EP0119384B1 - Method for the transport of goods with a ship from an arctic harbour to an icefree harbour as well as a transportship - Google Patents

Description

The invention relates to a method for the transport of goods by ship from an arctic port to an ice-free port using icebreaking transport ships.

If one looks at the route between the Canadian Arctic and the ice-free ports of North America and Europe, it follows that 30 to 40% of this route is covered by ice in heavy ice and 5 to 10% by ice. The annual average is around 30%, of which around half is still navigable with ice-reinforced ships. On average, icebreaking ships are therefore only required for 10 to 15% of the total distance traveled.

The plans for the transport of goods by ship from an arctic to an ice-free port, which have been designed so far, envisage the use of icebreaking ships for the entire route (CA-A-1099155). As a result, the transport process leaves something to be desired in terms of its economy. The ships' strength and drive power must be adapted to ice thicknesses of 2 to 3 m. As a result, the capital and operating costs are correspondingly high. In addition, when designing the ships, a compromise must be made between the ice-breaking properties and the driving properties in free water, especially in high seas. There can be no optimal design for any of the properties.

The invention is based, to improve the efficiency of the aforementioned method the task.

For this purpose, this method is characterized according to the invention. that the icebreaking transport ships are only used for the journeys between the arctic port and the migratory area of the seasonally shifting ice edge, while the journeys between this area and the ice-free port are carried out with ice-reinforced transport ships, the goods being transported in the area mentioned at sea from the icebreaking is transferred directly to the ice-reinforced transport ships.

The invention thus offers the possibility of optimizing the ice-breaking ships with regard to their ice-breaking properties and the ice-reinforced ships with regard to their driving properties in free water. The cargo is reloaded in the area of the edge of the ice, as swell is not expected to hinder cargo handling. The envelope can therefore be carried out safely. The area of the ice rim is subject to seasonal shifts. A short-term determination of the transshipment location ensures that the ships are only operated under the conditions for which they are designed.

A particularly advantageous development of the invention consists in that at least two ice-breaking transport ships carry out the trips between the Arctic port and the migratory region of the seasonally shifting ice edge in succession. The icebreaking ships therefore operate in tandem, with the first ship breaking the channel and thus facilitating the journey for the second ship. The second ship uses less propulsion energy. There is no problem that the first ship will leave a practically ice-free channel behind it. Under these circumstances, the second ship consumes only about 5% of the propulsion energy of the first ship.

Apart from that, tandem operation increases the reliability and safety of transportation. If necessary, the first ship can tow the second ship. It is also possible to change roles at any time. Since the ships can provide mutual support, the risk of damage is reduced.

The ice-breaking transport ships are preferably coupled to one another in direct contact when they jointly carry out the journeys between the arctic harbor and the migratory area of the seasonally shifting ice edge. This facilitates the journey of the second ship, since on this it is no longer necessary to ensure that an adequate distance is maintained and that it breaks out of the ice-free channel. If necessary, pushing operation is also possible without further notice.

According to the invention, an ice-reinforced transport ship can be loaded simultaneously by at least two correspondingly smaller ice-breaking transport ships during the reloading. The simultaneous loading of the ice-reinforced transport ship by at least two ice-breaking transport ships is preferably carried out on both sides, but there is also the possibility that the ice-breaking transport ships dock next to one another or one behind the other on one side of the ice-reinforced transport ship. In all cases, Fender ensures that no ship damage occurs. All ships are also equipped with active maneuvering devices, such as cross-beam systems.

According to the invention, at least two ice-breaking transport ships can be loaded simultaneously in the arctic port. It is particularly advantageous that the icebreaking transport ships lie in the arctic port when they are loaded at the same time or one behind the other and use their on-board loading equipment.

The simultaneous loading and reloading of the icebreaking transport ships ensures that tandem operations are not at the expense of handling times.

The process according to the invention is complete particularly advantageously applicable to the transport of liquefied natural gas (LNG) by tanker.

In addition to the saving in transport costs, it must be taken into account here that the concept according to the invention brings considerable developmental simplifications. On the one hand, we work with services that are within the normal range. On the other hand, the size differences between the icebreaking tankers and the tried and tested icebreakers are smaller, so that reliable results can be adopted more easily. Finally, the smaller icebreaking tankers allow a larger model scale in the ice channel, so that the accuracy of the results increases.

In tandem operation, according to the invention, there is no need to provide extremely wide auxiliary icebreakers, as would otherwise be required for LNG icebreakers. The operational safety of the smaller icebreaking tankers also increases, since they can be equipped with smaller cargo tanks.

If one of the icebreaking tankers should fail, the remaining tanker can generate 60 to 70% of the annual output using the schedule reserves. If one of the large ice-reinforced tankers fails, a normal LNG tanker can be used. The transhipment then takes place more on the edge of the ice-covered zone.

The invention also provides a ship for building up a ship's association by coupling it to at least one further ship, each with corresponding convex or concave surfaces at the bow or stern (CA-A-1 043 181). As an ice-breaking transport ship, it is particularly well suited for carrying out the method according to the invention. This transport ship is characterized by a convex, essentially spherical surface forming the stern and an approximately vertical concave channel located at the bow with an essentially part-circular cross section, the radius of which corresponds to that of the spherical surface. This ship can be articulated with a similar ship under direct contact - bow against stern - to carry out the tandem operation together. The contacting surfaces allow the relative movements occurring between the ships.

Particularly favorable conditions result from the fact that the center point of the spherical surface of the stern lies in the area of the displacement center of gravity of the transport ship and that the channel at the bow is possibly convexly curved in the vertical direction, the center point of the convex curvature in the area of the displacement center of gravity of the transport ship lies.

In order to reduce friction and wear, according to the invention there is the possibility that the spherical surface of the stern is occupied with horizontal-axis rollers and the groove of the bow with vertical-axis rollers.

In order not to reduce the strength in the case of narrow casters, both the horizontal-axis and the vertical-axis rollers are each offset from one another.

According to the invention, the peripheral surfaces of the rollers can match the contours of the associated ones. Bow or stern surfaces must be adapted.

The transport ship according to the invention can also be characterized by tensioning devices arranged on the bow and / or stern, the pretensioning force of which can be regulated. This makes it possible to produce an elastic bracing between two transport ships. Each tensioning device can have an automatic coupling for coupling to another icebreaking transport ship.

According to a further advantageous feature, the transport ship according to the invention is characterized by measuring devices arranged on the spherical surface of the stern and / or on the trough of the bow for regulating the pretensioning force to be applied by the tensioning devices during the coupled journey. On the one hand, this ensures the required firm connection and, on the other hand, prevents any overload.

The coupling process is an extremely difficult maneuver. To provide support here, the transport ship is characterized according to the invention by distance, speed, angle of rotation, draft and direction measuring and control devices for automatically carrying out the coupling to another icebreaking transport ship. The measuring and control devices can be designed as radio direction finders. In this way, the approach of two transport ships to be coupled can be mastered very well.

The drive and maneuvering device can preferably be connected for common control with the drive and maneuvering device of a further icebreaking transport ship. This means that two coupled transport ships can be maneuvered as a unit.

The transport ship according to the invention can also be characterized by a device for receiving and burning the boil-off of at least one coupled ice-breaking transport ship in its own propulsion system.

So if two icebreaking tankers drive with only one propulsion system, losses of gas can still be avoided.

• Figur 1 als schematischen Schnitt links das Heck und rechts den Bug eines eisbrechenden Transportschiffes ;
• Figur 2 einen schematischen Grundriß der Anordnung nach Fig. 1 ;
• Figur 3 eine Stirnansicht des Bug-Rollenmusters ;
• Figur 4 eine Stirnansicht des Heck-Rollenmuster ;
• Figur 5 eine Überlagerung von Heck- und Bug-Rollenmuster ;
• Figur 6 zwei Möglichkeiten für das gleichzeitige Beladen von zwei eisbrechenden Transportschiffen ;
• Figur 7 zwei Möglichkeiten für das gleichzeitige Umladen des Transportgutes von zwei eisbrechenden Transportschiffen auf ein eisverstärktes Transportschiff.

The invention is explained in more detail below on the basis of preferred exemplary embodiments in conjunction with the accompanying drawing. The drawing shows in:

• 1 shows a schematic section of the stern on the left and the bow of an icebreaking transport ship on the right;
• Figure 2 is a schematic plan view of the arrangement of Fig. 1;
• Figure 3 is an end view of the bow roller pattern;
• Figure 4 is an end view of the rear roller pattern;
• Figure 5 is an overlay of stern and bow roller patterns;
• FIG. 6 shows two options for the simultaneous loading of two ice-breaking transport ships;
• 7 shows two possibilities for the simultaneous reloading of the goods to be transported from two ice-breaking transport ships to an ice-reinforced transport ship.

1 and 2 show an icebreaking transport ship 1 with the stern 2 on the left and the bow 3 on the right. The stern is formed by a convex, spherical surface 4, the center of which lies in the area of the displacement center of gravity of the transport ship. At the bow there is a substantially vertical, concave groove 5 with a cylindrical cross section, the radius of which corresponds to that of the spherical surface 4. The trough 5, as can be seen in FIG. 1, is convexly curved in the vertical direction, the center point of the convex curvature likewise being in the region of the displacement center of gravity of the transport ship.

The spherical surface 4 of the tail 2 is occupied by horizontal-axis rollers 6. In a comparable manner, the trough 5 of the bow 3 is fitted with vertical-axis rollers 7.

3 and 4 that both the rollers 6 and the rollers 7 are each offset from one another. 5 shows the superimposition of the two roller patterns, that is to say the setting which results when two ice-breaking transport ships are coupled from bow to stern.

The contours of the rollers 6 are adapted to the spherical surface 4. In a comparable manner, the contours of the rollers 7 are adapted to the channel 5.

A tensioning device 8 is arranged on the stern 2 and on the bow 3. The tensioning devices 8 serve to couple two transport ships together. They have automatic clutches for this. Their pretensioning force can be regulated, specifically as a function of measuring devices (not shown) which are arranged on the spherical surface 4 or on the channel 5.

The icebreaking transport ships can be tankers with a length of around 260 m. The coupling of such ships is a difficult maneuver. To support this maneuver, the transport ship 1 has distance, speed, angle of rotation, draft and direction measuring and control devices (not shown), and these measuring and control devices can be designed as radio direction finders .

Means are also provided for connecting the drive and maneuvering device of the transport ship 1 for common control with the drive and maneuvering device of a further icebreaking transport ship. Finally, there is the possibility of boil-off in the propulsion system of the transport ship 1. to burn a docked transport ship.

FIG. 6 shows the simultaneous loading of two ice-breaking transport ships 1 via a loading bridge 9 in an arctic port. One of the transport ships lies at the loading bridge and is also connected to the other transport ship via the on-board loading equipment. In the left part of Fig. 6, the transport ships are one behind the other, in the right part next to each other.

FIG. 7 shows the simultaneous reloading of two ice-breaking transport ships 1 onto a larger ice-reinforced transport ship 10. The place of transshipment is the low-swell edge area of the ice-covered water. The on-board loading equipment is also used here. After the left part of FIG. 7, the reloading takes place on both sides, and after the right part on one side. In the latter case there is also the possibility that the transport ships 1 are not next to each other, but next to each other.

Claims (22)

1. A method of shipping goods by ice-breaking sea-going vessels (1) from an Arctic harbour or port to an ice-free harbour or port characterized in that said ice-breaking vessels exclusively make the passage between said Arctic harbour or port and a point close to the edge of the substantially ice-covered waters migrating during the year and sea-going vessels (10) that make the passage between said point and said ice-free harbour or port, said goods being transferred from said ice-breaking vessels to said ice-strengthened vessels at said point.

2. A method according to claim 1 characterized in that at least two such ice-breaking vessels, travelling behind each other, together make said passage between said Arctic harbour or port and said point close to the edge of the substantially ice-covered waters.

3. A method according to claim 2 characterized in that said ice-breaking vessels making said passage together are coupled together.

4. A method according to any one of claims 1 through 3 characterized in that goods are simultaneously transferred from at least two such ice-breaking vessels to one such ice-strengthened vessel.

5. A method according to claim 4 characterized in that said simultaneous transfer is made from both sides of said ice-strengthened vessel.

6. A method according to any one of claims 1 through 5 characterized in that at least two such ice-breaking vessels are loaded simultaneously in said Arctic harbour or port.

7. A method according to claim 6 characterized in that said ice-breaking vessels are positioned behind each other or adjacent to each other during simultaneous loading operations, on-board loading equipment being employed for said loading operations.

8. A method according to any one of claims 1 through 7 characterized in that said method is applied for the shipment of liquefied natural gas (LNG) by tankers.

9. A vessel and more particularly an ice-breaking vessel for the shipment of goods for forming a convoy by coupling with at least one other ship characterized in that the stern (2) of said vessel is represented by a convex and substantially hemispherical area (4) and further characterized in that the bow (3) of said ship includes a substantially vertical and concave channel (5) of a cross section substantially representing the arc of a circle, the radius of said circle corresponding to the radius of said substantially hemispherical area (4).

10. A vessel according to claim 9 characterized in that the centre of said hemisphere is located close to the centre of buoyancy of said vessel.

11. A vessel according to claim 9 or 10 characterized in that said channel (5) in said bow (3) is convexly curved in a vertical direction, the centre of the circle of which said convexly curved channel is an arc being located close to the centre of buoyancy of said vessel (1).

12. A vessel according to any one of claims 9 through 11 characterized in that said hemi-spherical area (4) of said stern (2) is fitted with rollers

(6), the axes (4) of said rollers (6) being in the horizontal direction and in that said channel is fitted with rollers (7), the axes of said rollers (7) being in the vertical direction.

13. A vessel according to claim 12 characterized in that said rollers (6) with axes in the horizontal direction and said rollers (7) with axes in the vertically direction are displaced relative to each other.

14. A vessel according to claim 12 or 13 characterized in that the contours of the circumferential surfaces of said rollers (6, 7) conform to the contours of the corresponding surfaces (4. 5) of said stern (2) and of said bow (3) respectively.

15. A vessel according to any one of claims 9 through 14 characterized in that said bow (3) and/or said stern (2) is/are equipped with tensioning devices (8) which allow the control of the tension applied.

16. A vessel according to claim 15 characterized in that each such tensioning device (8) is fitted with an automatic coupling device for coupling said vessel with any other such ice-breaking vessel (1).

17. A vessel according to claim 15 or 16 characterized in that said spherical area (4) of the stern (2) and/or said concave channel (5) of said bow (3) is/are equipped with measuring devices to allow the control of the tension to be applied by said tensioning devices when such vessels are coupled together while travelling.

18. A vessel according to any one of the claims 9 through 17 characterized in that said vessel is fitted with measurement and control devices for range, speed, angle of rotation and draught to allow coupling said vessel with any other such ice-breaking vessel automatically.

19. A vessel according to any one of claims 9 through 18 characterized in that the propulsion and manoeuvring equipment of said vessel and the propulsion and manoeuvring equipment of any other such ice-breaking vessel may be connected for the joint control of said vessel and said other vessel.

20. A vessel according to any one of claims 9 through 19 characterized in that said vessel is equipped with facilities and installations for receiving boil-off gas from at least one other such ice-breaking vessel (1) coupled to said vessel and with facilities and installations for firing the boil-off gas so received.

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