LOW-PROFILE CARGO VESSELS PROVIDING TRANSPORT OF SHIPPING CONTAINERS

Abstract

According to some embodiments of the present disclosure, a low-profile cargo vessel includes a cargo bed that is open to the stern, an engine compartment forward of the cargo bed, a fairing, and buoyancy volume. The cargo bed includes a cargo bed floor and first and second cargo bed walls on opposite sides of cargo bed floor. The cargo bed, interior portions of the first and second cargo bed walls, and interior portions of cargo bed floor are free-flooding to sea water. The fairing is configured to provide a hydrodynamic bow structure ahead of the engine compartment. The buoyancy volume is inside upper portions of the first and second cargo bed walls spaced apart from cargo bed floor so that the low-profile cargo vessel floats with a waterline above the cargo bed floor and more than half way up the first and second cargo bed walls.

Claims

1. A low-profile cargo vessel comprising: a cargo bed that is open to the stern, wherein the cargo bed includes a cargo bed floor and first and second cargo bed walls on opposite sides of cargo bed floor, and wherein the cargo bed, interior portions of the first and second cargo bed walls, and interior portions of cargo bed floor are free-flooding to sea water; an engine compartment forward of the cargo bed; a fairing configured to provide a hydrodynamic bow structure ahead of the engine compartment; and buoyancy volume inside upper portions of the first and second cargo bed walls spaced apart from cargo bed floor so that the low-profile cargo vessel floats with a waterline above the cargo bed floor and more than half way up the first and second cargo bed walls in the cargo bed.

2. The low-profile cargo vessel of claim 1 further comprising: wall fuel bladers in the first and second cargo bed walls between the buoyancy volume and the cargo bed floor, wherein a volume occupied by wall fuel bladers diminishes as fuel is consumed, and wherein the diminished volume of the wall fuel bladers is displaced by free-flooding sea water inside the first and second cargo bed walls.

3. The low-profile cargo vessel of claim 2 further comprising: wall panels on opposite sides of each of the first and second cargo bed walls so that the buoyancy volume and the wall fuel bladders in each of the first and second cargo bed walls are protected between the wall panels on the opposite sides of the respective cargo bed wall.

4. The low-profile cargo vessel of claim 2 further comprising: floor fuel bladers in cargo bed floor, wherein a volume occupied by floor fuel bladers diminishes as fuel is consumed, and wherein the diminished volume of the floor fuel bladers is displaced by free-flooding sea water inside cargo bed floor.

5. The low-profile cargo vessel of claim 4 further comprising: floor panels on top and bottom sides of the cargo bed floor so that the floor fuel bladders in the cargo bed floor are protected between the floor panels on the opposite sides of the cargo bed floor.

6. The low-profile cargo vessel of claim 1 further comprising: first and second longitudinal beams on opposite sides of cargo bed floor; a plurality of floor beams extending between the first and second longitudinal beams; a first plurality of frames extending from the first longitudinal beam to support the first cargo bed wall; a second plurality of frames extending from the second longitudinal beam to support the second cargo bed wall; and a bulkhead extending between one of the first frames and one of the second frames; wherein the bulkhead is between the engine compartment and the cargo bed, and wherein the engine compartment is coupled to the first and second longitudinal beams using a plurality of detachable couplings.

7. The low-profile cargo vessel of claim 6, wherein each of the first and second longitudinal beams is coupled with twist-lock receptacles forward and aft of the bulkhead, and wherein the detachable couplings comprises twist-locks securing the engine compartment to the twist-lock receptacles forward of the bulkhead.

8. The low-profile cargo vessel of claim 1, wherein the buoyancy volume comprises foam.

9. The low-profile cargo vessel of claim 1, further comprising: first and second propulsors on opposite sides of the low-profile cargo vessel, wherein the first and second propulsors are separately coupled with engine compartment to provide thrust steering.

10. The low-profile cargo vessel of claim 9, wherein the first and second propulsors comprise first and second propellers driven by respective first and second electric motors, wherein the engine compartment is configured to separately provide electrical power to the first and second electric motors to provide the thrust steering.

11. A low-profile cargo vessel comprising: first and second longitudinal beams arranged in parallel; a plurality of floor beams extending between the first and second longitudinal beams; floor panels above and below the floor beams to define a cargo bed floor having an interior floor volume; a first plurality of frames extending from the first longitudinal beam to support the first cargo bed wall; first inside and outside wall panels on the first plurality of frames to define a first cargo bed wall having a first interior wall volume; a second plurality of frames extending from the second longitudinal beam to support the second cargo bed wall; second inside and outside wall panels on the second plurality of frames to define a second cargo bed wall having a second interior wall volume; a bulkhead extending between one of the first frames and one of the second frames, wherein a cargo bed is defined as a space aft of the bulkhead between the first and second cargo bed walls; an engine compartment coupled to the first and second longitudinal beams with the bulkhead between the engine compartment and the cargo bed; and a fairing configured to provide a hydrodynamic bow structure ahead of the engine compartment.

12. The low-profile cargo vessel of claim 11, wherein the cargo bed is free-flooding to sea water, and wherein portions of the interior floor volume and the first and second interior wall volumes are free-flooding to sea water.

13. The low-profile cargo vessel of claim 12 further comprising: a buoyancy volume inside upper portions of the first and second interior wall volumes and spaced apart from the cargo bed floor so that the low-profile cargo vessel floats with a waterline above the cargo bed floor and more than half-way up the first and second cargo bed walls in the cargo bed.

14. The low-profile cargo vessel of claim 13, wherein the buoyancy volume comprises foam.

15. The low-profile cargo vessel of claim 13 further comprising: wall fuel bladers in the first and second interior wall volumes between the buoyancy volume and the cargo bed floor, wherein a volume occupied by wall fuel bladers diminishes as fuel is consumed, and wherein the diminished volume of the wall fuel bladers is displaced by free-flooding sea water in the first and second interior wall volumes.

16. The low-profile cargo vessel of claim 12 further comprising: floor fuel bladers in interior floor volume, wherein a volume occupied by floor fuel bladers diminishes as fuel is consumed, and wherein the diminished volume of the floor fuel bladers is displaced by free-flooding sea water in interior floor volume.

17. The low-profile cargo vessel of claim 11, wherein each of the first and second longitudinal beams is coupled with twist-lock receptacles forward and aft of the bulkhead, and wherein the detachable couplings comprises twist-locks securing the engine compartment to the twist-lock receptacles forward of the bulkhead.

18. The low-profile cargo vessel of claim 11, further comprising: first and second propulsors on opposite sides of the low-profile cargo vessel, wherein the first and second propulsors are separately coupled with engine compartment to provide thrust steering.

19. The low-profile cargo vessel of claim 18, wherein the first and second propulsors comprise first and second propellers driven by respective first and second electric motors, wherein the engine compartment is configured to separately provide electrical power to the first and second electric motors to provide thrust steering.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0008] Examples of embodiments of inventive concepts may be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings in which:

[0009] FIG. 1A is a top view of an LPV/SSV vessel according to some embodiments of inventive concepts;

[0010] FIG. 1B is a side view of the LPV/SSV vessel of FIG. 1A according to some embodiments of inventive concepts;

[0011] FIGS. 2A and 2B are block diagrams illustrating systems of the LPV/SSV vessel of FIGS. 1A and 1B according to some embodiments of inventive concepts;

[0012] FIG. 3 illustrates a shipping container and loading thereof according to some embodiments of inventive concepts;

[0013] FIG. 4A illustrates a shipping container and a propulsion attachment according to some embodiments of inventive concepts;

[0014] FIG. 4B illustrates the shipping container and propulsion attachment of FIG. 4A in water according to some embodiments of inventive concepts;

[0015] FIG. 4C is a block diagram illustrating systems of the propulsion attachment of FIGS. 4A and 4B according to some embodiments of inventive concepts;

[0016] FIGS. 5A and 5B are top and side views of a shipping container and a propulsion attachment with a drogue line and a drogue stowed in a water jet nozzle of propulsion attachment according to some embodiments of inventive concepts;

[0017] FIGS. 6A and 6B are top and side views of a shipping container and a propulsion attachment with a drogue line and a drogue deployed for stability according to some embodiments of inventive concepts;

[0018] FIG. 7 is a side view of a shipping container and a propulsion attachment grounded at a beach with a drogue line redeployed to drag the shipping container onto the beach according to some embodiments of inventive concepts;

[0019] FIG. 8 is a table providing a rope strength guide for ropes that may be used as a drogue line;

[0020] FIGS. 9A and 9B are top and side views of a shipping container and propulsion attachment with a sled according to some embodiments of inventive concepts;

[0021] FIG. 10A illustrates a shipping container with a loop bridal coiled for transport in the LPV/SSV of FIGS. 1A and 1B according to some embodiments of inventive concepts;

[0022] FIG. 10B is the shipping container of FIG. 10A with the loop bridal deployed for areal recover according to some embodiments of inventive concepts;

[0023] FIG. 10C illustrates the shipping container of FIGS. 10A and 10B with the loop bridal extended as it would to be pulled by a rotary wing aircraft to lift the shipping container from the water according to some embodiments of inventive concepts;

[0024] FIG. 11 is a cut away perspective view of a portion of a cargo bed of an LPV/SSV vessel according to some embodiments of inventive concepts;

[0025] FIG. 12A is a perspective view of elements of a floor of the cargo bed of FIG. 11 according to some embodiments of inventive concepts;

[0026] FIG. 12B is an expanded view of a portion of the cargo bed floor of FIG. 12A according to some embodiments of inventive concepts;

[0027] FIG. 12C is an enlarged view of a twist-lock of FIGS. 12A and 12B according to some embodiments of inventive concepts;

[0028] FIGS. 13A, 13B, 13C, and 13D illustrate frames used for sidewalls of the cargo bed of FIG. 11 and connections thereto according to some embodiments of inventive concepts;

[0029] FIGS. 14A and 14B illustrate panels used to cover walls of the cargo bed of FIG. 11 according to some embodiments of inventive concepts;

[0030] FIGS. 15A and 15B fuel bladers and buoyancy foam that may be used in the cargo bed of FIG. 11 according to some embodiments of inventive concepts; and

[0031] FIG. 16 is a cut-away illustration showing various features of LPV/SSV vessel of FIGS. 1A and 1B according to some embodiments of inventive concepts.

DETAILED DESCRIPTION OF THE INVENTION

[0032] Aspects and features of the present disclosure will now be described more fully with reference to the accompanying drawings. The following description shows, by way of example, combinations and configurations in which aspects, features, and embodiments of inventive concepts can be put into practice. It will be understood that the disclosed aspects, features, and/or embodiments are merely examples, and that one skilled in the art may use other aspects, features, and/or embodiments or make functional and/or structural modifications without departing from the scope of the present disclosure. Moreover, like reference numerals refer to like elements throughout, and sizes of elements may be exaggerated for clarity and/or conveniences of explanation.

[0033] According to some embodiments of inventive concepts illustrated in FIGS. 1A and 1B, a semi-submersible marine vessel (also known as a semi-submersible vessel SSV, low-profile vessel, or LPV) may include a low-profile hull where a majority of the hull volume is below the waterline (e.g., approximately 85% of the hull volume is submerged). The submerged hull volume is distributed to be neutrally buoyant, stable in longitudinal pitch while in motion, and hydrodynamically efficient. The semi-submersible marine vessel includes at least one cargo bed 111 that is free flooding to the sea, sized to enclose one or more standardized shipping containers, and the semi-submersible marine vessel can transport these containers. At least one self-buoyant standardized shipping container can be loaded in the cargo bed 111. The shipping container is allowed to flood with seawater, and the cargo therein is waterproofed. Moreover, the buoyancy of the container may be controlled such that the draft of the floating container matches the draft of the vessel's cargo bed 111. Accordingly, the shipping container can float into the cargo bed for loading, and then when released/unloaded for delivery, the shipping container can float out of cargo bed 111. According to some embodiments of inventive concepts, the semi-submersible marine vessel may be used as a logistics vessel providing end-to-end cargo movement with reduced/minimal requirements for material handling equipment and/or providing operation with low detectability.

[0034] An SSV according to some embodiments of inventive concepts may thus be a Low-Profile Vessel (LPV) that is capable of transporting standardized shipping containers in an operational environment where there is an active effort to find and stop the delivery, such as in the contested environment of a military conflict.

[0035] Moving cargo in a contested environment is of significant military value. Modern developments in autonomy, beyond line of sight (BLOS) communication, and hydrodynamically stable LPV hull forms are enabling development and employment of this new class of SSC/LPV vessel.

[0036] An SSC/LPV vessel according to some embodiments of inventive concepts may provide one or both of the following capabilities. The ability to carry an order of magnitude greater cargo payload compared with a parametrically similar design may be provided by making the containerized cargo self-buoyant. The ability to load and unload the cargo by the vessel without material handling equipment may be provided, whereby the self-buoyant containerized cargo can be released and allowed to float away.

[0037] A Low-Profile Vessel (LPV), or semi-submersible vessel is broadly defined as any watercraft constructed or adapted to be capable of operating with most of its hull and bulk under the surface of the water per 46 U.S. Code 70502. Such LPV/SSV vessels may provide benefits including; reduced detectability at relatively low cost and/or improved hydrodynamic efficiency per freight ton of cargo.

[0038] By its very nature, a low-profile vessel has a reduced/minimal amount of freeboard (hull and superstructure projecting above the waterline). This arrangement reduces/minimizes surface area available for visual, thermal, and electromagnetic detection. Accordingly, such vessels have reduced susceptibility of detection due to reduced visual, thermal, and/or electromagnetic signature.

[0039] In addition to just projected surface area, all aspects of radiated and/or reflected energy should be addressed/reduced to reduce the vessel's detectability. In some embodiments of inventive concepts, the LPV/SSV vessel may include one or more of the following measures to absorb, reduce, and/or eliminate the vessel's signature. To reduce acoustic detection, engine module(s) may be mounted using vibration isolating resilient mounts; engine exhausts may be provided underwater; exhaust mufflers may be provided; and/or low speed and/or ducted/nozzled propellers may be used. To reduce visible detection, the LPV/SSV vessel may have low freeboard; and/or dark or marine camouflage color may be used on portions of the vessel above the waterline. To reduce electromagnetic detection, the LPV/SSV vessel may have a low Radar Cross Section (e.g., having a small surface area exposed above the waterline, and/or using planform management). To reduce infrared detection, engine exhaust may be provided underwater; and/or the engine compartment (also referred to as the engine room) may be substantially submerged.

[0040] Moreover, these low detectability features may be achieved at relatively low cost. In contrast to submarines, an LPV/SSV vessel takes advantage of its proximity to the surface. It can be propelled by standard low-cost combustion engines because it has access to atmospheric air. It does not need to withstand high hydrostatic pressures because it does not dive, thus reducing/eliminating the costs to produce a pressure vessel. In addition, it does not need control surfaces and mechanisms to maneuver subsurface in three dimensions, further reducing cost.

[0041] Laboratory testing has revealed that a properly designed LPV can have a hydrodynamic resistance advantage over a vessel with similar characteristics operating fully on the surface to provide hydrodynamic efficiency. The drag bucket means that for the same amount of propulsive force, the LPV can be propelled faster, or can carry more cargo, than the equivalent vessel operating in a surface regime due to the reduced resistance effects of the water surface. Testing results and confirmed previous theories show that resistance is influenced by the location of the aft low-pressure point. Analytically determined Froude numbers for constructive wake interference based on submergence dependent aft low-pressure points coincided well with experimental results. These results established a drag dependence on both velocity and submergence level due to a pressure point location, as well as a general drag reduction due to immersion as indicated from surface ship standard series. Reduced/optimal drag may be achieved by not only considering traditional geometric factors and speed, but also the level of immersion or submersion.

[0042] The low drag advantages in operating at an optimal velocity and immersion may present undesirable seakeeping characteristics in traditional axisymmetric submarine type hulls due to an instability in pitch and roll induced by surface effects. A lack of reserve buoyancy above the waterline may reduce/prevent the development of a righting moment counter to undesired pitch or roll motions. Through hydrodynamic advances, designs according to some embodiments of inventive concepts may reduce/resolve this instability, primarily by replacing the buoyant force with a dynamic force both at the bow and the stern as speeds increase. According to some embodiments of inventive concepts, the LPV/SSV vessel may have an ability to carry an order of magnitude greater cargo payload compared with a parametrically similar design that is enhanced by the cargo shipping container producing its own buoyancy. What this means is that the host LPV/SSV vessel does not need to support the weight of the cargo shipping container, such that the cargo shipping container floats on its own. An analogy is a helium backpack. The wearer needs to move it around, but does not feel the weight of it.

[0043] A second advantage of this design is that the cargo shipping container can be deployed directly from the LPV/SSV vessel by releasing it, and allowing it to float out of the cargo compartment. No cargo handling cranes, hoists, lifts, etc. may be required. There are no existing low-profile ship systems known to the inventors of the present disclosure that take advantage of this technique to support a standardized cargo shipping container, while maintaining low detectability. According to some embodiments of inventive concepts, the LPV/SSV vessel is an autonomous, low-profile vessel that can transport tons of containerized cargo in one or more standard shipping containers, through a contested environment, directly to the end user, regardless of available receiving infrastructure.

[0044] According to some embodiments, the LPV/SSV vessel can be launched and recovered from shore with a mobile travel lift, crane, or boat ramp; from a gray-hull ship's well deck, or from a heavy-lift vessel of opportunity.

[0045] A size of LPV/SSV vessel may be purposefully constrained, allowing it to leverage the existing launch, handling and recovery infrastructure already built. In case of urgent need, it may be transportable via cargo aircraft such as a C-17 and/or a C-5.

[0046] According to some embodiments, the LPV/SSV vessel may have a designed range that is transoceanic, capable of operating in Sea State Four (SS4) and surviving Sea State Six (SS6).

[0047] To operate in a contested maritime environment the LPV/SSV vessel may be designed for survivability as a platform able to operate for long distances in the open ocean. The LPV/SSV vessel may be survivable because: it is less susceptible to targeting through visible, electromagnetic, and/or acoustic signature reduction; it has redundant propulsion, auxiliary, and cargo handling systems; and because each LPV/SSV vessel may be used as one of a system of many, distributed LPV/SSV vessels.

[0048] According to some embodiments of inventive concepts, the LPV/SSV vessel may provide end-to-end cargo delivery; and/or may be able to service unimproved beaches with nonexistent facilities, austere ports, and harbors without fully developed infrastructure. In support of forward forces, it can resupply without adding an undo material handling burden on the receiving military unit.

[0049] According to some embodiments of inventive concepts, the LPV/SSC vessel design may rely on fundamental physics, reduced/minimal mechanically-actuated and/or electrically-actuated systems, proven systems with high technical maturity, and redundancy.

[0050] FIG. 1A is a top view of an LVC/SSC vessel according to some embodiments of inventive concepts, and FIG. 1B is a port side view of the vessel of FIG. 1A. The following system details are discussed below with respect to the illustrations of FIGS. 1A and 1B. As shown, bow 101 of the vessel is on the left side of the page, and stern 103 is on the right side of the page. FIG. 1B is a view of the port side of the vessel of FIG. 1A.

[0051] The hull of the vessel is designed to provide semi-submersible operation. Traditional displacement vessels operate in a general level of immersion as constrained by design parameters as shown in standard series, such as the Taylor series, which are not applicable to operations in high immersion. Hull features providing high immersion operation may take advantage of both lifting surfaces at bow 101 and a surface at the stern 103 where low pressure is induced due to flow stagnation. Cargo Bed 111 opens to the stern 103 of the vessel, and cargo bed 111 has dimensions configured to accept one or more standard shipping containers. According to some embodiments of inventive concepts, the vessel is configured to transport cargo in standard sized shipping containers. Cargo bed 111 is sized to utilize the standardized ISO series of shipping containers. According to some embodiments, cargo bed 111 may be about 53 long from the stern 103 to the engine compartment 121. This dimension is based on the largest standard size shipping container.

[0052] Cargo bed 111 may be open to the ocean at stern 103, and cargo bed 111 is thus free-flooding. At no time is there a need to pump out or deballast the water in cargo bed 111. Just the opposite, the access of seawater to cargo bed 111 allows the buoyancy of the cargo shipping container to support the payload weight.

[0053] To facilitate movement of a cargo shipping container on and off the LPV/SSC vessel, cargo bed 111 has an opening directly to the sea, either through the transom (as shown in FIG. 1A) or the side(s). According to some embodiments, it may be hydrodynamically desirable to close a cargo access opening. In this case, a stern or side door/gate may be installed, using drop-stitch, composite and/or non-structural metal. Such a door/gate may allow flow of water into cargo bed 111, but may provide a faired hydrodynamic shape to improve resistance and pitch characteristics, but not a permanent structure that would impede/prevent impending cargo deployment out of the stern. If an inflatable drop-stitch material is used as a gate, when not inflated it would drop open to allow free movement in and out of the cargo bed. When pressurized, the added buoyancy would close the gate, holding it against the hull, and improving the hydrodynamics of the hull shape.

[0054] As an autonomous vessel, physical security and access into the internal machinery spaces may be restricted. While underway, there is no requirement for easy, convenient access to the internal spaces. To discourage unauthorized access, access to engine compartment 121 may only be available through a bolted soft patch 129 (also referred to as an access panel). Removal of the soft patch would require large tools, and removal of dozens of bolts. Once removed, a large opening, close to the waterline would greatly increase the risk of down flooding and sinking, if it is removed in an environment with any wave action.

[0055] Engine compartment 121 may thus be a removable modular component based on NO MAnning Required Ship (NOMARS) concepts. Moreover, engine compartment 121 may have external dimensions and fastening points consistent with a 10 ISO shipping container so that removable engine compartment 121 can be secured in the vessel using the same mechanisms (e.g., twist-locks) that are used for shipping containers in cargo bed 111.

[0056] As shown in FIGS. 1A and 1B, mast 181 may be provided over cargo bed 111. Mast 181 may include sensors and/or antennas used for communication and/or navigation. Mast 181 may also include snorkel 185 used to provide air to engine compartment 121. According to some other embodiments, mast 181 may be moved forward of cargo bay 111. Moreover, the snorkel may be provided on the hull separate from mast 181. For example, the snorkel may be provided on engine compartment 121 to reduce the path of air flow. Mast 181 may have a low radar cross section (RCS). Moreover, mast 181 may include Global Autonomous Reconnaissance Craft (GARC) level components for a Government Furnished Equipment (GFE) autonomy suite to support navigation and communication functions of control and distribution system 205.

[0057] In keeping with a simple/redundant design philosophy, prime movers may be provided as conventional, commercially available marine diesel engines 201a and 201b housed in engine compartment 121. For redundancy, two smaller capacity engines may be used as shown in FIGS. 2A and 2B. Combined, the two engines may be sized to produce approximately 110% of the required power load. If a low operational velocity is desired, a single engine may be operated to increase/maximize the loading and/or to improve/optimize specific fuel consumption. At higher speeds, including the design speed, both engines may be used at the same time. In case of a failure of either engine, the second engine is capable of completing the mission and returning the vessel to base.

[0058] Engine compartment 121 may be configured to provide modularity and repair access. To increase/maximize operational availability of the LPV/SSV vessel, the prime movers (e.g., engines 201a and 201b) may be installed in engine compartment 121 that is configured as a removable modular power system. The engine compartment 121 (including diesel engine power units) can be quickly disconnected from the host LPV/SSV vessel (output power, combustion air, exhaust, fuel supply and return, cooling water, control circuit). This modularity enables a maintenance concept of quickly and easily swapping one engine compartment 121 for another, and all engine maintenance may be performed off-board the vessel. Reinstalling a fully ready engine compartment 121 without the need to perform maintenance or repairs inside the vessel may reduce vessel downtime and/or cost/time of maintenance/repair.

[0059] According to some other embodiments, access patch 129 discussed above with respect to Physical Access may be located on engine compartment 121 directly above the engines, and sized to allow for removal of the engines without disassembly while engine compartment remains on the vessel.

[0060] The arrangement of cargo bed 111 may preclude use of a traditional shaft line to transfer power from the prime movers (near bow 101) to propulsors (near stern 103). Instead, the mechanical energy from the prime movers (e.g., diesel engines) may be converted into electrical power or hydraulic power that is used to drive propulsors 131a and 131b.

[0061] If electrical energy is used to drive propulsors 131a and 131b as shown in the block diagram of FIG. 2A, control and distribution system 205 can include power conditioning and motor controllers, and control and distribution system 205 can transmit electrical power from electrical generator 203 to electrical motors 231a and 231b used to drive propulsors 131a and 131b. The electrical distribution system may also provide power to one or more shipping containers 271 in cargo bed 111 through an umbilical 281 into the cargo bed 111.

[0062] Each of propulsors 131a and 131b in FIG. 2A, for example, may be provided as a Thrustmaster T-300 E-POD, 300 horsepower (HP) electrical thruster with a 40-inch diameter, and differential thrust steering may be used so that a rudder is not needed. Moreover, bow fairing 189 may be provided using poly carbinate-carbon fiber and integrated polyurea foam.

[0063] As shown in FIG. 2A, diesel engines 201a and 201b, electrical generator 203, and control and distribution system 205 may be housed in engine compartment 121, with couplings through engine compartment 121 provided to/from sensors/antennas 261 (e.g., housed in mast 181), fuel tanks/bladders 251 (e.g., housed in sidewalls of cargo bed), port/starboard motors 231a/231b, and shipping container(s) 271 in cargo bed 111. Diesel engines 201a and 201b may drive electrical generator 203 responsive to signaling from control and distribution system 205. Moreover, control and distribution system 205 may distribute electrical power from electrical generator 203 to port and starboard motors 231a and 231b to drive port and starboard propulsors 131a and 131b. In embodiments of FIG. 2, fast/efficient removal/replacement of engine compartment 121 from the vessel may be facilitated by providing quick connect/disconnect couplings with sensors/antennas 261, motor 231a/231b, shipping container 271, and/or fuel tank(s)/bladder(s).

[0064] In addition, control and distribution system 205 may provide directional steering control of the vessel by selectively distributing electrical power to port and starboard motors 231a and 231b so that a rudder is not required. Such control may be based on global position satellite (GPS) signals received through sensors/antennas 261 and/or based on inertial navigation included in control and distribution system 205. Control and Distribution System 205 may also control diesel engines 201a and 201b to provide sufficient electrical power for a desired power and/or speed. For example, a single engine may be used for low-speed operation, or both engines may be used to increase electrical output for higher speed operation.

[0065] In FIG. 2A, electrical generator(s) 203 may be provided as a single electrical generator configured to be driven by both engines 201a and 201b for higher output and to be driven by one of engines 201a or 201b for lower output. According to some other embodiments, electrical generator(s) 203 may include two generators, one generator for engine 201a and one generator for engine 201b.

[0066] Control and distribution system 205 can also be used to drive cargo handling system 293, for example, to lock a shipping container into cargo bed 111 at loading and to unlock the shipping container for unloading, for example, using electrically actuated twist-locks and/or electro-magnetic couplings. Once couplings for a shipping container are unlocked, the shipping container may float out of cargo bed 111 aided by water flow pushing from the bow and/or by a drogue employed out the stern as the LPV/SSV vessel moves forward.

[0067] Each of diesel engines 201a and 201b may be a Caterpillar C9.3 diesel engine, and each engine may be coupled to a respective DRS generator set of electrical generator 203. Moreover, control and distribution system 205 may include two ABB motor controllers used to control distribution of power respectively to motors 231a and 231b. According to some embodiments, closed loop cooling may be provided for engines 201a and 201b. According to some other embodiments, an open cooling system may draw in water from outside the engine compartment 121 for engine cooling and then expel the used cooling water to outside engine compartment 121.

[0068] According to some other embodiments of inventive concepts, hydraulic power distribution may be used as shown in FIG. 2B. In FIG. 2B, diesel engines 201a and 201b drive hydraulic power system 291 which provides hydraulic power to each of port and starboard propulsors 131a and 131b. Hydraulic power system 291 can also be used to drive auxiliary systems such as steering and/or cargo handling system 293. Control and distribution system 205 can thus control hydraulic power system 291 to separately drive propulsors 131a and 131b to propel and steer the vessel. Moreover, one diesel engine may be used to drive hydraulic power system 291 for low-speed operation with lower fuel consumption, and two diesel engines may be used to drive hydraulic power system 291 for higher speed operation.

[0069] Hydraulic power system 291 can be used to drive cargo handling system 293, for example, to lock a shipping container into cargo bed 111 at loading and to unlock the shipping container for unloading, for example, using hydraulically actuated twist-locks. Once couplings for a shipping container are unlocked, the shipping container may float out of cargo bed 111 aided by water flow pushing from the bow and/or by a drogue deployed out the stern as the LPV/SSV vessel moves forward. In an alternative, cargo handling system 293 of FIG. 2B may be electrically actuated using electrical power generated by an alternator of one or both of engines 201a/201b.

[0070] Propulsors 131a and 131b may thus be provided as electrically or hydraulically driven ducted thrusters positioned externally in one of several configurations. As shown in FIGS. 1A and 1B, two such ducted thrusters 131a and 131b may be provided at/near the bow on opposite sides of the vessel. Such embodiments may have an advantage of spacing the thrusters away from the stern where cargo loading and unloading occurs. Accordingly, a risk of damaging and/or fouling a propulsor during loading/unloading may be reduced. According to some other embodiments, two ducted thrusters may be provided at the stern on opposite sides of the vessel. According to still other embodiments two thrusters may be provided at the bow for directional control and one thruster may be provided at the stern for power. According to yet other embodiments, two thrusters may be provided on opposite sides at the bow and two thrusters may be provided on opposite sides at the stern for additional redundancy.

[0071] With propulsors on opposite sides of the vessel, steering can be accomplished using differential thrust, increasing and decreasing power on either side of the vessel, creating a thrust imbalance and creating a yawning force (turning to port or starboard).

[0072] According to some other embodiments of inventive concepts, external propulsors may be replaced with keel-mounted waterjets embedded in the forward engine compartment, ahead of cargo bed 111, with the wash splayed outboard or down slightly. By co-locating the water jet propulsors with the prime movers in/on engine compartment 121, the propulsion train may be shortened and/or simplified. Waterjet propulsive thrust at/near the bow can provide a positive bow up pitch force. With a 10-12 degree outboard splay, there may be no significant increase in frictional resistance due to high velocity wash along the sides or bottom. The jets can provide a resistance benefit due to entrained bubbles under the hull. If desired, it may be possible to bleed some of the waterjet discharge into the cargo bed to increase flow. This can be beneficial for several reasons including: creation of a virtual tail cone effect from the wake; and/or assisting in deploying buoyant cargo out the stern. For example, jetting water into cargo bed 111 ahead of the shipping container can be used to push the shipping container out the open stern of the vessel.

[0073] According to embodiments of FIG. 2A using diesel/electric power, the prime movers (e.g., diesel engines 201a and 201b) are coupled with generator(s) 203 that creates electrical power, the majority of which is used for propulsion. In addition to the propulsion load, hotel and auxiliary loads of the vessel may be carried by the generated electricity from generator(s) 203. These loads can include the autonomy, perception, and navigation systems (in control and distribution system 205) as well as the auxiliary systems such as bilge pumps, seawater pumps and fuel pumps.

[0074] According to embodiments of FIG. 2B where the propulsion power is transmitted hydraulically, the diesel-powered generators would be replaced by diesel powered hydraulic pumps of hydraulic power system 291. In such embodiments, electrical power generation may be provided by traditional engine-driven alternators. Potentially two high current alternators per engine may be used.

[0075] To reduce/minimize onboard systems, vessels of some embodiments may be steered using differential thrust of propulsive thrusters 131a and 131b on each side. The control system for this differential thrust could use a machine learning algorithm, for example, based on: outputs for the voltages to each of the propulsor motors (e.g., two outputs for two propulsor embodiments, three outputs for three propulsor embodiments, or four outputs for four propulsor embodiments); and inputs for magnetic heading, global positioning system (GPS) speed, desired heading, and desired speed. Such a control system may also consider one or more of: reducing/minimizing power/fuel consumption; autonomy; motion planning (e.g., including obstacle avoidance and adherence rules; optimized path and point-to-point navigation (including visual, and GNSS-denied); network capacity assignment (dynamically matching supply and demand/Uber); Networked Command and Control; and/or high-capacity, beyond-line-of-sight (BLOS) communications.

[0076] According to some embodiments of inventive concepts, standard marine diesel engine(s) seawater cooling may be used. To reduce risk of a cooling system failure, and thereby increase survivability, the seawater cooling system may have one or more of the following design features. For example, a single laterally oriented seawater header pipe may service all diesel engines in engine compartment 121. This header may be cross-fed with intakes on either end, and a duplex strainer may be provided at each intake (4 strainers total). In some embodiments, the seawater header may be pressurized by the orientation of the intake orifice allowing the movement of the vessel to force water into the system (based on the venturi effect).

[0077] Cooling air for the machinery space may be bought onboard through the snorkel system along with the combustion air discussed below. A snorkel system may be used to locate the air intake above the expected wave heights during normal operation, and/or intake opening(s) may be oriented toward the stern of the vessel. At the base of the snorkel, before it penetrates into the machinery space, an integrated dorade box (also called a dorade vent, collector box, cowl vent, or simply a ventilator) may be provided. This is a type of vent that permits the passage of air in and out of the engine compartment of a boat while keeping rain, spray, and sea wash out.

[0078] Once inside the machinery space, the snorkel air ductwork continues all the way down into the bilge. The intake air is discharged into the bilge, along with any residual water that may make it past the dorade box. The propulsion engine(s) take the combustion air directly from the machinery space, thus creating the negative pressure gradient and drawing more air in through the snorkel.

[0079] In the event of heavy weather, where sensors regularly detect water passing through the dorade box, the option exists to autonomously place the vessel into storm mode. In storm mode, the engines are shut down, and a valve in the dorade box is closed, sealing off the air intake pathway. Once the condition has passed, a command can be given (manually or autonomously) to reopen the air intake valve, and restart the propulsion diesels.

[0080] According to some embodiments of inventive concepts, combustion exhaust products from diesel engines 201a and 201b may be released below the vessel's waterline to reduce heat signature. For example, the exhaust gases may be expelled into a seawater tunnel or channel oriented longitudinally in the vessel, so that it intakes seawater near the bow, and discharges near the stern. A transverse seawater cooling header may branch from this tunnel, and farther downstream, the seawater and exhaust may be exhausted from an underwater exhaust outlet.

[0081] In some embodiments, a diameter of the seawater tunnel is tapered from larger to smaller diameter at the seawater cooling intake and from smaller to larger at the exhaust outlet, using the Venturi effect to pressurize the seawater cooling intake water, and reduce pressure to create a vacuum for the exhaust outlet. In such embodiments, the discharge location is below the water line at full operating RPM, but may require a discharge above the waterline to reduce back pressure for low RPM and starting.

[0082] According to some embodiments, engine exhaust may be used to provide an effluent bubble train that can be channeled under the hull to reduce frictional resistance, or channeled into the cargo compartment below the waterline to increase flow through the cargo deck.

[0083] In general, it may not be necessary to actively adjust the weight of the vessel through ballasting because the vessel is not required to support the weight of the cargo (which is self-buoyant). During cargo loading operations it may be useful to adjust the draft and trim of the vessel to facilitate easy movement of containers into and out of the cargo bed.

[0084] In some embodiments, it may be useful to trim the vessel with the stern deeper to provide clearance for the shipping container(s) to float into the cargo bed. A single shipping container or a series (train) of shipping containers connected end-to-end, could be floated into the stern of the vessel, through the open transom. As the train reaches the forward extent of cargo bed 111, it contacts a fender located on the forward bulkhead of cargo bed 111. In this location, the corner locking twist-locks on the containers are positioned immediately above the matched cargo retention system on the vessel. As the containers are held in place against the fender, a ballast system may then remove seawater from the stern of the vessel, decreasing the trim by the stern, and scissoring the top of the cargo bed up into contact with the base of the container train. To reduce/minimize complexity, increase/maximize reliability, and/or reduce/eliminate onboard systems, compressed air used to conduct ballasting operations for cargo loading may be provided by an external compressor (located pier side, or as part of a host ship's auxiliary systems).

[0085] A low-pressure air connection and manifold may be located in an enclosure on the deck of the vessel, and accessible from the outside while the vessel is afloat. Internally, compressed air flask(s) may be installed to supply compressed air for cargo release & reballasting while underway (if needed).

[0086] Thousands of gallons of diesel fuel may be used to obtain a desired operating range. To reduce/minimize the impact to the total vessel displacement and the center of gravity, the fuel tanks may be seawater compensated. Seawater compensated fuel storage tanks using bladders or membranes, for example, may be enclosed within the side hulls (wing tanks) and center hull (keel section).

[0087] To reduce/minimize mechanically actuated systems and to increase simplicity and reliability, steering can be accomplished by differential thrust from propulsors on opposite sides of the vessel. By increasing and decreasing power on either side of the vessel, a thrust imbalance may be used to creating a yawning force. According to some other embodiments, the steering system may include differential thrust from the propulsors combined with a lateral thruster to create a yaw moment. Additionally, some configurations may use a traditional rudder system.

[0088] To enable the Low-Profile Vessel/Semi-submersible Vessel (LPV/SSV) concept of operations, the buoyancy of the cargo container(s) may be adjusted to match the containers' waterline to the waterline of the host vessel. This buoyancy adjustment may be accomplished by adjusting a volume of an air-filled buoyancy bag 303 (or dunnage bag) within container 301.

[0089] Such embodiments can be used to provide the intentional, partial, and controlled flooding of the cargo shipping container. This process can be applied to any existing shipping container, and does not require specialized equipment.

[0090] FIG. 3 illustrates perspective and cross-sectional views of a standard 20 ISO shipping container 301. In embodiments illustrated the cross-sectional view of FIG. 3, four cargo B payloads are provided in standard 20 ISO container 301. Note the free flood portion, and the specific volume of air called for to result in the desired 7 ft waterline.

[0091] As the loaded vessel travels to its destination, the cargo shipping container(s) must not be allowed to float away from the host LPV/SSV. Because ISO standardized shipping containers are used, the tie-down points in the cargo bed should also comply with standard spacings.

[0092] As an autonomous vessel, subsystem reliability should be increased/maximized. Accordingly, mechanically actuated, moving parts may be reduced/minimized. Techniques to reduce such parts are discussed below.

[0093] According to some embodiments of inventive concepts, pins and hold-down clips may be used to restrain a shipping container 301 in cargo bed 111. More particularly, a system of structural pins may be fitted into the ISO shipping container corner tic-down points. These pins align, and mate with a series of holes in the deck of cargo bed 111. These pins restrict/prevent movement of shipping container 301 in the longitudinal and transverse directions. To restrict/prevent vertical movement of cargo shipping container 301 prior to planned release, a series of actuated clips may extend out from the vessel and engage the horizontal surfaces of cargo shipping container 301. These clips could be spring loaded to fail open or closed, depending on mission requirements. The clips could be actuated electrically, pneumatically, or hydraulically, to retract and allow cargo shipping container 301 to move vertically. At that point the cargo could float free, lifting the pins from the retaining points.

[0094] According to some embodiments of inventive concepts, a magnetic cargo deck connection/hold-down mechanism may be used to restrain a shipping container 301 in cargo bed 111. In addition or in an alternative, a cargo tie-down system may use segmented electro-magnets along tracks in the cargo bay, allowing various combinations of ISO shipping containers to be retained, and individually released at the destination/destinations, without any moving parts. The segment of magnets associated with each container is turned on/off to retain or release the cargo.

[0095] According to some embodiments of inventive concepts, the vessel of FIGS. 1A and 1B may release a free-floating shipping container into the sea at/near its destination without requiring external assistance. Such a release, however, may be performed in water sufficiently deep for navigation, and may thus be well off-shore. Additional embodiments of inventive concepts may provide last mile delivery of the shipping container to the shore as discussed below.

[0096] According to some embodiments of inventive concepts illustrated in FIGS. 4A, 4B, and 4C, propulsion attachment 401 (illustrated as a propulsion wedge) may be used to complete the journey of shipping container 301 from navigable water to the beach. Propulsion attachment 401 may comply with the ISO standardized size and connection points for compatibility with shipping container 301. In some embodiments, propulsion attachment 401 may be shaped like a triangular prism that attaches to cargo shipping container 301 with standard twist-locks, and propulsion attachment 401 may include a rudimentary propulsion system such as steerable water jet 403 including water jet nozzle 405.

[0097] When combined with shipping container 301 as shown in FIG. 4B, propulsion attachment 401 propels cargo shipping container 301 a relatively short distance through water 411 from the LPV/SSV vessel release point in navigable water to the beach. A ground unit can then recover the cargo shipping container 301 without any specialized equipment (helicopters, small boats, etc.). With a water jet 403, moving parts may be internal, reducing risk to personnel and/or reducing risk of propeller entanglement. As shown in FIG. 4B, a relatively small portion of shipping container 301 and propulsion attachment 401 are visible above waterline 431 based on loading an air bag(s) 303 as discussed above with respect FIG. 3.

[0098] To enable autonomous operations and system reliability, propulsion attachment 401 may include a small steerable water jet 403, controller 455, electric propulsion motor 407, and battery 409 (e.g., implemented as a set of batteries) as shown in FIG. 4C. Initial calculations indicate the ability to propel a laden container 301 for 2 hours at about 5 knots (10 NM range) with existing battery technology. Controller 455 controls operations of electric propulsion motor 407 and steerable water jet 403 to navigate shipping container 301 to the beach. Such navigation may be performed by controller 455 based on a compass heading, based on GPS signaling, and/or based on inertial navigation. Moreover, by using battery 409 to power propulsion attachment 401, there is no need to supply air for propulsion. More particularly, steerable water jet 403 includes nozzle 405 from which water is jetted to propel attachment 401 and shipping container 301, and controller 455 controls a direction of nozzle to steer attachment 401 and shipping container 301.

[0099] FIGS. 4A and 4B illustrate propulsion attachment 401 next to a standard half height 20 ft ISO shipping container 401, and the water jet intake 457 is visible in FIG. 4A to the left of water jet 403. Water jet 403 thus includes water jet intake 457, water jet nozzle 403, and a motor and impeller (internal to attachment 401) that draw water in through intake 457 and jet water out of nozzle 403 to propel and steer attachment 401 and shipping container 301. FIG. 4B shows propulsion attachment 401 mated to the half-height shipping container 301 and immersed in water 411. Steerable water jet 403 nozzle is visible below the waterline 431, in the center.

[0100] According to some embodiments of inventive concepts illustrated in FIGS. 5A, 5B, 6A, and 6B, a drogue 501 may be used with shipping container 301 and propulsion attachment 401 to support launch from the LPV/SSV vessel, directional stability under power, and recovery at the beach.

[0101] To rapidly separate cargo shipping container 301 from cargo bed 111 of the transport LPV/SSV vessel, a drogue can be deployed from propulsion attachment 401 behind the vessel into its wake. Drogue 501 (shown in FIGS. 6A and 6B) is attached to shipping container 401 by a high tensile strength, synthetic, floating drogue line 505. The release of drogue 501 is coordinated with the release of shipping container 301 so that once free from the cargo bed 111 hold down system, shipping container 301 is pulled by drogue 501 quickly out and away from the vessel.

[0102] If a self-propelled container 301 (using propulsion attachment 401) is making its way through the surf-line, there is the potential for directional stability issues (i.e., wave action can cause it to broach sideways to the surf). Additionally, the ground troops on the beach will likely need the ability to drag the container out of the surf line to unload the container.

[0103] This same high tensile strength synthetic drogue line 505, with drogue 501 at the end, can be used to address both issues. According to some embodiments of inventive concepts, one end of drogue line 505 is fixed to the bow of cargo shipping container 301 at attachment point 509. Drogue line 505 is fed through an angled chock 511 at the stern of cargo shipping container 301, and excess line 505 and drogue 501 are stowed in and/or around waterjet nozzle 405 during transit in cargo bed 111 of the LPV/SSV vessel.

[0104] When launching, the waterjet is turned on to eject drogue 501 and drogue line 505 into the wake of LPV/SSV vessel so that the drogue 501 is drawn out into the wake of LPV/SSV vessel, and the resulting drag helps pull shipping container 301 and attachment 401 from cargo bed 111. Once shipping container 301 and attachment 401 are free of cargo bed 111, drogue 501 is dragged behind the self-propelled shipping container to enhance stability as shown in FIGS. 6A and 6B. Stern chock 511 keeps the reaction point at the stern, resisting sideways movement of shipping container 301, thus resisting broaching (being turned sideways by wave action).

[0105] Once shipping container 301 grounds on seafloor 705 at the beach 701 as shown in FIG. 7, personnel recover the synthetic drogue line 505, thread drogue line 505 out of the angled chock slot (of chock 511) so that drogue line 505 is only attached at the bow of the container (at attachment point 509), and detach drogue 501. The free end of drogue line 505 is then attached to a tow vehicle 703 or wince (in place of drogue 501), so that drogue line 505 can then be used to pull shipping container 301 out of the water and onto the beach. Drogue 501 and drogue line 505 can thus be used for launch from cargo bed 111, waterborne directional stability, and land-based towing-enabled by stern chock 511. As used herein, the term chock may refer to any attachment point that secures drogue line 505 to the stern while in transit in cargo bed 111 and while under power of attachment 401 after deployment from cargo bed 111 while allowing recovery personnel to quickly remove drogue line 505 from chock 511 without cutting drogue line 505 or decoupling drogue line 505 from bow attachment point 509. For example, chock 511 may be implemented as a closed retaining structure (e.g., a loop) through which the free end of drogue line 511 may be pulled by recovery personnel after removing drogue 501.

[0106] Based on the ground reaction force of a 67,000 pounds container on coral, a tensile strength of 53,600 lbs. would be adequate for drogue line 505. (For example, this could be achieved by 1 diameter polyester double braid line according to the rope strength guide of FIG. 8.) A force required to pull shipping container 301 out of the water and onto beach 701 may be calculated using the formula:

[00001]$F=1.12R,$ [0107] where F is the pulling force required to free shipping container 301 in short tons, where is the coefficient of static friction, and wherein R is the ground reaction in long tons. Coefficients of friction based on seafloor type are provided below in Table 1.

TABLE-US-00001 TABLE 1 Type of Seafloor Coefficient of Friction Silty Soil or Mud 0.2 to 0.3 Sand 0.3 to 0.4 Coral 0.5 to 0.8 Rock 0.8 to 1.5

[0108] A cargo shipping container 301 that was propelled from the open ocean onto a beach as discussed above, and now must be dragged up the beach out of the water, has the potential to require more force to move it up the beach than a tow vehicle can deliver.

[0109] To reduce friction between shipping container 301 and the beach surface, and also to reduce/prevent the leading edge of shipping container 301 from digging into the beach, a beach sled may be used. According to some embodiments illustrated in FIGS. 9A and 9B, the sled has multiple runners 901 with the tips angled up that reduce/prevent digging in and reduce the surface area in contact with the beach. Separate runners 901 may be joined by cross beams 903. According to some other embodiments, the sled may be continuous under the leading edge of shipping container 301. Stated in other words, the sled may be implemented as a single ski having a width approximately the same as a width of shipping container 301.

[0110] According to embodiments of FIGS. 9A and 9B, the sled (implemented using a single continuous ski or multiple parallel skis) has the width of a standard ISO container (8 ft) and length of about 5-10 ft (so that it does not extend under a full length of the entire shipping container, just the first - of the length as shown in FIGS. 9A and 9B). In such embodiments, the sled may have pins and twist-lock connections that mate with the ISO standard container.

[0111] The tails of the sled runners may be placed immediately on the shore-side of the beached container, and buried in the beach below the level of the container. The container is dragged over and onto the sled and eventually onto the twist-lock mating points. Ultimately, the combined sled/container is drug up the beach to an appropriate unloading point.

[0112] According to some other embodiments, a smaller sled may serve first as a cargo support/retention system inside the shipping container. Here, the smaller sled is loaded with the cargo inside container 301 at the origination site. Upon grounding on the beach, container 301 is opened and the smaller sled with attached cargo is drug up the beach (and the container is left in place, reducing the amount of weight to be moved).

[0113] According to still other embodiments of inventive concepts, a last-mile delivery method may include a floating bridle designed to enable a heavy-lift helicopter to retrieve a floating container.

[0114] At the origination site, shipping container 301 intended for rotary wing retrieval is outfitted with a floating loop bridle 1001 as shown in FIG. 10A. When initially outfitted for transport, loose portions of floating loop bridal 1001 are secured in coils 1001a.

[0115] Once shipping container 301 is released by the delivery LPV/SSV vessel, the floating loop bridle 1001 is automatically activated. The system may also include a locator beacon in addition to the lifting equipment. Stated in other words, after releasing shipping container 301, coils 1001a of floating loop bridal 1001 are released so that floating loop bridal 1001 springs out to provide a large loop as shown in FIG. 10B.

[0116] As further shown in FIG. 10A, floating bridle loop 1001 may be rigged to corner points 301a, 301b, 301c, and 301d of shipping container 301 at the depot prior to departure and deployment. In addition to the individual pennants to each corner, floating loop bridle 1001 includes coiled loops 1001a of high tensile strength synthetic floating line when initially rigged as shown in FIG. 10A.

[0117] According to some embodiments, the floating loop section of floating loop bridle 1001 includes a stiff (composite or wire) structural member embedded in the rope fiber. This stiffener acts as a spring that creates a force attempting to straighten the line. When released, this force opens the coiled portion 1001a of the floating loop bridle, creating a floating target loop approximately 10-40 ft in diameter as shown in FIG. 10B.

[0118] The retrieving aircraft is fitted with a long line pennant (greater than 40 ft) as a retrieving line to reduce/minimize rotor wash and sea spray. A weighted grappling hook (or similar mechanism) is provided at the end of the retrieving line.

[0119] To retrieve the cargo, the pilot places the aircraft in a high hover approximately above the loop, drops the hook into the loop, and translates the aircraft sideways approximately 5-20 ft (depending on the loop size). When the lifting line engages the loop, the pilot increases altitude engaging the hook to the loop bridle; and the pilot continues to increase altitude gradually straightening the lifting bridle and taking up the load. At this point, floating loop bridle 1001 is straightened vertically as shown in FIG. 10C. By further increasing altitude of the aircraft, the pilot can lift shipping container 301 free of the water and fly the aircraft and shipping container to a desired landing zone.

[0120] To deposit the cargo shipping container 301, when shipping container 301 is set down and the load is removed from the loop of bridle 1001, the spring force will again try to open the loop, and this may be enough to disengage the hook. If not, the ground crew will remove the hook from the loop bridle 1001.

[0121] FIG. 10A illustrates the coiled bridle 1001 stowed on top of shipping container 301, and FIG. 10B illustrates the deployed bridle 1001 with the interior stiffener forcing the line into a circular target area for the long-line grappling recovery hook.

[0122] FIG. 11 is a cut away perspective view of a portion of cargo bed 111 of the LPV/SSV vessel of FIGS. 1A and 1B into which shipping container 301 can be loaded. As shown, cargo bed 111 includes cargo bed floor 111a, cargo bed walls 111a and 111b, and cargo bed floor 111c. As indicated by waterline 431, most of cargo bed 111 and shipping container 301 are submerged. As further shown in FIG. 11, smooth panels 1401 provide smooth exterior surfaces for walls 111a and 111b and floor 111c (both inside and outside cargo bed 111), and frames 1301 provide structural integrity for walls 111a and 111b. The structure of FIG. 11 will be discussed in greater detail below.

[0123] FIG. 12A is a perspective view illustrating the structure of cargo bed floor 111c of FIG. 11 in greater detail. Longitudinal beams 1205 and floor beams 1201 provide structural integrity for cargo bed floor 111c, conduits 1207 may be provided in longitudinal beams 1205, and beams 1201 and 1205 may be foam filled box beams. Rails 1231 may be provided on longitudinal beams 1205 to provide attachment to frames 1301 and panels 1401 of sidewalls. As shown, each rail 1231 may include outer and inner U-channels 1203a and 1203b configured to receive respective outer and inner wall panels, and twist-locks 1209 to secure respective frames. Each rail 1231 may also include a plurality of receptacles 1232 configured to receive a twist-lock connector used to provide connection with a shipping container. FIG. 12B is an enlarged cross-sectional view of a longitudinal beam 1205 and respective rail 1231 with twist-locks 1209 and U-Channels 1203a and 1203b shown in greater detail. FIG. 12C is an enlarged view of one twist-locks 1209.

[0124] FIG. 13A illustrates connection of one frame 1301 to rail 1231 of cargo bed floor 111c using twist-locks 1209. As shown in FIG. 13B, each of longitudinal cap 1305 and longitudinal tie 1307 may run the length of the cargo bed wall coupling the frames 1301 of the wall and providing attachment for outer wall panels. Moreover, tension cables 1303 may be provided to support frames 1301 in the longitudinal direction. FIG. 13C shows that a respective deck beam 1321 may be provided on each frame 1301. FIG. 13D shows a length of longitudinal beam 1205 and rail 1231 with respective floor beams 1201 and frames 1301 coupled thereto.

[0125] FIG. 14A illustrates panels 1401 that may provide smooth surfaces of walls 111a and 111b and floor 111c of cargo bed 111, both inside and outside of cargo bed 111 (facing outside the structures of walls 111a and 111b and floor 111c). Panels 1401 may be corrugated with corrugations 1451 facing inside the structure and smooth surfaces facing outside the structure to provide a hydrodynamic shape while using the added strength provided by corrugation. Pannels 1401 for inner wall of cargo bed may be anchored by longitudinal cap 1305 and inner U-Channel 1209b. Pannels for upper portions of outer wall may be anchored by longitudinal cap 1305 and longitudinal tie 1307, and panels 1401 for middle portions of outer wall may be anchored by longitudinal tie 1307 and outer U-Channel 1209a. FIG. 14B shows panels anchored in outer and inner U-Channels with corrugations facing inside the structure of the wall.

[0126] FIG. 15A illustrates placement of buoyancy foam 1503 and fuel bladders 1501a and 1501b in walls and floor of cargo bed 111 according to some embodiments of inventive concepts. Panels 1401 are not shown in FIG. 15A to provide clearer illustration of buoyancy foam and fuel bladders, but in a completed vessel, buoyancy foam and fuel bladders would be behind panels 1401 that provide outer surfaces of cargo bed walls and floor. According to some embodiments, fuel bladders 1501a and 1501b may be provided in cargo bed floor and in portions of cargo bed wall below the waterline so that all fuel bladders are below the waterline of the vessel. Moreover, because interior spaces of cargo bed floor and walls are free flooding and because the fuel bladders are flexible, the fuel bladders will collapse as fuel is consumed and water will fill the volume vacated by the collapsing fuel bladders, effectively providing a buoyancy compensation. In fact, cargo bed 111 will ride lower as more fuel is consumed making it easier for a shipping container 301 to float out when released. Buoyancy foam 1503 is provided above fuel bladders 1501b in the wall to ensure sufficient buoyancy for cargo bed 111 even when all fuel bladders are empty. FIG. 15B is an exploded view of the cargo bed floor and wall of FIG. 15A. According to some embodiments, buoyancy foam 1503 may be provided as a spray foam above and below waterline 431. For example, the foam may be a closed cell foam that remains buoyant after extended exposure to water.

[0127] FIG. 16 is a partial cut-away and exploded view illustrating elements of the LPV/SSV vessel discussed above. As shown, longitudinal beams 1205 may extend forward beyond cargo bed 111 to support engine compartment 121, and engine compartment 121 may be secured to longitudinal beams 1205, for example, using twist-locks. Moreover, bow fairing 189 may be configured to slide on and off of engine compartment: to provide a hydrodynamic structure and to protect engine compartment 121 when underway; and to allow full access to engine compartment 121 for repair and/or replacement. Accordingly, engine compartment 121 can be easily removed and/or replaced to facilitate repair and maintenance. Bulkhead 191 may be provided between engine compartment 121 and cargo bed 111 to protect engine compartment 111 from a shipping container 301 in cargo bed 111. Moreover, floor and wall fuel bladers may be daisy chained, and the combination of fuel bladers may provide on the order of about 9,000 gallons of fuel. In FIG. 16, rails 1231 may extend along longitudinal beams 1205 both fore and aft of bulkhead 191 to provide twist-lock receptacles 1232 both fore and aft of bulkhead 191. Accordingly, twist-lock couplings 1232 are available to provide twist-lock couplings for engine compartment 121 and to provide twist-lock couplings for one or more shipping containers 301 in cargo bed 111.

[0128] The structure of cargo bed 111 discussed above with respect to FIGS. 11, 12A-C, 13A-D, 14A-B, 15A-B, and 16 thus separates the structural and buoyancy functions of the vessel's hull. Structural integrity may be provided, for example, by floor beams 1201, longitudinal beams 1205, frames 1301, and tension cables 1303 that provide a truss and tension cable system for walls 111a and 111b. Buoyancy may be provided by buoyancy foam 1503 inside walls 111a and 111b near and above waterline 431. Smooth surfaces of panels 1401 are exposed inside and outside cargo bed 111 to provide smooth surfaces adjacent shipping container 301 and to provide hydrodynamic surfaces for the outside of the hull. The interior portions of walls 11a and 111b and floor 111c (between wall panels and between floor panels) are free flooding to allow semisubmersible low-profile operation.

[0129] Moreover, this structure of cargo bed 111 may enable wide-spread construction at boat yards and even non-marine fabricators. Stated in other words, construction at a tier 3 shipyard is not required. Moreover, this structure may reduce manhours and/or cost required for production.

[0130] As discussed above, conduit 1207 may be provided in longitudinal beams 1207. Conduit 1207 may be used to house fuel lines used to transport fuel from fuel bladders 1501a and 1501b to engine compartment 121. In addition or in an alternative, conduit 1207 may be used to house electrical, hydraulic, and/or pneumatic control signaling/pressure from engine compartment 121 to remotely control cargo couplings (e.g., twist-locks and/or magnetic couplings) used to restrain/release shipping container 301.

[0131] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of inventive concepts. As used herein, the singular forms a, an and the are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms comprises, comprising, includes and/or including, when used herein, specify the presence of stated features, integers, steps, operations, elements and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and/or groups thereof. The term and/or includes any and all combinations of one or more of the associated listed items.

[0132] Spatially relative terms, such as beneath, below, lower, above, upper, and the like, may be used herein for ease of description to describe one element's or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as below or beneath other elements or features would then be oriented above the other elements or features. Thus, the term below can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations), and the spatially relative descriptors used herein may be interpreted accordingly.

[0133] It will be understood that, although the terms first, second, third, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another element. Thus, a first element discussed herein could be termed a second element without departing from the scope of the present inventive concepts.

[0134] It will also be understood that when an element is referred to as being on, connected to/with, or coupled to/with another element, it can be directly on, directly connected to/with, or directly coupled to/with the other element, or intervening elements may be present. In contrast, when an element is referred to as being directly on, directly connected to/with, or directly coupled to/with another element, there are no intervening elements present. Moreover, if an element is referred to as being on another element, no spatial orientation is implied such that the element can be over the other element, under the other element, on a side of the other element, etc.

[0135] Embodiments are described herein with reference to illustrations (e.g., cross-sectional and/or perspective illustrations) that are schematic illustrations of idealized embodiments (and intermediate structures). As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments should not be construed as limited to the particular shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of the present inventive concepts.

[0136] The operations of any methods disclosed herein do not have to be performed in the exact order disclosed, unless an operation is explicitly described as following or preceding another operation and/or where it is implicit that an operation must follow or precede another operation. Any feature of any of the embodiments disclosed herein may be applied to any other embodiment, wherever appropriate. Likewise, any advantage of any of the embodiments may apply to any other embodiments, and vice versa. Other objectives, features and advantages of the enclosed embodiments will be apparent from the description herein.

[0137] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the inventive concepts herein belong. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0138] While inventive concepts have been particularly shown and described with reference to examples of embodiments thereof, it will be understood that various changes in form and details may be made therein without departing from the spirit of the following claims.