CN110601090A - Pre-laying anchor cable auxiliary ship-moving method and system composition of long-distance sandbar section - Google Patents

Abstract

The invention relates to the technical field of submarine cable laying, and discloses a pre-laid anchor cable auxiliary navigation method and system composition for a long-distance sandbar section. It is characterized in that: two pre-laid anchor cables are pre-laid across the sandbar area; when the tide rises to the water depth and meets the sailing requirements, the winch mill is started to twist the cables, and the cable-laying ship continues to sail along the cable design route, while laying and burying. cable. The laying of pre-laid anchor cables does not take up the main operation time; when the cable-laying ship passes through the sandbar area, it relies on the winch mill to twist the pre-laid anchor cables to provide forward power. Therefore, under the condition that the water depth meets the requirements of sailing during a high tide, the ship can be sailed uninterruptedly to achieve the purpose of maximizing the efficiency of cable laying; thus ensuring that the cable laying ship can pass through the sandbar section to complete the cable laying construction during a large tide.

Description

A pre-laid anchor cable assisted sailing method and system composition for a long-distance sandbar section

technical field

The invention relates to the technical field of submarine cable laying, in particular to a pre-laid anchor cable auxiliary navigation method and system composition for a long-distance sandbar section.

Background technique

Submarine cables are important power transmission and signal transmission facilities connecting offshore facilities and land facilities. As the diameter of submarine cables increases, the difficulty of laying long-distance submarine cables at sea becomes more and more difficult. Therefore, it is necessary to select appropriate construction methods according to local conditions according to the environmental conditions of submarine cable laying construction, especially the water depth conditions.

For long-distance sandbar sections characterized by water at high tide and exposed beaches at low tide, there are two alternative construction methods for submarine cable laying: the first is to use small boats such as anchor boats to tow and lay the cable during high tide periods The ship sails while laying and burying the cable; the second is to use the low-tide open beach to lift and drop anchor as described in the patent application "A Cable-laying Vessel Deck Layout and Construction Method for Laying Long-distance Sandbar Section Submarine Cables" submitted at the same time. Utilize the twisted cable to sail when there is water at high tide, and simultaneously lay and bury the cable.

For the first method, because small boats such as anchor boats provide both forward power and steering power for the cable-laying ship, limited by the water depth conditions in the sandbar area, small boats that meet the sailing conditions have small drafts and limited power. In the case of poor sea conditions, the power is obviously insufficient, resulting in slow sailing speed and low cable laying efficiency when helping tow the cable laying ship. Especially when the cable laying ship is in cross wind and waves, the actual cable laying route is more likely to deviate from the cable design route.

For the second method, due to the limited length of the anchor cable that is released each time the anchor is lifted and dropped, usually not more than 500m, the distance that the cable-laying ship sails at each high tide is relatively short, usually not more than 350m, so the cable-laying ship sails and lays the cable less efficient.

To sum up, both the first method and the second method have the problems of low efficiency of laying cables by boat and long construction period. For the construction of long-distance submarine cable laying in the sandbar section, usually only the water depth conditions at the high tide of 3-5 days during the big tide flood can meet the requirements for sailing. If the cable laying work cannot be completed within 3-5 days when the water depth meets the sailing requirements, the cable laying ship will have to sit on the beach and wait for the next big tide in nearly half a month. There will be serious hidden dangers to ship safety and cable safety during the standby period.

Therefore, it is an urgent technical problem to be solved in the industry to improve the efficiency of cable-laying ships, shorten the construction period, and ensure that the submarine cable laying construction across the long-distance sandbar section can be completed during a large tide.

Contents of the invention

In order to improve the cable laying efficiency of the long-distance sandbar section submarine cable laying and ensure that the submarine cable laying construction across the long-distance sandbar section is completed during a big tide, the present invention proposes a pre-laid anchor cable auxiliary sailing method for the long-distance sandbar section and system composition.

As a first aspect, the present invention proposes a pre-laid mooring cable-assisted sailing method for a long-distance sandbar section, which is characterized in that it includes the following steps:

1) Pre-lay two pre-laid anchor cables on both sides of the cable design route across the sandbar area;

2) Pre-arrange and install two winch mills on the cable-laying ship;

3) Before the arrival of the big tide, the cable-laying ship sails to the beginning of the pre-laid anchor cable, salvages the beginning of the pre-laid anchor cable to the deck of the cable-laying ship, and connects it to the winch mill;

4) When the tide rises until the water depth meets the sailing requirements, start the winch mill to twist the cable, and the cable-laying ship continues to sail along the cable design route, while laying and burying the cable;

5) When the ebb tide does not meet the requirements of sailing, stop the cable laying, and the cable laying ship sits on the beach and waits for the next high tide;

6) Cycle according to steps 4 and 5. During the high tide, the cable laying ship will use the high tide to cross the long-distance sandbar section and complete the cable laying construction.

The two winch mills are installed on the side deck of the cable-laying ship in the forward direction for the cable-laying ship with side outlet.

The two winch mills are installed on the bow deck for the cable-laying ship that goes out from the stern, and are arranged symmetrically.

The length of the two pre-laid anchor cables is sufficient to cross the sandbar area.

The two pre-laid anchor cables are parallel to the cable design route, and keep a distance of 100m-250m.

The distance between the two pre-laid anchor cables close to the starting ends is gradually reduced until the distance between the two pre-laid anchor cables is approximately the same as the distance between the two winches on the cable-laying ship.

As a second aspect, the present invention proposes a pre-laid anchor cable system for a long-distance sandbar section, including a ship anchor, and an anchor cable connected to the ship anchor through an anchor shackle at one end. It is characterized in that the anchor cable includes several sections of the first Steel wire rope slings and shackle swivels connecting two adjacent sections of the first steel wire rope slings.

The other end of the anchor cable is connected to one end of a second wire rope sling through a common shackle.

The other end of the second steel wire rope sling is connected with a floating ball group with a nylon rope.

The length of the second wire rope sling is not less than the sum of the water depth at high tide and the freeboard height of the cable-laying ship, and an appropriate margin is left.

One end of an anchor cable is connected to the anchor shackle; the other end of the anchor cable is connected to a floating ball group with a nylon rope.

A floating ball is connected with a nylon rope near the position of the shackle swivel; a warning light is fastened on the floating ball.

The connection length of the nylon rope is determined by more than two-thirds of the volume of the floating ball floating on the water surface when the highest water level is met.

The floating ball group is composed of no less than two floating balls, and each floating ball is painted with a different color; a warning light is attached to the floating ball group.

As a third aspect, the present invention proposes a construction method for laying pre-laid anchor cables on a long-distance sandbar section, which is characterized in that it includes the following steps:

1) Shipment and transportation: Load all parts of the pre-laid anchor cable including the anchor, the first wire rope sling, the float group, and the float on the deck of the crane ship at the dock; the second excavator boards the ship; Then the crane ship is transported to the vicinity of the offshore installation location; each of the first wire rope slings is wound on a drum, which is convenient for hoisting, transportation, and on-site layout;

2) The crane ship is on the beach: the crane ship uses the high tide to sail to the position near the cable design route crossing the sandbar section and anchors in place; after the ebb tide, the crane ship is on the beach;

3) Disembarking of the second excavator: After the ebb tide and the beach, the lifting ladder structure is hoisted and erected with the assistance of the crane on the crane, and the second excavator disembarks along the ladder structure;

4) Hoist the anchor in place: the crane ship lifts the anchor out of the crane ship, lifts the anchor by the second excavator, and transports it to the anchor position of the pre-laid anchor cable under the guidance of GPS navigation, and places it on the tidal flat mud surface;

5) The first wire rope rigging is laid: the second excavator returns to the vicinity of the crane ship, hoists a drum with the first wire rope sling that is hoisted by the crane ship near the anchor position; One end is connected to the ship anchor with an anchor shackle; the second excavator hoists the drum and travels along the designed laying track of the pre-laid anchor cable, and at the same time lays the first wire rope sling with the rotation of the drum until the first wire rope sling is completely Detach from the drum; according to the above method, lay the second section of the first steel wire rope sling, and connect the second section of the first steel wire rope sling and the first section of the first steel wire rope sling with a shackle swivel; follow the above method until the entire sling The first wire rope slings of each section of the pre-laid anchor cable are all laid and connected;

6) Accessory connection: With the assistance of the second excavator, connect the anchor head cable and the second wire rope sling respectively; then connect the floating ball and floating ball group with nylon rope at the corresponding position, and connect the warning light;

7) Crane boat evacuation: After the two pre-laid anchor cables are all laid, the second excavator returns to the crane boat; the crane boat leaves the sandbar area at high tide after rising water and returns to the dock.

The above steps 4-6 are carried out at low tide and on the beach; before the high tide, the second excavator is withdrawn to the crane ship and is on standby; after the low tide is on the beach again, disembark and continue construction.

The beneficial effects of the present invention are: the laying of the pre-laid anchor cables can be carried out before the laying of the cables at sea, without taking up the main operation time; Therefore, under the condition that the water depth meets the requirements of sailing during a high tide, the ship can be sailed uninterrupted to maximize the efficiency of cable laying; thus ensuring that the cable laying ship can cross the sandbar section to complete the cable laying construction during a big tide.

Description of drawings

Further details will be given below in conjunction with the accompanying drawings and specific embodiments.

Fig. 1 is the plane layout diagram of Embodiment 1 of the present invention;

Fig. 2 is the layout drawing of the cable-laying ship on the ship's side of the first embodiment;

Fig. 3 is the plane layout drawing of the second embodiment of the present invention;

Fig. 4 is the layout drawing of the cable-laying ship of the stern of the second embodiment;

Figure 5 is a schematic diagram of the composition and connection of pre-laid anchor cables;

Fig. 6 is the loading layout of the crane ship;

Fig. 7 is a schematic diagram of a crane ship anchored in place;

Fig. 8 is a schematic diagram of disembarking the second excavator;

Fig. 9 is a schematic diagram of the second excavator transporting the anchor;

Fig. 10 is a schematic diagram of laying the main wire rope by the second excavator.

Among them: 1- cable design route; 2- pre-laid anchor cable; 3- cable laying ship; 4- winch mill; 5- sandbar area; 6- main direction; 7- cable; 8- small boat; 9- crane ship ;21-anchor; 22-anchor shackle; 23-anchor cable; 31-electric cable storage reel; 32-cable laying line; 33-buried plow; 34-starboard anchor cable; -Second excavator; 92-Ladder structure; 231-First wire rope rigging; 232-Shackle swivel; 233-Second wire rope rigging; 234-Ordinary shackle; ; 237-anchor head cable; 238-nylon rope; 239-warning light; 2311-roller.

Detailed ways

As shown in Fig. 1 and Fig. 3, a pre-laid anchor cable 2 assisted sailing method for a long-distance sandbar section includes the following steps:

1) Two pre-laid anchor cables 2 are pre-laid on both sides of the cable design route 1 across the sandbar area 5.

2) Prearrange and install two winch mills 4 on the cable laying ship 3 .

3) Before the arrival of the big tide, when the cable-laying ship 3 sails to the beginning of the pre-laid anchor cable 2, the beginning of the pre-laid anchor cable 2 is salvaged to the deck of the cable-laying ship 3, and connected to the winch 4.

4) When the tide rises until the water depth meets the requirements for sailing, start the winch mill 4 to twist the cable, and the cable laying ship 3 continues to sail along the cable design route 1 while laying and burying the cable.

5) When the ebb tide does not meet the requirements for sailing, stop the cable laying, and the cable laying ship sits on the beach and waits for the next high tide.

6) Cycle according to steps 4 and 5. During the flood season, the cable laying ship 3 uses the high tide to cross the long-distance sandbar area 5 and the cable laying construction is completed.

The length of the pre-laid anchor cables 2 is sufficient to cross the sandbar area 5, and the two pre-laid anchor cables 2 are parallel to the cable design route 1, and keep a distance of 100m.

The distance between the two pre-laid anchor cables 2 close to the starting ends is gradually reduced until the distance between the two pre-laid anchor cables 2 is approximately the same as the distance between the two winch mills 4 on the cable-laying ship 3 .

As shown in Fig. 1 and Fig. 2, embodiment 1: for the situation that the main direction 6 of the construction sea area is substantially perpendicular to the cable design route 1, the cable laying ship 3 that goes out from the ship's side should be used. Two winch mills 4 are installed on the port deck of the cable laying ship 3, and the cables 7 from the electric cable storage reel 31 go out from the starboard side through the cable laying operation line 32, and are buried below the seabed by the laying plow 33. The pre-laid anchor cable 2 provides continuous power for the cable-laying ship 3 to sail through the twisted cable of the winch mill 4, and the two starboard anchor cables 34 of the cable-laying ship 3 control the cable-laying ship 3 not to deviate excessively from the cable design route 1. The anchor lifting and handling of the starboard anchor cable 34 is carried out by the first excavator 35 disembarking when the low tide is exposed.

The hull of the cable-laying ship 3 is generally along the flow direction, and the flow force is relatively small, which is overcome by the anchor cable 34 on the starboard side; In the time of water depth condition, the efficiency of laying and burying the cable 7 is greatly improved.

As shown in Fig. 3 and Fig. 4, embodiment 2: for the situation that the main direction 6 of the construction sea area is basically consistent with the direction of the cable design route 1, it is advisable to use the cable laying ship 3 with the cable coming out from the stern. Two winch mills 4 are installed on the bow deck of the cable-laying ship 3 and arranged symmetrically. The cable 7 from the electric cable storage reel 31 goes out from the stern of the ship through the cable laying operation line 32, and is buried below the seabed by the embedding plow 33. The pre-laid anchor cable 2 provides continuous power for the cable-laying ship 3 to sail through the twisted cable of the winch mill 4. There is a small boat 8 on both sides of the cable-laying ship 3 to control the cable-laying ship 3 so as not to deviate excessively from the cable design route 1.

The hull of the cable-laying ship 3 is generally along the flow direction, and the flow force is small, and is overcome by two small boats 8; the sailing of the cable-laying ship 3 relies on the pre-laid anchor cable 2 across the sandbar area 5 to provide power, so it can fully use the high tide to meet the requirements of sailing. In the time of water depth condition, the efficiency of laying and burying the cable 7 is greatly improved.

As shown in Figure 5, a pre-laid anchor cable system for a long-distance sandbar section consists of a ship anchor 21, an anchor cable 23 connected to the ship anchor 21 through an anchor shackle 22 at one end, and is characterized in that the anchor cable 23 includes several first A wire rope sling 231 and a shackle swivel 232 connecting two adjacent first wire rope slings 231 .

Each first steel wire rope rigging 231 is wound on the drum 2311, and the weight is appropriate, which is convenient to use the second excavator 91 to lift and the first steel wire rope rigging 231 to pull and release; use the shackle swivel 232 to connect the two first steel wire ropes The tool 231 is conducive to releasing the torsion force when the first wire rope rigging tool 231 is pulled and released.

The other end of the anchor cable 23 is connected to one end of a second wire rope sling 233 through a common shackle 234 . The other end of the second wire rope rigging 233 is connected with a floating ball group 235 with a nylon rope 238 . The length of the second wire rope rigging 233 is not less than the sum of the water depth at high tide and the freeboard height of the cable-laying ship 3, and an appropriate margin is left.

One end of an anchor cable 237 is connected to the anchor shackle 22; the other end of the anchor cable 237 is connected 238 with a float group 235 by a nylon rope. A nylon rope 238 is used to connect a floating ball 236 near the position of the shackle swivel 232; a warning light 239 is fastened on the floating ball 236. The connection length of the nylon rope 238 is determined by more than two thirds of the volume of the floating ball 236 or the floating ball group 235 when the highest water level is met. The floating ball group 235 is composed of no less than two floating balls, and each floating ball is painted with a different color; a warning light 239 is tied to the floating ball group 235 .

The floating ball 236 and the floating ball group 235 mark the position of the pre-laid anchor cable 2 during the day, and the warning light 239 installed on it marks the position of the pre-laid anchor cable 2 at night, which is convenient for passing ships to observe and avoid.

As shown in Fig. 6-Fig. 10, the present invention proposes a kind of pre-laid anchor cable 2 laying construction method of long-distance sandbar section, comprises the following steps:

1) Shipment transportation: at the wharf, all parts of the pre-laid anchor cable 2 including the anchor 21, the first wire rope sling 231, the float group 235, and the float 236 are all loaded on the deck of the crane ship 9 , the second excavator 91 is boarded, and then the crane ship 9 is transported to the vicinity of the offshore installation location; wherein each first wire rope sling 231 is wound on a drum 2311, which is convenient for hoisting, transportation, and on-site layout;

2) Crane ship 9 is on the beach: when the crane ship 9 sails to the cable design route 1 across the sandbar area 5 and anchors in place when it is at high tide; after low tide, the crane ship 9 is on the beach;

3) The second excavator 91 disembarks: after the ebb tide and the beach, the crane of the crane ship 9 assists in hoisting and erecting the ladder structure 92, and the second excavator 91 disembarks along the ladder structure 92;

4) hoisting the anchor 21 in place: the lifting ship 9 lifts the anchor 21 outside the lifting ship 9, lifts the anchor 21 by the second excavator 91, and transports it to the place where the anchor cable 2 is pre-laid under the guidance of GPS navigation. Anchor position, and placed on the tidal mud surface;

5) Laying of the first wire rope rigging 231: the second excavator 91 returns to the vicinity of the crane ship 9, hoists a drum 2311 with the first wire rope rigging 231 hoisted by the crane ship 9 to the vicinity of the anchor position; One end of the first wire rope sling 231 is connected with the ship anchor 21 with the anchor shackle 22; the second excavator 91 hangs the drum 2311 and travels along the pre-laid anchor cable 2 design laying track, and simultaneously lays the first anchor cable along with the rotation of the drum 2311. Wire rope sling 231, until this section of the first wire rope sling 231 all breaks away from the drum 2311; according to the above method, the second section of the first wire rope sling 231 is laid, and the second section of the first steel wire rope 231 and the first section of the first section A wire rope sling 231 is connected with a shackle swivel 232; according to the above method, until the first wire rope sling 231 of each section of the whole pre-laid anchor cable 2 is all laid and connected;

6) Accessory connection: with the assistance of the second excavator 91, respectively connect the anchor head cable 237 and the second wire rope sling 233; then connect the floating ball 236 and the floating ball group 235 with a nylon rope 238 at the corresponding position, and connect the warning light 239;

7) Lifting ship 9 withdraws: after two pre-laid anchor cables 2 are all laid out, the second excavator 91 returns to the lifting ship 9; pier.

The above 4-6 steps are carried out when the low tide is exposed; before the high tide, the second excavator 91 is withdrawn to the crane ship 9 and is on standby; after the low tide is exposed again, disembark to continue construction.

Claims (18)

1. A pre-laying anchor cable auxiliary ship-moving method for a long-distance sandbar section is characterized by comprising the following steps:

1) two pre-laid anchor cables are pre-laid on two sides of a cable design route spanning a sandbank area;

2) arranging and installing two winching machines on a cable laying ship in advance;

3) before a flood comes, a cable laying ship travels to the position of the starting end of the pre-laid anchor cable, the starting end of the pre-laid anchor cable is salvaged to a deck of the cable laying ship, and a winching machine is connected;

4) when the condition of rising tide to water depth meets the requirement of a traveling ship, starting a winch for stranding, and continuously traveling the ship along the cable design route by a cable laying ship while laying and burying the cable;

5) when the water depth condition from the tide to the water depth does not meet the requirement of sailing, stopping stranding, laying a cable boat and sitting on the beach, and waiting for the next tide rising;

6) and (5) circulating according to the steps 4 and 5, and finishing cable laying construction of the cable laying ship by utilizing high tide to pass through the long-distance sand continent section in the flood season of the flood tide.

2. The method for assisting the sailing of the pre-laid anchor cable across the long-distance sandbank section according to claim 1, wherein: and the two winching machines are arranged on the ship board deck in the advancing direction of the cable laying ship for the cable laying ship with the side cable outlet.

3. The method for assisting the sailing of the pre-laid anchor cable across the long-distance sandbank section according to claim 1, wherein: the two winching machines are arranged on a bow deck and symmetrically arranged for the cable laying ship with the stern cable outlet.

4. The method for assisting the sailing of the pre-laid anchor cable across the long-distance sandbank section according to claim 1, wherein: the two pre-laid anchor lines are of sufficient length to traverse the sandbar section.

5. The method for assisting the sailing of the pre-laid anchor cable across the long-distance sandbank section according to claim 1, wherein: the two pre-laid anchor cables are parallel to the cable design route and keep a distance of 100m-250 m.

6. The method for assisting the sailing of the pre-laid anchor cables across the long-distance sandbars according to claim 1, wherein the distance between the two pre-laid anchor cables near the beginning is gradually decreased until the distance between the beginning of the two pre-laid anchor cables is approximately the same as the distance between two winches on the cable-laying ship.

7. The pre-laid anchor cable system for the long-distance sandbar section comprises a ship anchor and an anchor cable, wherein one end of the anchor cable is connected with the ship anchor through an anchor shackle.

8. The pre-laid anchor line system composition for long-reach sandbars according to claim 7, wherein the other end of the anchor line is connected to one end of a second wire rope rigging by a conventional shackle.

9. The pre-laid anchor line system composition of claim 8, wherein the other end of the second wire rope rigging is connected to a buoyant ball group with nylon rope.

10. The pre-mooring anchor line system composition for long-distance sandbars according to claim 8, wherein the length of the second wire rope is not less than the sum of the water depth at high tide and the freeboard height of the mooring vessel, and a proper margin is left.

11. The pre-laid anchor line system assembly of claim 7, wherein the anchor shackle is connected to an end of an anchor line.

12. The pre-laid anchor line system composition for long-reach sandbars according to claim 11, wherein the other end of the anchor line is connected to a buoyant ball group with nylon rope.

13. The pre-laid anchor line system assembly of a long-haul sandbank section of claim 7, wherein a float ball is attached to the shackle near the location of the shackle.

14. The system of claim 9 or 12, wherein the floating ball group comprises at least two floating balls, and each floating ball is painted with different colors.

15. The pre-laid anchor line system composition of a long-reach sandbank section according to claim 9, 12 or 13, wherein the connection length of the nylon rope is determined by the volume of more than two thirds of the floating ball floating above the water surface when the highest water level is met.

16. A pre-laid anchor line system for long-haul sandbars as claimed in claim 9, 12 or 13 wherein a warning light is attached to said float ball or float ball set.

17. A pre-laid anchor cable laying construction method for a long-distance sandbar section is characterized by comprising the following steps:

1) shipping and transporting: loading each part assembly of a pre-laid anchor cable comprising a ship anchor, a first steel wire rope, a floating ball group and a floating ball on a deck of a crane ship at a wharf, loading a second excavator on the ship, and transporting the crane ship to the position near the offshore installation position; each first steel wire rope is wound on a roller, so that the hoisting, transportation and field laying are facilitated.

2) The crane ship sits on the beach: the crane ship sails to a position near a cable design route crossing sandbar section by utilizing high tide and is anchored in place; after the tide falls, the crane ship sits on the beach.

3) The second excavator is launched: after the tide is removed and the dew is exposed, the hoisting boat crane assists to hoist and set up the ladder stand structure, and the second excavator is driven to descend along the ladder stand structure.

4) Hoisting the ship anchor in place: the crane ship lifts the ship anchor out of the crane ship, the ship anchor is lifted by a second excavator, and the ship anchor is conveyed to an anchor position of a pre-laid anchor cable under the guidance of GPS navigation and is placed on the mud surface of the mud flat.

5) Laying a first steel wire rope rigging: the second excavator returns to the position near the crane ship, and a roller which is hung by the crane ship and is coiled with a first steel wire rope is hoisted to the position near the anchor position; connecting one end of a first steel wire rope tool with the anchor shackle for the ship anchor; the second excavator hangs the roller and runs along the designed laying track of the pre-laid anchor cable, and simultaneously a first steel wire rope rigging is laid along with the rotation of the roller until the first steel wire rope rigging is completely separated from the roller; laying a second section of first steel wire rope rigging according to the method, and connecting the second section of first steel wire rope rigging with the first section of first steel wire rope rigging by using a shackle swivel; according to the method, the first steel wire rope of each section of the whole pre-laid anchor cable is completely laid and connected.

6) Connecting accessories: under the assistance of a second excavator, an anchor head cable and a second steel wire rope rigging are respectively connected; then the nylon rope is used for connecting the floating ball and the floating ball group at corresponding positions and connecting the warning lamp.

7) And (3) evacuating the crane ship: after the two pre-laid anchor cables are completely laid, the second excavator returns to the crane ship; the crane ship leaves the sandbank area at the time of high water and high tide and returns to the wharf.

18. The construction method for laying anchor cables in advance for the long-distance sandbar according to claim 17, wherein the 4-6 steps are performed in low tide and open beach; before the flood tide, the second excavator withdraws the crane ship for standby; and taking the ship out for continuous construction after the tide is low again and the beach is exposed.