ES2991674T3 - A boat - Google Patents

Abstract

A vessel (1) comprises a hull (2) including a bow (3) and a stern (4) and having a length-to-beam ratio that is less than 10:1, preferably less than 5:1. The hull (2) has a vertical centre plane (CP) extending in a direction from the bow (3) to the stern (4). On either side of the centre plane (CP) the vessel (1) has at least two azimuth thrusters (6) including respective propellers (6a), the azimuth thrusters (6) being located side by side in a direction transverse to the centre plane (CP). Each azimuth thruster (6) is driveably coupled to its own prime mover (7). (Automatic translation with Google Translate, without legal value)

Description

DESCRIPTION

A boat

The present invention relates to a tugboat comprising a hull including a bow and a stern and having a length to beam ratio that is less than 5:1, wherein the hull has a vertical center plane extending in a direction from the bow to the stern.

Such a vessel is known, for example, in the form of a tugboat whose length to beam ratio is about 3:1. A typical known tugboat has two azimuth thrusters for propelling and manoeuvring the tugboat, the azimuth thrusters of which are located on either side of the centre plane. The azimuth thrusters are driveably coupled to respective diesel engines and can be operated by a helmsman, for example, by means of respective control levers.

WO 2016/023080 relates to a marine craft for surface level operation comprising a body, at least one propulsion mechanism coupled to the body and a controller carried by the body and configured to control operation of the at least one propulsion mechanism. The marine craft further comprises a wireless transceiver communicably coupled to the controller to facilitate wireless communication between the controller and a remote computing device and at least one coupler for removably coupling the craft to a vessel, wherein the marine craft is configured for unmanned surface level operation to dock with the vessel and undock from the vessel under control of the controller.

US 4,580,517 relates to a semi-submersible vessel comprising an operating platform supported by columns from two parallel hulls, each hull forming a closed unit defined by a deck and side and bottom plates, each hull further carrying propulsion means including a plurality of 360° rotatable propulsion propellers mounted in casings projecting from the hulls.

US 3,750,607 relates to a shallow draft vessel which is operated by omnidirectional propulsion means located beneath the flat hull, which is stabilized and protected by one or more keel stubs. The vessel has a high beam-to-length ratio, a low draft-to-length ratio, and a low draft-to-beam ratio. Its hull is double-ended and symmetrical along both the longitudinal axis and the transverse axis, and the hull has a fully developable surface allowing construction from flat plates without compound curvature.

Document CN 103 482 037 relates to a small-sized tugboat belonging to the technical field of tugboats and comprising a tugboat body, a mooring line, a stern roller, a shark jaw, a large trailer, a superstructure, an anchor windlass, anchors, bow thrusters, a left propeller, a mid-propeller, a right propeller and solid wheels. The tug boat body is formed by welded steel plates, the stern of the tug boat body is provided with the cylindrical stern roller, the superstructure is arranged on the upper surface of the main deck of the tug boat body, the anchor windlass is arranged in front of the superstructure, anchors are arranged on the anchor windlass in suspension mode through anchor chains, the large trailer is arranged behind the superstructure, the shark jaw is arranged between the large trailer and the stern roller, the midpoints of the large trailer, stern roller and shark jaw form a straight line, the bottom of a bow is provided with the bow thruster, the bottom of the stern is provided with the left propeller, middle propeller and right propeller from left to right, and the periphery of the tug boat is provided with the solid wheels.

US 3,934,531 relates to a cargo unit vessel with an elongated flat bottom and vertical sides with a specially configured high-speed bow having a forward-cantilevered horizontal bottom panel of full hull width, predetermined projection length and vertical thickness that controls the bow wave of the hull, with an upwardly inclined aft bottom with multiple keel heels. A plurality of detachably connected power module vessels and a single control module vessel arranged side-by-side are detachably connected to each other and to the stern. Submerged at adjustable depths, torpedo-shaped drive units of the power module vessels support vertical housings thereon that protrude above the water level and pass through flotation collars that provide flotation and stability to the power module vessels as independent vessels when separated from the cargo unit vessel.

An object of the invention is to provide a highly maneuverable vessel.

This object is achieved by the tugboat according to claim 1. Therefore, a row of at least four azimuth thrusters extends in the transverse direction of the hull. In practice, the same number of azimuth thrusters will be located on both sides of the centre plane.

Due to the relatively small length-to-beam ratio, the relatively wide beam provides the possibility of applying a plurality of azimuth thrusters on each side of the centre plane. To achieve a similar power level, an increasing number of azimuth thrusters may have decreasing propeller diameters of the individual azimuth thrusters. Consequently, the total height of the azimuth thruster array can be kept relatively small.

The application of relatively small azimuth thrusters also provides the opportunity to apply relatively small cooperating prime movers. An advantage of relatively small azimuth thrusters and prime movers is that their response time is relatively short, which leads to improved maneuverability of the vessel.

In a practical embodiment, the azimuth thrusters are aligned in the transverse direction of the center plane. The distances between the center lines of the propellers of every two neighboring azimuth thrusters may be the same in order to achieve a symmetrical arrangement. The distance between the center lines of the propellers of the neighboring azimuth thrusters that are located on either side of the center plane, i.e. the two azimuth thrusters that are located closest to the center plane, may be different from the distance between the center lines of the propellers of every two neighboring azimuth thrusters on either side of the center plane.

In a particular embodiment, the propellers of the at least two azimuth thrusters have different diameters. The propeller of one of the at least two azimuth thrusters that is located at a greater distance from the central plane than the other of the at least two azimuth thrusters may have a larger diameter than the propeller of the other of the at least two azimuth thrusters.

Azimuth thrusters can be located at the bow or stern.

At least one of the prime movers is an internal combustion engine. The internal combustion engine is a diesel engine having a maximum speed above 1000 rpm. Such a diesel engine may be known as a high-speed diesel engine. If the desired power per single azimuth thruster is relatively large, so that a low-speed diesel engine must be applied, according to the present invention it is preferred to apply a larger number of relatively small azimuth thrusters, including the high-speed diesel engines, rather than applying a smaller number of relatively large azimuth thrusters, including the low-speed diesel engines.

The at least two azimuth thrusters and their prime movers may be operably coupled to a common controller to operate the at least two azimuth thrusters simultaneously. The common controller may be a joystick such that an operator may operate two joysticks, one to simultaneously control the at least two azimuth thrusters, including their prime movers, on one side of the centerplane and one to simultaneously control the at least two azimuth thrusters, including their prime movers, on the other side of the centerplane.

In a particular embodiment, a keel stub is mounted on each side of the centre plane on a lower side of the hull, which keel stub extends in the longitudinal direction of the hull, for example from the bow to about the middle of the hull. In this embodiment, the towing vessel has at least two keel stubs which may have a relatively small height, which reduces the draft of the towing vessel, improves seakeeping and facilitates easy docking. Furthermore, at least two keel stubs improve course stability and manoeuvrability and allow relatively large steering forces during escort of a large vessel.

The keel heel may be located in a horizontal position between the axes of rotation of the respective propellers of the at least two azimuth thrusters, as viewed in a direction from the stern to the bow.

Furthermore, the maximum keel heel height may be less than the diameter or 1.5 times the diameter of each of the respective azimuth thruster propellers, or even less than 80% of it.

The invention will be elucidated hereinafter with reference to highly schematic drawings showing embodiments of the invention by way of example.

Fig. 1 is a side view of an embodiment of a vessel according to the invention.

Fig. 2 is a plan view of a portion of the vessel as shown in Fig. 1 on a larger scale. Fig. 3 is a rear view of the vessel as shown in Fig. 1 on a larger scale.

Fig. 4 is a view similar to Fig. 3, but showing an alternative embodiment.

Figs. 1-3 show an embodiment of a vessel according to the invention. The vessel is a tug boat 1, having a hull 2 including a bow 3 and a stern 4. Such a tug boat 1 is typically used as an escort tug, anchor handling tug, salvage tug, oil recovery vessel, safety standby vessel or as a ship handling tug near offshore terminals and FPSOs (Floating Production, Storage and Offloading vessels). The tug boat 1 can be used to assist large ships that are much larger than the tug boat 1. The tug boat 1 can be connected to the large ship by a towing cable to tow the large ship in a specific direction or the tug boat 1 is maneuvered against the large ship in order to be able to push it in a certain direction.

The hull 2 of the tugboat 1, as shown in Figs. 1-3, has a length of about 50 m and a beam of about 16 m, therefore a length to beam ratio of about 3. The hull 2 has a vertical center plane CP extending in a direction from the bow 3 to the stern 4, see Figs. 2 and 3. A center keel heel 5 is mounted on a lower side of the hull 2. The center keel heel 5 extends in the longitudinal direction of the hull 2 from the bow 3 to about the middle of the hull 2 in the center plane CP.

The tugboat 1 is provided with an array of four azimuth thrusters 6, which are arranged in an aligned row extending in the transverse direction of the centre plane CP. The azimuth thrusters 6 have respective propellers 6a which are located below the hull 2, in this case at the stern 4. In an alternative embodiment, the azimuth thrusters 6 may be located at the bow 3 or anywhere in between.

The application of an azimuth thruster to propel a vessel is well known, for example in ASD (azimuth stern drive) tugboats. The entire propulsion unit can rotate in the horizontal plane and thrust can be produced in any desired direction.

In the embodiment shown in Figs. 1-3 on either side of the center plane, two azimuth thrusters 6 are located side by side in the transverse direction of the center plane CP and the azimuth thrusters 6 are driveably coupled to respective prime movers in the form of high speed diesel engines 7 through respective propeller shafts 8. The high speed diesel engines 7 are located within the hull 2 below a deck 9. The high speed diesel engines 7 provide quick response when higher thrust is desired.

Fig. 3 shows that the propellers 6a of the two outer azimuth thrusters 6 have larger diameters than the propellers 6a of the two inner azimuth thrusters 6.

The pair of azimuth thrusters 6 and their prime movers 7 on one side of the center plane CP can be operated simultaneously by a first joystick and the pair of azimuth thrusters 6 and their prime movers 7 on the other side of the center plane CP can be operated simultaneously by a second joystick.

Fig. 4 shows an alternative embodiment, which is distinguished from the embodiment shown in Fig. 3 in that two keel stubs 5a, 5b are mounted on a lower side of the hull 2. The keel stubs 5 extend in the longitudinal direction of the hull 2 from the bow 3 to about the middle of the hull 2 at a distance from the centre plane CP. As seen from the rear of the hull 2, each of the keel stubs 5a, 5b is situated in a horizontal position between the axes of rotation of the propellers 6a of the neighbouring azimuth thrusters 6. Due to the application of two keel stubs 5a, 5b their dimensions in the vertical direction are relatively small, which creates a relatively shallow draft. Therefore, the combination of at least two relatively small azimuth thrusters 6 and at least one keel stub 5a, 5b on each side of the centre plane CP allows for a shallow draft and facilitates docking, for example. The height of each of the keel stubs 5a, 5b may vary along their longitudinal direction. The maximum height may be less than the diameter or 1.5 times the diameter of each of the propellers 6a.

The invention is not limited to the embodiments shown in the drawings and described above, which can be varied in different ways within the scope of the claims.

Claims (11)

1. A tugboat (1) comprising a hull (2) including a bow (3) and a stern (4) and having a length to beam ratio that is less than 5:1, wherein the hull (2) has a vertical center plane (CP) extending in a direction from the bow (3) to the stern (4), wherein the tugboat (1) has at least two azimuth thrusters (6) including respective propellers (6a), which azimuth thrusters (6) are located next to each other in the transverse direction of the center plane (CP) and wherein each azimuth thruster (6) is driveably coupled to its own prime mover (7), wherein the at least two azimuth thrusters (6) are on either side of the center plane (CP), i.e. constituting at least four azimuth thrusters in total, wherein at least one of the prime movers is a propeller (6) and the hull (2) has a vertical center plane (CP) extending in a direction from the bow (3) to the stern (4), wherein ... diesel (7) having a maximum speed above 1000 rpm. 2. A tugboat (1) according to claim 1, wherein the azimuth thrusters (6) are aligned in the transverse direction of the center plane (CP). 3. A tugboat (1) according to claim 1 or 2, wherein the distances between the centre lines of the propellers (6a) of every two neighbouring azimuth thrusters (6) are the same. 4. A tugboat (1) according to any of the preceding claims, wherein the propellers (6a) of the at least two azimuth thrusters (6) have different diameters. 5. A tugboat (1) according to claim 4, wherein the propeller (6a) of one of the at least two azimuth thrusters (6) that is located at a greater distance from the central plane (CP) than the other of the at least two azimuth thrusters (6) has a larger diameter than the propeller (6a) of the other of the at least two azimuth thrusters (6). 6. A tugboat (1) according to any of the preceding claims, wherein the azimuth thrusters (6) are located at the bow (3) or at the stern (4). 7. A tugboat (1) according to any of the preceding claims, wherein the at least two azimuth thrusters (6) and their prime movers (7) are operatively coupled to a common controller to operate the at least two azimuth thrusters (6) simultaneously. 8. A tugboat (1) according to claim 7, wherein the common controller is a joystick such that an operator can operate two joysticks, one for simultaneously controlling the at least two azimuth thrusters including their prime movers on one side of the center plane and one for simultaneously controlling the at least two azimuth thrusters including their prime movers on the other side of the center plane. 9. A tugboat (1) according to any one of the preceding claims, wherein on each side of the centre plane (CP) a keel heel (5a, 5b) is mounted on a lower side of the hull (2), which keel heel (5a, 5b) extends in the longitudinal direction of the hull (2). 10. A tugboat (1) according to claim 9, wherein the keel heel (5a, 5b) is located in a horizontal position between the axes of rotation of the respective propellers (6a) of the at least two azimuth thrusters (6) as viewed in a direction from the stern (4) to the bow (3). 11. A tugboat (1) according to claim 9 or 10, wherein the maximum height of the keel heel (5a, 5b) is less than the diameter or 1.5 times the diameter of each of the propellers (6a) of the respective azimuth thrusters (6).