GB2096065A - Push-towing of barges by tugs. - Google Patents

Abstract

In a system for releasably inter- locking tugs and barges, the tug (1) is provided with a bow having a predetermined rake and contour and the barge (2) is provided at its stern with a notch (3) having a configuration adapted to receive the bow of the tug in a close-fitting relationship. The barge is provided on each of its wings (5) defining the sides of the notch (3) at the stern with a rail (6), said rails extending in a transverse plane parallel to the rake of the tug bow. The tug is provided, in its bow region on both port and starboard sides, with hydraulically actuated clamps (4) in tug recesses which are engageable with the rails (6) on the barge (2) and optionally with rails on the tug (1) to hold the tug to the barge in a releasable manner. The barge may have a bow clamp attachment comprising an anchor pin (31), and the tug may have a coupling with a head which passes through a slot in the pin. <IMAGE>

Description

SPECIFICATION Improvements in or relating to the pushtowing of barges This invention relates to the push-towing of barges and is particularly concerned with releasable interconnections between tugs and barges.

Numerous proposals have been made for the releasable interlocking of tugs and barges and one prior system for this purpose is disclosed in my British Patent Specification No. 2053807. This prior system comprises releasably interlockable tugs and barges in which the tugs and barges are provided at port and starboard with fore-and-aft extending rails and channels so that when a tug is joined to a barge each of said rails fits into a respective complementary one of said channels. Lugs are provided on each side of each tug and complementary slots are provided at the rear of each barge so that when a tug is joined to a barge each of the lugs fits snugly into a respective one of the slots.

A problem with this prior system and with other known rigid coupling systems of this type is to match the draft and trim of the tug to that of the barge. There is a swell even in sheltered harbours and a slight list of either the tug or the barge to port or starboard can cause problems in connecting the tug to the barge. This is because the system depends on the axially disposed rails and channels in horizontal planes being brought into intimate engagement when joining the tug to the barge. The load bearing elements are usually parallel to the central axis of the tug and barge so that the draft, trim and heel of both the tug and barge must be adjusted within close limits prior to attempting connection which can be critical with effects of swell and wind.Draft can be compensated by ballasting adjustments of the tug or by similar means on the barge but this only compensates for the major problem and takes time to accomplish and verify.

Another system which has been proposed is the semi-rigid system of the type known as the ACB Hydropad System which also employs a notch system in the barges for receiving tugs. This system can couple tugs and barges having differences in draft but it relies on the tug being retained in the notch in the barge by means of a very heavily loaded cable system which forces the tug into the bottom of the notch against rubber tyred rollers. The tug is restrained laterally in the notch by a considerable number of hydraulically loaded friction pads so that the tug tends to rise and fall vertically with wave action, under normal conditions, until moderate sea-state conditions are exceeded. The tug must then be disconnected and withdrawn from the notch to take the barge under line tow when the weather conditions are least favourable for such a manoeuvre.Alternatively, if the master receives unfavourable weather reports before sailing, and schedules do not permit delay, he has to put the barge on a line at the outset which means a much slower voyage with higher fuel consumption. However, even with the tug fitted in the barge notch, hydrodynamic losses are much higher than with rigid coupling systems because of the tug oscillating in the notch and because the conventional form of the bow of the tug leaves a gap at the bottom of the notch which reduces speed and increases fuel consumption. Moreover, if one of the cables on either the port or starboard side of the interconnected tug/barge system should fail under duress at sea before the tug could be released, the results could be catastrophic for the safety of both the tug and the barge not to mention the danger to any hand on deck on the side where the cable failed.

Thus while the semi-rigid couplingsystem eliminates the problem of matching the draft of the tug to that of the barge, it creates other problems and cannot be used in the open sea under all weather conditions.

The present invention aims to provide a system of releasably interconnecting tugs and barges which overcomes all of the abovementioned problems.

According to the invention, there is provided a system for releasably interlocking a tug and a barge in which the tug is provided with a bow having a predetermined rake and contour and the barge is provided at its stern with a notch having a configuration adapted to receive the bow of the tug in a close-fitting relationship wherein the barge is provided on each of its wings defining the sides of the notch at the stern with a rail, said rails extending in a transverse plane parallel to the rake of the tug bow, and the tug is provided, in its bow region on both port and starboard sides, with clamping means engageable with the rails to hold the tug to the barge in a releasable manner.

Preferably, the clamping means comprise at least one clamp pivotally mounted on each of the port and starboard sides of the tug in the bow region thereof.

By means of clamps on the tugs and rails on the barges of the system according to the invention, coupling between a barge and a tug can be accomplished immediately without regard to variations in the draft or trim of the tug in relation to the barge. A tug can drop off a fully laden barge and immediately pick up an empty or partially laden barge without any adjustment to the draft of the tug having to be made. Moderate differences in trim or list of the barge would not inhibit coupling because of the relatively short length of axial engagement of the tug. The clamping system is readily visible so that failure to function can be easily detected. It is also easy to detect when the tug is seated in the barge notch.

Preferably, a plurality of clamps are provided on each side of the tug so that failure of any clamp during service will not impair the operation and efficiency of the system.

According to a preferred embodiment of the invention, the clamps are so shaped as to draw the tug and barge together with suitable allowance for manufacturing tolerances and wear of components. The clamps are desirably arranged to act at right angles to the joints.

The tug and/or the barge may be provided, on its port and starboard sides, with nonmetallic bearing surfaces engageable with the barge or tug when the tug is received in the barge notch and rigidly clamped in position by the clamps. Said non-metallic bearing surfaces may comprise strips made from a resilient material.

The clamps may be actuated by either electrical or hydraulic power through screw-jacks or other means, such as toggles, which are desirably self-locking in the "power-off" condition so that, in the event of power failure in service, the coupling is maintained. Means should then be provided for manual actuation in the event of release being required in an emergency.

The invention will now be further described, by way of-example, with reference to the drawings, in which: Figure 1 is a side elevation of a tug and a barge interconnected by one embodiment of a system according to the invention; Figure 2 is a plan view of the interconnected tug and barge shown in Fig. 1; Figure 3 is a side elevation, to an enlarged scale, of part of one of the interface joints between the tug and barge shown in Figs. 1 and 2; Figure 4 is a section taken on the line IV-IV in Fig. 3 in the direction of the arrows; Figure 5 is a section taken on the line V-V in Fig. 3 in the direction of the arrows; Figure 6 is a section taken on the line VI-VI in Fig. 3 in the direction of the arrows showing the clamp actuating means; Figure 7 is a section, corresponding to Fig.

4, showing an alternative embodiment of clamp; Figure 8 is a side elevation of a tug and a barge interconnected by a further embodiment of a system according to the invention; Figure 9 represents a series of horizontal sections taken through the bow of the tug shown in Fig. 8; Figure 10 represents a series of sections taken parallel to the rake of the bow of the tug shown in Fig. 8; Figure 11 is a plan view of the interconnected tug and barge shown in Fig. 8; Figure 12 is a partial sectional view, to an enlarged scale, of the clamping system employed on the tug and barge shown in Fig. 8; Figure 13 is a section taken on the line Xlll-Xlll in Fig. 12 in the direction of the arrows; Figure 14 is a part sectional view taken on the line XIV-XIV in Fig. 12 in the direction of the arrows;; Figure 15 is a part sectional view taken on the line XV-XV in Fig. 1 2 in the direction of the arrows; and Figure 16 is a part sectional plan view of part of the clamping system shown in Fig. 1 2.

In the drawings, like parts are denoted by like reference numerals.

Reference will first be made to Figs. 1 and 2 of the drawings which show a tug 1 and barge 2 interconnected by means of a system according to the invention. As shown in Fig.

2, the stern of the barge 2 has a notch 3 which is shaped to receive the bow of the tug 1. The bottom of the notch 3 has a rake angle which is substantially the same as the rake of the bow of the tug 1 as indicated by the dotted lines in Fig. 1.

Extending in a plane substantially parallel to the rake of the bow are a plurality, in this case four, of clamps 4 on each side of the tug. The clamps on each side of the tug are engageable with a rail 6 provided at the end of each wing 5 at the stern of the barge, said wings defining the notch 3 between them.

The two rails 6 extend in a plane which is substantially parallel to the bottom of the notch 3 and hence to the rake of the bow of the tug. The rails are preferably formed of extruded metal sections which are welded or otherwise secured to the rear ends of the wings 5 of the barge.

Each clamp 4 is pivotable about an axis which is substantially parallel to the rake of the bow of the tug by means of a pivot pin 7 extending through a lug 8 mounted on the side of the tug in a recess 9 as shown in Fig.

4. Each clamp 4 is further pivotally connected by a pivot pin 11 to a plunger 1 2. The plunger may constitute the piston of a hydraulic ram or it may comprise part of the toggle linkage system shown in Fig. 6. As shown in Fig. 4, the plunger 1 2 is provided with a curved surface 1 2a which bears directly on a curved surface 4a of the clamp 4 and the pivot pin 11 passes through an elongaged slot 10 in the plunger 1 2 to allow for relative movement between the clamp and plunger when the plunger is operated in the manner hereinafter described.

In the system shown in Fig. 6, the plunger 1 2 is slidably mounted in a sleeve 13 mounted in the side wall of the tug and its end remote from the clamp 4 is connected by a pivot pin 14 to a toggle lever 1 5. The toggle lever 1 5 and a second toggle lever 1 6 are pivotally connected by a pin 1 7 to a hydro-mechanical jack 1 8 and the other end of the lever 16 is connected by a pivot pin 1 9 to a lug 21 on a fixed part 22 of the tug. A similar toggle linkage system may be con nected to the other end of the jack 1 8 so that said jack can operate two clamps 4 simultaneously.If the tug is provided with four clamps on each side, making eight clamps altogether, four jacks 1 8 will be required for their operation.

The tug is further provided on each side with a strip of non-metallic material 23 against which the rails 6 are intended to bear when the tug and barge are coupled together as will be more fully described hereinafter.

The clamp 24 illustrated in Fig. 7 is arranged to operate in a similar manner to the clamp 4 but, in this case, the rail 26 is provided with a recess 27 in which a shaped projection 25 on the clamp 24 is engageable.

This embodiment is otherwise similar in every respect to the embodiment shown in Figs. 1 to 6.

The bow clamp attachment shown in Fig. 1 is an optional feature and may not be required for some smaller barges, for example 2,000 DWT. When provided, the attachment comprises an anchor pin 31 which is mounted on the barge 2 with its axis extending substantially parallel to the rake angle of the bottom of the notch 3 at the stern of the barge. A longitudinal slot (not shown) is provided in the pin 31 and the ends of the pin are located in bearings mounted in bores provided in lugs 34 extending from the bottom of the notch 3 in the barge stern. The lugs 34 are desirably formed by projections extending in a recess 35 provided in the stern of the barge at the bottom of the notch 3.

The bow of the tug 1 is provided with an actuator mechanism 36 which serves to advance and rotate a coupling member consisting of a shaft 37 having a partially-spherical head. The actuator mechanism 36 is mounted on the tug 1 by means of a spherical bearing and a number of adjustable links and the bow of the tug 1 is provided with a large bore over which a conical member 42 is fitted on the interior side of the tug casing. The spherical bearing is provided at the smaller end of the conical member 42 and the actuator mechanism 36 extends through said member. The adjustable links allow the actuator mechanism 36 as well as the shaft 37 to pivot freely in all directions.The longitudinal axis of the actuator mechanism 36 as well as that of the shaft 37 will however normally extend substantially at right angles to the rake of the bow of the tug and thus substantially perpendicular to the axis of the anchor pin 31.

The shaft 37 is rotatable through 90 and the head is substantially rectangular as viewed from the end of the shaft. This configuration permits the head to pass through the slot in the anchor pin 31 when the head is aligned with the slot and to hold the shaft in the slot when the shaft is rotated through 90 so that the head is out of alignment with the slot in the pin 31.

When it is desired to connect a tug 1 to a barge 2, the tug is manoeuvred into the notch 3 at the stern of the barge and at this stage the plungers 1 2 are fully retracted to move the clamps 4 to the position shown in dotted lines in Fig. 4. As the tug advances into the notch 3, the head of the shaft 37 will pass through the slot in the anchor pin 31. The slot has a considerabie length in order to accommodate large differences between the respective drafts between the tug and the barge. The shaft 37 is advanced until the head reaches a position in which it is clear of the pin 31 and the shaft is then rotated to move the head to the position in which it is out of alignment with the slot whereupon the shaft is retracted by the actuator mechanism 36 until the head of said shaft bears against the anchor pin 31.Further retraction of the shaft 37 by the actuator mechanism 36 is effective to draw the tug into the notch 3 in the barge 2. The resilient mounting of the actuator mechanism 36 and shaft 37 allows for compensation for the effects of swell and other external influences to be made during the drawing-in of the tug.

As the tug moves further into the notch 3, the strips 23 of non-metallic material engage the sides of the notch in the barge. Once the strips 23 bear hard against the wings 5 of the barge, the hydrn-mechanical jacks 1 8 can be actuated to force the connected plungers 1 2 outwardly (to the right as viewed in Fig. 6).

This results in the surfaces 1 2a of the plungers 1 2 engaging the surfaces 4a of the associated clamps 4 so that the clamps are moved by the plungers 1 2 into the position shown in full lines in Fig. 4 in which they engage the rails 6 so that the rails are then positively gripped between the clamps 4 and strips 23 to give a rigid coupling between the barge and tug.

The movement of the plungers 1 2 is essentially axial whereas the movement of the clamps 4 is pivotal and the provision of the elongated slot 1 0 in the plunger 1 2 compensates and provides the necessary clearance. It should be noted that the pin 11 does not bear any force but serves only to keep the clamp 4 and plunger 1 2 connected together. The force of the plunger 1 2 on the clamp 4 is transmitted solely via the curved surfaces 1 2a and 4a.

Each rail 6 preferably has a surface extending at an angle of 25 to the side of the barge on the side of said rail facing the notch 3 and a surface extending at an angle of 40 to said barge side on its other side as shown in Fig. 4 whereby the end of the rail remote from the associated wing 5 is wider than the end adjoining said wing 5 and the clamps overlap the rails 6 in both fore and aft and beamwise direction of the tug/barge combination. This construction serves to reinforce the clamping action of the clamps 4 on the associated rails and prevents disengagement of the clamps from the rails when they are put under heavy stress. A reliable interconnection of the barge and tug is thereby ensured.

In the embodiment shown in Figs. 8 to 1 6 of the drawings, as with the embodiments shown in Figs. 1 to 7, the notch 3 in the stern of the barge 2 has a rake angle and shape which is exactly matched to the rake angle and shape of the bow of the tug 1. Fig.

9 shows in plan view a series of horizontal planes through the bow of the tug taken on the lines a-g in Fig. 8 and Fig. 10 shows a series of transverse planes through the bow of the tug parallel to the rake of the tug bow.

Since the notch 3 has the same shape and configuration, the bow of the tug will fit into the notch 3 irrespective of differences in draft between the barge and the tug. In Fig. 8, the situation in which the drafts of the barge and tug are more or less matched is indicated in full lines. This represents the situation in which the barge is partially loaded. When the barge is fully laden or unladen, the position of the tug relative to the barge is indicated by the chain-dotted lines in one case above and in the other case below the full lines in Fig. 8.

It will be seen that perfect matching between the tug bow and the notch in the stern of the barge is achieved in all three positions.

In this case, the bow of the tug 1 is provided on each side with six clamps 41 which extend in a transverse plane parallel to the rake of the bow of the tug. The clamps 41 are engageable with rails 6 provided on the wings 5 at the stern of the barge 2 and the rails may again be formed of extruded metal sections welded or otherwise secured to the rear ends of the wings 5 of the barge. The two rails 6 also extend in a transverse plane which is parallel to the base of the notch 3 and to the rake of the bow of the tug.

As shown in Figs. 1 2 and 13, each clamp 41 is pivotally mounted on a respective link 42 by means of a pivot bolt 43 and the associated link 42 is pivotally mounted by means of a pivot bolt 44 on the end of a plunger 45. The plunger is axially movable in a bore provided in a casting 46 which is mounted on the wall of the tug 1, said wall being cut away in the region of the casting to permit the plunger to extend therethrough.

The casting 46 is provided with a rail 47 which extends parallel to the rake of the tug bow and which is engageable by the clamps 41.

A bearing sleeve 48 is provided between the plunger 45 and the bore in the casting 46 and the inner end of the plunger 45, after passing out of the said bore, is located in a boss 49 provided on a web 51 which is secured to or formed integrally with the cast ing 46. Again, a bearing sleeve 52 is pro vided between a sleeve 61 on the plunger 45 and the bore wall of the boss 49. As shown in Fig. 15, a collar 53 is mounted on the plunger 45 intermediate its ends and a pair of links 54 are pivotably mounted on the collar which is restrained from movement relative to the plunger 45 by providing a shoulder on said plunger as shown in Fig. 16. One side of the collar 53 abuts against the shoulder on the plunger 45 and the sleeve 61 abuts against the other side of the collar.The sleeve 61 is retained on the plunger 45 by means of a nut 62 engaged with a screw-thread provided on the inner end of the plunger 45.

Each link 54 is pivotally mounted on a respective stub shaft or sleeve 55 and the two shafts or sleeves are connected by a saddle 56 which is pivotally mounted on the shafts or sleeves and is connected, intermediate its ends, to the piston 57 of a hydraulic ram the cylinder casing 58 of which is pivotally mounted by means of a pivot bolt 59 on the casting 46. The plunger 45 is provided with cutaway regions 62 to permit movement of the shafts or sleeves 55 in response to actuation of the piston 57 without fouling the plunger 45. Also mounted on each shaft or sleeve 55 is a respective link 64 and the two links 64 are in turn pivotally mounted on stub shafts 65 provided on the casting 46.

In this embodiment, the strips 23 of nonmetallic material are mounted on the barge wings 5 and extend at a somewhat steeper angle than the rest of the wall of the notch 3.

These strips 23 should also desirably extend substantially parallel to the rake of the tug bow. With this embodiment, when it is desired to connect a tug 1 to a barge 2, the tug is manoeuvred into the notch 3 at the stern of the barge as before and at this stage, the plungers 45 and the links 54 and 64 are in the position indicated by dotted lines in Fig.

1 2 in which the plungers extend outwardly from the wall of the tug 1 and the clamps 41 are out of engagement with the rails 47.

The tug moves into the notch 3 until flat surfaces 66 on the castings 46 abut against the strips 23. The hydraulic rams are then actuated to retract the associated pistons 57.

This has the effect of, in each case, moving the links 54 and 64 towards the position indicated by full lines in Fig. 1 2. Since the links 64 are fixed to the casting 46 at one end, the shafts or sleeves 55 are thus moved laterally inwardly with respect to the tug wall and this inward movement causes the collar 53 also to move inwards through the connection afforded by the links 54. The pivotal mounting of the ram casing 58 permits this movement. The plunger 45 is entrained by the collar 53 and is thus moved inwards so that the clamp 41 is forced into engagement with the rails 6 and 47 to clamp the tug to the barge. The provision of the link 42 and the pivotal mounting of the clamp 41 on the plunger 45 permit any slight deformations or misalignments of the rails 6 and 47 to be compensated.

The rails 6 and 47 and the clamps 41 are so shaped that the engaging surfaces of the rails and clamps extend substantially parallel to each other to provide a secure engagement to hold the tug to the barge.

As shown in Fig. 12, the plunger 45 extends at an angle of about 90 to the beam of the tug. However, although this angle is preferred, it is not essential and the angle of the plunger to the beam of the tug may vary between 45 and 90 .

It will be appreciated that, by means of the system according to the invention, a tug can be connected to a barge without having to match the trim of the tug to the barge since the clamps on the tug can engage the rails on the barge over a wide difference between the trim of the barge and tug.

By employing what is best defined as a "raked slot", the benefit of "mating" unaffected by draft differences is combined with a hydrodynamically desirable form of bow for the tug. While a curbed prow has been depicted in the drawings with tangential flanks this is not essential and a truncated form may be chosen if desired. The shape of the bow form can be curved on the flanks if desirable because the fundamental principle of a raked slot or notch places no restriction on the choice of "true" form.

In order to reduce the cost of construction, the cross frames are desirable canted to match the rake of the bow so that they are then simply of rectangular form of equal depth.

The side plates and bow plate do not require "working because there are no compound curvatures. If a truncated prow and straight flanks are chosen, the bow plate is a rectangular flat plate and the flanks are flat plates. If a curved prow is desired, the bow plate is rolled to the specified radius and the flanks are flat plates. If an elliptical bow form is desired, the prow can again consist of a rolled bow plate and the flanking plates are simply wrapped around the frames after any necessary pre-rolling which may be required by the curvature. Regardless of the choice of construction, the result is a tug with a bow of acceptable hydrodynamic form.

The system according to the invention provides a canted joint across the principal axis of shear and bending and shares the stress between the pair of barge wings which terminate far enought aft, at their lower extremity, to be near the centre of gravity of the tug which greatly reduces the resultant bending moment when the tug is temporarily unsupported in heavy seas.

The invention is not restricted to the abovedescribed embodiments but variations and modifications may be made without departing from the scope of the invention. For example, the clamps may be recessed further into the tug sides to protect them from damage. Further, although the above-described embodiments illustrate systems according to the invention having four and six clamps on each side of the tug bow, each embodiment may be provided with any number of clamps on each side although it is preferred to have more than one clamp on each side.

Claims (16)

1. A system for releasably interlocking a tug and a barge in which the tug is provided with a bow having a predetermined rake and contour and the barge is provided at its stern with a notch having a configuration adapted to receive the bow of the tug in a close-fitting relationship, wherein the barge is provided on each side of its wings defining the sides of the notch at the stern with a rail, said rails extending in a transverse plane parallel to the rake of the tug bow, and wherein the tug is provided, in its bow region on both port and starboard sides, with clamping means engageable with the rails to hold the tug to the barge in a releasable manner.

2. A system according to claim 1, wherein the clamping means comprise at least one clamp pivotally mounted on each of the port and starpoard sides of the tug in the bow region thereof.

3. A system according to claim 2, wherein a plurality of clamps are provided on each side of the tug.

4. A system according to claim 2 or claim 3, wherein the clamps are so shaped as to draw the tug and barge together with suitable allowance for manufacturing tolerances and wear of components.

5. A system according to any one of claims 2 to 4, wherein the clamps are arranged to act substantially at right angles to the joints.

6. A system according to any one of claims 2 to 5, wherein the clamps are arranged to be hydraulically actuated.

7. A system according to claim 6, wherein each clamp is pivotally connected to a plunger which is provided with hydraulic actuation means.

8. A system according to claim 7, wherein the plunger of each clamp is connected to a hydraulic ram by a toggle linkage.

9. A system according to claim 7 or claim 8, wherein each plunger is axially movably mounted in a respective bore provided in a casting secured to the wall of the tug.

10. A system according to claim 9, wherein each casting is provided with a rail which is engageable by the associated clamp or clamps when the corresponding rail on the barge is engaged by the clamp or clamps.

11. A system according to any one of claims 7 to 10, wherein each clamp is connected to the associated plunger by a link pivotally connected at one end to the clamp and at the other end to the plunger.

1 2. A system according to any preceding claim, wherein the tug is provided, on its port and starboard sides, with non-metallic bearing surfaces engageable with the barge when said tug is received in the notch in the stern of the barge.

1 3. A system according to any preceding claim, wherein the barge is provided, on both sides of the notch, with non-metallic bearing surfaces engageable with the respective sides of the tug when said tug is received in the notch in the stern of the barge.

14. A system according to claim 1 2 or claim 13, wherein said non-metallic bearing surfaces comprise strips made from a resilient material.

1 5. A system for releasably interlocking a tug and a barge substantially as described herein with reference to Figs. 1 to 7 of the drawings.

16. A system for releasably interlocking a tug and a barge substantially as described herein with reference to Figs. 8 to 1 6 of the drawings.