thruster well, spaced a vertical distance above the lower seal face portion of the thruster well, said second sealing device comprising one or more circumferential operable sealing members extending along an inner circumference of the thruster well, said one or more sealing members being adapted to seal the annular gap by sealingly engaging the circumferential seal face portion of the lower end portion of the casing structure when the thruster assembly is in its retracted position, so that
• in its retracted position the thruster assembly is raised with its one or more sealing members of the first sealing device above the level of the second sealing device, thereby allowing access to the one or more sealing members of the first sealing device for inspection and maintenance, and so that with the thruster assembly in its operative extended position the one or more sealing members of the second sealing device are accessible for inspection and maintenance.

A vessel with an underwater demountable and retractable thruster assembly, the vessel comprising a hull, a vertical thruster well within the hull, said thruster well having a bottom opening in a bottom plane of the hull,

• the vessel further comprising an underwater demountable and retractable thruster assembly,
• wherein the thruster assembly comprises:
• a thruster head with a propeller,
• a casing structure vertically guided in the thruster well, the casing structure having a lower end portion to which the thruster head is mounted with its top end so as to extend below the casing structure, the casing structure including a watertight compartment, a propeller drive motor being housed in said compartment,
• wherein the thruster assembly is vertically displaceable between an operative extended position, in which the thruster head projects downward beyond the bottom plane of the hull, and a retracted position, in which the thruster assembly is raised and the thruster head is received within the thruster well,
• wherein the thruster assembly has negative buoyancy, and wherein the vessel further includes a thruster assembly hoisting device adapted to lower the thruster assembly downwards fully out of the thruster well as well as lift the thruster assembly from a position fully outside of the hull upward into the thruster well.

A vessel with a retractable thruster assembly, the vessel comprising a hull, a vertical thruster well within the hull, said thruster well having a bottom opening in a bottom plane of the hull,

• the vessel further comprising a retractable thruster assembly,
• wherein the thruster assembly comprises:
• a thruster head with a propeller,
• a casing structure vertically guided in the thruster well, the casing structure having a lower end portion to which the thruster head is mounted so as to extend below the casing structure, the casing structure including a compartment, a propeller drive motor being housed in said compartment,
• wherein the thruster assembly is vertically displaceable between an operative extended position, in which the thruster head projects downward beyond the bottom plane of the hull, and a retracted position, in which the thruster assembly is raised and the thruster head is received within the thruster well,
• the vessel further comprising a retraction device for vertical displacement of the thruster assembly between said operative extended position and said retracted position,
• wherein the vessel further includes an operable locking device having one or more mobile locking members, said locking device being adapted to lock the thruster assembly with respect to the thruster well at least in its operative extended position, at least in vertical direction,
• wherein the vessel further includes an operable positioning device having one or more mobile positioning members that are distinct from the one or more mobile locking members, said positioning device being adapted to bring, or at least assist in bringing, the thruster assembly in a pre-locking position with respect to the thruster well,
• and wherein the vessel is adapted to first operate the positioning device and bring the thruster assembly in its pre-locking position and then to operate the locking device and lock the thruster assembly with respect to the thruster well.

A thruster installation to be mounted in a hull of a vessel comprising a vertical thruster well and a retractable thruster assembly, said thruster well having a bottom opening adapted to extend in a bottom plane of the hull,

• wherein the thruster assembly comprises:
• a thruster head with a propeller,
• a casing structure vertically guided in the thruster well, the casing structure having a lower end portion to which the thruster head is mounted so as to extend below the casing structure, the casing structure including a compartment, a propeller drive motor being housed in said compartment,
• wherein the thruster assembly is vertically displaceable between an operative extended position, in which the thruster head projects downward beyond the bottom opening, and a retracted position, in which the thruster assembly is raised and the thruster head is received within the thruster well,
• the installation further comprising a retraction device for vertical displacement of the thruster assembly between said operative extended position and said retracted position,
• wherein the installation further includes an operable locking device having one or more mobile locking members, said locking device being adapted to lock the thruster assembly with respect to the thruster well at least in its operative extended position, at least in vertical direction,
• wherein the installation further includes an operable positioning device having one or more mobile positioning members that are distinct from the one or more mobile locking members, said positioning device being adapted to bring, or at least assist in bringing, the thruster assembly in a pre-locking position with respect to the thruster well,
• and wherein the installation is adapted to first operate the positioning device and bring the thruster assembly in its pre-locking position and then to operate the locking device and lock the thruster assembly with respect to the thruster well.