Abstract
A seabed plow capable of over-the-stern release and retrieval is usable in any of boulder clearing, trench cutting and backfill modes. In its boulder clearing mode, the plow uses its skid in torquing configuration followed by moldboards to push boulders out of the path to be trenched. In the trench cutting mode, the plow uses the skid in the same configuration with its share and moldboards for initial trench depth and the same share and moldboards with moldboard extensions for increasing trench depth in subsequent passes. In the backfill mode, the plow uses its skid in trench-straddling configuration following a blade with a passage designed to discharge fragmented spoil directly onto the pipe being covered. Thus, a single plow can be reconfigured for all modes for release and retrieval to and from a relatively small vessel without use of heavy lifting equipment.
Claims
1. A seabed-plow chassis, comprising: a. a substantially unitary, elongated member, comprising: 1. a substantially linear longitudinal axis; 2. a bottom surface; 3. a first end disposed at one end of the substantially linear longitudinal axis; and 4. a second end disposed at an opposite end of the substantially linear longitudinal axis; b. a skid mounted to the first end, the skid configured to support the first end of the elongated member above a seabed and to push boulders outward from a path traveled by the skid; c. a tool mounted to the elongated member towards the second end and extending outward from the elongated member, the tool comprising a curved portion; and d. a tow connection connected to the first end.
2. The seabed-plow chassis of claim 1, wherein: a. the first end of the elongated member defines a leading edge of the seabed-plow chassis; b. the tool is mounted to the second end of the elongated member in a trailing relationship to the skid; and c. the curved portion of the tool comprises a moldboard configured to clear boulders pushed by the skid further outward from a path on the seabed as the skid leads the tool along the path.
3. The seabed-plow chassis of claim 2, wherein the moldboard further comprises: a. a first moldboard extending from a first side of the elongated member; and b. a second moldboard extending from a second side of the elongated member opposite the first side of the elongated member.
4. The seabed-plow chassis of claim 1, wherein: a. the first end of the elongated member defines an aft end of the substantially unitary, elongated member; b. the tool further comprises a blade operatively connected to and spanning a predetermined portion of a bottom edge of the curved portion of the tool, the blade comprising: 1. a rear apex; and 2. a passage at its rear apex; c. the curved portion of the tool is sized and oriented to span a predetermined dimension of a trench, the curved portion of the tool further configured to cooperatively interact with the blade to sequentially collect, funnel inward, and release spoil lying outside of the trench downward into the trench as the blade and the curved portion of the tool lead the skid along the seabed; and d. the skid is configured to straddle the predetermined dimension of the trench.
5. The seabed-plow chassis of claim 1, wherein the skid further comprises: a. a crossbar mounted at the first end of the chassis, the crossbar comprising a first end and a second end; b. a first skid post connected to the first end of the crossbar; c. a first ski connected to a bottom of the first skid post; d. a second skid post connected to the second end of the crossbar; e. a second ski connected to a bottom of the second skid post.
6. The seabed-plow chassis of claim 1, wherein the tow end further comprises: a. a tow bar extending laterally from the first end of the elongated member; and b. a set of pulling line connection pulling points symmetrically arranged along a length of the tow bar.
7. The seabed-plow chassis of claim 1, further comprising a first transition surface extending between the skid and the tool, the first transition surface contoured to selectively pivot about a fulcrum on a stern of a vessel.
8. The seabed-plow chassis of claim 7, wherein: a. the fulcrum comprises roller; and b. the first transition surface contour comprises a set of continuous, symmetrically opposing longitudinal axis points aligned with the substantially linear longitudinal axis of the elongated member, the set of continuous, symmetrically opposing longitudinal axis points defining a contoured path adapted to maintain contact with the roller as the first transition surface crosses the roller.
9. The seabed-plow chassis of claim 7, wherein a vertical longitudinal cross-section of the first transition surface is concave.
10. The seabed-plow chassis of claim 7, wherein the bottom surface comprises the first transition surface.
11. The seabed-plow chassis of claim 7, further comprising a transition attachment mated to the bottom surface, the transition attachment further comprising: a. a transition surface comprising the first transition surface; and b. a non-transition surface on an opposing side of the transition attachment from the transition surface, the non-transition surface configured to allow the transition attachment to mate to the bottom surface.
12. The seabed-plow chassis of claim 7, further comprising a second transition surface extending between the skid and the tool.
13. The seabed-plow chassis of claim 12, wherein the shapes of each of the first and second transition surfaces and the weight of the elongated member are configured to cooperatively resist roll of the tool about the longitudinal axis of the elongated member.
14. The seabed-plow chassis of claim 12, wherein a longitudinal vertical cross-section of each of the first and second transition surfaces is concave.
15. The seabed-plow chassis of claim 12, wherein: a. the fulcrum comprises a roller; and b. a path defined by a set of continuous symmetrically opposite points of each of the first and second transition surfaces is contoured to maintain contact with the roller as the tool crosses the roller.
16. A method of performing a function subsea using a plow which comprises a seabed-plow chassis comprising a substantially unitary, elongated member comprising a substantially linear longitudinal axis, a bottom surface, a first end disposed at one end of the substantially linear longitudinal axis, and a second end disposed at an opposite end of the substantially linear longitudinal axis; a skid mounted to the first end, the skid configured to support the first end of the elongated member above a seabed and to push boulders outward from a path traveled by the skid; a tool mounted to the elongated member towards the second end, the tool extending outward from the elongated member and comprising a curved portion; and a tow connection connected to the first end comprising a set of pulling line connection pulling points symmetrically arranged in relation to the longitudinal axis of the chassis, the method comprising: a. propelling the plow on a deck of a vessel toward and across a fulcrum on a stern of the vessel; b. connecting a pulling line to a predetermined pulling line connection pulling point of the set of pulling line connection pulling points; c. releasing the plow into the sea; d. allowing the plow to rotate about the fulcrum as the plow crosses the fulcrum and is released from the fulcrum into the sea; e. lowering the released plow at a tow-line end of the pulling line toward the seabed via the pulling line; f. positioning the plow bow-forward in the direction of an initial seabed path; g. propelling the plow along the initial seabed path; h. using the tool to perform a subsea function subsea; and i. if a wider seabed path is desired, 1. repositioning the plow bow-forward in a direction opposite the initial seabed path direction and on a further seabed path along one of the two sides of the initial seabed path; 2. once so repositioned, propelling the plow along the further seabed path and using the tool to perform the subsea function subsea; and 3. repeating steps (i)(1)-(i)(2) until the desired seabed path width is achieved.
17. The method of claim 16, further comprising: a. raising the plow at the tow-line end toward the fulcrum on the stern of the vessel at another end of the tow line; and b. pulling the plow across the fulcrum onto the deck of the vessel.
18. The method of claim 16, wherein the chassis further comprises a first transition surface, the method further comprising placing the first transition surface and the fulcrum into contact as the first transition surface crosses the fulcrum during release of the tool into the sea from the vessel and during retrieval of the tool from the sea onto the vessel.
19. The method of claim 16, wherein the plow comprises a boulder clearing plow, the curved portion of the tool further comprises a moldboard, and the function further comprises clearing boulders from the seabed path, wherein: a. the method further comprises using the skid to push boulders outward of the initial seabed path traveled by the skid; and b. using the tool to perform the subsea function subsea further comprises using the moldboard to clear the boulders from the seabed path by pushing the boulders from the seabed path to one of the starboard and port sides of the plow.
20. The method of claim 16, wherein the plow comprises a backfill plow, the curved portion of the tool further comprises a moldboard, and the tool further comprises a blade operatively connected to and spanning a predetermined portion of a bottom edge of the curved portion of the tool, the blade comprising a passage at its rear apex, wherein using the tool to perform the subsea function subsea further comprises backfilling spoil into a seabed trench present within the seabed path by: a. propelling the blade to travel in a predetermined direction on the seabed along the initial seabed path; b. collecting spoil along the sides of the trench as the blade travels; c. funneling the collected spoil toward a rear apex of the blade; and d. allowing the funneled spoil to be discharged through an opening in the blade apex into the trench.
21. The method of claim 20, wherein a pipe is disposed in the trench, the method further comprising: a. allowing the funneled spoil to be discharged through the opening in the blade apex onto a top portion of the pipe in the trench; and b. fragmenting the discharged spoil before the discharged spoil reaches the pipe.
22. The method of claim 20, further comprising leveling the spoil after it is discharged into the trench.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0050] Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings in which:
[0051] FIG. 1 is a top, left, rear perspective view illustrating a chassis adapted for use in any of boulder clearing, trench cutting and backfill modes;
[0052] FIG. 2 is a bottom, right, front perspective view of the chassis of FIG. 1;
[0053] FIG. 3 is a side elevation view of the chassis of FIG. 1;
[0054] FIG. 4 is a top plan view of the chassis of FIG. 1;
[0055] FIG. 5 is a bottom plan view of the chassis of FIG. 1;
[0056] FIG. 6 is a top, left, front perspective view of a transition attachment for use with the chassis of FIG. 1;
[0057] FIG. 7 is a bottom, left, front perspective view of the transition attachment of FIG. 6;
[0058] FIG. 8 is a top plan view of the transition attachment of FIG. 6;
[0059] FIG. 9 is a side elevation view of the transition attachment of FIG. 6;
[0060] FIG. 10 is a top, left, front perspective view illustrating a skid configured for use in the boulder clearing mode and the first pass of a plow in trench cutting plow mode;
[0061] FIG. 11 is a top, left, front perspective view illustrating a crossbeam usable to convert two skids as seen in FIG. 10 into a skid configured for use in the backfill plow mode;
[0062] FIG. 12 is a front elevation view illustrating a skid configured for use in the second and subsequent passes of a plow in the trench cutting plow mode;
[0063] FIG. 13 is a top, right, rear perspective view illustrating the chassis of FIG. 1 used in the boulder clearing plow mode;
[0064] FIG. 14 is a bottom, right, front perspective view of the boulder clearing plow of FIG. 13;
[0065] FIG. 15 is a top plan view of the boulder clearing plow of FIG. 13;
[0066] FIG. 16 is a side elevation view of the boulder clearing plow of FIG. 13;
[0067] FIG. 17 is a front elevation view of the boulder clearing plow of FIG. 13;
[0068] FIG. 18 is a top, left rear perspective view of a typical keel plate for use with the boulder clearing plow of FIG. 13 and the backfill plow of FIG. 37;
[0069] FIG. 19 is a side elevation view of the boulder clearing plow of FIG. 13 during release from/retrieval to a vessel with the plow skid pivoting on the stern of a vessel;
[0070] FIG. 20 is a side elevation view of the boulder clearing plow of FIG. 13 during release from/retrieval to a vessel with the plow chassis angled portion pivoting on the stern of a vessel;
[0071] FIG. 21 is a side elevation view of the boulder clearing plow of FIG. 13 during release from/retrieval to a vessel with the plow transition attachment pivoting on the stern of a vessel;
[0072] FIG. 22 is a side elevation view of the boulder clearing plow of FIG. 13 during release from/retrieval to a vessel with the plow keel plates pivoting on the stern of a vessel;
[0073] FIG. 23 is a top plan view illustrating the boulder clearing plow of FIG. 13 positioned to clear a path through a field of boulders;
[0074] FIG. 24 is a graphic representation of a typical boulder clearance route pattern of the boulder clearing plow of FIG. 13;
[0075] FIG. 25 is a side elevation view of the boulder clearing plow of FIG. 13 in operation;
[0076] FIG. 26 is a top, left, rear perspective view illustrating the chassis of FIG. 1 used in the trench cutting plow mode;
[0077] FIG. 27 is a top plan view of the trench cutting plow of FIG. 26;
[0078] FIG. 28 is a side elevation view of the trench cutting plow of FIG. 26;
[0079] FIG. 29 is a front elevation view of the trench cutting plow of FIG. 26;
[0080] FIG. 30 is a top, left, front perspective view of a detachable share for use with the trench cutting plow of FIG. 26;
[0081] FIG. 31 is a bottom, right, rear perspective view of the detachable share of FIG. 30;
[0082] FIG. 32 is a vertical, longitudinal, center cross-sectional view of the detachable share of FIG. 30;
[0083] FIG. 33 is a side elevation view of the trench cutting plow of FIG. 26 during release from/retrieval to a vessel with the skid post passing over the stem of a vessel;
[0084] FIG. 34 is a side elevation view of the trench cutting plow of FIG. 26 during release from/retrieval to a vessel with the chassis angled portion passing over the stem of a vessel;
[0085] FIG. 35 is a side elevation view of the trench cutting plow of FIG. 26 during release from/retrieval to a vessel with the chassis transition surface and share attachment plates passing over the stem of a vessel;
[0086] FIG. 36 is a side elevation view of the trench cutting plow of FIG. 26 during release from/retrieval to a vessel with the moldboards passing over the stem of a vessel;
[0087] FIG. 37 is a top, left, front perspective view illustrating the chassis of FIG. 1 used in the backfill plow mode;
[0088] FIG. 38 is a top plan view of the backfill plow of FIG. 37;
[0089] FIG. 39 is a side elevation view of the backfill plow of FIG. 37;
[0090] FIG. 40 is a front elevation view of the backfill plow of FIG. 37;
[0091] FIG. 41 is a top, left, rear perspective view illustrating a spoil collecting blade for use with the backfill plow of FIG. 37;
[0092] FIG. 42 is a top, right, rear perspective view illustrating a flapper board for use with the backfill plow of FIG. 37;
[0093] FIG. 43 is a side elevation view of the backfill plow of FIG. 37 during release from/retrieval to a vessel with the plow skid pivoting on the stem of a vessel;
[0094] FIG. 44 is a side elevation view of the backfill plow of FIG. 37 during release from/retrieval to a vessel with the chassis angled portion pivoting on the stem of a vessel;
[0095] FIG. 45 is a side elevation view of the backfill plow of FIG. 37 during release from/retrieval to a vessel with the plow transition attachment pivoting on the stem of a vessel;
[0096] FIG. 46 is a side elevation view of the backfill plow of FIG. 37 during release from/retrieval to a vessel with the plow keel plates pivoting on the stem of a vessel.
[0097] FIG. 47 is a top plan view of the backfill plow of FIG. 37 in operation;
[0098] FIG. 48 is a side elevation view of the backfill plow of FIG. 37 in operation;
[0099] FIG. 49 is a top plan view illustrating the boulder clearing plow of FIG. 13 positioned to backfill a wide trench on a typical wide trench backfill route pattern; and
[0100] FIG. 50 is a side elevation view illustrating a plow suspended below the stern roller of a vessel.
[0101] FIG. 51 is a top, right, front perspective view of an externally mounted instrumented bottle embodiment of a BAS plow having no moldboards;
[0102] FIG. 52 is a front elevation view of a the BAS plow of FIG. 51;
[0103] FIG. 53 is a side elevation view of a the BAS plow of FIG. 51;
[0104] FIG. 54 is a top, left, rear perspective view of the BAS plow of FIG. 51;
[0105] FIG. 55 is a top plan view of a the BAS plow of FIG. 51;
[0106] FIG. 56 is a top, right, front perspective view of an externally mounted instrumented bottle embodiment of a BAS plow with moldboards mounted on a straight extension;
[0107] FIG. 57 is a front elevation view of a the BAS plow of FIG. 56;
[0108] FIG. 58 is a side elevation view of a the BAS plow of FIG. 56;
[0109] FIG. 59 is a top, left, rear perspective view of the BAS plow of FIG. 56;
[0110] FIG. 60 is a top plan view of a the BAS plow of FIG. 56;
[0111] FIG. 61 is a top, right, front perspective view of an externally mounted instrumented bottle embodiment of a BAS plow with moldboards mounted on an angled extension;
[0112] FIG. 62 is a front elevation view of a the BAS plow of FIG. 61;
[0113] FIG. 63 is a side elevation view of a the BAS plow of FIG. 61;
[0114] FIG. 64 is a top, left, rear perspective view of the BAS plow of FIG. 61;
[0115] FIG. 65 is a top plan view of a the BAS plow of FIG. 61;
[0116] FIG. 66 is a top, right, front perspective view of an internally mounted instrumented bottle embodiment of a BAS plow without boulder clearance boards;
[0117] FIG. 67 is a front elevation view of a the BAS plow of FIG. 66;
[0118] FIG. 68 is a side elevation view of a the BAS plow of FIG. 66;
[0119] FIG. 69 is a top, left, rear perspective view of the BAS plow of FIG. 66;
[0120] FIG. 70 is a top plan view of a the BAS plow of FIG. 66;
[0121] FIG. 71 is a trenching profile created by the BAS plow of FIG. 51;
[0122] FIG. 72 is a trenching profile created by the BAS plow of FIG. 56;
[0123] FIG. 73 is a trenching profile created by the BAS plows of FIGS. 61 and 66;
[0124] FIG. 74 is a schematic diagram illustrating the operation of the plow share tip sensor;
[0125] FIG. 75 is a schematic diagram illustrating the contents and operation of the instrumented bottle;
[0126] FIG. 76 is a side elevation view of a first/fifth sequential pivot of a BAS plow in release/retrieval from/to a vessel to/from the sea;
[0127] FIG. 77 is a side elevation view of a second/fourth sequential pivot of a BAS plow in release/retrieval from/to a vessel to/from the sea;
[0128] FIG. 78 is a side elevation view of a third sequential pivot of a BAS plow m release/retrieval from/to a vessel to/from the sea;
[0129] FIG. 79 is a side elevation view of a fourth/second sequential pivot of a BAS plow in release/retrieval from/to a vessel to/!from the sea; and
[0130] FIG. 80 is a side elevation view of a fifth/first sequential pivot of a BAS plow in release/retrieval from/to a vessel to/from the sea.
[0131] While the invention will be described in connection with preferred embodiments thereof, it will be understood that it is not intended to limit the invention to those embodiments or to the details of the construction or arrangement of parts illustrated in the accompanying drawings.
DETAILED DESCRIPTION
[0132] Single Mode and Multi-Mode Chasses
[0133] Turning first to FIGS. 1-5, a seabed-plow chassis 10 for use as a component of various seabed plows has an elongated member 11 adapted for mounting a skid on one of its ends 13 and one or more tools on its other end 15.
[0134] As seen in FIGS. 13-17, the chassis 10 is used in a first mode of operation as part of a boulder clearing plow 100. In the first mode 100, boulders B on or partially buried in the seabed are initially pushed by the skid 40 outward of the path P traveled by the skid 40. The tool includes moldboards 90 which push the boulders B initially pushed away by the skid 40 and other boulders B in the path of the moldboards 90 further outward as the skid 40 leads the moldboards 90 along the seabed S.
[0135] As seen in FIGS. 26-29, the chassis 10 is used in a second mode of operation as part of a trench cutting plow 200. In the second mode 200, the tool includes a plow share 210 and moldboards 90 which sequentially cut and move spoil M to create a trench T as the skid 40 leads the plow share 210 and the moldboards 90 along the seabed S.
[0136] As seen in FIGS. 37-40, the chassis 10 is used in a third mode of operation as part of a backfill plow 300. In the third mode 300, the tool includes a blade 310 and moldboards 90 which cooperate, as the blade 310 and moldboards 90 lead the skid 40 along the seabed S, to sequentially collect spoil M lying outside of the trench, funnel the collected spoil M inward, and release the funneled spoil M downward into the trench T.
[0137] The chassis 10 is uniquely configured to facilitate over-the-stern launch and retrieval of a plow 100, 200 or 300 from and to, respectively, the deck D of a vessel V and to and from, respectively, the seabed S. The movement of the plow 100, 200 or 300 from or to a resting place on the deck D of the vessel V to or from a point at which all contact of the plow 100, 200 or 300 with the vessel V is terminated is herein referred to as transition. Looking at FIGS. 15, 27 and 38, the plows 100, 200 or 300 described herein have longitudinal axes 101, 201 and 301, respectively. As shown, the longitudinal axes 101, 201 and 301 are aligned in parallel with their anticipated directions of movement on the seabed S. Looking at FIGS. 19-22, 33-36 and 43-46, the plow axes 103, 203 and 303 are aligned in the direction of transition of the plows 100, 200 and 300, respectively, on the deck D. As shown, the longitudinal axes 101, 201, and 103 of FIGS. 15, 27 and 38 are aligned with the transition axes 103, 203, and 303 of FIGS. 19-22, 33-36 and 42-46, respectively. The plows 100, 200 and 300 need not, however, be aligned on the deck D in the same orientation they assume in operation on the seabed S. Therefore, as used herein, a transition axis is any axis, longitudinal or not, which extends through a plow 100, 200 or 300 in a direction parallel to the anticipated direction of movement 39 of the plow during launch or retrieval.
[0138] It is preferred that the plows 100, 200 or 300 will have their weight distribution and the location of their surfaces which contact the deck D and the fulcrum/roller R on the stern of the vessel V during release or retrieval so coordinated as to resist roll of the plows 100, 200 or 300 about their respective transition axes 103, 203 and 303, respectively. As shown and described, the chassis 10, skid 40 and skid posts 45, transition attachment 70, moldboards 90 and keel plates 110 and 370 have various surfaces contoured to support their plows in sliding contact with the deck D and to pivot about the fulcrum/roller R on the stern of the vessel V as the plow 100, 200 or 300 crosses the fulcrum/roller R during release/retrieval of the plow. Other components can be used or specially added for the purpose.
[0139] Chassis Structure
[0140] Returning to FIGS. 1-5, a preferred embodiment of the chassis 10 can be used in any of the plow modes 100, 200 and 300 seen in FIGS. 13, 26 and 37, respectively. As best seen in FIGS. 1 and 2, in the preferred embodiment of the chassis 10, the skid and tool ends 13 and 15 of the elongated member 19 are substantially horizontal and joined by a midsection 27 which angles down from the skid end 13 to the tool end 15. A post receptacle 19 extends vertically through the skid end 13. Fork lift receptacles 21 extend widthwise across the top of the tool end 15 of the elongated member 11. One receptacle 21 is at the junction of the tool end 15 with the angled portion 17 of the elongated member 11. The other receptacle 21 is further to the rear of the elongated member 11 and immediately in front of a spaced pair of share connection plates 23 which extend above the elongated member 11.
[0141] A transition member 25 extends above the tool end 15 of the elongated member 11 between the fork lift receptacles 21. As best seen in FIG. 3, the top surfaces of the receptacles 21, the share connection plates 23 and the transition member 25 form a substantially continuous transition surface 27 useful for launch and recovery purposes as hereinafter explained in relation to the second/trench cutting mode 200.
[0142] Side extension plates 29 taper downwardly from the tool end 15 and a back flange plate 31 caps the tool end 15 of the elongated member 11. A share connection slot 33 extends through the bottom of the tool end 15 of the elongated member 11 between the share connection plates 23.
[0143] Looking at FIGS. 13-17, 26-29 and 37-40, each of the plows 100, 200 and 300 has pulling points 65, as shown on tow bars 67 extending laterally from the skid end 13 of the elongated member 11, for connection of a pulling line L to the plow 100, 200 and 300. Preferably, the pulling points 65 are symmetrically arranged in relation to the central longitudinal axes 101, 201 and 301 of the plows 100, 200 and 300 and are displaced from the points of contact of the plows 100, 200 and 300 with the deck D or roller R by a height less than a radius of the roller R to facilitate passage of the points of contact across the roller R.
[0144] Transition Attachment
[0145] Turning to FIGS. 6-9, a transition attachment 70 is configured to extend between the skid and tool ends 13 and 15 on the bottom of the elongated member 11 of the chassis 10 when the chassis is used in either of its first/boulder clearing or third/trench cutting modes 100 or 300 as seen in FIGS. 13, 26 and 37.
[0146] As shown in FIGS. 6-9, the transition attachment 70 extends in a generally horizontal wishbone shape with its tines 71 opening from its front to its rear ends 73 and 75. The top surface 77 of the transition attachment 70 is contoured to mate against the bottom surface 31 of the elongated member 11 of the chassis 10 against which the transition attachment 70 will be secured by pinning the transition member 25 of the chassis 10 between the transition clevis plates 83, as is best seen in FIGS. 16 and 39. The bottom surface 79 of the transition attachment 70 is contoured to make contact with and pivot about fulcrum R on the stern of a plow transporting/towing vessel V, seen in FIGS. 21 and 22 and 44 and 45, as the plow 100 or 300 crosses the fulcrum/roller R during its release from the vessel into the sea and during its retrieval from the sea onto the vessel.
[0147] The shape of the attachment bottom surface 79 and the weight of the elongated member 11 and attachment 70 are coordinated so as to resist roll of the chassis 11 about the plow transition axis 103 or 303 as the plow 100 or 300 moves on the deck D toward or away from the fulcrum R.
[0148] Preferably, the fulcrum R is a roller and, as best seen in FIG. 9, the vertical longitudinal cross-sections of the attachment bottom surface 79 are concave. Looking at FIGS. 16, 39 and 50, the radius of the concavity 79 is greater than the radius of the fulcrum R so as to facilitate passage of the transition attachment 70 across the fulcrum R during release and retrieval of the plows 100 and 300. Looking at FIG. 8, the concavity 79 is symmetric about a longitudinal vertical plane centered on the attachment 70. The surface 79 can have any shape as long as it provides paths which facilitate the over-the-stern release and retrieval of the plow 100 or 300. The paths may be linear or planar and are preferably symmetrically defined by continuous opposite points of the attachment bottom surface 79.
[0149] As shown, the front end 73 of the attachment 70 has a leading face 81 which is angled to smooth the transition to and from the skid end 13 of the elongated member 11 of the chassis 10. Back plates 85 are provided on the ends of the tines 71 for connection to the moldboards 90. The gap 87 between the tines 71 functions as a passageway for debris in the third/backfill mode 300, as is hereinafter explained.
Skid
[0150] Turning to FIGS. 10 and 11, a preferred embodiment of the skid 40 is adaptable for use in any of the plow modes 100, 200 and 300 seen in FIGS. 13, 26 and 37, respectively.
[0151] In FIG. 10, the skid 40 is shown configured for use in the first/boulder clearing and second/trench cutting modes 100 and 200, seen in FIGS. 13 and 26, respectively. When used in the first/boulder clearing or second/trench cutting mode 100 or 200, the parallel outer skis 41 of the skid 40 are in close proximity to each other, bolted on opposite sides of a center ski 43. In this bolted configuration, a head 51 can be mounted on the front of the skis 41 and 43 in either the first/boulder clearing mode or for a first pass, the second/trench cutting mode 100 or 200. Alternatively, as shown in FIG. 12, the outer skis 41 can be pivotally mounted on the center ski 43 using linkages 48 so that the outer skis 41 can be canted laterally upward from the center ski 43, provided the head 51 is not attached to the skis 41 and 43. The use of canted outer skis 41 is specially applicable to second and subsequent passes in this second/trench cutting mode 200, enabling the canted skis 41 to conform to the side walls of the trench T and facilitating the deepening of the trench T by a second and subsequent passes of the trench cutting plow 200. Thus, deeper trenches can be cut without need for a larger trenching plow.
[0152] In of the above bolted or pivotal configurations for the outer skis 41, whether or not the head 51 is used, a post 45, which is pinned in a receptacle 47 in the center ski 43, extends upward to a top 49 which is convex from front to back. As shown, the outer skis 41 have receptacles 47 which are the same as the center ski receptacles 47. When used in the first/boulder clearing mode 100, the boulder clearing head 51 is preferably added to the leading end of the skid 40 across the fronts of the skis 41 and 43. As shown, the leading faces 53 of the head 51 are angled rearward from a vertical, longitudinal center plane of the skid 40 and are tapered rearward from their top edges 55. The angled and tapered faces 53 will torque partially buried boulders out of the seabed and away from the skid 40 and, if necessary, allow the plow 200 to ride over a boulder B which strikes the head 51 below its top edges 55.
[0153] When used in the second/trench cutting mode 200, either the bolted configuration of the skis 41 or the pivotal configuration of the skis 41 in an uncanted condition can be used, preferably with the head 51 in place for the first pass of the plow 200. For subsequent passes, it is preferred that the pivotal configuration of the skis 41 be used in the canted condition without the head 51. In the second/trench cutting mode 200, trenches up to 25 meters wide can be cut using multiple passes.
[0154] In FIG. 11, a crossbeam 57 is shown for converting the outer skis 41 of the skid 40 shown in FIG. 10 for use in the third/backfill mode 300. In the backfill mode 300, a crossbeam 57 spaces a pair of open ended receptacles 63 apart from a center post 59 extending upward from the midpoint of the crossbeam 57. As seen in FIG. 37, two posts 45 are seated, one in each of the receptacles 47 of the two outer skis 41 as shown in FIG. 10. The posts 45 extend up from their respective outer skis 41, pass through their respective open ended receptacles 63 in the crossbeam 57 and are pinned with the skis 41 at the desired distance below the crossbeam 57. The crossbeam center post 59 is pinned in the chassis post receptacle 19 to set the desired height of the chassis 10 above the skis 41. The crossbeam 57 as shown has a front surface 61 configured to also serve as a spoil leveler in the backfill mode 300.
Boulder Clearing Plow and Methods
[0155] Looking at FIGS. 13-17, the boulder clearing plow 100 includes the chassis 10, the skid 40, the transition attachment 70 and the moldboards 90. The skid 40, in the configuration shown in FIG. 10 with the head 51 is mounted on and supports the skid end 13 of the chassis 10 above the seabed S. The moldboards 90 include primary, secondary and tertiary moldboards 91, 93 and 95 mounted on the tool end 15 of the chassis 10. The transition attachment 70 is mounted under the chassis 10 between the skid 40 and the primary moldboards 91.
[0156] As best seen in FIG. 13, in the first/boulder clearing mode 100 the chassis 10 is oriented upside down in comparison to its orientation as shown in FIGS. 1 and 2. That is, in the boulder clearing plow 100, the skid end 13 is lower than the tool end 15 of the elongated member 11 and the skid post 45 extends upward through the receptacle 19 in the skid end 13 of the chassis 10.
[0157] As seen in FIGS. 13-17, the primary moldboards 91, which may be permanently or detachably mounted on the tool end 15 of the chassis 10, are angled outward and rearward from the tool end 15 of the chassis 10 and the transition attachment 70. The secondary moldboards 93 are mounted below the primary moldboards 91 and the transition attachment 70 to increase the overall depth of the moldboards 91. The tertiary moldboards 95 are used when wider paths are to be cleared of boulders B. They are mounted at the free ends of the primary and secondary moldboards 91 and 93 and increase the length of the moldboards 90 for the full depth of the combined primary and secondary moldboards 91 and 93.
[0158] As best seen in FIGS. 13-15, when the tertiary moldboards 95 are used, a chassis extension 33 is connected by its front flange 35 to the back flange plate 31 of the chassis 10. A supporting structure 37 of beams and struts connects the chassis extension 33 to the tertiary moldboards 95. Recovery fins 97 are appended to the free ends of the moldboards 90. The fins 97 have divergingly arcute ends 99 for contact with the roller R during launch and recovery.
[0159] The boulder clearing plow 100 may also include keel plates 110, shown in detail in FIG. 18. The keel plates 110 have a vertical center plate 111 and horizontal base plates 113 which extend laterally from the center plate 111. The base plates 113 and the center plates 111 support a vertical mounting plate 115 at an angle complementary to the angle of the moldboards 90. This structure is reinforced by small and large vertical support plates 117 and 119. At least one keel plate 110 mounted on the front of and extending under each set of moldboards 90. As best seen in FIGS. 14, 15, 17 and 18, the keel plates 110 are mounted in parallel at the junctions of the secondary and tertiary moldboards 93 and 95. The primary function of the keel plates 110 is to steady the path of the boulder clearing plow 100 as the head 51 and moldboards 90 encounter boulders B, spoil M and/or other obstacles on the seabed S.
[0160] Turning to FIGS. 19-22 and 50, the over-the stern release (FIGS. 19-22) and retrieval (FIGS. 22-19) of the boulder clearing plow 100 from a vessel V to the seabed S or from the seabed S onto a vessel V, respectively, are illustrated. During release, the plow 100 is preferably and as shown initially positioned on the deck D with its moldboards 90 aft and the longitudinal axis 101 of the plow 100 aligned on the transition axis 103 of the plow 100. The skid 40 and keel plates 110 provide the initial contact points or surfaces of the plow 100 with the deck D. As seen in FIG. 19, as the plow 100 is propelled, by winch or other suitable push/pull equipment (not shown), along the deck D of the vessel V toward and across the fulcrum/roller R at the stern of the vessel V, when the keel plates 110 have cleared the fulcrum/roller R, the plow 100 drops onto the moldboard 90 and slides on the moldboards to the concave surface of the transition attachment 70, at which point the moldboards slide to the transition attachment 70 and the skid 40 begins to rise from the deck D. All contact between the plow 100 and the vessel V has transferred to the transition attachment 70 and the fulcrum/roller R of the vessel V. Looking at FIG. 20, as the transition attachment 70 travels travel sternward beyond the fulcrum/roller R, all contact between the plow 100 and the vessel V remains on the concave transition surface 79 of the attachment 70 and the fulcrum/roller R of the vessel V and the plow 100 continues to tip toward the sea and the skid 40 continues to rise. As seen in FIG. 21, as the attachment 70 travels further sternward on the fulcrum/roller R, all contact between the plow 100 and the vessel V is still between the transition attachment 70 and the fulcrum/roller R but the skid 40 is nearly vertical. Looking at FIG. 22, as the plow 100 continues to rotate on and travel across the fulcrum/roller R, the buoyancy of the sea water and the travel speed of the vessel V limit rotation of the plow 100. As the transition attachment 70 slides off the fulcrum/roller R, the skid 40 becomes the final contact with the fulcrum/roller R until the plow 100 is fully released at the end of a pulling line L to the seabed S.
[0161] Retrieval of the boulder clearing plow 100 at the end of the pulling line L from the seabed S is accomplished by reversal of the release method. As seen in FIG. 22, as the plow 100 is raised at the end of the line L toward the fulcrum/roller R on the stern of the vessel V, the skid 40 will first contact the fulcrum/roller R. As noted above, the pulling points 65 of the plow 110 are located so as to assure that the head 51 and skis 41 and 43 of the sled 40 will not hang-up on the fulcrum/roller R. Further contact with the fulcrum/roller R transfers sequentially to the transition surface 79 of the transition attachment 70 as seen in FIG. 21, the concave portion of the attachment transition surface 79 as seen in FIG. 20 and then along the bottom of the moldboards 90, as seen in FIG. 19, until they contact the keel plates 110 and the plow 100 has been pulled fully across the fulcrum/roller R and comes to rest with the skid 40 and keel plates 110 as the contact points on the deck D of the vessel V.
[0162] Turning to FIG. 23-25, the use of the boulder clearing plow 100 to clear boulders B from a path P on the seabed is illustrated. As seen in FIG. 24, the plow 100 is positioned with the plow 100 bow-forward in the direction of an initial seabed path P.sub.1 which will be at the center of the intended final path P. The pattern of the final path P spirals out from the initial path P.sub.1. The plow 100 is then propelled, perhaps at the end of the pulling line L, powered by a winch or by the travel of the vessel, along the initial path P.sub.1 to clear boulders B from the initial path P.sub.1 to the port and starboard sides of the plow 100. After the initial path P.sub.1 is cleared, boulder clearing continues, if a wider path P is necessary, by repositioning the plow 100 bow-forward, for travel in a direction opposite the initial seabed path direction, on a second seabed path P.sub.2 along, as shown, the starboard side of the initial path P.sub.1. The plow 100 is then propelled along the second path P.sub.2 to clear boulders in the second path P.sub.2 further away from the path P.sub.1. After the second path P.sub.2 is cleared, boulder clearing continues, if a wider path P is necessary, by repositioning the plow 100 bow-forward, for travel in the direction of the initial seabed path direction, on a third seabed path P.sub.3 along the port side of the initial path P.sub.1. The plow 100 is then propelled along the third path P.sub.3 to clear boulders from the third path P.sub.3 further away from the first path P1. If a still wider path P is necessary, boulder clearing can further include repeating the widening along the path P resulting from the contiguity of the initial, second and third paths P.sub.1, P.sub.2 and P.sub.3, as shown along paths P.sub.4 and P.sub.5. The boulder clearing process anticipates repetition of the widening steps to widen successively contiguous paths P.sub.r, until a single path P of desired width has been cleared along the seabed.
[0163] Looking at FIG. 25, as the head 51 strikes one or more boulders B in its initial path P.sub.1, the boulders B will be torqued out of the seabed and around the port or starboard side of the head 51, depending on which side of the head 51 strikes the boulders B. The trailing moldboards 90 will torque and push the boulders B further to port or starboard away from the plow 100. On ensuing paths P.sub.2-11, only the outside of the head 51 and the outside moldboards 90 are on a path to strike the boulders B, pushing them further away from the initial path P.sub.1. As seen in FIG. 22, boulders B which have been pushed aside will be deposited in a small spoil heap H created aft of the plow 100 by the partial penetration of the seabed by the moldboards 90.
Trench Cutting Plow and Methods
[0164] Looking at FIGS. 26-29, the trench cutting plow 200 includes the chassis 10, the skid 40, the moldboards 90 and the share 210. The skid 40, in the configuration shown in FIG. 10, is mounted on and supports the skid end 13 of the chassis 10 above the seabed. The moldboards 90 initially include only the primary moldboards 91 mounted on the tool end 15 of the chassis 10. If more than one pass of a trench cutting plow 200 is to be performed, the secondary and tertiary moldboards 93 and 95 can be added. Wedges (not shown) can be positioned between the chassis 10 and the moldboards 90 to angle the moldboards at a desired angle upward and rearward from the chassis 10 for second and subsequent passes of the plow. The transition attachment 70 is not used. As shown, the head 51 may optionally be attached to the skid 40 in the first pass of the second/trench cutting mode 200.
[0165] As best seen in FIG. 20, in the second/trench cutting mode 200 the chassis 10 is oriented right-side up as shown in FIGS. 1 and 2. That is, in the trench cutting plow 200, the skid end 13 is higher than the tool end 15 of the elongated member 11 and the skid post 45 extends upward through the receptacle 19 in the skid end 13 of the chassis 10.
[0166] The plow share 210 may be permanently or detachably mounted on the chassis 10. A preferred embodiment of the share 210 shown in FIGS. 26-32 includes a shoe box 211 joining the bottoms of center ribs 213 and side plates 215 which support the parting plates 217 of the share 210. A vertical plate 219 aligned with the shoe box 211 extends upwardly above the parting plates 217 and is inserted between the share connection plates 23 on the chassis 10. A pin 221 inserted through a boss 223 on the vertical plate 219 and the connection plates 23 secures the share 210 to the chassis 10.
[0167] Turning to FIGS. 33-36, the over-the stern release (FIGS. 36-33) and retrieval (FIGS. 33-36) of the trench cutting plow 200 from the vessel V to the seabed S and from the seabed S onto the vessel V, respectively, are illustrated. During release, the plow 200 herein described is initially positioned upside down on the deck D with moldboards 90 aft and the longitudinal axis 201 of the plow 200 aligned on the plow's transition axis 203. The arcuate top 49 of the skid post 45 and the free ends of the moldboards 90 provide the initial contact points or surfaces with the deck D. As seen in FIG. 36, as the plow 200 is propelled, by winch or other suitable push/pull equipment (not shown), along the deck D of the vessel V toward and across the fulcrum/roller R at the stern of the vessel V, only the moldboards 90 and the arcuate top 49 of the post 45 will remain in contact with the fulcrum/roller R until the share connection plates 23 reach the fulcrum/roller R. As seen in FIG. 35, as the plow 200 continues sternward travel, only the tops of the share connection plates 23 followed by the trailing top or transition surface 27 of the transition member 25 and the arcuate top 49 of the post 45 will remain in contact with the fulcrum/roller R. As seen in FIG. 34, as the center of gravity of the plow 200 has passed the fulcrum/roller R, the cantilevered weight of the plow 200 causes the plow 200 to pivot on the transition surface 27 of the transition member 25, allowing the moldboards 90 to drop toward the seabed S and the skid post 45 to rise from the deck D. At this point in transition, all contact between the plow 200 and the vessel V transfers to the angled portion 17 of the chassis elongated member 11 and the fulcrum/roller R of the vessel V. Looking at FIG. 33, after the angled portion 17 of the chassis elongated member 11 has traveled sternward beyond the fulcrum/roller R, the plow 200 will have rotated further toward the seabed S and all further contact between the plow 200 and the vessel V will have transferred to the arcuate top 49 of the skid post 45 and the fulcrum/roller R of the vessel V. The arcuate top 49 of the skid post 45 provides the final contact with the fulcrum/roller R as the plow 200 is fully released at the end of a pulling line L to the seabed S.
[0168] Retrieval of the trench cutting plow 200 at the end of the pulling line L from the seabed S is accomplished by reversal of the release method. As seen in FIG. 33, as the plow 200 is raised at the end of the line L toward the fulcrum/roller R on the stern of the vessel V, the arcuate top 49 of the skid post 45 will first contact the fulcrum/roller R. As noted above, the pulling points 65 of the plow 110 are located so as to assure that the post 45 will not hang up on the fulcrum/roller R. Further contact with the fulcrum/roller R transfers sequentially to the angled portion 17 of the chassis elongated member 11 as seen in FIG. 34, to the transition surface 27 as seen in FIG. 35, and to the tops of the share connection plates 23 as seen in FIG. 36. When the plow 200 has been pulled fully across the fulcrum/roller R, it will come to rest with the arcuate top 49 of the skid post 45 and the tops of the free ends of the moldboards 90 as the contact points on the deck D of the vessel V.
Backfill Plow and Methods
[0169] Turning to FIGS. 37-40, for backfilling spoil into a seabed trench, the backfill plow 300 includes the chassis 10, the skid 40 configured to straddle the trench being backfilled, the moldboards 90 mounted on the chassis 10 forward of the skid 40 and the blade 310 mounted on and spanning the bottom edges of the moldboards 90.
[0170] As best seen in FIG. 37, in the third/backfill mode 300, the chassis 10 is oriented upside down in comparison to its orientation as shown in FIGS. 1 and 2. That is, in the backfill plow 300, the skid end 13 is lower than the tool end 15 of the elongated member 11, as in the first/boulder clearing mode 100 shown in FIG. 13, and the crossbeam center post 59 extends upward through the receptacle 19 in the skid end 13 of the chassis 10, similar to the post 45 in the first/boulder clearing mode 100 shown in FIG. 13. However, the chassis 10 is oriented in reverse in comparison to the first/boulder clearing mode 100 shown in FIG. 13, so that the skid 40 is at the trailing end of the backfill plow 300. In comparison to the first/boulder clearing mode 100, the skis 41 are also reversed in the third/boulder clearing mode 300 for forward travel in a trailing position.
[0171] As seen in FIGS. 37-40, in the third/backfill mode, the moldboards 90, including the primary moldboards 91, the secondary moldboards 93 and the tertiary moldboards 95, are mounted on the chassis 10 in the same way as described in relation to the first/boulder clearing mode 100 of FIGS. 13-17 by use of the chassis extension 33 and supporting structure 37. The transition attachment 70 is also mounted to the chassis 10 in the same manner as described in relation to the first/boulder clearing mode 100 of FIGS. 13-17. The recovery fins 97 are appended to the free ends of the tertiary moldboards 95 as described in relation to the first/boulder clearing mode 100 of FIGS. 13-17.
[0172] Looking at FIG. 41, the blade 310 has a passage 311 at its rear apex 313. The passage 311 is configured to dispense the spoil collected by the blade 310 and funneled by the moldboards 90 onto the top of a pipe or cable C disposed in the trench T below the passage 311. The side edges of the blade 310 are secured to the lower portions of their respective moldboards 90 by use of side plates 315 and to the chassis extension 33 by use of an upright mounting structure 317. The mounting structure 317 is centered on the leading edge 319 of the blade 310 and, as shown, extends from the blade edge 319 to the passage 311. The blade 310 may be stiffened by ribs 321. As shown, the passage 311 is slightly greater than semi-circular with a diameter 323 parallel to the blade leading edge 319. The stiffening ribs 321 fan out from points along the passage circumference 325 to respective points along the blade leading edge 319.
[0173] Looking at FIG. 42, the backfill plow 300 preferably further includes a flapper board 340 aft of the passage 311. The flapper board 340 includes a plate 341 fixed to and swinging below a horizontal shaft 343. The shaft 343 is journalled to reciprocate on an axis parallel to the passage diameter 323. A weight 345 biases the plate 341 toward a vertical orientation. The slapping action of the flapper board 340 fragments spoil discharged through the blade passage 311. Large and small stiffeners 347 and 349 reinforce the plate 341. The reciprocating swing of the plate 341 on its shaft 343 is caused as water and spoil discharging through the passage 311 swings the plate 341 toward the rear and the weight 345 causes the plate 341 to swing back toward vertical.
[0174] The backfill plow 300 may also include keel plates 370, at least one keel plate 370 extending on opposite sides of the spoil passage 311. The keel plates 110, shown in FIG. 18 for use in the first/boulder clearing mode 100, can be used in the third/backfill mode 300 except that, in the backfill mode 300, they are mounted on the front of the moldboards 90 and extend under the blade 310. As seen in FIGS. 38-40, the keel plates 370 are mounted in parallel at the junctions of the secondary and tertiary moldboards 93 and 95. The primary function of the keel plates 370 is to steady the path of the backfill plow 300 as the blade 310 and moldboards 90 encounter and collect spoil M on the seabed S.
[0175] Turning to FIGS. 43-46, the over-the stern release (FIGS. 46-43) and retrieval (FIGS. 43-46) of the backfill plow 300 from a vessel V to the seabed S or from the seabed S onto a vessel V, respectively, are illustrated. During release, the plow 300 described herein is initially positioned on the deck D with moldboards 90 aft and the longitudinal axis 301 of the plow 300 aligned on the transition axis 303 of the plow 300. The skid 40 and bottoms of the keel plates 370 provide the initial contact points with the deck D. As seen in FIG. 46, as the plow 300 is propelled, by winch or other suitable push/pull equipment (not shown), along the deck D of the vessel V toward and across the fulcrum/roller R at the stern of the vessel V, the keel plates 370 clear the fulcrum/roller R, allowing the moldboards 90 to drop toward the seabed S. The plow begins to pivot on the transition surface 79 and the skid 40 begins to rise from the deck D. At this point in transition, all contact between the plow 300 and the vessel V has transferred to the transition attachment 70 and the fulcrum/roller R of the vessel V. Looking at FIG. 45, as the plow 300 travels further sternward across the fulcrum/roller R, all contact between the plow 300 and the vessel V has transferred to the concave portion of the transition surface 79 of the attachment 70 and the fulcrum/roller R of the vessel V. As seen in FIG. 44, as the attachment 70 has traveled sternward beyond the fulcrum/roller R, all contact between the plow 300 and the vessel V remains on the angled portion 17 of the chassis elongated member 11 and the fulcrum/roller R of the vessel V. The plow 300 has tipped so that the skid 40 nears vertical. Looking at FIG. 43, as the plow 300 continues to rotate on and travel across the fulcrum/roller R, the buoyancy of the sea water and the travel speed of the vessel V limit rotation of the plow 300 as the transition attachment 70 slides off the fulcrum/roller R. The shape of the attachment 70 affords a smooth transition from the transition surface 79 to the skid 40. The skid 40 becomes the final contact with the fulcrum/roller R until the plow 100 is fully released at the end of a pulling line L to the seabed S.
[0176] Retrieval of the backfill plow 300 at the end of the pulling line L from the seabed S is accomplished by reversal of the release method. As seen in FIG. 43, as the plow 300 is raised at the end of the line L toward the fulcrum/roller R on the stern of the vessel V, the skid 40 will first contact the fulcrum/roller R. As noted above, the pulling points 65 of the plow 300 are located so as to assure that the head 51 and skis 41 and 43 of the sled 40 will not hang up on the fulcrum/roller R. Further contact with the fulcrum/roller R transfers sequentially to the angled portion 17 of the chassis elongated member 11 as seen in FIG. 44, to the attachment transition surface 79 as seen in FIG. 45 and to the bottom of the keel plates 370 as seen in FIG. 46. When the plow 300 has been pulled fully across the fulcrum/roller R, it will come to rest with the skid 40 and keel plates 370 as the contact points on the deck D of the vessel V.
[0177] Turning to FIGS. 47 and 48, in backfilling spoil M to cover a pipe P laid in a seabed trench T, the backfill plow 300, with the blade 310 forward, is propelled to travel on the seabed S and collect spoil M along the sides of the trench T. The moldboards 90 funnel the collected spoil M toward the rear apex 313 of the blade 310 and the funneled spoil M is discharged through the passage 311 in the blade apex 313 and onto the top surface of the pipe P disposed in the trench T. Preferably, the discharged spoil M is fragmented, as shown by the flapper board 340, before the discharged spoil M reaches the pipe P and the spoil M discharged onto the pipe P and into the trench T is leveled by the front surface 61 of the skid crossbar 57. The use of the passage 311 to discharge the spoil M directly onto, rather than to the sides of, the pipe P reduces the likelihood that the more dense spoil M will lift the pipe P in the trench T during backfilling.
[0178] Turning to FIG. 49, for trenches wider than the widest span of the moldboards 90, the boulder clearing plow 100 seen in FIG. 13 can be used to narrow the width of the trench T. This is accomplished by aligning the longitudinal axis 101 of the plow 100 outside of the spoil M one side of the trench T, as shown with only the starboard moldboards 90 pushing the spoil M. On the first pass P.sub.a the spoil M in the path of the starboard moldboards will be pushed toward or into the trench T. When the first pass P.sub.a is completed, the plow 100 is aligned on the other side of the trench T, as shown again with only the starboard moldboards 90 pushing the spoil M. On the second pass P.sub.b, the spoil M in the path of the starboard moldboards will be pushed toward or into the trench T. When the second pass P.sub.b is completed, the process can be repeated for passes P.sub.a until the trench T is filled or until the trench T is sufficiently filled to complete backfilling using the backfill plow 300.
[0179] Turning to FIG. 50, the plows 100, 200 or 300 can be retrieved by use of the tow line L connected to the retrieval fins 97. Depending on which of the plows 100, 200 or 300 is retrieved, the orientation of the plow 100, 200 or 300 can be rotated 180 about the axis of the tow line L to a suitable retrieval position. In either 180 orientation, the arcuate ends 99 of the fins 97 will enable the plow 100, 200 or 300 to pass over the fulcrum/roller R.
[0180] The plows 100, 200 and 300 are made using steel plates which are welded, bolted or pinned, depending on the intended permanency or detachability of the components being connected. The same chassis 10, skids 40, transition attachment 70, moldboards 90, and keel plates 110 can be configured into three different modes of operation and the share 210 and blade 310 added as needed for their respective modes. The need for a large vessel, cranes and supporting equipment is eliminated since the plow modes 100, 200 and 300 are all capable of over-the-stern launch and recovery.
[0181] While the convention apparatus and methods have been described in relation to laying pipe, it is also applicable to laying cable. Furthermore, all of the plows 100, 200 and 300 can be adapted for use with a remotely operated vehicle (ROV) which can dock on the plow to provide additional mechanical functionality such as skid height adjustment or electrical functionality such as cameras, lights, and load measurement.
BAS Plow and Method
[0182] FIGS. 51-55, 56-60, 61-65 and FIGS. 66-70 illustrate a number of possible embodiments of an instrumented bottle-type BAS plow 400. The BAS plow embodiments shown in FIGS. 51-70 may all use the same chassis 10 and skid 40 hereinbefore described in relation to the trench cutting plow 200 of FIGS. 26-29. They all may also use the same plow share 210 hereinbefore described in relation to the trench cutting plow 200 of FIGS. 26-29, except that a BAS plow sensor 410 is added to the tip of the trench cutting plow share 210. Furthermore, if they use moldboards at all, they may use the same moldboards 90 hereinbefore described in relation to the trench cutting plow 200 of FIGS. 26-29 but, if used, they are mounted on either a straight BAS extension 430 or on an angled BAS extension 450 added at the tool end 15 of the chassis 10. The extensions 430 and 450 can be added to the chassis 10 of the BAS plow in a manner as described in relation to the extension 33 added to the boulder clearing plow 100 of FIGS. 13-15. In all of the BAS embodiments, an instrumented bottle 470 is added, externally or internally, to the chassis 10. The BAS plow can be structurally modified to eliminate or reduce spoil heaps created by digging the BAS plow trench. The self-backfilling embodiments of the BAS plow are especially beneficial when multiple routes, none of which may be used, are trenched and when seabed restoration and minimal seabed impact are desirable.
[0183] In FIGS. 51-55, the instrumented bottle 470 is mounted externally on the chassis 10 and the BAS plow 400 has no moldboards. As shown, the instrument bottle 470 is secured to the top of, and in longitudinal axial alignment with, the tool end 15 of the chassis 10. This is the most convenient embodiment of the BAS plow 400 because the trench cutting plow 200 can be created by merely adding the moldboards 90 to the BAS plow 400 after the burial assessment surveys are completed. The instrumented bottle 470 could be left on the trench cutting plow 200 or could, if desired, be removed. The trenching profile 500 resulting from the first pass of the BAS plow embodiment of FIGS. 51-55 is seen in FIG. 71 in which the V-trench 501 below the seabed 503 is flanked by the spoil 505 dispersed above the seabed 503 and extending the walls of the V-trench 501 above the seabed 503.
[0184] Looking at FIGS. 56-60, the instrumented bottle 470 is mounted externally on the chassis 10 of the BAS plow 400 and the mold boards 90 are mounted on the straight extension 430 of the tool end 15 of the chassis 10. This embodiment is used when it is desirable to backfill the trench created by the BAS plow 400 but is unlike the backfill plow 300 described in relation to FIG. 37. In the backfill plow 300, the moldboards 90 lead the skid 40 with the apex of the moldboards 90 directed at the skid 40. In the BAS plow 400 of FIGS. 56-60, the moldboards 90 trail the skid 40 with the apex of the moldboards 90 directed away from the skid 40. This is the opposite of the moldboards 90 of not only the backfill plow 300 of FIG. 37 but also of the trench cutting plow 200 of FIG. 26, so conversion of this embodiment of the BAS plow 400 to the trench cutting plow 200 would require removal of the extension 430 and moldboards 90 and attachment of the moldboards 90, if desired, directly to the chassis 10. As best seen in FIG. 60, the straight extension 430 is T-shaped. The T-shaped extension 430 has a leg 431 mounted on and extending rearward from the trailing end 15 of the chassis 10 and arms 433 extending outward from a trailing end of the leg 431. The moldboards 90 extend outward and forward from distal ends of the arms 433. As best seen in FIGS. 57 and 58, the bottom surfaces of the leg 431, the arms 433 and the moldboards 90 are in a common plane 435. This embodiment is especially useful when there are no large boulders on the pipeline or cable path. Large, as herein used, refers to boulders which would be expected not to fit within the cross-section of the trench. However, the elevation of the moldboards 90 can be adjusted on the arms 433 of the extension 430 to accommodate the sand/boulder content of the seabed and best backfill the trench. The trenching profile 510 resulting from the first pass of the BAS plow embodiment of FIGS. 56-60 is seen in FIG. 72 in which the V-trench 511 below the seabed 513 is filled with spoil or spoil and small boulders 515.
[0185] Looking at FIGS. 61-65, the instrumented bottle 470 is mounted externally on the chassis 10 of the BAS plow 400 and the mold boards 90 are mounted on the angled extension 450 of the tool end 15 of the chassis 10. This embodiment of the BAS plow 400 is similar to the embodiment of FIGS. 56-60 and is also used to backfill the trench created by the BAS plow 400. It is unlike the embodiment of FIGS. 56-60 in that, while T-shaped, the leg 451 of the T is angled rearward and upward to its arms 453 and the outer portions of the arms 453 of the arms 453 are angled outward and downward to the moldboards 90. Thus, the bottom surfaces of the leg 451 and the arms 453 define an arch 455 permitting spoil and large objects such as boulders to pass between the moldboards 90 and be deposited in and/or lie on the trench within the confines of the inner perimeter of the arch. The elevation of the moldboards 90 can be adjusted on the arms 453 of the extension 450 to accommodate the sand/boulder content of the seabed and best backfill the trench. The trenching profile 520 resulting from the first pass of the BAS plow embodiment of FIGS. 61-65 is seen in FIG. 73 in which the V-trench 521 below the seabed 523 is filled by the collected spoil or spoil and boulders 525 and covered by the collected spoil or spoil and boulders 527 which has passed through the arch 455.
[0186] Turning to FIGS. 66-70, the illustrated embodiment of the BAS plow 400 is in all respects the same as the embodiment illustrated in FIGS. 61-65, except that the instrumented bottle 470 is mounted internally in the chassis 10 of the BAS plow 400. As with the external bottle embodiments, the internal instrument bottle 470 is secured in longitudinal axial alignment with the tool end 15 of the chassis 10. The instrumented bottle 470 can similarly be mounted within the chassis 10 of the BAS plow 400 embodiments of FIGS. 51-55 and 56-60. The trenching profile 520 resulting from the first pass of the BAS plow embodiment of FIGS. 66-70 is seen in FIG. 73 in which the V-trench 521 below the seabed 523 is filled by the collected spoil or spoil and boulders 525 and covered by the collected spoil or spoil and boulders 527 which has passed through the arch 455.
[0187] As seen in FIGS. 51, 56, 61 and 66, in all configurations of the BAS plow herein shown and discussed, the sensor 410 is mounted on the tip of the plow share 210. Looking at FIG. 71, the tip of the sensor 410 houses a load cell 411 which calculates the shearing force applied by the tip of the plow 400 to the seabed 523. It measures the force required to shear the seabed material and feeds the data 481 back to a data logger 471 contained in the instrumented bottle 470. As seen in FIG. 72, the instrumented bottle 470 includes a power source 471, the data logger 473, a gyro 475 and a load sensors input 477. The gyro measures the pitch, roll, heading, yaw, three dimensional positioning and speed of the plow 400 and the V-trench depth. In addition, load cells 479 mounted on the tow points 65 of the skid 40 calculate the tow force applied to the plow 400 and this load cell data 483 is fed through the load cell input connection 477 to the data logger 473. The difference between the shearing force and the towing force measured at the plow chassis 10 is indicative of the proportion of the force that is actually cutting at the top of the plow share 40. All collected data is stored in the data logger 473 which can be swapped at regular intervals to download data or can be connected to the towing vessel V by an umbilical to provide a live data feed. Alternatively, a hydro-acoustic link could be used to transmit data, but the hydro-acoustic link would at best afford all is well signals due to the currently achievable slow transmission rates. The bottle instrumentation effectively monitors the BAS plow reaction to the seabed to image the orientation of the BAS plow 400 on the seabed. As the BAS plow 400 is towed along a possible pipeline or cable burial path, a continuous stream of data is acquired and stored to facilitate a plot of the tow force against the seabed surface position of the BAS plow 400.
[0188] The anchor-type plow share 210 herein described affords greater seabed penetration than knife-type seabed cutters. If still deeper trenches are desired, in any of the moldboard configurations of the BAS plow 400 the moldboards 90 can be extended by addition of tertiary moldboards 93 and 95, as is described in relation to the trench cutting plow 200 of FIGS. 26-29. This will facilitate multi-pass BAS plow use, as is also earlier explained in relation to the trench cutting plow 200 of FIGS. 26-29.
[0189] The various embodiments of the BAS plow 400 can be configured for release and retrieval over-the-stern using the principles hereinbefore described in relation to the boulder clearing/trench cutting/backfill plows 100/200/300, respectively. Looking at FIGS. 76-80, the over-the stern release (FIGS. 76-80) and retrieval (FIGS. 80-76) of the BAS plow 400, as shown with an internal instrumented bottle 470 and moldboards 90 mounted on a straight extension 430 as herein described, from the vessel V to the seabed S and from the seabed S onto the vessel V, respectively, are illustrated. During release, the plow 400 is initially positioned upside down on the deck D with moldboards 90 aft and the longitudinal axis of the plow 400 aligned on the plow's transition axis. The arcuate top 49 of the skid post 45 and the free ends of the moldboards 90 provide the initial contact points or surfaces with the deck D. As seen in FIG. 76, as the plow 400 is propelled, by winch or other suitable push/pull equipment (not shown), along the deck D of the vessel V toward and across the fulcrum/roller R at the stern of the vessel V, only the moldboards 90 and the arcuate top 49 of the post 45 will remain in contact with the fulcrum/roller R until the share connection plates 23 reach the fulcrum/roller R. As seen in FIG. 77, as the plow 400 continues sternward travel, only the tops of the share connection plates 23 followed by the trailing top or transition surface 27 of the transition member 25 and the arcuate top 49 of the post 45 will remain in contact with the fulcrum/roller R. As seen in FIG. 78, as the center of gravity of the plow 400 has passed the fulcrum/roller R, the cantilevered weight of the plow 400 causes the plow 400 to pivot, allowing the moldboards 90 to drop toward the seabed S and the skid post 45 to rise from the deck D. At this point in transition, all contact between the plow 400 and the vessel V transfers to the angled portion 17 of the chassis elongated member 11 and the fulcrum/roller R of the vessel V. Looking at FIG. 79, after the angled portion 17 of the chassis elongated member 11 has traveled sternward beyond the fulcrum/roller R, the plow 400 will have rotated further toward the seabed S and all further contact between the plow 200 and the vessel V will have transferred to the arcuate top 49 of the skid post 45 and the fulcrum/roller R of the vessel V. The arcuate top 49 of the skid post 45 provides the final contact with the fulcrum/roller R. As seen in FIG. 80, the plow 400 is fully released at the end of a pulling line L to the seabed S.
[0190] Retrieval of the BAS plow 400 at the end of the pulling line L from the seabed S is accomplished by reversal of the release method. As seen in FIG. 80, as the plow 400 is raised at the end of the line L toward the fulcrum/roller R on the stern of the vessel V, the arcuate top 49 of the skid post 45 will first contact the fulcrum/roller R. As noted above, the pulling points 65 of the plow 110 are located so as to assure that the post 45 will not hang up on the fulcrum/roller R. Further contact with the fulcrum/roller R transfers sequentially to the angled portion 17 of the chassis 10 as seen in FIG. 79, to the transition surface 27 as seen in FIG. 78, and to the tops of the share connection plates 23 as seen in FIG. 77. When the plow 400 has been pulled fully across the fulcrum/roller R, it will come to rest with the arcuate top 49 of the skid post 45 and the tops of the free ends of the moldboards 90 as the contact points on the deck D of the vessel V, as seen in FIG. 76.
[0191] The present method and apparatus are useful in the performance of burial assessment surveys. They are capable of producing continuous streams of data descriptive of the V-trench cross-sections of possible pipeline or cable paths. Since they create a V-trench which can be used as a first pass of a trench cutting process, they are also capable of reducing the total time required for combined BAS and actual pipeline or cable V-trench cutting processes. And, since they are also capable of enabling backfilling of a BAS V-trench, they can be used to perform burial assessment surveys without leaving a disrupted seabed when the trace is completed.
[0192] Thus, it is apparent that there has been provided, in accordance with the invention, a multi-mode seabed plow and plow release, operation and retrieval methods that fully satisfy the objects, aims and advantages set forth above. It is also apparent that there has been provided, in accordance with the invention, a method and apparatus for performing burial assessment surveys that fully satisfies the objects, aims and advantages set forth above. While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications and variations as fall within the spirit of the appended claims.
