Abstract:
A system and method for a large ship to immobilize malicious small watercraft comprises of an unmanned underwater vehicle. The vehicle can be launched immediately upon detection of the threat. When the watercraft comes close, preparing to start boarding attack, the vehicle either uses it&#39;s onboard propulsion or is towed with a cable to sneak up on the watercraft and deliver an immobilizing effect, such as a hard crash or a stalling entanglement, on the propulsion mechanism of the watercraft.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application claim priority from provisional patent application No. 61/941,314, filed on Feb. 18, 2014 
     
    
     BACKGROUND  
       [0002]    1. Prior Art 
         [0003]    The following is a tabulation of some prior art that presently appears relevant: 
       U.S. Patents 
       [0004]      
         [0000]    
       
         
               
               
               
               
             
           
               
                   
               
               
                 Pat. No. 
                 Kind Code 
                 Issue Date 
                 Patentee 
               
               
                   
               
             
             
               
                 8,776,710 
                 B2 
                 2014-07-15 
                 Gayton 
               
               
                 8,256,336 
                 B2 
                 2012-09-04 
                 Larkin et al. 
               
               
                 8,552,282 
                 B1 
                 2013-10-08 
                 Garcia et al. 
               
               
                 8,720,361 
                 B2 
                 2014-05-13 
                 DiBruno, Sr. et al. 
               
               
                   
               
             
          
         
       
     
       U.S. Patent Application Publication 
       [0005]      
         [0000]    
       
         
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Publication Nr 
                 Kind Code 
                 Issue Date 
                 Patentee 
               
               
                   
                   
               
             
             
               
                   
                 20140041516 
                 A1 
                 2014-02-13 
                 Brewer 
               
               
                   
                   
               
             
          
         
       
     
       Foreign Patent Documents 
       [0006]      
         [0000]    
       
         
               
               
               
               
               
             
           
               
                   
               
               
                 Foreign 
                   
                   
                   
                   
               
               
                 Doc. Nr. 
                 Cntry Code 
                 Kind Code 
                 Pub. Dt 
                 App or Patentee 
               
               
                   
               
             
             
               
                 2013072704 
                 WO 
                 A1 
                 2013-05-23 
                 Stevens 
               
               
                   
               
             
          
         
       
     
         [0007]    2. Field of the Invention 
         [0008]    The current invention relates to non-lethal defense system and means for ships to immobilize small watercraft. 
       BACKGROUND OF THE INVENTION 
       [0009]    Modern day pirates use small watercraft to attack merchant ships by boarding and hijacking the crew and the ship. These activities pose serious threats to the safety of the crew. Merchant ships responded by hiring onboard security guards and operating with high uneconomical speed. It also drew large fleets of naval ships to patrol some areas. Even though they seem effective, these deterrents are expensive, and the way these ships operate are producing unwarranted pollution. Due to regional anarchy situation, the threat around some costs of Africa could remain for the foreseeable future. And furthermore, similar kinds of piracy had also increased in other areas of the world such as southeast Asia. 
         [0010]    To counter this threat, there had been a few propeller entanglement or disabling systems proposed. U.S. Pat. No. 8,776,710 to Gayton (2014), a passive towed array of entanglement lines. This system might stop the first uninformed attacker. Once the pirates learned what this is, they could attack by destroying the supporting structure such as cutting the suspension cables. After all, its rigging is openly visible. Even just a few whacks with a knife at the entanglement lines can send them tumbling down dangerously toward the ship&#39;s own propeller. 
         [0011]    U.S. Pt. No. 8,256,336 to Larkin et al. (2012), an entanglement device between two hulls as unmanned underwater vehicles. In one embodiment, the two hulls will be separately guided. The entanglement linkage between the hulls will create an interference very difficult for the guiding process to handle. Another difficulty for this guiding scheme is that, when the two hulls come close to the target, they need to each aim at the acoustic signal with a changing side angle. In another embodiment, the two hulls are connected to a third hull with a variable link. This could make the whole setup cumbersome and not agile enough to chase a moving boat. On top of these issues, for all the embodiments presented, the entanglement net is directly coupled to the hulls and both hulls are at the same depth as the entanglement net. This will have a high chance of hitting the watercraft with the hull itself. In case of a head on or sideway interception, such collision would be catastrophic, which is undesirable. 
         [0012]    U.S. Pat. No. 8,552,282 to Garcia et al. (2013), an unmanned underwater vehicle in the form of a torpedo with a protruding rod or rods. This approach added excessive difficulty by chasing a not too big moving propeller with a very small rod. It is like trying to poke a fly in the air with a toothpick. We all know it is easier to hit a fly with a swatter, especially if we know where the fly is going. The last two patents discussed both added unnecessary difficulties to the task such that, even if they can be realized, their systems could still be too complicated for nonmilitary merchant crew to operate. 
         [0013]    There are other passive barrier type of security setups such as razer wires or bulwark. These could either be circumvented or destroyed by force because the setups are visible to the attackers, showing where they are vulnerable. One can only hope to be a less desirable target with these measures. 
         [0014]    What seems still lacking is an effective defense system that is easy enough to be operated by a trained merchant crew. It will be beneficial if we can provide a non-lethal and cost effective way to protect against pirate boats so that a ship can travel safely anywhere in the world. 
       SUMMARY OF THE INVENTION 
       [0015]    The present invention provides an easy-to-operate and non-lethal way to immobilize small watercraft. It can be used to protect merchant ships from pirates trying to board using small boats. It can also be used for apprehension operation by law enforcement or for antiterrorism by the military. In accordance with the illustrative embodiments of the invention, a system for immobilizing small watercraft comprises an underwater vehicle equiped with a structure to deliver a crippling effect to the propulsion mechanism of the watercraft. The vehicle is either self propelled or towed with a winch system. The structure for delivering crippling effect is either an entanglement device or a bumper for ramming the propeller. The vehicle is maintain onboard the ship and deployed in the water as soon as the threat is detected. 
         [0016]    In case of a pirate boarding attack, the vehicle is launced and set waiting close to the ship behind where the pirate boat is heading. As the boat is about to be running next to the ship, the vehicle is brought forward alongside the ship, engage the boat and immobilize it. 
         [0017]    In cases for counter terrorism or law enforcement, the launched vehicle is guided to intercept and immobilize the target watercraft at a distance from the ship. The guiding can be done using a homing guidance onboard the vehicle or an inertial guidance, with tracking information provided by the ship. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]      FIG. 1  depicts a towed vehicle  100  in use as an illustration of the general method. 
           [0019]      FIGS. 2A-2C  depict an embodiment of a towed vehicle  100 . 
           [0020]      FIG. 3  depicts the first embodiment of a winch system. 
           [0021]      FIG. 4A-4B  depict another embodiment of a towed vehicle  300 . 
           [0022]      FIG. 5A-5C  depict yet another embodiment of a towed vehicle  400 . 
           [0023]      FIG. 6A-6B  depict the second embodiment of a winch system. 
           [0024]      FIG. 7A-7B  depict an embodiment of an unmanned underwater vehicle (UUV)  500 . 
           [0025]      FIG. 8A-8D  depict the UUV  500  and a tether cable  124  in use. 
           [0026]      FIG. 9A-9B  depict another embodiment of UUV  600 . 
           [0027]      FIG. 10A-10G  depict yet another embodiment of UUV  700 . 
       
    
    
     DETAILED DESCRIPTION 
       [0028]    One critical perception the current invention discloses is as follows. As the pirates try to board the ship, they will bring their boat side by side next to the ship. For this window of time, they turn themselves into an easy target. Based on this understanding, many approaches become feasible for immobilizing such a sitting duck pirate boat. The underwater vehicle for this situation only needs to move along a preset course next to the ship. Therefore, it can either be a towed body, somewhat like a paravane, or it can be a self propelled unmanned underwater vehicle (UUV), without a need for homing capability. 
         [0029]    In a towed body configuration, the cable serves as a means for both driving and guiding. The vehicle may even further use the side of the ship as a guide so active steering is not required. However, remotely controlled steering may allow for some off-course chasing capability. The depth control mechanism can be preset as well for proper delivery of the crippling effect. To cover the length of the ship, the winch system is pulling the vehicle from close to the bow and uses a guiding arm adjustable for different draft conditions. When not in use, this guiding arm can be retracted or folded up to reduce drag. To be stealth, this arm is completely underwater. Advantage of this approach is a low cost, low maintenance vehicle. 
         [0030]    In an UUV configuration, the vehicle has onboard propulsion and steering. This means minimal or even no modification to the hull of the operating ship—a factor likely more appealing for ships already in service. The UUV can be controlled remotely by manual adjustment in steering and propulsion. The depth control mechanism can be preset but might just as well be made adjustable. Even though in this configuration, a tether cable between the vehicle and the ship is not required, such a cable could provide many additional benefits. It allows the vehicle to conserve power while waiting for the attacker to approach. It can be used to help with retrieval of the vehicle after the mission. It can also serve as a restraint to ensure that the vehicle will not hit and damage the ship&#39;s own propeller. For better serviceability, the signal wire for remote control may be combined and built into this tether cable. 
         [0031]    In some other cases, such as for smaller ships, ships with low freeboard, or defense against terrorist attack, it may not be a good idea to allow the malicious watercraft to come too close to the ship. While, in a law enforcement apprehension operation, the watercraft is likely fleeting. The embodiments in the UUV configuration can further include a guiding or even homing mechanism on board whereby the UUV can intercept the watercraft and immobilize it at a good distance form the ship. 
         [0032]    A few additional features can be shared with both the towed vehicle and the UUV configurations. In some embodiments, a camera system is used to provide surveillance so the operating crew can stay in the safe citadel. The camera can be mounted at high spots on the ship such as by the bridge or on an unmanned aerial vehicle drone. To make the vehicle or UUV easier to be identified by the surveillance system, one or more light sources are mounted on some of the embodiments. These light souces only emit light invisible to the human eye so as to keep the adversaries uninformed. In some other embodiments, a motion control subsystem can be used to coordinate the steering and other functions. This control system can incorporate data such as water flow parameters around the ship. Position of the vehicle relative to the ship can, for example, be extracted from processing the surveillance image or using a sonar. It is within the capability for those skilled in the art to implement such a subsystem. By doing so, the system does not requires skilled steering, and the operation can be as easy as entering a position referenced to the ship and hitting a go button. 
         [0033]    Referring now to the drawings and in particular to  FIG. 1 , the first embodiment of a system for immobilizing small watercraft in use is illustrated in a perspective view. Pirate watercraft  210  is approaching operating ship  200 . Towed vehicle  100  is positioned under water for the strike. Tow cable  120 , attached to vehicle  100 , is driven by winch  130  and redirected by cable guiding arm  132 . Winch  130  and guiding arm  132  are either inside ship  200  or under water so the complete system are out of sight from the pirates. 
         [0034]      FIG. 2A  depicts towed vehicle  100  as the first embodiment in a perspective view. In this embodiment, vehicle body  102  is shaped as a hydrofoil itself It is negatively buoyant. At the designed towing speed, the buoyancy balances with the hydrofoil lift to set vehicle  100  at proper depth. Bumper area  103  as part of vehicle  100  is toothed. Bumper edge  105  is also toothed. Tail fins  106  are simply fixed to body  102 . Keel plate  104  stabilizes vehicle  100 . 
         [0035]      FIG. 2B  is a bottom view of towed vehicle  100 . The lopsided front of bumper edge  105  is for pushing the watercraft away from ship  200  after immobilizing it. One way to set the course for towed vehicle  100  is to allow the bank effect to push it against ship  200 . Some roller fenders (not shown) can be added to body  102  in this case.  FIG. 2C  depicts a side view of towed vehicle  100  moving forward toward propeller  212  of watercraft  210 . Keel plate  104  provides a low offset attachment point for tow cable  120 . This offset positions tow cable  120  low enough to prevent it form the possibility of being impeded by watercraft  210 . 
         [0036]    As described earlier, vehicle  100  is deployed before watercraft  210  is anywhere near ship  200 . Referring to  FIG. 1 , vehicle  100  waits by the stern. The operation can be simply hitting the start button at the right moment for the winch system to tow vehicle  100  toward the bow of ship  200 . Vehicle  100  bumps and disables watercraft  210 , pushes it away from ship  200 , keeps going for other watercraft ahead or moves back to the stern area until all threat is cleared. 
         [0037]      FIG. 3  depicts a sectional view of ship  200  at where winch  130  is located (refer also to  FIG. 1 ). In this embodiment for a winch system, guiding arm  132  can be extended to the proper position. When not in use, it is retracted to reduce drag. Winch  130  is positioned above the waterline. Mounted at the tip of guiding arm  132 , pulley  134  redirects cable  120 . Two sets of this system are illustrated. On the left side, towed vehicle  100  is deployed in the water, with guiding arm  132  extended. One the right side, guiding arm  132  is retracted and vehicle  100  is on crain  202 . Also shown here are cameras  204  mounted by the bridge for surveillance. 
         [0038]    Referring now to  FIGS. 4A and 4B .  FIG. 4A  depicts a perspective view of another embodiment as towed vehicle  300  with entanglement device  314 . Main body  302  has two arms  306  which are shaped as vertical fins. Ultraviolet lights  307  are mounted on top of arms  306 . Wings  308  are hydrofoils which provide lift to keep arms  306  at the correct posture. A plurality of strands  315  are attached to and form part of entanglement device  314 . Strands  315  are designed for both propeller and jet drive intake to ensnare. Entanglement device  314  is coupled to arms  306  by holders  312 , which provide a sideway pull to keep entanglement device  314  taut (e.g. grip with two groved wheels).  FIG. 4B  depicts a side view. Body  302  holds multiple pieces of entanglement device  314  in a roll, with weak links in between pieces. Depth control subsystem  310  is onboard body  302 . Entanglement device  314  is positively buoyant such that it floats toward the water surface to form a shallow scooping net, ready to snare a propeller in its path. Therefore, remote control in depth change is not needed in this embodiment. Vehicle  300  deploys entanglement device  314  one piece at a time the same way as an automatic paper towel dispenser. When propeller  212  catches and yanks on entanglement device  314 , it is allowed to break at the weak link and detach from vehicle  300 . On board sensor and mechanism enable vehicle  300  to deploy one more entanglement device  314  and the system is ready to function again. The operation of vehicle  300  is similar to vehicle  100 . 
         [0039]      FIG. 5A through 5C  depict yet another embodiment of a towed vehicle  400 . In  FIG. 5A , a perspective view, two hulls  402 A and  402 B form the main body, to which a top bumper area  403  and front bumper  405  are attached. Towing bracket  404  for tow cable  122  also serves as a connection port for control data wires. Rudder  406  and diving plane  408  are remotely controlled. Two light sources  407  are mounted on the hulls  402 A and  402 B. As further depicted in  FIG. 5B , front view and  FIG. 5C , side view, the depth control also includes ballast systems  410  and hydrofoils  412 . In operation, as soon as watercraft  210  comes within range, towed vehicle  400  is maneuvered to be underneath propeller  212 . After watercraft  210  steadied itself relative to the ship, vehicle  400  is brought upward to engage and grind away the propeller. This method is a low impack, gentler way to immobilize a watercraft. In this embodiment, at least the depth variation is remotely controlled. Cable  122  also houses the control signal link (e.g., a coaxial cable with steel strands forming a tension bearing shell with electrical wires in the middle). Front bumper  405  is added as an option for taking out watercraft quickly when hard pressed. It can be as simple as a wide bar, or multiple bars (as shown here) to accomodate variation in depth of propellers. 
         [0040]    Another embodiment for a winch system is illustrated in  FIGS. 6A and 6B  as partial sectional views of ship  200 . Guiding arm  138  folds in and out similar to a fin stabilizer, swings up and down and further comprising telescoping sections. Winch  136  includes an underwater cable spool.  FIG. 6A  depicts the stowed configuration with vehicle  400  stored on deck.  FIG. 6B  depicts the system deployed. As we have demonstrated, different forms for such a winch system can be designed to meet the needed functions, as those skilled in the art will be capable of. It is to be understood that the illustrated designs of winch systems are just examples. 
         [0041]      FIGS. 7A and 7B  depict UUV  500 , which is an embodiment of a vehicle in the configuration of an UUV with an entanglement device. In  FIG. 7A , a perspective view, UUV  500  has main body  502  in the form of a torpedo, equiped with propulsion  504 , rudder  506 , and diving plane  508 . Tether cable  124  slacks off when propulsion  504  is driving the vehicle. Arms  512  hold entanglement device  514  higher than and behind body  502 , while also keep it taut. The combination of arms  512  and entanglement device  514  is like an archery bow, wherein arms  512  are elastic. Preset strain on arms  512  allows them to keep the proper shape while under pressure from the water flow. Entanglement device  514  and strands  515  are similar to that used in vehicle  300 . Here however, small buoys  516  are added to help it float. The coupling between arms  512  and entanglement device  514  is made weak in the front-to-back direction, such that it will break at the moment when entanglement device  514  gets snatched. 
         [0042]      FIG. 7B  depicts a side view of UUV  500 . Watercraft  210  (partial) and it&#39;s propeller  212  are also illustrated for their relative position in depth. Main body  502  will clear watercraft  210  from underneath it. Even arms  512  are light and flexible, so UUV  500  can run fast without the risk of a detrimental collision or sinking of watercraft  210 . Depth control subsystem  510  is indicated here onboard body  502 . Tether cable  124  houses the signal link for the remote control. A coaxial cable with steel strands forming a tension bearing shell can be used. The signal link in the middle of cable  124  can use an electrical or fiberoptic cable. Cable  124  may further house electric wires for power, if UUV  500  is not using onboard power source (e.g., battery). Cable  124  is adjusted to be only slightly negatively buoyant such that, when being slack, it does not seriously interfere with UUV  500 . 
         [0043]    Referring now to  FIGS. 8A through 8D ,  FIG. 8A  depicts side view, and  FIG. 8B  front view, of UUV  500  just being deployed. Tether cable  124  connects ship  200  and UUV  500 , holding vehicle  500  in position under tension. The length of cable  124  is limiting UUV  500  from reaching the propeller of ship  200 .  FIG. 8C  depicts side view, and  FIG. 8D  front view, of UUV  500  moving toward watercraft  210 . Tether cable  124  sinks and stay out of the way. Operation of UUV  500  is similar to that of vehicle  300 , except it has only one entanglement piece. 
         [0044]      FIGS. 9A and 9B  depict UUV  600 , which is another embodiment of a vehicle in an UUV configuration having a wide bumper area.  FIG. 9A  depicts a perspective view. Main body  602  is shaped also like a torpedo, with propulsion  604 , rudder  606 , light source  607 , and diving plane  608 . Attached on top of the front end of body  602 , wing  612  has a hydrofoil profile to generate lift. Wing  612  is equipped with ailerons  614  to help with roll control, which can be driven based on sensor feedback. The main reason for Wing  612  is to provide a frame for setting up wide bumper area  603 , which formed a slop to reduce shock of the impact, while the hight of the slop accommodates variation in depth of target propellers. The slots in bumper area  603  has spacings such that it is not necessary to use high relative speed for ramming. Rather, the structure chews up a propeller. Wing  612  is further reinforced with two braces  618 . RF antenna  616  receives remote control signal from operating ship  200 .  FIG. 9B  depicts a side view of UUV  600  and onboard depth control subsystem  610  is indicated. 
         [0045]    The operation for UUV  600  to immobilize pirate watercraft is similar to towed vehicle  100 , except that UUV  600  is self propelled and remote controlled through RF or other types of wireless signals. The advantage of this embodiment is no hull modification for ship  200 , while a concern is the limited power and hence the endurance of the vehicle. Especially if a pirate watercraft takes a long time approaching. A temporary leash from above the deck of ship  200  can be used after launch, which is to be released when the pirate watercraft comes near. 
         [0046]    Referring now to  FIG. 10A through 10G , which is another embodiment of the vehicle as UUV  700  with an entanglement device that has more than one piece of entanglement material.  FIG. 10A  depicts a perspective view of UUV  700 . UUV  700  is similar to UUV  500 , with body  702 , propulsion  704 , rudder  706  and diving plane  708 . The difference from UUV  500  is that UUV  700  has two sets of arms  712 A and  712 B and use optical cable  126 . Arms  712 A and  712 B can rotate and fold in, each attached with entanglement devices  714 A and  714 B respectively. The operating sequence is illustrate in  FIGS. 10B ,  10 D and  10 F as side views and  FIGS. 10C ,  10 E and  10 G as top views.  FIGS. 10B and 10C  depict UUV  700  during initial approaching, where both arms  712 A and  712 B are folded in at a low angle to reduce drag.  FIGS. 10D and 10E  depict UUV  700  with entanglement device  714 A deployed by raising and opening arms  712 A.  FIGS. 10F and 10G  depict UUV  700  with entanglement device  714 B deployed, after entanglement device  714 A has been snared and released. The benefits of having multiple usage per vehicle per launch are more than cost savings. As pirate attacks were often carried out with multiple watercrafts, the operating ship needs to be prepared for attack by more than one watercraft on the same side of the ship. In some cases, operating two or more UUVs in a small area may be complicated and risky. Optical cable  126  is used in this embodiment as the link for control commands. It is reinforced and adjusted to be negatively buoyant to keep it out of the way. 
         [0047]    As mentioned earlier, for small ships, antiterrorist or law enforcement, it is desirable to immobilize a watercraft much farther away from the operating ship. Embodiments such as UUVs  500 ,  600  and  700  can be used for such applications. Due to the reason that the entanglement devices and wide bumper areas allow a large margin of aiming error, a non-homing type of guidance system can be used on the UUVs. Means onboard the operating ship, such as sonar or visual surveillance, can be used to extract the position and velocity of both the UUVs and the watercrafts. Programs onboard the operating ship can then guide the UUVs with motion commands for interception. Of course, the UUVs can further include an onboard homing guidance mechanism, which is well known in the art. 
         [0048]    As pointed out through detailed descriptions and illustrations, the advantages of the current invention are numerous. The presented methods greatly increase the prospect of success while being very simple to operate. The system takes advantage of stealth so the adversaries will not be able to counteract easily. It will achieve a speedy termination of the threat, while not putting the targeted personnel in danger. It does not add burden to the ship when no threat is present, and consumes only minimal energy during operation. 
         [0049]    The current invention was illustrated with many embodiments in various forms and shapes. Simply mixing some of the featured components from different embodiments presented can easily provide more new ones. Therefore, it is clear to be understood that what the disclosure teaches are just examples, not to be taken as limitations. And, the scope of the present invention is to be determined by the following claims.