US3368515A - Submersible barge - Google Patents

Description

Feb. 13, 1968 MICHIMASA ENDo 3,368,515

SUBMERS I BLE BARGE Filed May 20, 1966 5 Sheets-Sheet 1 INVENTOR.

MICH/MASA ENDO A free/VFY Feb. 13, 1968 MlcHlMAsA ENDO SUBMERS I BLE BARGE '5 sheets-sheet 2 Filed May 20, 1966 ,NHMH

FILHH@ INVENTOR MICH/MASA E/voo Feb. 13, 1968 MICHIMASA ENDO SUBMERS I BLE BARGE 5 Sheets-Sheet 5 Filed May 20, 196

INVENTOR. )MICH/MASA ENDO QQm.

United States Patent O 3,368,515 SUBMERSIBLE BARGE Michimasa Endo, Nishinomiya-shi, Sumaku, Kobe-shi, Japan, assignor to Continental Oil Company, Ponca City, Okla., a corporation of Delaware Filed May 20, 1966, Ser. No. 551,616 Claims priority, application Japan, Feb. 4, 1966, 41/ 6,485 5 Claims. (Cl. 114-235) ABSTRACT 0F THE DHSCLOSURE This invention relates generally, as indicated, to a sub` mersible barge; and more particularly, but not by way of limitation, to a submersible tow vessel for use in transporting crude oil.

The prior art reveals a few instances lof teachings to the general concept of submarine towage but, to this date, no practical method or equipment has been devised. One of the main problems appears to have been in the proposed practice of ballasting the barge down, below the Surface of the water, and then maintaining contr'ol of the vessel which is negatively buoyant relative to the surface. This results in various problems related to the acts of controlling the ballasting and de-ballasting of the vessel, since it is under water during part of each of the procedures. Also, the prior art vessels were erratic of contr`ol when underway and in the cruising attitude. It was generally found necessary to maintain surface control of some type, e.g., via electrical conduit, pneumatic controls, etc., in order to effectively utilize the submerged barges for transportation of cargo.

It has been decided that transport by submersible barge would be desirable for moving large quantities of crude oil, especially if the same tranpsort route is run at regular intervals. The submerged tow encounters much less resistance during its use than would any ofthe known types of surface transport barges. The main advantage is that the submerged barge encounters no sea resistance from surface turbulence, e.g. waves, wind, etc. This detriment can be very large and tends to reduce greatly the maximum tow-speed which can be achieved with surface hauling equipment. The surface barge requires a seagoing tugboat and can be towed at only a few knots if given good sea conditions; while the submerged barge, as presented herein, can be hauled by a merchant-type vessel at speeds up to around sixteen knots. The towing force required of the hauling ship is still considerably less in th-e case of the submerged tow than it would be with a dredge-type barge of comparable size, and thus, it enables a faster tow with less towing force.

The submerged barge concept is also attractive from the cost viewpoint, both in manpower and in maintenance. The submersible vessel of this disclosure is designed so that no manpower is required at any time during the voyage or when left to await loading or unloading; and also, the vessel enables savings in docking fees since it requires no port facilities while tied up or anchored out. In one planned usage the unmanned, submersible barge can 4be fully loaded with cargo and then hauled to a first port at standard speed by a fully loaded tanker or 3,368,515 Patented Feb. 13, 1968 cargo ship. The barge can then be dropped off at the first port and fthe tanker or cargo ship can proceed to another destination with its remaining cargo.

The present invention contemplates a submersible barge which is free of control adjustments as t'o the submergence of the barge at the loading port, navigation con* trol underway, and surfacing of the barge at the destination. The present invention contemplates a submersible barge which has a revolute, streamlined shape, a weight and buoyancy distribution, and appertinent stabilizing members, such that the barge can be reliably towed at high sea speeds with its depth dependent upon the speed of -tow fand/ or the length of the tow cable. In a more limited aspect, the present invention provides a submersible tow vessel, which, when fully loaded, can be ballasted to Ahave a predetermined reserve buoyancy which floats the vessel at the surface. Upon 'commencement of towing, the

' a submersible barge which can be towed underwater without the necessity for direct barge control functions.

It is lanother object of the present invention to provide a submersible tow vessel which is entirely controlled underway by the speed of tow and/or the length of the towline.

It is still another object of the present invention to provide a tow vessel for underwater transportation which has a predetermined shape, weight and buoyancy and which interacts with the various forces of underwater tow to render it a stable and reliable vehicle.

Finally, it is an object of the present invention to provide a submersible barge which is capable of high speed,

low cost transportation of crude oil and which has the same properties 'of nautical behavior in either the cargo loaded or unloaded condition.

Other objects and advantages of the invention will be evident from the following detailed description when read in conjunction with the accompanying drawings which illustrate the invention.

In the drawings:

FIGS. 1A, 1B and 1C illustrate the submersible barge in three successive operating attitudes;

FIG. 2 is a side view of the preferred form of the barge in vertical section;

FIG. 3 is a section taken along line 3--3 of FIG. 2;

FIG. 4 is a section taken along line 4 4 of FIG. 2;

FIG. 5 is a section taken along line 5 5 of FIG. 2;

FIG. 6 is a top plan view of the preferred form of submersible barge;

FIG. 7 is a schematic illustration of the fluid distribution and control system of the submersible barge; and

FIG. 8 is a graph of towing speed versus the barge depth which illustrates the towing characteristics of the submersible barge.

General and theoretical The invention of this disclosure has been specifically designed for use in transporting crude oil in the Mediterranean Sea; however, it should be understood that the design parameters may be varied for any particular usage and/or area. The submersible barge, as described herein, has a principal function of transporting crude oil from a source port to a renery port and then the barge is returned to the source port to refill and repeat the run.

There are many obstacles to be overcome in constructing a submersible barge which can be reliably towed with acceptable eiciency. Heretofore, the theoretical designs which have been recorded were very basic disclosures havin-g neither the awareness of the problems to be encountered nor the scope of experimental findings which would enable a solution to the various problems. The design as set forth in this disclosure is the result of win-d tunnel and sea tests which have provided the empirical data and hardware knowledge which allow construction of a highly efficient transport which can move cargo via the water subsurface and at greatly increased speeds.

The submersible barge as disclosed herein has been designed wi-th a specific shape and weight such that the best and most stable operating characteristics are achieved. The craft is balanced and ballasted so that it will have a known function of movement and it will travel in an equilibrium condition when under tow. T-hat is, given the proper amount of cargo, and when the craft is then properly ballasted and trimmed, the towed submersible barge will travel in a desired pattern without any necessity for further direct control. The barge can then be controlled to a sufficient degree by the speed of tow and/ or the length of the towline.

The submersible vessel depends upon exact conditions for the equilibrium behavior; hence, when the vessel is loaded with a known amount of cargo it must be properly ballasted and trimmed before getting underway. The design criteria establish that a reserve buoyancy of fifty (50) tons to the fully loaded barge will give consistant results as to towing efiiciency and reliability. The barge, loaded and ballasted, does not sink entirely below the surface of the water, but rides with a very small freeboard. Then upon getting underway new forces enter in to submerge and stabilize the barge in the desired manner.

When the speed of tow approaches about nine (9) knots, the barge will star-t to submerge and will continue to submerge as a function of the speed of tow and/or the length of the to-wline. The submergence force is a resultant of (1) drag due to frictional resistance of the hull, (2) lift forces of wings and hull, (3) tension of the towing wire at the connecting point to the barge, and (4) the reserved buoyancy of the barge. These same forces combine to an equilibrium condition of their resultant at a given tow speed and towline length. With t-his particular barge design, considering the loaded weight and the adjusted reserve buoyancy of fifty (50) tons, it has been found that a tow ship cruising at fourteen and one-half (141/2) knots with a tow line of 300 meters will maintain the submerged barge cruising in its equilibrium condition at a depth of about twenty-five (25) meters.

This then gives rise to three more considerations which must be decided in order that the ensuing design parameters will be properly proportioned and/or weighted. First, the mean specific gravity of the water in which the vessel will operate. This was found to be 1.030 for the central Mediterranean area. Second, the specific gravity of the crude oil to be carried by the vessel, and -this was found to be a value of at least 0.84 for crude oil shipped from the source port. Third, the depth of water through which the submerged barge travels. The safe minimum for this depth is fifty (50) meters and a suitable sealane has been established.

Investigation of underwater towing with vessels of large size has shown that the buoyancy of the vessel is an extremely sensitive factor. The specific gravity of sea water will vary with changes in salinity and/or temperature and it has been found that when passing through a gradient of specific gravity change the stability of the vessel is varied by an inordinate amount.. The specific gravity ol' the cargo then enters into the consideration and the empirical findings support a design which strikes a balance as to the optimum size of the barge with regard to the buoyancy effects to be encountered.

Under the conditions anticipated above, i.e., sea water specific gravity of 1.03 while the crude oil specic gravity will be not less than 0.84, the following dimensions were found to be consonant wit-h the best operation of a submersible vessel.

Meters Length (main hull) 72.2 Length (overall) 75.2 Breadth 12.0 Depth (main hull) 12.0 Depth (overall) 15.15

These dimensions result from considerations of the desired vol-unie of cargo and ballast space to be disposed within a submersible barge of the type as disclosed herein.

FIG 1A shows the submersible vessel or barge 10 as it would be at rest in the body of .water 12 in its fully loaded and properly ballasted condition. It.is apparent that the vessel 10 floats very low in the water with but small freebo'ard showing above the water surface 14. The mother or tow ship 16 is provided with a suitable winch 17 for providing a towing connection, towline 18, to the tow vessel 10. The winch 17 is preferably one having sufficient power and speed capabilities for rendering reliable control over the towline 18 since the length of the towline is one means of controlling t-he vessel 10.

The vessel is formed by a streamlined, revolute hull portion 20 having bow wings 22, stern wings 24 and vertical fin 26 affixed thereto in the manner shown and as will be more fully described. The bow wings 22 and stern wings 24 (having trailing edge flaps to be described) are each adjustable as to their forward slope or angle of attack. A fairwater 28 is disposed along the top 0f hull member 20 and serves as the superstructure portion which houses various control and valving devices as will be de scribed below. The ballast keel 30, on the underside of hull 20, is made to carry solid ballast (not shown) of a prescribed weight and distribution in accordance with the design criteria of the vessel.

The vessel 10 is provided with a suitable tow connection 32 to which is attached the tow line 18 which may be, for example, a 21/2 inch stainless steel cable. It should be understood that the tow connection may be located anywhere from the exact bow-center back to about the forward end of fairwater 28, so long as the necessary compensating adjustments are made to the slope of bow wings 22 and the trailing edges of the stern wings 24; such that the vessels hydrodynamic characteristics will remain in the proper range to compensate for the static characteristics of the vessel 10 and its particular point of tow.

FIGS. 1A, 1B and 1C show the vessel in three different attitudes which the system would go through when a tow ship, towing the submersible vessel, starts from dead in the water and accelerates to its cruising speed of 141/2 knots. In FIG. 1A, vessel 10, under the tension of tow line 18, would proceed at the surface 14 through the early speeds of acceleration. At about nine (9) knots the forces acting are sufficient to take the vessel into a dive. In FIG. 1B the vessel 10 and tow line 18 show the system in its descending attitude at tow speeds in the intermediate range. Then, when tow speed acceleration stops and the designated cruising speed of 141/2 knots is reached, as in FIG. 1C, the vessel 10 attains its stable cruising attitude wherein an equilibrium condition of the static and hydrodynamic forces is reached. In the cruising attitude, the depth of vessel 10 can be regulated by either slight changes in speed, changing the length of the towline, or a combination of both functions.

As it was previously stated, the predominant forces in the interaction are:

(l) drag due to frictional resistance of thc hull, (2) the lift-force of wings and hull,

(3) the tension of the towing wire at the connecting point to the barge, and (4) the reserve buoyancy of the barge.

Each of these forces will vary with the exception of the reserve buoyancy. The reserve buoyancy must not vary and it should be a specic value at all times. In the barge as presently designed, the reserve buoyancy is maintained to be fifty (50) tons at all times when the barge is trimmed for underwater travel. This requires then that the remainder of the design parameters of the barge also have a known and proportionate value, all of which, are related to the specific gravities of the liquid cargo and the sea water of the operating locale. The dimension values found applying were the measurements set forth previously which result in a volume of about 6600 cubic meters of hold space and a barge deadweight of 5200 tons metric.

Fifty (50) tons of reserve buoyancy is comparatively small in relation to the total size and weight of the vessel hence, with increasing forward towing movement of vessel 10 (FIG. 1A) the downward forces due to hull drag and towing tension soon tend the vessel forward in the water. This tendency is progressively aided by the resultant downward force of the bow wing 22 and the reserve buoyancy acting upwardly (at the center of buoyancy) about the forward force centers (the axes of bow wings 22 and the tow point 32); such that, at a given tow velocity of about nine (9) knots, the vessel submerges and quickly goes into a dive.

As the vessel accelerates through speeds above nine (9) knots the vessel is in a diving attitude as depicted in FIG. 1B. Here, the vessel 10 now experiences equalized hull drag forces since all surfaces are wetted and frictional resistance is evenly distributed. The reserve buoyancy, always present, acts upward at about the center of gravity (designated CG in the drawings) and tends to raise the stern of hull relative to the tow point 32 and bow wings 22 to aid and increase the combination of diving forces; that is, the forward momentum (along the longitudinal centerline) of vessel 10, and the depressive forces of bow wings 22. With continued acceleration of tow speed, the vessel 10 proceeds in its diving attitude until the relationship of hydrodynamic forces tends to stabilize the vessel. As the vessel dives deeper the towing angle increases, thus increasing the upward component of force at tow point 32 until it is sufficient to counteract the diving forces and cause the vessel to start to level off. The fact that the tow speed (tow tension) is constantly increasing also tends to increase the upward component of force at the bow for a constant depth. Thus, at a speed of around twelve (12) to thirteen (13) knots, the forces are such that the vessel 10 is hydrodynamically affected to seek a particular depth and balance of forces when the tow speed is maintained constant with a particular tow line length. FIG. 8 shows the response curves which will apply.

It should be reiterated here that the dimensions, weight, trim, buoyancy, etc. of a vessel will interact to varying degrees at different speeds and tow line lengths; hence, the dimensions and weights of the vessel, as stated in this specification, have been derived for underwater tow operation cruising at 141/2 knots with a tow line of about 300 meters.

In the equilibrium, constant speed, cruising state, as with vessel 10 in FIG. 1C, the drag forces due to frictional resistance along the hull will still be, for all practical purposes, equally distributed along all surfaces of the vessel 10 since the vessel is horizontally trailing and completely surrounded by the sea water. The reserve buoyancy, always present and acting from the center of buoyancy (almost the same as center of gravity CG), will still bias the vessel 10 toward a forward leaning attitude; however, the depressive force of winglift from bow wing 22, and the upward component of tow tension at tow point 32, will interact to equalize the forward bias and the vessel 10 will cruise on an even keel at constant speed and constant depth. In the case chosen, a tow speed of 141/2 knots -with 300 meters of tow line will cause the vessel to seek a depth of about 25 meters, as measured from the Waters surface to the point of tow 32.

Generally, with conditions as set forth herein, the vessel 10 will dive somewhat deeper at the intermediate accelerating speeds and then will tend to rise again to seek its constant depth equilibrium state after the steady cruising speed has been reached. With a further increase in speed, the vessel will dive somewhat and then tend to seek a more shallow cruising level; and, by shortening the towline, the vessel will again seek a more shallow level. Hence, it is in this manner that navigation control is exercised over the submersible barge by means of the two line alone. This control is carried out on the tow ship 16 which is outfitted with a suitable towing winch 17 for effecting the towing connection and control. The stern wing sections 24 and vertical fin 26 have little to do with the diving and equilibrium seeking conditions other than the fact that they act to stabilize the vessel 10 both vertically and horizontally at all times. The forward slope or angle of attack of the bow wings 22 are adjusted once for a given overall operation and then left alone. This adjustment is made to establish the most desirable behavior pattern in each of the diving, cruising and surfacing phases of the operation. The trailing edge 25 of the stern wings 24 (see FIG. 6) are also adjustable as to slope and are set for most desirable stabilizing operations under the known conditions of tow.

Detailed description The hull 20 is compartmented into ten separate spaces as shown in FIG. 2. These are the after and forward nonpressure- resistant cargo tanks 36 and 38, respectively; a pressure-resistant cargo tank 40 located amidships; the fore and aft main ` ballast tanks 42 and 44; the fore, aft and midships trim lanks 46, 48 and 50; and, nally, a pair of lnon- watertight spaces 52 and 54 located extremely at the bow and stern ends, respectively, of the hull 20. The ten compartments are divided vertically by six bulkhead members 56, 53, 60, 62, 64 and 66, as placed transversely from fore to aft in hull 20.

The nonpressure- resistant cargo tanks 36 and 38 are `constructed in the longitudinal system of framing with the longitudinal strengthening members 68 and transverse webs 70 supporting the plating or hull 20. The after nonpressure-resistant tank 36 is spaced between the transverse bulkheads 62 and 64 and is constructed to be of a certain volume in accordance with design criteria. Collection and expansion tanks in space 72 (to be more fully described) are separated off from the after cargo tank 36 by a vertical plate member 74 and a transverse horizontal plate 76. The tankage area in space 72 is constructed in the transverse system with longitudinal ring 78 providing stiffening. While the expansion and collection tanks in space 72 are separated by panel 74, they are, nevertheless, in liquid communication with the respective cargo tank 36, as will be described.

The forward nonpressure-resistant tank 38 is constructed similar `to after tank 36; that is, the construction system is longitudinal with framing members 68 supporting transverse webs 70 and forming the cargo space within hull 20 and bulkheads 58 and 60. This forward nonpressure-resistant tank 38 also has a space 78, set off by plate 80 and transverse plate 82, which contains the attendant expansion and collection tanks.

The expansion and collection tanks which are present in each of spaces 72 and 7S of cargo tanks 36 and 38, respectively, are described with reference to FIG. 3. Here the sectional view of space 78 shows the forward expansion tank 84 and the forward collection tank 86 as they are disposed within the cargo tank space 38. Each of the forward and after expansion and collection tank pairs are of similar arrangement and symmetrical location (see FIG. 6).

The purpose of the expansion and collection tanks is (i) to aid in filling and emptying cargo and (ii) to provide an expansion chamber while underway. That is, in the event that the cargo undergoes temperature change and expands, no crude oil must necessarily be lost through pressure relief to the outside of the vessel. The excessive volume of crude oil can displace sea water in the expansion tank with the consequent expelling of an equal volume of sea water through a suitable relief device (not shown) to the outside.

Referring to FIG. 3, the horizontal cross member 82 and vertical plate 88 separate off the space 78 into two tanks; the expansion tank 84 which is four (4) percent of the total volume of cargo tank 38, and, second, the collection tank 86, which constitutes three (3) percent of the total volume of cargo tank 38. The expansion tank 84 communicates with the bottom of cargo tank 38 only through the pipe 90, while the collection ltank 86 is connected for direct of fluid communication through suitable passages 92 in the structural plate member 82. Vertical iiow direction plates 94 and 96 are attached as shown to provide an inverted trap so that the crude oil (which is immiscible with and lighter than sea water) can ow (be oated) through the passages 92 over the top of the rising plate 94 and down under the flow direction plate 96. Effectively, this provides liquid communication between the topmost part of cargo tank 38 and the bottom of collection tank 86.

A pipe 90 leads from the top of the expansion tank 84 down to a rosebox 91, a strainer head, which is located close to the bottom of cargo tank 38. A suction head 93 is placed on the bottom of expansion tank 84 to lead up -through pipe 95 to valve 97 and a dockside connection 99. The collection tank S6 is connected via a pipe 101 and valve 103 to another dockside connection 105. The dockside connections 99 and 105 will be reversible piping arrangements, depending upon the phase of operation, loading or unloading, with pipe 105 carrying crude oil and pipe 99 carrying sea water. The purpose and functions of the expansion and collection tanks will be more fully described in the operation section of the specication.

The midships cargo tank 40 (FIG. 2) is a pressureresistant tank and it is constructed to be airtight since in `certain phases of operation it will be maintained void. The midships tank 40 is transversely framed with transverse webs 98 supporting the pressure-resistant plating 100 of the hull 20 to define the tank volume within the reinforced, pressure- resistant bulkheads 60 and 62 and a deckplate 102. The deckplate 102 is airtight but not necessarily of pressure-resistant strength since the trim tank 50 located below the plate 102 is also a pressure-resistant enclosure as will be described.

The main ballast tanks 42 and 44, forward and aft respectively, are nonpressure-resistant spaces constructed with longitudinal system of framing and they are each disposed above the respective forward and after trim tanks 46 and 48. The trim tanks are airtight and pressure-resistant. At the forward end, the ballast tank 42 and trim tank 46 are spaced between the bulkheads 56 and 58 and bounded by the hull 20. A deck plate 104 separates the two tanks as shown in FIG. 4. The deck plate 104, a pressure-resistant plate, is bent downward at each side (portions 106) and welded to the inner plating of hull 20. The lower hull plating 100 is of the reinforced, pressure-resistant type. The tanks are strengthened by the longitudinal rings 108 and 110 located on the centerline in each of the tanks 42 and 46, respectively. Flooding holes 112 are provided on each lower side of the ballast tank 42 for the purpose of providing water passage for ballasting and de-ballasting. These operations are controlled by venting and blowing of tank 42 as will be described.

The after ballast tank` 44 and the after trim tank 48 arc of similar structure to their forward counterparts in that they are spaced between the after bulkheads 64 and 66 and separated by a bent, pressure-resistant deck plate 114. Also, the trim tank 48 is constructed to be airtight and pressure-resistant. The tanks 44 and 48 are both of trans- Verse framing with webs 116 and 118 supporting hull 20 and a reinforced hull section 100. A longitudinal stifener 120 is provided in the ballast tank 44. A cross-section of ballast tank 44 and trim tank 48 appears in FIG. 5. This shows the configuration of trim tank 48, similar to that of forward trim tank 46, and the manner in which the horizontal . stiffeners 120 and 122 support along the centerline. Also, in the after portion of the ship, the horizontal side members 124 are present in the framing (as shown in FIG. 5). Flooding holes 126 are provided at each lower side of the ballast tank 44 for the purpose of flooding with or evacuation of sea water as will be described.

The remaining spaces, the fore and aft non-watertight spaces 52 and 54 are merely waste space within the hull. These spaces are allowed to fill with sea water and require no further attention. Each of the spaces is sui ccntly framed by transverse system, longitudinals 128 and 130 and transverse webs 132 and 134, fore and aft respectively, such that the spaces are arequately maintained as to the maximum strength ratings required of the vessel.

The fairwater 28, another non-watertight space, forms the superstructure and it contains all of the auxiliary operating equipment associated with the craft (see FIGS. 2 and 6). Extensive piping and valving equipment (not shown) is located in fairwater 28, as well as, the cornpressed air cylinders 136 and electrical equipment located in the space 138. The space 138 is an airtight and pressure-resistant .space of suitable marine design. The pressure-resistant space 138 comprises three sections; the first section 140 houses electromagnetic relay and valving equipment (not shown) for controlling the compressed air supply which is used for blowing and venting the ballast tanks, as will be described.

The second section 142 is adapted to contain any radio equipment which is on board; in particular, radio control receiving equipment of conventional design which can receive radio signals from the tow ship which signal to blow olf the ballast. This is not to imply that this is the manner of control by which the submersible vessel 10 is surfaced. It serves to increase the buoyancy of the vessel 10 to a value somewhat greater than the required 50 tons and the radio control can only be effected when the vessel 10 is surfaced. It is also contemplated to provide further radio equipment in space 142 for beacon homing and identifying, and radio remote control equipment for actuating a mechanism to release the tow line 18 upon command. The various electronic equipments would be well-known and of conventional design.

The third section 144 contains the electrical batteries necessary to fulfill the power requirements of the various auxiliary equipment.

Venting passages 146 are provided in the pressure-resistant space 138 to allow escape of any pressure and gases which may build up within the space. Also, the section 138 would contain a suitable safety regulation device (not shown) of conventional design which would respond to a maximum allowable pressure and automatically blow off all ballast to raise the vessel 10. The pressure actuation point is adjusted to a value indicative of about sixty (60) meters in depth. This setting is made in accordance with rated depth of vessel 10.

The top surface of fairwater 28 also supports mooring equipment such as the fore and aft bollards 148 and their respective closed fair leaders 150. Ather fixtures may be added or shifted to tit particular mooring situations. A radio antenna 152 is also mounted on fairwater 28 by suitable submarine mounting arrangement and it is connected in electrical communication with the pertinent radio equipment in section 142.

At the forward end of fairwater 28, one type of towing hookup is shown wherein the tow cable 18 is led through a leader passage 154 in the fairwater shell and attached to a suitable attaching or towing device 156. This is an alternative, but as it was stated before, the point of tow can be anywhere from about the position of device 156 forward to the point of the bow; so long as proper trim is adjusted into the vessel 10.

Manholes 158, some of which are shown, are provided throughout the vessel to allow access to every space within the vessel. Where necessary, ladders and/or steps (not shown) are provided. The vessel also provides passages (not shown) to allow access for cleaning by means of Butterworth machines and other equipment common to maintenance of tankage facilities.

An adjusting mechanism 160 is provided in the fairwater 28 for effecting adjustment of the bow wing 22. This adjustment is made via suitable connecting rod arrangement as shown by the dotted l-ines 162 connecting to the axis 164 of each bow wing 22. The adjusting mechanism 160 would preferably take the form of a hand pump in control of hydraulic angular positioning equipment, several types of which are well known in the art. The trailing edge of each stern wing 24 is similarly controlled by a connecting linkage 166 which is positioned by the adjusting mechanism 168 located high up in the vertical fin 26.

Referring to FIG. 6, there is a top plan view of the vessel 10 which shows some features of the invention to better advantage. The compartmentation is evident from the transverse dotted lines which divide the hull into the different spaces; that is, non-watertight spaces 52 and 54, main ballast tanks 42 and 44, the nonpressure- resistant cargo spaces 38 and 36, and, amidships, the pressureresistant cargo space 40. The layout of the expansion and collection tanks is shown in dotted lines although, actually, in the volumetric considerations, these are each parts of their respective cargo spaces. The expansion tank 84 and collection tank 86 (space 78 of FIG. 2) function with the nonpressure-resistant cargo space 38 and the eX- pansion tank 170 and collection tank 172 (space 72 of PIG. 2) function with the after nonp-ressure-resistant cargo space 36.

The bow wings 22 are shown with their axis members 164 connected through suitable tiller and connecting linkages 162 to the adjusting mechanism 160 which is accessible in the fairwater 28. Also, the stern wing adjustment system is shown with the axis 166 suitably connected for control by adjustment mechanism 168, located in an access enclosure on the vertical fin 26. This adjustment of stern wing flaps 25 and bow wings 22 is only rarely necessary. Usually, the settings will remain the same over a long period of time.

FIG. 6 also shows the manner in which the compressed air sources, bottles 136, are stored in banks within the fairwater 28. This is to ensure a suiiicient supply of compressed air through all operations on the voyage. The bottles are interconnected and paralleled to the necessary valve and reducing gear, also located in fairwater 28 but not shown.

As is necessary and appertinent to any vessel handling liquid cargo, extensive piping and valving is present and arranged for access in the fairwater 28. FIG. 7, a functional layout of the barge, shows compartmentation and the schematic routing of air pressure and sea water lines for operation of the ballast and trim tanks. The main ballast tank 42 is supplied with high-pressure compressed air via line 180 to a -blowing port 182, while the after main ballast tank 44 is connected to a similar line 184 at blowing port 186. The high pressure air source is the multiple of bottles of gas 136 and suitable air valving devices located in fairwater 28. The introduction of the air blows off the sea water ballast through the flood holes 112 and 126, fore and aft respect-ively. In order to ood the ballast tanks, the air within them is vented to allow sea water to rush into the tanks through the flood holes. High-pressure air on lines 188 and 190 is made to actuate the vent valves 192 and 194, respectively, thus venting the ballast tanks 42 and 44 and recharging them with sea water through the flood holes 112 and 126. The blowing and venting of ballast is carried out independently by each ballast tank and its respective air circuitry.

The forward trim tank 46 is connected by line 196 to a reversible sea water source located at the dockside facility. This source -is preferably tted with suitable How-metering means whereby the exact volume of water entering the trim tank can be monitored. The midships trim tank 50 is fitted to a similar sea water line 198 while after trim tank 48 utilizes a sea water line 200. Each of the lines 196, 19S, and 200 is terminated with a suction head (not shown) located in the bottom of the respective trim tank. In the tank emptying phase of operation, the suction of the pipes 196, 198 and 200 requires booster power; hence, medium-pressure compressed air is sup- Iplied on line 202 through each of three branches 204, 206 and 208 to the top areas of the respective trim tanks.

The crude oil and sea water lines connected to the nonpressure- resistant tanks 36 and 38, through their respective expansion and collection tank pairs, have been described in connection with FIG. 3. Also, FIG. 7 shows the crude oil line 99 which should be attached to a reversible docksides source and led into the collection tank 86. The crude oil line 210 connects in similar manner with the after collection tank 172. Each of the expansion tanks is connected for sea water handling. The forward expansion tank 84 has a pipe 105 connected to supply or suction out sea water at the bottom of expansion tank 84. The after expansion tank receives sea water from a pipe 212 to the appropriate dockside source.

The pressure-resistant cargo tank 40 requires a somewhat diferent piping arrangement since, on a return voyage, it is to be maintained void; hence, sea water llotation is not used in emptying the tank. The crude oil line 214 leads from a reversible dockside source to the bottom of the pressure-resistant tank 40. The loading of cargo is done by direct tiow into the tank 40; however, olf-loading requires the reverse or suctioning out of the cargo from the -bottom of tank 40 and, therefore, mediumpressure compressed air must be supplied as booster power at the top of cargo tank 40. This air pressure is supplied on line 216 from source 202, the same source which is utilized as `boosting power in the trim tanks.

The various pipes and valves used for dockside connection and control, as shown figuratively atop the hull 20 in FIG. 7, would be located, and find operational access, within the fairwater 28. It should also be understood that suitable venting and air relief devices, of known type and usage are employed in all tanks requiring such for their operation.

Operation It shall be assumed that the vessel 10 is tied up at a dockside facility and ready to take on cargo. Refer to FIG. 7. The pressure-resistant cargo tank 40 is loaded by directly pumping the liquid cargo into the cargo tank 40 through the dockside connecting line 214. This requires nothing further except a suitable oil level detector or flow-metering device to indicate when the cargo tank 40 has reached capacity.

The nonpressure- resistant tanks 36 and 38 are each loaded in a different manner and will be described with reference to FIG. 3. If the cargo tank 3S is completely void, the cargo is pumped in via the dockside connecting line 105, valve 103, and pipe 101 to the collection tank 86. The tank 86 allows crude oil to ow through the trap area formed by the ow direction plates 94 and 96 and down through the passage 92 into the cargo tank 38. A suitable oil level detector or flow meter may be used to verify capacity. The expansion tank S4 is lled with a volume of sea water for cargo expansion purposes in case the load undergoes a temperature change while underway.

In the event that the cargo tank 38 is filled with sea water when loading begins, sea water must be pumped out at dockside connecting line 99 simultaneously with loading of crude oil through the line 105. The sea water is pumped out of the expansion tank 84 at suction head 93, and the sea water in expansion tank 84 is continually replaced by the suction of line 90 and rosebox 91 at the bottom of the cargo tank 38. The crude oil is immiscible with the sea water and ioats on top so that when a small quantity of crude oil is detected in the expansion tank 84 as suctioned from the bottom of cargo tank 38, the loading is indicated as complete.

All cargo spaces having been loaded, it is then necessary to ballast and trim the vessel. Refer again to FIG. 7. The main ballast tanks 42 and 44 are ooded by venting the air from within. This is done by air control of vent valves 192 and 194 via the pneumatic lines 188 and 190, operated from the fairwater 28 access area. Hence, the fully loaded vessel 10 has been ballasted down to a position in the water where just the fairwater and a small amount of hull is visible above the surface. This is a condition where the reserve buoyancy of the vessel is about fifty (50) tons of upward force.

The exactness of the reserve buoyancy can then be adjusted with the trim tanks while, at the same time, the vessel is balanced as to its tioating attitude. Each of the trim tanks 46, 48 and 50 can be filled with the required amounts of sea water which are necessary to so adjust the vessel 10. The sea water supply lines, from dockside connection 196, 198 and 200, are each suitably valved and flow-metered to enable proper control of the individual trim tank ballast. Thus, with the vessel 10 fully loaded, balanced and ballasted to have a reserve buoyancy of fifty (50) tons, the vessel is then secured for underwater tow travel.

Referring to FIG. lA, the tow vessel 16, outtted with the necessary towing equipment 17 is connected by towline 18 to the vessel 10. Upon getting underway the vessell 10 will remain at its surface attitude, or very closely thereto, up to a speed of about nine (9) knots. This then includes all piloting speeds in and around ports and channels when the vessel 10 remains at the surface, visible and more easily maneuvered. Upon reaching open water of suicient depth the tow speed is accelerated through nine (9) knots and the vessel 10 submerges. At submergence, the drag or water resistance along the bottom of vessel 10 becomes great enough, coupled with the upward movement exerted by fty (50) tons of reserve buoyancy and the force of bow wings 22, to tend the vessel forward in the water. The increasingly aiding forces finally cause the vessel to dive at about nine (9) knots.

After the dive, the vessel then goes through a period of descension and stabilization at a predetermined depth. It has been decided, that for the particular barge design in one contemplated use, a towing speed of 141/2 knots with a three hundred meter towline was most desirable. These conditions of tow allow the best cruising depth of about twenty-tive (25) meters with a maximum of control, as enabled by the speed of tow and length of the towline.

As the barge or vessel 10 accelerates from nine (9) knots to the cruising speed of 141/2 knots, it undergoes a period wherein it is in the diving attitude and seeking equilibrium conditions. As shown in FIG. 1B, the vessel 10 is in a relatively steep dive as the tow speed is accelerating. In this attitude, the towing angle is increasing as the vessel 10 goes deeper, and thus, an upward cornponent of force at the tow point 32 (relative to the longitudinal centerline of the vessel 10) is increasing to begin the counteraction of the forces and momentum of vessel l which aid the dive. Simultaneously, the upward coniponent of force at tow point 32 is being further increased by the increasing tow tension as the acceleration proceeds;

that is, the faster the tow speed, the greater the upward component exerted at tow point 32. As the tow speed approaches 141/2 knots, the vessel 10 levels off and rises somewhat in the water, causing towing angle to decrease and thereby decreasing the up force at tow point 32. At the same time, the depressive force of bow wings 22 increases, and with the reserve buoyancy remaining the same, the forces acting upon vessel 10 approach an equilibrium condition to allow stable cruising at a constant depth.

FIG. 1C shows the vessel 10 as it cruises in equilibrium condition. At 141/2 knots the forces are such that they are in stable equilibrium and the vessel 10 is at about 25 meters depth. The up forces of reserve buoyancy and the tow line component balance the down force of bow wings 22; and the vertical tin 26 and stern wing 24 serve to further stabilize the vessel. This is the stable state for sea towing and it should be apparent that very high speed cargo transportation is afforded.

It has been found that .small changes .in the specific gravity of the sea water can cause noticeable lchanges in the depth of the barge. Contrary to what it would seem, a slight increase in specic gravity will cause the vessel to dive deeper while a decrease will cause the vessel to rise. This is due to the fact that the reserve buoyancy, acting at the center of buoyancy of the vessel, changes the attitude of the vessel such that the bow wings 22 will carry the vessel further as they are each directed. That is, when the buoyancy increases, the stern of vessel 10 will tend to rise; however, the increased forward declination angle of bow wings 22 will carry the vessel deeper until it once again reaches an equilibrium condition.

`It has been established that a sea water specific gravity change of .001 can cause a depth change of six (6) meters to the vessel 10. In certain instances, e.g., crossing a body of water such as the gulf stream, this becomes an extremely important factor. In order to combat this, powerful and rapid towline control should be exercised at the mother ship. By decreasing the speed of tow from the cruising speed the vessel 10 will go deeper, by increasing the length of the towline 18 the vessel will go deeper and vice-versa in each instance. It is preferable then to employ a very heavy winch 17 which can rapidly lengthen or shorten the tow line 18, and which can work integrally in conjunction with changes in the tow speed as set by the mother ship.

The graph of FIG. 8 shows the relationship of barge depth, towline length and towing speed for the vessel 10 as it is set forth herein having fifty (50) tons of reserve buoyancy. It is apparent from the graph as to the manner vin Vwhich the barge dives and then seeks a more shallow cruising level. The towline length of 300 meters has been found to be best, both from the standpoint of control and when `considering the average depths to be encountered.

The barge is constructed in accordance with certain depth requirements such that the maximum rated depth is about sixty (60) meters. In the event that an unexpected condition should be encountered (large specific gravity change of sea water, etc.) the barge includes pressure-sensitive safety detectors which serve to blow all ballast when the barge approaches its maximum depth rating. This blown ballast condition imparts sufficient additional buoyancy to take the vessel through its hydrodynamic stall point and cause it to rise to the surface.

Upon entering port, the tow ship reduces to inland or channel speeds and the barge travels at the waters surface with fairwater 28 exposed. It can then receive radio Icontrol signals from the mother ship which signal the blowing of all ballast. This raises the barge somewhat further out of the water and aids the docking and access functions. When the barge has been secured at a suitable dockside facility, the cargo unloading sequences may begin.

Referring to FIG. 7, the main crude oil cargo tank 40 is suctioned out by the dockside connecting line 214 and, simultaneously, booster air of medium-high pressure is applied by line 21'6 at the to-p of cargo tank 40. Tank 40 is a pressure-resistant cargo tank and, after off-loading of crude oil, it will be maintained airtight and void for the return Voyage.

The fore and aft cargo tanks 36 and 38 will each be emptied of crude oil and, simultaneously, filled with sea water. This practice results in .adherence to the ballast requirement 4for the return voyage. Referring to FIG. 3, the off-loading proceeds by pumping sea water in at the dockside connecting line 99 and thus displacing sea water and/ or a small amount of oil from the top of expansion tank 84 to the bottom of the cargo tank 318. This, in turn, floats crude oil up through the trap (over vertical plate 94) and into the collection tank 86 where the oil is removed from the top of the tank by pipe 101, valve 103, and so lon to the dockside connecting line 105. The removal of crude oil from the after cargo tank 36 is done in the salme manner with the aid of the expansion tank 170 and collection tank 172.

This then leaves the nonpressure- resistant cargo tanks 36 and 38 .filled with sea water and the pressure-resistant cargo tank 40 void. In this condition, due to the differential in specic gravities of the liquids and distribution of volume between the tanks, the barge can then be re- -ba'llasted and retrimmed for return towage to the loading port and having the same weight, distribution and buoyancy characteristics. This, of course, is only one of many possible functions as it may be advantageous to arrange ballast for the return of another cargo.

It should be understood that the preferred embodiment, as disclosed herein, may be altered to a great extent and still remain within the bounds o-f structure and size which will allow the particular advantageous functions. The compartmentation may be arranged in any of several different manners as a matter of design; there Amay be a greater or lesser number of compartments and they may be aligned horizontally instead of vertically as shown herein.

The specificaton has set forth a novel submersible barge whereby l-arge scale liquid cargo transportation can be effected at speeds which were heretofore unattainable with towed devices. IFurther, due to utilization of subsurface barge travel and its attendantt advantages, the liquid cargo can .be towed by another merchant-type ship which can also carry its ful-l load of cargo. The submersible barge as set forth herein has the capability of fast undersea transport in either its loaded or cargo unloaded condition due to the particular size, disposition and distribution of the pressure-resistant and nonpressureresistant hold spaces. When either loaded or unloaded with cargo, the barge can be ballasted with sea water to a particular weight and a specified reserve buoyancy. Given these characteristics the barge will then respond to highspeed towing in the stable manner both on the cargo loaded voyage and on the unloaded return voyage.

Changes may be made in the combination and arrangement of elements as heretofore set forth in this specification and shown in the appended drawings, it being understood, that changes may be made in the embodiment disclosed without departing from the spirit and scope of the invention as defined in the following claims.

What is claimed is:

1. A submersible barge for underwater transport of liquid cargo having a known specific gravity, comprising:

a hull member shaped as an elongated body of revolution;

cargo spaces of predetermined volume compartmented throughout the hull interior, said cargo spaces being yformed as a pressure-resistant cargo space located centrally in said hull member and nonpressureresistant cargo spaces located in balanced relationship to said pressure-resistant space;

keel means fixed along the bottom of said hull and having a predetermined weight;

main ballast tanks located fore and aft in said hull and each having predetermined volume;

trim tanks located fore, aft and amidships in said hull for adjusting the buoyancy and balance of the barge;

means controlling disposition of ballast in said main ballast tanks and said trim tanks which means adjust said hull member to have a predetermined buoyancy;

bow wings located on each forward quarter of the hull member and having a preset angle of forward inclination; and

tow means connected to said hull at a point forward of said bow wings whereby the hydrodynamic forces of the barge can achieve an equilibrium condition with the tow tension and buoyancy such that a tow means of predetermined length moving at a predetermined speed will tow said submersible barge at a preselected depth.

2. A submersible barge as set forth in claim 1 wherein:

said predetermined buoyancy is a value of fifty tons metric; and

said tow means is three hundred meters long and tows at the speed of fourteen and one-half knots.

3. A submersible barge as set forth in claim 1 wherein:

said tow means length can be Varied to control the depth of the barge; and

said tow means speed can be varied to control the depth of the barge.

4. A submersible barge as set forth in claim 1 which is further characterized to include:

a vertical fin member on the stern of said hull member to stabilize horizontal movement of the barge; and

horizontal stern wing members having adjustable trailing edge iiaps for stabilizing the barge vertical movement.

5. A submersible barge as set forth in claim 4 wherein:

said bow wings and said stern wing flaps are individually adjustable as to forward angle of inclination.

References Cited UNITED STATES PATENTS 1,201,051 10/1916 Jack 114-05 3,085,533 4/1963 Goryl et al. 114-235 X 3,301,211 1/1967 Novak et al. 114-235 FOREIGN PATENTS 1,387,875 12/1964 France.

MILTON BUCHLER, Primary Examiner.

5 T. M. BLIX, Assistant Examiner.

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