CA1210280A - Capturing and towing icebergs - Google Patents
Capturing and towing icebergsInfo
- Publication number
- CA1210280A CA1210280A CA000486479A CA486479A CA1210280A CA 1210280 A CA1210280 A CA 1210280A CA 000486479 A CA000486479 A CA 000486479A CA 486479 A CA486479 A CA 486479A CA 1210280 A CA1210280 A CA 1210280A
- Authority
- CA
- Canada
- Prior art keywords
- iceberg
- net
- rope
- foot
- vessel
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING
- B63B35/00—Vessels or similar floating structures specially adapted for specific purposes and not otherwise provided for
- B63B35/08—Ice-breakers or other vessels or floating structures for operation in ice-infested waters; Ice-breakers, or other vessels or floating structures having equipment specially adapted therefor
- B63B35/086—Vessels for displacing icebergs, or related methods
Abstract
ABSTRACT
Marine structures are protected from damage caused by icebergs by capturing the iceberg with a towing vessel and towing the iceberg safely away from the marine structure. To capture the iceberg, an iceberg capturing structure is used which comprises a net having a buoyant head rope and a foot rope which in use is deeply submerged. Bridles connect the net to the towing vehicle. The lengths of the lines of the bridles are adjustable so that the head rope contacts the iceberg before the foot rope contacts the iceberg so that the iceberg tends to be rolled into the net structure between those two ropes.
Marine structures are protected from damage caused by icebergs by capturing the iceberg with a towing vessel and towing the iceberg safely away from the marine structure. To capture the iceberg, an iceberg capturing structure is used which comprises a net having a buoyant head rope and a foot rope which in use is deeply submerged. Bridles connect the net to the towing vehicle. The lengths of the lines of the bridles are adjustable so that the head rope contacts the iceberg before the foot rope contacts the iceberg so that the iceberg tends to be rolled into the net structure between those two ropes.
Description
This invention is concerned with the protection of marine structures threatened by icebergs and growlers and is particularly concerned with apparatus for and a method of capturing and towing icebergs and growlers (for the sake brevity hereinafter referred to generically as "icebergs" where the context permits~.
Icebergs pose a grave risk to oil and gas rigs off the east coast of Canada and many techniques have been used to divert them or destroy them. The most successful approach has been to capture the icebergs with a rope trailed from a towing vessel which circles the iceberg and takes up the trailed end of the rope. In some instances, it has proven possible to capture growlers with a loop of rope trailed from the towing vessel.
The success of this technique has been limited by the shape of the iceberg. l~he center of gravity of the iceberg is well below the surface of the water and as the rope pulls on the iceberg, it tends to cause the iceberg to roll and the rope often moves over the top of the iceberg. In many instances, it has proven impossible to capture an iceberg and in these instances, it has proven necessary to move the rig which it threatens and this is an enormously costly and complicated procedure.
According to one aspect of the present invention, there is provided a method of protecting a marine structure threatened by an iceberg which comprises trailing an iceberg capturing structure from a towing vessel, said structure comprising a net having a buoyant head rope and a deeply submerged foot rope and bridle lines connecting the net to the vessel, positioning the ,.
~2~
net so that the iceberg lies between it and the vessel, drawing the net to capture the iceberg and towing the iceberg to a non-threatening location.
When capturing a large iceberg it is appropriate that the iceberg capturing structure should be trailed by the bridle at one end of the net, the vessel being caused to circle the iceberg and the other bridle being recovered so that the iceberg lies within a loop formed by the net and bridles.
To capture a growler the iceberg capturing structure is trailed as a loop from the vessel and the vessel manoeuvered to dispose the loop about the growler.
The method preferably includes the step of adjusting the lengths of the top and bottom lines of the bridles so the head rope contacts the iceberg before the iceberg is contacted by the foot rope, in this way to cause the iceberg to roll into the net between the head rope and the foot rope.
According to another aspect of the present invention, there is provided apparatus for protecting a marine structure threatened by an iceberg which comprises a net having a buoyant head rope and a non-buoyant foot rope, the length of the net between the head rope and the foot rope being such that when deployed, the foot rope is disposed below the center of gravity of an iceberg which is to be captured, and bridles secured to the ends of the net for connecting the net to a towing vessel.
Most desirably the length of the net between the foot and head ropes is such that the foot rope is disposed below the iceberg to be captured. Preferably the net ls reinforced by supports connected between the head rope and the foot ropeO Additional reinforcement may be provided extending between the end lines of the net.
The head rope may be provided with a plurality of -` ~Zl~
~loatation devices to support the head rope at the surface of the water. The foot rope may be of chainO
According to yet another aspect of this invention there is provided equipment for protecting a marine structure threatened by an iceberg which comprises a towing vessel, a net having head and foot ropes, the head rope being buoyant and the length of the net between head and foot ropes being such that the foot rope, when deployed, is below the center of gravity of an iceberg to be captured, and bridles connecting the net to the vessel.
hmbodiments of the present invention are illustrated, schematically, in the accompanying drawings in which:
Figure l illustrates an iceberg capturing structure;
Figure 2 is a side view of a vessel in the process of capturing an iceberg;
Figure 3 shows the iceberg after capture;
Figure 4 shows the manner in which the apparatus of Figure 1 is used to capture a growler, and Figure 5, 6 and 7 illustrate the manner in which the device of Figure l is used to capture an iceberg.
The apparatus of Figure 1 comprises a net lO having a head rope 12 provided with a plurality of floats 14 and a foot rope 16 of chain. End lines 18 and 20 interconnect the ends of the head and foot ropes. The net comprises a mesh indicated at 22 supported by support straps 24 which extend between the head rope 12 and foot rope 16 and support straps 26 which extend between the end lines 18 and 20. Bridles 28 and 30 are made up of top lines 32 and 34 and bottom lines 36 and 38 respectively~
'3 ~
....
~ ~2~0~
The top and bottom lines o~ bridle 28 are connected by a shackle 40 to tow line 41 and those of bridle 30 are connected by shackle 42 to tow line 43. The end lines are typically one hundred feet long, but of course this will vary with the duty to which the device is put.
In Figure 2 the bridles, of which only one is illustrated, are connected, by the tow lines, to a towing vessel V about to capture an iceberg B. The top line 32 of the bridle is adjusted so that the head rope 12 of the net first contacts the iceberg so that the iceberg will tend to roll, as viewed in the drawings, clockwise so that the iceberg moves towards the belly of the net. It is to be noted that the foot rope 16 of the net is disposed below the center of gravity of the iceberg so that the iceberg will be captured as illustrated in Figure 3 so that it may be towed to safety.
Figure 4 illustrates a technique used for capturing a growler indicated at G. The vessel V trails the net capturing structure as a loop with the bridles 28 and 30 being secured to crash bars 44 and 46 respectively or to any sturdy part of the vessel V. Iceberg lines ~8 and 50 are trained about winches 52 and 54 respectively. The vessel is manoeuvered to place the tow line adjacent to the growler and then moves to the side so that the growler passes the tow line to be disposed within the loop.
The vessel is then moved ahead so that the head rope 12 of the net contacts the growler above its center of gravity tending to cause it to roll into the belly of the net.
In Figures 5, 6 and 7 there is illustrated a technique for using the device of Figure 1 to capture a large iceberg. In this instance, the net 10 is trailed by bridle 28 with the 0~
bridle 30 trailing behind the net. If necessary, a messenger line 56 is secured to bridle 30. As illustrated in Figure 6 the vessel circles the iceberg B and moves to the position illustrated in Figure 7 where it recovers messenger line 56.
The bridle 30 is then secured and the vessel moved ahead to capture the iceberg and thereafter to tow it to safety.
1~
'~
~, ~
Icebergs pose a grave risk to oil and gas rigs off the east coast of Canada and many techniques have been used to divert them or destroy them. The most successful approach has been to capture the icebergs with a rope trailed from a towing vessel which circles the iceberg and takes up the trailed end of the rope. In some instances, it has proven possible to capture growlers with a loop of rope trailed from the towing vessel.
The success of this technique has been limited by the shape of the iceberg. l~he center of gravity of the iceberg is well below the surface of the water and as the rope pulls on the iceberg, it tends to cause the iceberg to roll and the rope often moves over the top of the iceberg. In many instances, it has proven impossible to capture an iceberg and in these instances, it has proven necessary to move the rig which it threatens and this is an enormously costly and complicated procedure.
According to one aspect of the present invention, there is provided a method of protecting a marine structure threatened by an iceberg which comprises trailing an iceberg capturing structure from a towing vessel, said structure comprising a net having a buoyant head rope and a deeply submerged foot rope and bridle lines connecting the net to the vessel, positioning the ,.
~2~
net so that the iceberg lies between it and the vessel, drawing the net to capture the iceberg and towing the iceberg to a non-threatening location.
When capturing a large iceberg it is appropriate that the iceberg capturing structure should be trailed by the bridle at one end of the net, the vessel being caused to circle the iceberg and the other bridle being recovered so that the iceberg lies within a loop formed by the net and bridles.
To capture a growler the iceberg capturing structure is trailed as a loop from the vessel and the vessel manoeuvered to dispose the loop about the growler.
The method preferably includes the step of adjusting the lengths of the top and bottom lines of the bridles so the head rope contacts the iceberg before the iceberg is contacted by the foot rope, in this way to cause the iceberg to roll into the net between the head rope and the foot rope.
According to another aspect of the present invention, there is provided apparatus for protecting a marine structure threatened by an iceberg which comprises a net having a buoyant head rope and a non-buoyant foot rope, the length of the net between the head rope and the foot rope being such that when deployed, the foot rope is disposed below the center of gravity of an iceberg which is to be captured, and bridles secured to the ends of the net for connecting the net to a towing vessel.
Most desirably the length of the net between the foot and head ropes is such that the foot rope is disposed below the iceberg to be captured. Preferably the net ls reinforced by supports connected between the head rope and the foot ropeO Additional reinforcement may be provided extending between the end lines of the net.
The head rope may be provided with a plurality of -` ~Zl~
~loatation devices to support the head rope at the surface of the water. The foot rope may be of chainO
According to yet another aspect of this invention there is provided equipment for protecting a marine structure threatened by an iceberg which comprises a towing vessel, a net having head and foot ropes, the head rope being buoyant and the length of the net between head and foot ropes being such that the foot rope, when deployed, is below the center of gravity of an iceberg to be captured, and bridles connecting the net to the vessel.
hmbodiments of the present invention are illustrated, schematically, in the accompanying drawings in which:
Figure l illustrates an iceberg capturing structure;
Figure 2 is a side view of a vessel in the process of capturing an iceberg;
Figure 3 shows the iceberg after capture;
Figure 4 shows the manner in which the apparatus of Figure 1 is used to capture a growler, and Figure 5, 6 and 7 illustrate the manner in which the device of Figure l is used to capture an iceberg.
The apparatus of Figure 1 comprises a net lO having a head rope 12 provided with a plurality of floats 14 and a foot rope 16 of chain. End lines 18 and 20 interconnect the ends of the head and foot ropes. The net comprises a mesh indicated at 22 supported by support straps 24 which extend between the head rope 12 and foot rope 16 and support straps 26 which extend between the end lines 18 and 20. Bridles 28 and 30 are made up of top lines 32 and 34 and bottom lines 36 and 38 respectively~
'3 ~
....
~ ~2~0~
The top and bottom lines o~ bridle 28 are connected by a shackle 40 to tow line 41 and those of bridle 30 are connected by shackle 42 to tow line 43. The end lines are typically one hundred feet long, but of course this will vary with the duty to which the device is put.
In Figure 2 the bridles, of which only one is illustrated, are connected, by the tow lines, to a towing vessel V about to capture an iceberg B. The top line 32 of the bridle is adjusted so that the head rope 12 of the net first contacts the iceberg so that the iceberg will tend to roll, as viewed in the drawings, clockwise so that the iceberg moves towards the belly of the net. It is to be noted that the foot rope 16 of the net is disposed below the center of gravity of the iceberg so that the iceberg will be captured as illustrated in Figure 3 so that it may be towed to safety.
Figure 4 illustrates a technique used for capturing a growler indicated at G. The vessel V trails the net capturing structure as a loop with the bridles 28 and 30 being secured to crash bars 44 and 46 respectively or to any sturdy part of the vessel V. Iceberg lines ~8 and 50 are trained about winches 52 and 54 respectively. The vessel is manoeuvered to place the tow line adjacent to the growler and then moves to the side so that the growler passes the tow line to be disposed within the loop.
The vessel is then moved ahead so that the head rope 12 of the net contacts the growler above its center of gravity tending to cause it to roll into the belly of the net.
In Figures 5, 6 and 7 there is illustrated a technique for using the device of Figure 1 to capture a large iceberg. In this instance, the net 10 is trailed by bridle 28 with the 0~
bridle 30 trailing behind the net. If necessary, a messenger line 56 is secured to bridle 30. As illustrated in Figure 6 the vessel circles the iceberg B and moves to the position illustrated in Figure 7 where it recovers messenger line 56.
The bridle 30 is then secured and the vessel moved ahead to capture the iceberg and thereafter to tow it to safety.
1~
'~
~, ~
Claims (11)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A method of protecting a marine structure threatened by an iceberg comprises trailing an iceberg capturing structure from a towing vessel, said structure comprising a net having a buoyant head rope and a deeply submerged foot rope and bridle lines connecting the net to the vessel, positioning the net so that the iceberg lies between it and the vessel, drawing the net to capture the iceberg and towing the iceberg to a non-threatening location.
2. The method according to Claim 1 for use in capturing an iceberg in which the iceberg capturing structure is trailed by a bridle at one end of the net, steering the vessel to cause it to circle the iceberg, re-capturing the bridle at the other end of the net so that the iceberg lies within a loop formed by the net and bridles.
3. The method as claimed in Claim 1 for use in capturing a growler in which the iceberg capturing structure is trailed as a loop from the vessel and the vessel manouevered to dispose the loop about the growler.
4. A method as claimed in any of Claims 1 to 3 in which the lengths of top and bottom lines of the bridles are adjusted so that the head rope of the net contacts the iceberg before the iceberg is contacted by the foot rope, in this way to cause the iceberg to roll into the net between the head rope and the foot rope.
5. Apparatus for protecting a marine structure threatened by an iceberg comprises a net having a buoyant head rope and a non-buoyant foot rope, the length of the net between the head rope and the foot rope being such that when deployed, the foot rope is disposed below the center of gravity of an iceberg which is to be captured, and bridles secured to the ends of the net for connecting the net to a towing vessel.
6. Apparatus as claimed in Claim 5 wherein the net is reinforced by supports connected between the head rope and the foot rope.
7. Apparatus as claimed in Claim 5 wherein the net is reinforced by supports extending between end lines of the net.
8. Apparatus as claimed in Claim 5 wherein the head rope is provided with a plurality of floatation devices.
9. Apparatus as claimed in Claim 5 wherein the foot rope is of chain.
10. Equipment for protecting a marine structure threatened by an iceberg comprises a towing vessel, a net having head and foot ropes, the head rope being buoyant and the length of the net between the head and foot ropes being such that the foot rope, when deployed, is below the center of gravity of an iceberg to be captured, and bridles connecting the net to the vessel.
11. Equipment as claimed in Claim 10 wherein means are provided for adjusting the lengths of ropes forming the bridles.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000486479A CA1210280A (en) | 1985-07-08 | 1985-07-08 | Capturing and towing icebergs |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000486479A CA1210280A (en) | 1985-07-08 | 1985-07-08 | Capturing and towing icebergs |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1210280A true CA1210280A (en) | 1986-08-26 |
Family
ID=4130951
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000486479A Expired CA1210280A (en) | 1985-07-08 | 1985-07-08 | Capturing and towing icebergs |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1210280A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8612129B2 (en) | 2011-05-23 | 2013-12-17 | Ion Geophysical Corporation | Marine threat monitoring and defense system |
| US10071791B2 (en) | 2013-11-12 | 2018-09-11 | Ion Geophysical Corporation | Comparative ice drift and tow model analysis for target marine structure |
-
1985
- 1985-07-08 CA CA000486479A patent/CA1210280A/en not_active Expired
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8612129B2 (en) | 2011-05-23 | 2013-12-17 | Ion Geophysical Corporation | Marine threat monitoring and defense system |
| DK178136B1 (en) * | 2011-05-23 | 2015-06-15 | Ion Geophysical Corp | Marine Danger Monitoring and Defense System |
| US10032381B2 (en) | 2011-05-23 | 2018-07-24 | Ion Geophysical Corporation | Marine threat monitoring and defense system |
| US10071791B2 (en) | 2013-11-12 | 2018-09-11 | Ion Geophysical Corporation | Comparative ice drift and tow model analysis for target marine structure |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |