Method for the maintenance of a retractable thruster

Abstract

A method for the maintenance of a ship or platform propulsion assembly includes providing a hull insert forming a watertight housing located within a hull of a ship except for an opening. A motor is in the hull external to the housing and a thruster is external to the hull. A telescopic driving shaft sealingly passes through one of the walls of the housing to operatively connect the motor and the thruster to transmit movement to the thruster. Moving the thruster includes retracting the thruster into the housing through the opening. A separable submersible movable hatch is lowered by removable hanging cables. The submersible movable hatch externally engages the housing and sealingly closes the opening to close the housing and form a watertight closed chamber. Fluids within the closed chamber are evacuated even when the hull is floating and partially submersed, with the thruster at least partially in air.

Claims

1. A method for maintenance of a ship or platform propulsion assembly while floating, comprising the steps of: providing a hull insert, or trunk, forming a housing, or propeller case, located within a hull of a ship; providing for said housing to be watertight with respect to the hull in all walls thereof, except for an opening externally to the ship hull; arranging a motor in said hull externally to said housing without changing position of the motor with respect to the hull; providing a thruster, which is suitable to be arranged externally to said hull to generate a propulsion thrust; providing a telescopic driving shaft passing sealingly through one of the walls of said housing operatively connecting said motor and said thruster, to transmit movement from the motor to the thruster for the movement of said thruster; retracting said thruster within said housing passing through said opening; lowering externally to the hull a submersible movable hatch in a separate piece and completely disconnected from said thruster and from said housing, by removable hanging cables; associating said submersible movable hatch externally to said housing and sealingly closing said opening of said housing, closing said housing and forming a watertight closed chamber with respect to outside of said hull containing said thruster; evacuating possible fluid, which is present within said closed chamber even when the hull or platform are floating and partially submersed, to arrange said thruster at least partially in air.

2. The method according to claim 1, further comprising the steps of: accessing through a maintenance access hatch said chamber in said housing for the maintenance of the thruster.

3. The method according to claim 1, further comprising the steps of: replacing propeller seals; disassembling seal protection rings; replacing the worn propeller seals with new propeller seals; evacuating personnel from said chamber of said housing making the personnel to go up through said maintenance access hatch to upper decks; sealingly closing said hatch for accessing said housing; flooding said chamber; removing the submersible movable hatch from the outside of the hull; bringing said submersible movable hatch back to surface by passing externally to the ship.

4. The method according to claim 1, further comprising the steps of: arranging said housing in operative conditions at least partially under a free water surface.

5. The method according to claim 1, further comprising the steps of: disassembling, with the ship or platform floating, the entire thruster and extracting the thruster from the hull to bring the thruster back to the surface, by passing externally to said hull of the floating ship or platform; installing the submersible movable hatch in the proximity of the opening of the housing of the hull insert, or trunk, by hanging cables; pumping to evacuate the residual water from the chamber, or propeller case, by a fluid evacuating device; when the case is emptied, making personnel access in said case through a hatch for accessing said housing, lashing the propeller foot with the aid of hanging cables; uncoupling the joint by disconnecting the first flange and the second flange of the connecting joint of the telescopic driving shaft to the thruster, or propeller foot; lowering the entire propeller foot to allow securing protection cuffs to the free ends of the shafts and the thruster; evacuating the personnel from the propeller case and sealingly closing said hatch for accessing said housing; flooding said chamber; removing the submersible movable hatch from outside the hull; bringing said submersible movable hatch and said propeller foot back to the surface, passing externally to the hull.

6. The method according to claim 1, further comprising the steps of: suspending said submersible movable hatch externally to the hull by chains and cables or suspension or hanging cables; wherein said method comprises the steps of: suspending said thruster or propeller foot by suspension cables or chains passing through said housing; inserting in said housing, through closeable passages provided through the walls of said housing, suspension cables or chains for suspending said submersible movable hatch, passing through said housing or for suspending said thruster also by disconnecting said thruster from said telescopic driving shaft.

7. The method according to claim 1, further comprising the steps of: inclining by a preset angle a thruster axis, or thrust actuating axis, with respect to the telescopic shaft axis so as to orient thruster thrust with respect to a hull or other obstacles.

8. The method according to claim 1, further comprising the steps of: guiding said telescopic driving shaft, at least one length thereof that is located within said housing, by a guide cross; unloading to the hull thrust actions of the thruster by said guide cross.

9. The method according to claim 1, further comprising the steps of: installing in different programmed times the submersible movable hatch in proximity of different openings of different housings of hull or trunk inserts by hanging cables and an optional aid by underwater personnel.

10. The method according to claim 1, further comprising the steps of: bringing said submersible movable hatch and various propeller feet back to the surface by passing externally to the hull.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further characteristics and advantages of the assembly according to the invention will be apparent from the description set forth below of preferred embodiment examples thereof, given by way of illustrative, non-limiting example, with reference to the appended figures, in which:

(2) FIG. 1 shows an axonometric and partially sectioned view, so as to show the contents thereof, of a retractable thruster assembly for ships or floating platforms;

(3) FIG. 2 illustrates a side, partially sectioned view of the assembly of FIG. 1;

(4) FIG. 3A shows a front, partially sectioned view of the assembly of FIG. 1;

(5) FIG. 3B shows a front, partially sectioned view of the assembly of FIG. 1, but with the thruster in the extended position and the telescopic driving shaft in an elongated position;

(6) FIGS. 4A and 4B represent a bottom view and a sectioned view, respectively, of the section immediately above the thruster as seen towards the thruster of the assembly of FIG. 1;

(7) FIG. 5 shows the side, partially sectioned view of a retractable thruster assembly in a first maintenance step, in which it is lowered to the sea laterally to the hull when the submersible movable hatch closes the housing for the thruster;

(8) FIG. 6 shows the side, partially sectioned view of the retractable thruster assembly of FIG. 5 in a second maintenance step, in which the submersible movable hatch is brought near to the housing opening;

(9) FIG. 7 shows the side, partially sectioned view of the retractable thruster assembly of FIG. 5 in a third maintenance step, in which the submersible movable hatch is hung from hanging cables passing through the housing;

(10) FIG. 8 shows the side, partially sectioned view of the retractable thruster assembly of FIG. 5 in a fourth maintenance step, in which the submersible movable hatch is coupled to the opening;

(11) FIG. 9 shows a sectioned view of a detail of the coupling between the submersible movable hatch and a coupling edge of the hull insert defining the opening;

(12) FIG. 10 shows the side, partially sectioned view of the retractable thruster assembly of FIG. 5 in a fifth maintenance step, in which the closed chamber that is formed by coupling the submersible movable hatch to the housing opening is at least partially emptied of water by putting in air at least the part of the thruster that is ready for the maintenance in situ or for other maintenance operations;

(13) FIG. 11 shows the side, partially sectioned view of the retractable thruster assembly of FIG. 5 in a sixth maintenance step, in which the thruster is supported hanging from hanging cables passing through a housing wall;

(14) FIG. 12 shows the side, partially sectioned view of the retractable thruster assembly of FIG. 5 in a seventh maintenance step, in which the thruster supported hanging from hanging cables is uncoupled from the telescopic driving shaft and sealing cuffs are fitted on the free coupling end between shaft and thruster;

(15) FIG. 13 shows the side, partially sectioned view of the retractable thruster assembly of FIG. 5 in an eighth maintenance step, in which the closed chamber is filled with water again, the submersible movable hatch is uncoupled from the edge of the opening, which is open, and the thruster supported hanging from hanging cables is gradually lowered outside the hull;

(16) FIG. 14 shows the side, partially sectioned view of the retractable thruster assembly of FIG. 5 in a ninth maintenance step, in which the thruster supported hanging from hanging cables is supported by chains that are external to the hull and gradually lifted high outside the hull.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

(17) With reference to the above-mentioned figures, a ship or floating platform propulsion assembly 1 comprises a hull insert 2, also referred to as a trunk, forming a housing 3, also referred to as a propeller case, located within a hull 4 of a ship or platform.

(18) In accordance with an embodiment, said housing 3 is a housing watertight with respect to the hull in all the walls 5 thereof, except for an opening 6 opening externally to the hull 4 of the ship or platform.

(19) Advantageously, said assembly further comprises a motor 7 and a thruster 8, for example a propeller foot.

(20) In accordance with an embodiment, said thruster 8 is suitable to be arranged externally to said hull 4 to generate a propulsion thrust on said ship or floating platform. Said thruster 8 is further retractable within said housing 3 passing through said opening 6.

(21) In accordance with an embodiment, said motor 7 is arranged in said hull 4, but externally to said housing 3, and it is arranged stationary with respect to said hull 4, i.e., so as not to move with respect to the hull even during the extraction or retraction movement of said thruster into said housing 3.

(22) In accordance with an embodiment, said assembly 1 further comprises a telescopic driving shaft 9. Advantageously, said telescopic driving shaft 9 is arranged passing sealingly through one of the walls 5 of said housing 3 to operatively connect said motor 7 and said thruster 8 and to transmit the movement from the motor to the thruster for the movement of said thruster 8.

(23) In accordance with an embodiment, said assembly 1 further comprises a submersible movable hatch 10, made in a separate piece and completely disconnectable from said thruster 8 and said housing 3.

(24) In accordance with an embodiment, said movable hatch is suitable to associate externally to said housing 3, passing externally to said hull 4.

(25) In accordance with an embodiment, said movable hatch 10 is suitable to sealingly close said opening 6 of said housing 3, forming a watertight closed chamber 11 with respect to the outside of said hull 4.

(26) In accordance with an embodiment, said assembly 1 further comprises a fluid evacuation device 12 for evacuating fluid 13, for example, sea water, which is present within said closed chamber 11 so as to arrange said thruster 8 at least partially in air, when retracted in said housing 3 that is closed by said hatch to form said closed chamber.

(27) In accordance with an embodiment, said housing 3, under operative conditions of the ship or platform, is arranged at least with a part thereof under the free surface W-W of the fluid 13, for example, sea water, on which said hull 4 is floating.

(28) In accordance with an embodiment, said walls 5 of said housing 3 are walls that are integrated in the hull 4, and they avoid the need to use a hull seat, for example, an interspace, in which said housing 3 and all the structures interlocked to the movement of the thruster are to be inserted.

(29) In accordance with an embodiment, said telescopic driving shaft 9 is sealingly received with a portion thereof in one of the walls 5 of said housing 3 to operatively connect said motor 7 and said thruster 8 in a selectively detachable manner, in order to transmit the movement from the motor to the thruster for the movement of said thruster 8 and to allow, in the case of a maintenance, separating the thruster from the motor.

(30) In accordance with an embodiment, said thruster 8 is retractable within said housing 3 passing through said opening 6 so as not to project externally to said hull 4, when it is in a completely retracted position thereof.

(31) In accordance with an embodiment, the fluid evacuation device 12 for evacuating fluid 13 present within said closed chamber 11 is for example at least a ballast/bilge pump connected with said chamber 11.

(32) In accordance with an embodiment, said telescopic driving shaft 9 comprises a shaft axis V-V, for example, arranged vertical, in other terms, substantially transversal to the free water surface W-W. In accordance with an embodiment, said shaft 9 comprises an azimuthal driving shaft 14 and a telescopic power driving shaft 15.

(33) In accordance with an embodiment, said thruster has a thruster axis, or thrust actuating axis P-P, which is adjustable in inclination with respect to said telescopic shaft axis V-V by a predetermined angle A, so as to orient the thrust of the thruster with respect to the hull 4 or other obstacles that are present under the hull.

(34) In accordance with an embodiment, said fluid evacuation device 12 is suitable to pump fluid again into the closed chamber 11, for example, at the end of the maintenance operations.

(35) In accordance with an embodiment, said assembly further comprises an air pumping-in device 16 for pumping air into the closed chamber 11 when it is emptied of the fluid and to allow a recirculation of air when maintenance personnel is present therein. For example, the air pumping-in device 16 comprises tubes for the connection of the closed chamber, or propeller case, with the inside of the hull.

(36) In accordance with an embodiment, said assembly further comprises a maintenance access hatch 17 for the watertight opening and closure, of a portion of a wall 5 of said housing 3, allowing accessing the closed chamber 11 by maintenance personnel of the thruster 8.

(37) In accordance with an embodiment, said assembly further comprises suspension chains and/or cables, or hanging cables 18, connectable to said submersible movable hatch 10 for the handling thereof externally to the hull and the coupling thereof to said opening 6.

(38) In accordance with an embodiment, said assembly further comprises passages 31 provided for in at least one of the walls 5, for example, the upper roof, or sky 32, of said housing 3, to insert hanging cables or chains 18, 20 into said housing to hang said submersible movable hatch 10 passing through said housing 3 or to hang said thruster 8 when it is to be disconnected or it is disconnected from said telescopic driving shaft 9.

(39) In accordance with an embodiment, said assembly further comprises pulleys 33, as the only means for handling the hanging cables 18 of said submersible movable hatch 10, as well as for handling the hanging cables 20 of said thruster 8.

(40) In accordance with an embodiment, a guide cross 21 is provided for in said housing 3, to guide said telescopic driving shaft 9 in at least one, or also in at least one length thereof located within said housing 3 and discharging the thrust actions of the thruster 8 onto the hull 4.

(41) In accordance with an embodiment, said assembly further comprises a telescopic driving shaft and thruster connection joint 22 suitable to removably connect the thruster 8 to the telescopic driving shaft 9 to completely separate said thruster from said shaft and immerse said thruster 8 by extracting it from said housing 3 into a fluid, for example, sea water, to leave said hull 4 in a floating condition.

(42) In accordance with an embodiment, said assembly further comprises a first watertight protection, or covering closing cuff 23 that is removably connectable to the shaft free end 9, or first joint flange 24.

(43) In accordance with an embodiment, said assembly further comprises a second watertight protection, or covering closing cuff 25 removably connectable to the portion for the connection to the shaft of the thruster 8, or second joint flange 26.

(44) In accordance with an embodiment, said motor 7 is an electric motor.

(45) In accordance with an embodiment, said assembly further comprises a thruster lifting device 27, for example of the oleo-dynamic type, connected to a support device or support 28 for the handling of a movable portion of the telescopic driving shaft 9 and of the thruster 8 to extend it outside said housing 3, or to retract said thruster 8 into said housing 3.

(46) In accordance with an embodiment, said assembly further comprises guide candles 19 for guiding the movement of said support 28.

(47) In accordance with an embodiment, said hull insert, or trunk 2, is a structure integrated into the structure of the hull 4 that does not need, to define said watertight walls, a separate cell added to an interspace obtained in the hull.

(48) A method for the maintenance of a ship or platform propulsion assembly 1 during the floating thereof is described herein below.

(49) Said method, according to a general embodiment method thereof, comprising the steps of:

(50) providing for a hull insert or trunk 2 forming a housing 3, or propeller case, located within a hull 4 of a ship;

(51) providing for said housing 3 to be watertight with respect to the hull 4 in all the walls 5 thereof, except for an opening 6 opening externally to the hull 4 of the ship;

(52) arranging a motor 7 in said hull externally to said housing 3, avoiding the change of the position thereof with respect to the hull 4;

(53) providing for a thruster 8, for example, a propeller foot, which is suitable to be arranged externally to said hull 4 to generate a propulsion thrust on said ship or floating platform;

(54) providing for a telescopic driving shaft 9 sealingly passing through one of the walls 5 of said housing, operatively connecting said motor 7 and, in a preferably but not necessarily removable manner, said thruster 8, to transmit the movement from the motor to the thruster for the movement of said thruster.

(55) Said method provides for the further steps of:

(56) retracting said thruster 8 within said housing 3 passing through said opening 6, preferably, but not necessarily, preventing it from projecting externally to said hull;

(57) lowering a submersible movable hatch 10 externally to the hull in a separate piece and completely disconnected from said thruster 8 and said housing 3;

(58) associating said submersible movable hatch 10 externally to said housing 3 and

(59) sealingly closing said opening 6 of said housing, closing said housing and forming a watertight closed chamber 11 with respect to the outside of said hull containing said thruster;

(60) evacuating any fluids, for example, sea water 13, which are present within said housing even when the hull or platform is floating and partially submersed, when it is closed by said submersible movable hatch 19, so as to arrange said thruster 8 at least partially in air.

(61) In accordance with a possible further method, the following steps are optionally further provided for, of

(62) accessing through a maintenance access hatch 17 said chamber 11 in said housing 3 for the maintenance of the thruster 8.

(63) In accordance with a possible further method, said maintenance step comprises the step of replacing propeller seals 29.

(64) In accordance with a possible further method, said maintenance step comprises the step of:

(65) disassembling seals protection rings 30

(66) replacing worn propeller seals 29 with new propeller seals 29

(67) evacuating personnel from said chamber 11 of said housing 3 making it to get to the upper decks through said maintenance access hatch 17

(68) sealing closing said housing access hatch 17

(69) flooding said chamber 11

(70) removing the submersible movable hatch 10 from externally to the hull

(71) bringing said submersible movable hatch 10 back to the surface by passing externally to the ship.

(72) In accordance with a possible further method, said housing 3 under operative conditions is arranged at least partially under the free water surface W-W.

(73) In accordance with a possible further method, said maintenance step further comprises the step of:

(74) Disassembling, when the ship or platform is floating, of the entire thruster or propeller foot 8 and extracting it from the hull to bring it back to the surface by passing externally to the floating ship or platform.

(75) In accordance with a possible further method, said maintenance step comprises the steps of:

(76) installing the submersible movable hatch 10 in the proximity of the opening 6 of the housing 3 of the hull insert, or trunk 2, by hanging cables 18, and by means of the optional aid of diving personnel

(77) pumping for evacuating the residual water from the chamber, or propeller case 11, by a fluid evacuation device, for example, but not necessarily, ballast/bilge pumps of the ship 12

(78) when the case 11 is emptied, allowing personnel access said case,

(79) lifting the propeller foot 8 with the aid of said hanging cables

(80) uncoupling the joint 22 by disconnecting the first flange 24 and the second flange 26 of the joint for the connection of the telescopic driving shaft 9 to the thruster, or propeller foot 8

(81) lowering the entire propeller foot 8 to allow securing protection cuffs 23, 25 at the free ends of the shafts and the thruster;

(82) evacuating personnel from the propeller case 11, and

(83) sealingly closing said housing access hatch 17

(84) flooding said chamber 11

(85) removing the submersible movable hatch 10 from externally to the hull

(86) bringing said submersible movable hatch 10 and said propeller foot 8 back to the surface by passing externally to the hull.

(87) In accordance with a possible further method, said maintenance step comprises the steps of:

(88) hanging said submersible movable hatch externally to the hull by suspension chains and cables or hanging cables 18.

(89) In accordance with a possible further method, said maintenance step comprises the steps of:

(90) hanging said thruster or propeller foot 8 by hanging cables or chains 20 passing through said housing 3.

(91) In accordance with a possible further method, said maintenance step comprises the steps of:

(92) inserting into said housing, through closable passages 31 provided for through the walls 5 of said housing 3, hanging cables or chains 18, 20 to hang said submersible movable hatch 10 passing through said housing or to hang said thruster 8 also disconnecting it from said telescopic driving shaft 9.

(93) In accordance with a possible further method, said maintenance step comprises the steps of:

(94) inclining by a predetermined angle A the thruster axis, or thrust actuating axis P-P, with respect to the telescopic shaft axis V-V so as to orient the thrust of the thruster with respect to the hull 4 or other obstacles.

(95) In accordance with a possible further method, said maintenance step comprises the steps of:

(96) guiding said telescopic driving shaft 9 in at least a length thereof located within said housing by a guide cross 21.

(97) In accordance with a possible further method, said maintenance step comprises the steps of:

(98) discharging onto the hull the thrust actions of the thruster by said guide cross 21.

(99) In accordance with a possible further method, said maintenance step comprises the steps of:

(100) installing the submersible movable hatch 10 in the proximity of the opening 6 of the housing 3 of the hull insert or trunk 2 by hanging cables 18, and optionally by the aid of diving personnel.

(101) In accordance with a possible further method, said maintenance step comprises the steps of:

(102) bringing said submersible movable hatch 10 and said propeller foot 8 back to the surface by passing externally to the ship.

(103) It shall be apparent that those skilled in the art, with the aim of meeting contingent, specific needs, will be able to make a number of modifications and variations to the method for the maintenance of an assembly according to the invention, all of which anyhow falling within the protection scope of the invention, as defined by the following claims.

(104) TABLE-US-00001 REFERENCES 1 propulsion assembly 2 hull insert 3 housing or propeller case 4 ship hull 5 housing walls 6 housing opening 7 motor 8 thruster 9 telescopic driving shaft 10 submersible movable hatch 11 closed chamber within housing 12 fluid evacuation device from the chamber 13 fluid - sea water 14 azimuthal driving Shaft 15 power driving shaft 16 air pumping-in device 17 maintenance access hatch 18 chains or hanging cables for submersible movable hatch 19 guide candles 20 suspension chains or hanging cables of thruster 21 guide cross 22 thruster shaft connection joint 23 first watertight protection or covering closure cuff 24 first shaft side joint flange 25 second watertight protection or covering closure cuff 26 second thruster side joint flange 27 thruster lifting device 28 support device handling shaft and propeller foot 29 propeller seals 30 propeller seals protection 31 passages for chains or cables in housing walls 32 housing or chamber upper roof, sky, 33 pulleys for handling hanging cables 34 edge of hull insert defining the opening for the coupling to the hatch V-V shaft axis P-P thrust actuating axis, for example, thruster axis or propeller axis W-W free water surface A angle between V-V and P-P