Abstract:
A composite barge-tug vessel is provided which comprises a detachable tug and barge which when brought into full engagement form an integrated vessel capable of use on the high seas. The barge includes, at the aft end thereof, a pair of spaced rearwardly extending stern fins the upper surfaces of which form inclined mating or aligning planes. The tug includes laterally extending wings whose undersurfaces form aligning planes that mate with the aligning planes of the barge, the sliding engagement between the pair of aligning planes enabling the wings of the tug to be driven up onto the stern fins of the barge. A prow tongue on the tug engages in a slot formed between the stern fins and projections at the tip ends of the stern fins engage in connection apertures formed at the sides of the tug. Wedging surfaces at the connections between the tug and barge prevent lateral movement while a wedging assembly located at the aligning planes fixes the longitudinal positions of the tug and barge.

Description:
FIELD OF THE INVENTION 
     The present invention relates to an integrated composite barge-tug vessel formed by a detachable barge and tug. 
     BACKGROUND OF THE INVENTION 
     A number of different approaches have been taken with regard to the problems of providing a composite sea-going barge-tug vessel wherein the tug or propulsion portion is detachable from the barge or cargo-carrying portion and wherein the tug is capable of operation as a seagoing tug. In general, these approaches fall into two classes, viz., &#34;articulated&#34; barge-tug vessels and &#34;rigid-connected&#34; barge-tug vessels. In an articulated vessel, the barge generally includes a notched or recessed aft portion which is hingedly attached to the bow of the tug. This form of detachable connection is disadvantageous because, inter alia, the barge and tug are permitted to pitch and roll independently of one another and this prevents use of the vessel at sea during unfavorable weather conditions. 
     The &#34;rigid-connected&#34; vessels of the prior art, while overcoming this particular disadvantage, suffer a number of important disadvantages themselves. For example, the tug, when detached from the barge, should itself be of a seaworthy design and many such detachable tugs are simply not seaworthy. Another serious disadvantage of some constructions is the complexity of the interlocking shapes which are used in connecting the barge and tug together. These complex shapes are difficult and expensive to reproduce and hence the manufacturing costs of such vessels are high. Yet another important disadvantage of the prior art is the difficulty encountered in engaging and disengaging the barge and tug. 
     Although, as stated, a number of different approaches have been taken, three of these such approaches will be briefly considered here for purposes of comparison. U.S. Pat. No. 3,698,349 (Stevens) discloses a seagoing barge and tug construction wherein an aft section of the barge is received between the twin hulls of a catamaran type tug. One disadvantage of this arrangement is that the forward end connection between the tug and barge does not engage enough of the barge to evenly distribute the strain. Moreover, this design includes a large number of curves and angles making the construction difficult to build. Further, because of the manner in which the barge and tug mate, substantial vertical ballasting is required to bring the two into the alignment required to bring the two into engagement. 
     A barge-tug construction which presents even more complex ballasting problems in providing engagement and disengagement of the tug and barge is that disclosed in U.S. Pat. No. 3,610,196 (Lowry). More specifically, the Lowry patent discloses a segmented ship system wherein a series of keys and keyways formed respectively on a portion of the tub tongue and portions of the barge that form a mating slot, are utilized to provide interlocking between the tug and barge. The locations of the keys and keyways require that the barge and tug be ballasted such that the tongue of the tug is first raised above the portions of the barge forming the slot. The tug is then moved forward and finally dropped so that the keys engage in the keyways. This engagement operation is obviously time consuming and, as noted, requires complex ballasting. Further, the interlocking shapes disclosed in the Lowry patent are extremely complex and the construction would be very difficult to manufacture. 
     A third patent of particular interest here is U.S. Pat. No. 3,556,742 (Gainsley) which discloses a composite barge-tug vessel made of interlockable sections wherein the tug or propulsion unit is &#34;plugged-in&#34; to the aft end of the barge or cargo-carrying hull. Again, the interlocking shapes employed are complex and the tug itself is of a design which is of questionable seaworthiness. In addition, engagement and disengagement require substantial ballasting to ensure proper alignment. 
     Other patents disclosing combination barge-tug vessels include U.S. Pat. Nos. 3,345,970 (DeLong); 3,362,372 (Peterson); 3,417,721 (Vienna); 3,492,964 (Garcia); 3,550,550 (Fletcher); 3,613,628 (Garcia); 3,735,722 (Hooper et al); 3,756,183 (Clemence, Jr.); 3,837,315 (Giblon), although it will be understood that this listing is not, nor is it represented to be exhaustive. 
     SUMMARY OF THE INVENTION 
     In accordance with the invention, a composite &#34;integrated&#34; barge-tug vessel is provided which overcomes the disadvantages of the prior art. For example, the tug or propulsion portion of the vessel is of an extremely seaworthy design and, in general, the interlocking connections between the barge and tug are relatively simple as compared with the prior art. Further, the connections between the barge and tug provide optimumly located points of control and a well balanced distribution of strain. The barge and tug when in full engagement form a rugged vessel which is capable of use on heavy seas. The construction of the barge portion is relatively simple and a conventional barge could be correspondingly modified with relatively few changes and at low cost as compared with barge sections of prior art vessels. A particularly important feature of the invention is the ease with which engagement and disengagement can be effected. As will become more clear from the description which follows the barge and tug can be brought into full engagement with a minimum of ballasting in contrast to the constructions disclosed above wherein proper alignment between the tug and barge is critical before the two can be brought together into interlocking engagement. 
     According to a preferred embodiment thereof, the composite barge-tug vessel of the invention include a detachable barge including first and second spaced rearwardly extending stern fins each of which includes a longitudinally extending mating plane. The tug includes a pair of laterally extending wings each of which defines a longitudinally extending mating plane that is adapted to slidingly engage a corresponding mating plane of the stern fins so as to enable the tug and barge to be brought into full engagement. Advantageously, the mating planes are inclined at an angle of 0° to 45° and preferably between 5° and 20°, inclusive depending on use. A tongue and slot connection is provided between the bow of the tug and the aft end of the barge and a further connection is provided between the tip ends of the stern fins and the sides of the tug. This latter connection is preferably made by means of projections which are located at the free ends of the stern fins and which are received in connection apertures at the sides of the tug. An arrangement for restraining lateral movement between the barge and tug is provided at one, at least, of the connections referred to. Further, a means is provided for fixing the longitudinal positions of the barge and tug when the two are brought into full engagement. 
     The provision of the longitudinally extending mating planes referred to above enable the tug and barge to be readily brought together in full engagement. Ballasting, where required, is limited to fore and aft trimming so as to align the planes such that the uppermost mating plane can come into contact with and subsequently slide up along the lowermost mating plane. This engagement operation contrasts with that required by vessels such as that disclosed in the Lowry patent discussed above wherein ballasting is required so that the interlocking surfaces are brought into position wherein the keys of the tug overlie the keyways of the barge, and then dropped down to provide engagement. 
     The connections referred to above lie generally along the same plane and, as mentioned, provide control points in strategic locations which, in combination with the broad contact area provided by the mating planes, affords a balanced distribution of forces. 
     Other features and advantages of the invention will be set forth in, or apparent from, the detailed description of a preferred embodiment found hereinbelow. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of integral barge-tug vessel in accordance with a preferred embodiment of the invention, with the barge and tug disengaged; 
     FIG. 2 is a side elevational view of the barge-tug vessel of FIG. 1, with the barge and tug in engagement; 
     FIG. 3 is a plan view of the barge-tug vessel of FIG. 2, with constructional details of the barge and tug omitted; 
     FIG. 4 is a side elevational view similar to that of FIG. 2, but to an enlarged scale; 
     FIG. 5 is a sectional view taken generally along line V--V of FIG. 4 (and FIGS. 2 and 3); 
     FIG. 6 is a sectional view taken generally along line VI--VI of FIG. 4 (and FIGS. 2 and 3); 
     FIG. 7 is a sectional view taken generally along line VII--VII of FIG. 4 (and FIGS. 2 and 3); 
     FIG. 8 is a sectional view taken generally along line VIII--VIII of FIG. 4; 
     FIG. 9 is a detail, drawn to an enlarged scale, of the aligning wedge assembly, which is also shown in FIG. 4; and 
     FIG. 10 is a schematic representation of the bow of the tug and aft end of the barge used in explanation of the mating operation. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring particularly to FIGS. 1 to 3, the integral barge-tug construction of the present invention basically comprises a tug T and a barge B which are capable of being connected together to form an integral unit as shown in FIGS. 2 and 3 as well as disengaged or detached to form separate units as shown in FIG. 1. 
     Barge B is of conventional construction except for the aft end thereof and thus can take a number of common forms overall, apart from the aft end construction. At the aft end thereof, barge B includes first and second spaced rearwardly extending stern fins or projections 10 and 12. Stern fins 10 and 12 are preferably constructed of mild rolled structural steel and are of hollow cross-section as indicated in FIG. 7. As can be seen from FIGS. 1 to 3 taken together, fins 10 and 12 are the mirror images of each other, and hence only the shape of fin 10 will be considered in detail. As is perhaps best illustrated in FIG. 4, stern fin 10 tapers rearwardly in a vertical plane from the area of connection to the aft of the barge, denoted 10a, to the free or tip end thereof, denoted 10b. The inclined upper surface of fin 10 constitutes a first mating plane, denoted 10c and is an important feature of the invention as will be explained hereinbelow. As shown in FIG. 3, fin 10 is also tapered in a horizontal plane with the inner surface of the fin 10 extending substantially parallel to the longitudinal axis of the barge B and the outer surface being inclined inwardly from the lateral surface of the barge proper. 
     The aft end surfaces of barge B between stern fins 10 and 12 forms a vertical plane 14 having a recess or slot 16 located near the top thereof as can best be seen in FIG. 1. Slot 16 extends the entire width of the forward end of tug T and as is shown in FIGS. 2 and 4, tapers inwardly in a vertical plane to wedgingly receive a reciprocally shaped prow tongue of the tug T as described below. As illustrated in FIG. 3, the sides of slot 16 also taper inwardly in a horizontal plane. In the illustrated embodiment, the portion of the aft end which overlies slot 16, and which is denoted 18, extends rearwardly of the vertical plane 16 a small distance so as to aid in bringing the tug T and barge B into integral engagement. 
     The free or tip ends of stern fins 10 and 12 are also of a specific configuration which serves in providing engagement between barge B and tug T and which will be described hereinbelow together with at least one other feature of the barge B which can best be understood in terms of its cooperation with tug T. 
     Tug T is of generally conventional construction apart from those features thereof which provide integral engagement between the tug and the barge. Thus, for example, the tug can be driven by a single screw or twin screws and the power plant, deck layout, and the like, can take conventional forms. As noted above, one feature of the invention is that the tug itself, when separated from the barge, is of an extremely seaworthy design, as is evident, for example, from FIGS. 1 and 4. 
     In accordance with an important aspect of the construction thereof, tug T includes a pair of laterally extending wings or projections 20 and 22 which extend laterally outwardly from opposite sides of the tug and an integral forwardly extending prow tongue or extension 24 which extends outwardly from the bow of the tug T. Wings 20 and 22 are of a like configuration and only wing 20 will be considered in detail. As is perhaps best seen in FIGS. 1 and 4, while a rear portion of the upper surface of wing 20 is subtantially flat, the remainder thereof, denoted 20a, slopes upwardly from a point roughly three-quarters of the distance aft. A first aft portion of the undersurface of wing 20, denoted 20b, slopes downwardly from the aft end for a distance roughly equal to the flat portion of the upper surface while a second portion 20c slopes downwardly from forward end of tug T to intersect the first portion 20b. The continuous planar portion of the undersurface 20c constitutes a mating or aligning plane which is the reciprocal of, and mates with, the aligning plane constituted by the upper surface 10c of stern fin 10. With this arrangement, the undersurface 20c of wing 20 rides up on, and rests on, the upper surface 10c of stern fin 10 (see, in particular, FIG. 6). As discussed hereinabove, these aligning planes or surfaces serve in providing ready engagement and disengagement of the tug and barge. In general, the angles formed by these mating or aligning planes should be greater than 0° and less than 45°, depending upon the service and freeboard of the vessel, with an angle of between about 5° and 20° being preferred. The sloping upper surface of wing 20 is helpful in bringing the tug and barge into engagement as will become more evident hereinafter. 
     Prow tongue 20 is integral with wings 20 and 22 and extends completely across the bow end of tug T (see FIGS. 1 and 7). The shape of prow tongue 24 is the reciprocal of that of slot 16, tongue 24 being tapered in cross-section (see FIGS. 2 and 4) and including tapered side surfaces 24a and 24b (FIG. 3), so as to produce a wedging action when received in slot 16. The end surface of prow tongue 24 is preferably flat as shown but can also be rounded (radius section). It will be understood that it would be possible to reverse the locations of tongue 24 and slot 16 so that the latter would be located in the Tug T and the former on the barge B. 
     As stated hereinabove, the tip end 10b of stern fin 10 is a special configuration so as to provide positive engagement with the tug T. In particular, the tip end 10b includes an upper connection pin or projection 10d, and a lower connection notch 10e located therebeneath (see FIG. 4). Connection pin 10d is received in a connection aperture 20d which is formed between a support member 26 and the undersurface 20c of wing 20. Support member 26 extends laterally outwardly from the side of tug T and is joined to wing 20 through a connecting plate 28 which is suitably affixed to both by conventional means such as bolting. A corresponding support member 30 and connecting plate 32 are located on the opposite side of the tug T (see FIG. 5). The forward end of support member 26 is shaped to form a connecting projection or nose 26a which is received in notch 10e of wing 10. Thus, a double connection between tip 10a of stern fin 10 and the tug T is provided by receipt of connection pin 10d in aperture 20b and receipt of nose 28a in notch 10e. It will be understood that the connection between the free end of the stern fins 10, 12 and the tug proper can take other forms and that, again, a pin and slot connection which is the reverse of that shown could be employed. 
     The longitudinal position of the center of gravity of tug T is located at a point forward of the tip connection of the stern fins 10, 12. Preferably, referring to FIG. 2, wherein the center of gravity is denoted CG, the distance L 2  between the stern fin tip connection and the center of gravity CG is at least 5% of the overall distance L 1  between the stern fin tip connection and the bow of the tug T. 
     To prevent relative lateral movement between barge B and tug T, aperture plate 28 is provided with an inwardly extending wedging surface 28a which tapers inwardly in a horizontal plane as indicated in FIG. 8. The tip end 10a of stern fin 10 also tapers inwardly in a horizontal plane as indicated at 20f so that aperture 20d wedgingly receives the surface 20f. Although not illustrated, a similar wedging action is provided between tip 12a of stern fin 12 and mounting plate 32. The lateral restraint provided by mating surfaces 20f and 28a, and the corresponding mating surfaces of connecting plate 32 and stern fin 12 (not shown), together with that provided by the wedging action of the inclined or sloping lateral edges 24a and 24b of prow tongue 24, substantially prevent relative lateral movement between the tug T and barge B when the two are brought into full engagement. 
     A pair of wedge assemblies 34 and 36 (see FIGS. 2, 4, and 9) is used to lock or otherwise fix the longitudinal positions of the tug T and barge B relative to one another. Again, considering assembly 34 as exemplary and referring particularly to FIG. 9, wedge assembly 34 includes a tapered slot or recess 38 formed in stern fin 10 and opening into the upper mating surface 10c of stern fin 10. Slot 38 includes an inclined wall 38a and a straight wall 38b which extends perpendicular to mating surface 10c. A straight slot 40 is formed in wing 20 which opens onto surface 20c and houses a wedge 42. The housing for wedge 42 can extend above the upper surface of wing 20, as illustrated, and wedge 42 is connected to a suitable actuator (not shown) through a connecting rod 44. An oversized fit is preferably provided between the sides of the wedge 42 and the sides of slots 38, 40 although these dimensions are not critical. The front and rear surfaces 42a and 42b and wedge 42 are matched to edges 38a and 38b of slot 38 and thus by driving wedge 42 down into slot 38, slots 38 and 40 are brought into axial alignment and the longitudinal positions of mating surfaces 10c and 20c are fixed relative to one another. 
     It will be seen that the wedging action provided by wedge assemblies 34 and 36 put prow tongue 24 into compression. Although these relationships are not essential, in accordance with an advantageous embodiment, the compressive forces in the direction of the longitudinal axis at the forward end of tug T, that is, at tongue 24, is greater than the vertical compressive (wedging) forces in the direction of the longitudinal axis at the tip ends 10b and 12b of stern fins 10 and 12 which is, in turn, greater than the horizontal compressive (wedging) forces transversely of the vessel provided at the tip ends 10a and 10b, i.e., between wedging surfaces 28a and 10d. To this end, prow tongue 24 can be constructed of a resilient material such as a resilient metal. As illustrated, wedge assemblies 34 and 36 are located forwardly of the tip end connections of stern fins 10 and 12 although their precise locations are a matter of design. It will be understood that the wedging assemblies 34 and 36 can be replaced by an equivalent arrangement which will (i) impart tension to the stern fins 10 and 12 and (ii) place the prow tongue 24 under compression. 
     In order to provide a smooth line transition between the hull of the barge B and that of tug T and, in particular, to eliminate the discontinuity that would normally exist between the stern section of the barge hull and the bow portion of the tug hull, a plate 50 is secured to the bottom of barge B. Plate 50 is bifurcated as shown in FIG. 3 so as to generally conform to the shape of the adjacent portion of the bow of the tug T and extends inwardly from the undersurface of stern fins 10 and 12 in the same plane as these surfaces (see FIGS. 6 and 7) so as to be adjacent to, but spaced from the corresponding surfaces of the bow of tug T. It will be understood that this same purpose can be accomplished in other ways and that, for example, the stern fins can be shaped and suitably faired so as to provide an even smoother transition and thus further improve the flow lines of the composite vessel. 
     Considering the operation of the composite vessel of the invention, an important feature of the invention is that the tug T can be brought into engagement with the barge B in a relatively simple manner. In this regard, one advantage of the invention is that the barge and tug may be ballasted &#34;in trim,&#34; i.e., fore and aft, avoiding vertical ballasting, in order to provide the alignment necessary. While, in general, the tug and barge are ballasted so that the mating planes 10c and 12c of the barge B are parallel to the mating planes 20c and 22c of the tug T, the two sets of planes can be brought into contact, and the tug and barge brought into engagement, even though substantial misalignment exists. It will be understood that when, for example, portions of mating planes 20c and 22c are brought into contact with the outboard ends of stern fin mating planes 10c and 12c, the mating planes 20c and 22c can simply ride up onto the stern fin mating surfaces 10c and 12 c, and even if the angle of intersection is substantial, the tug will ride up on these surfaces until the weight of the bow end causes the mating surfaces 20c,22c to automatically bear down onto mating surfaces 10c,12c. The surfaces 20c,22c will then slide simply therealong until the tug and barge are brought into full engagement. This is illustrated in FIG. 10 wherein as shown in full lines the mating plane 20c initially engages plane 10c at an angle but, as shown in dashed lines, rides therealong as the tug is drawn up further. Preferably, a lubricant is used to prevent galling between the mating planes although different metals can also be used for this purpose. It will be understood that the tug and barge can be brought into engagement using a conventional winch which can be located on either the tug or the barge. When the tug and barge are brought into engagement the wedge assemblies 34 and 36 are actuated so that the mating planes are secured in position and hence the longitudinal positions of the tug and barge are fixed. 
     Although the invention has been described relative to exemplary embodiments thereof, it will be understood that other variations and modifications can be effected in these embodiments without departing from the scope and spirit of the invention.