Abstract:
A method and apparatus for stopping an impeller-driven watercraft is includes distributing a plurality of submunitions in advance of a path of the impeller-driven watercraft. Each of the submunitions includes a buoyant member, a first end cap, and a second end cap; the second end cap is heavier than the first end cap. A lanyard connects the first end cap to the second end cap, optionally passing through the buoyant member. At least one of the submunitions enters an intake vent of the impeller-driven watercraft and attaches to a blade of an impeller of the impeller-driven watercraft, causing cavitation and imbalance, thereby slowing the impeller-driven watercraft

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of Great Britain provisional application no. GB1416475.0 titled, “Impeller Cavitation System,” filed on Sep. 17, 2014. 
       FIELD 
       [0002]    This invention relates to the field of law enforcement and more particularly to a system for creating floating security barriers against vessels propelled by water jet or impeller drives. 
       BACKGROUND 
       [0003]    There exists a need for law enforcement to be able to stop watercraft for boarding, inspection, and possible arrests and confiscation of contraband. In many jurisdictions, probable cause is not sufficient reason for opening fire on a watercraft and/or an operator of that watercraft. Often, well equipped law enforcement watercrafts are able to go faster than a suspect&#39;s watercraft, but without firing of a weapon, it is difficult to force the suspect to slow down and stop for boarding. The issue is further complicated by potential risk to the public should the suspect lose consciousness and the watercraft continues to move as well as the environmental concerns should fluids escape from the watercraft after being shot. 
         [0004]    Certain vessels can be stopped by use of prop entanglement systems such as US Coast Guard SNARE as described in U.S. Pat. No. 8,402,894 or US Coast Guard RGES as described in U.S. Pat. No. 7,975,639. Some law enforcement agencies run alongside the suspect&#39;s watercraft and shoot the engines of such vessels with specially designed rounds of ammunition that are designed to disable the engine of a vessel. These existing systems and techniques do not work on small personal watercraft such as jet skis with jet drives consisting of an impeller in a tubular housing. Any watercraft lacking an exposed propeller is unaffected by running over existing entanglement systems. Furthermore, in many such watercrafts, the engine is located close to the driver or possibly between the driver&#39;s legs making it impossible to shoot at the engine without risking life and limb of the driver or any passengers. There are situations where the operator is unconscious or otherwise incapacitated and the watercraft needs to be stopped without hurting the operator. 
         [0005]    With respect to maritime and riverine law enforcement, there exists a problem in not being able to stop certain classes of watercraft such as small personal watercraft, often referred to as jet skis. 
         [0006]    What is needed is a system that will stop or slow watercraft that utilize internal impellers for propulsion. 
       SUMMARY 
       [0007]    One aspect of the present invention provides a floating submunition that, after being sucked into the inlet of a jet drive and hit by the impeller, causes the impeller to cavitate. The submunition is hit by the advancing impeller blade, deforms around the leading edge of the impeller blade and creates cavitation as it is swept around the jet drive unit. 
         [0008]    In order to be sucked into the inlet of the jet drive, the submunition is designed to float, preferably in a vertically orientation. The submunition includes a buoyant body and a weight at one end to maintain an upright posture. 
         [0009]    In some embodiments, multiple submunitions are placed in a cartridge that is fired in advance of the suspect&#39;s watercraft, for example, by a pneumatic launcher, a rocket, firearm, or a spigot mortar, sending the multiple submunitions into the water in front of the suspect&#39;s watercraft so that one or more of the submunitions are sucked into the inlet of the jet drive of the suspect&#39;s watercraft. 
         [0010]    In some embodiments, the buoyant portion of the submunitions is made of closed cell foam or other highly buoyant material, or, in some embodiments, the buoyant portion is a sealed container or tube having a gas or air within the container to provide buoyancy. 
         [0011]    In some embodiments, multiple submunitions are placed in a grenade or bomb that is detonated in advance of the suspect&#39;s watercraft. In some embodiments, the submunitions are deployed using a sabot that opens once the round has left the barrel of the launcher. 
         [0012]    In some embodiments, the materials used to produce the submunitions are selected to biodegrade over relatively short time periods. 
         [0013]    In one embodiment, the submunition consists of a buoyant float with a weight at one end and a retaining element such a disc at the other end. A cord, line or wire runs through the buoyant float, joining the weight and the retaining element. It is anticipated that the weight be metal or ceramic with a central hole through which the cord/line/wire runs and is attached. 
         [0014]    In some embodiments, the submunitions are between 0.25 inches and 1.5 inches in diameter to facilitate passing through input grates of target watercraft. In some embodiments, the submunitions are less than 1.0 inch in diameter to facilitate passing through input grates of target watercraft. In some embodiments, the submunitions are less than 4.0 inches long to facilitate passing through input grates of target watercraft. 
         [0015]    In some embodiments, the submunitions are provided with a range or mix of diameters and lengths to facilitate passing through input grates of target watercraft. 
         [0016]    In some embodiments, the submunitions have a proportion of their length above the water when floating vertically, and in some such embodiments between one tenth and one third of the submunitions length is above the water when floating vertically, assuming distilled water. 
         [0017]    In one embodiment, a submunition is disclosed including a buoyant member, a first end cap and a second end cap. A lanyard (or other connecting member) connects the first end cap to the second end cap, in some examples, passing through the buoyant member. The second end cap is heavier than the first end cap promoting an upright orientation when suspended in a fluid such as water. 
         [0018]    In another embodiment, a method of stopping an impeller-driven watercraft is disclosed including distributing a plurality of submunitions in advance of a path of the impeller-driven watercraft, each of the submunitions includes a buoyant member, a first end cap, and a second end cap; the second end cap is heavier than the first end cap. A lanyard (or other connecting member) connects the first end cap to the second end cap. At least one of the submunitions enters an intake vent of the impeller-driven watercraft and attaches to a blade of an impeller of the impeller-driven watercraft, causing cavitation and imbalance, thereby slowing the impeller-driven watercraft. 
         [0019]    In another embodiment, a submunition is disclosed including a buoyant member made of low-density polyethylene foam, a first end cap made of steel and a second end cap also made of steel, the second end cap being heavier than the first end cap. A lanyard (or other connecting member) connects the first end cap to the second end cap, passing through the buoyant member. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    The invention can be best understood by those having ordinary skill in the art by reference to the following detailed description when considered in conjunction with the accompanying drawings in which: 
           [0021]      FIG. 1  illustrates a cross sectional view of a submunition. 
           [0022]      FIG. 2  illustrates a cross sectional view of a submunition. 
           [0023]      FIG. 3  illustrates a cross sectional view of a submunition. 
           [0024]      FIG. 4  illustrates a plan view of a first end of the submunition. 
           [0025]      FIG. 5  illustrates a plan view of a second end of the submunition. 
           [0026]      FIG. 6  illustrates multiple submunitions in a pack ready for deployment. 
           [0027]      FIG. 7  illustrates the deployment of one or more submunitions in advance of a watercraft. 
           [0028]      FIG. 8  illustrates one of the submunitions entering the intake of a watercraft. 
           [0029]      FIG. 9  illustrates one of the submunitions adhering to a blade of an impeller of a watercraft. 
       
    
    
     DETAILED DESCRIPTION 
       [0030]    Reference will now be made in detail to the presently preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. Throughout the following detailed description, the same reference numerals refer to the same elements in all figures. 
         [0031]    Referring to  FIGS. 1-5 , cross sectional views and end views of a submunition  10  are described. The submunition  10  is an impeller jamming system. As shown in  FIGS. 7-9 , one or more of the submunitions  10  is launched into the water in front of a watercraft  20  (any impeller-propelled watercraft  20  such as a jet ski, etc.). The intent is for one or more of the submunitions  10  to clamp onto a blade  27  of the impeller  26  (see  FIG. 8 ) of the watercraft  20 . Once one or more submunitions  10  clamp onto the blade  27  of the impeller  26 , the submunition(s)  10  move with the blade  27  of the impeller  26  as it rotates, causing cavitation within the impeller cavity  30 , reducing the thrust  28 / 28 ′ and slowing the watercraft  20  for boarding by, for example, a law enforcement personnel. 
         [0032]    It is desired that the submunition  10  float on the water in front of the watercraft  20  so that the submunition  10  submerges slightly when hit by the bow of the watercraft  20 , then by way of the buoyancy of the submunition  10 , the submunition  10  quickly recovers and is sucked into the intake  21  (see  FIGS. 8 and 9 ) of the watercraft  20 . The submunition  10  is then hit by the impeller  26  and bends around the leading edge of a blade of the impeller  26  and remains on the blade  27  of the impeller  26  by way of memory of the lanyard  4  and/or by way of an optional adhesive applied to the submunition  10 . In some embodiments, once the engine of the watercraft  20  is stopped, the submunition  10  falls off of the blade  27  of the impeller  26 , allowing future use of the watercraft  20  with no or minimal damage to the watercraft  20  and the impeller  26 . 
         [0033]    The submunition  10  comprises a buoyant body  7  with two endcaps  3 / 5  at each end. The endcaps  3 / 5  are connected to each other by a lanyard  4  (or other connecting member) that in some embodiments passes through the buoyant body  7 . Each endcap  3 / 5  is affixed to respective ends of the lanyard  4  by any way known for affixing, including, but not limited to welding, soldering, adhesive, a knot, crimping, etc. For example, in  FIGS. 4 and 5 , the lanyard  4  is shown affixed to the endcaps  3 / 5  by a weld  9 . 
         [0034]    So that the submunition  10  floats in an upright fashion, the upper endcap  3  is of less mass than the lower endcap  5  and, therefore, when placed in water, the upper endcap  3  remains at or above the surface of the water and the lower endcap  5  sinks below the surface of the water. By providing this upright orientation, the probability of being sucked into the intake  21  of the watercraft  20  is greatly enhanced. 
         [0035]    The buoyant body  7  is made of a material or has a structure that makes the buoyant body  7  lighter than water (e.g., sea water, river water, lake water), providing sufficient buoyancy as to keep the submunition  10  and endcaps  3 / 5  afloat until external forces are applied (e.g., until hit by the leading edge of a hull of the watercraft  20 ). In the example shown in  FIG. 2 , the buoyant body  7  is made of a material  1  that has a specific gravity relative to water that is less than 1.0. It is further desired that the overall specific gravity relative to water of the entire submunition  10  is less than 1.0, allowing the submunition  10  to partially float with the upper endcap  3  at or above the surface of the water. It is understood that the specific gravity with respect to water depends upon the type of water (e.g., salt water or fresh water) as well as the temperature and air pressure. To this, the submunition  10  is designed to operate in one or more types of target water (e.g. a submunition  10  designed for fresh water or a submunition  10  designed for salt water, etc.). 
         [0036]    In some embodiments, the buoyant body  7  is made of a material  1  that is a foam material such as low-density polyethylene foam that is often used in packing materials. In some embodiments, the buoyant body  7  is made of a buoyant material  1  that is starch-based or starch-based foam that biodegrades relatively quickly when exposed to water. In some embodiments, the buoyant body  7  is made of a buoyant material  1  that is edible by marine life. In this embodiment, it is anticipated that when the blade  27  of the impeller  26  hits the submunition  10 , the buoyant body  7  deforms or exits the submunition  10 . 
         [0037]    In some embodiments, as shown in  FIG. 3 , the buoyant body  7  is made as an enclosed tube  12  having seals  13  at each end, providing buoyancy due to air, gas, or, even by being evacuated within the cavity contained by the tube  12  and seals  13 . In this embodiment, it is anticipated that when the blade  27  of the impeller  26  hits the submunition  10 , the tube  12  fractures. In some embodiments, the enclosed tube  12  is the connecting member, connecting the end caps  3 / 5 . 
         [0038]    In some embodiments, as shown in  FIG. 1 , the buoyant body  7  is coated with an outer layer  15 . In some such embodiments, the outer layer is made of paper or a water-soluble film that slows water ingress into the buoyant material  1 , thereby slowing the decomposition of the buoyant material  1 . In some embodiments, the outer layer  15  includes an adhesive that, when struck by a blade  27  of the impeller  26  of a watercraft  20 , the adhesive of the outer layer  15  aids in adherence of the submunition  10  to the blade  27  of the impeller  26 . In some embodiments, the adhesive is water activated or micro encapsulated to prevent the submunitions  10  from bonding to each other in the launch cartridge but then the submunitions  10  become sticky when exposed to water or when the submunitions  10  are hit by the impeller blade  27 . 
         [0039]    Although there is no limitation on size, it is preferred that the submunition be longer (the distance between the endcaps  3 / 5 ) than wider. In some embodiments, the submunitions are between 0.25 inches and 1.5 inches in diameter to facilitate passing through intake grates of target watercraft  20 . In some embodiments, the submunitions  10  are less than 1.0 inch in diameter to facilitate passing through intake grates of target watercraft  20 . In some embodiments, the submunitions  10  are less than 4.0 inches long (the distance between the endcaps  3 / 5 ) to facilitate passing through intake grates of target watercraft  20 . 
         [0040]    It is fully anticipated that the submunitions  10  are provided with a range or mix of shapes, diameters, and lengths to facilitate passing through intake grates of a variety of target watercrafts  20 . 
         [0041]    In some embodiments, the submunitions  10  have a proportion of their length above the water when floating vertically (endcap  5  submerged and endcap  3  at or above the surface), and in some such embodiments between one tenth and one third of the submunitions length is above the water when floating vertically, assuming a specific type of water such as fresh water, salt water, etc. 
         [0042]    The lanyard  4  is made of a material that is sufficiently strong as to not break under the initial force of a hit by the blade  27  of the impeller  26 . Suitable materials are fishing line, braided fishing line, annealed wire (e.g., baling wire), etc. Although not required, it is preferred to use a material that has plastic properties, in that, when bent, the material remains bent. For example, annealed wire will remain bent after the submunition  10  bends around the leading edge of the blade  27  of the impeller  26 . 
         [0043]    It is anticipated that in some embodiments the endcaps  3 / 5  are made of metal or ceramic with a central hole through which the lanyard  4  runs and is attached. To achieve an upright posture when in the water, the upper endcap  3  has less mass than the lower endcap  5 . For example, the upper endcap  3  is a 24 gauge steel washer and the lower endcap  5  is a 12 gauge steel washer. In some embodiments, the endcaps  3 / 5  are made from a material that is not harmful to the environment and will eventually biodegrade such as steel or iron. In some embodiments, the lower endcap  5  is made from a formed piece of metal, shaped so as to create cavitation bubbles when the submunition  10  is situated on the leading edge of a rotating blade  27  of an impeller  26 . 
         [0044]    Referring to  FIG. 6  illustrates multiple submunitions  10  in a pack  50  ready for deployment. In this example, the pack  50  is launched from a weapon by way of pneumatic pressure or an explosive charge, sending the multiple submunitions  10  into the air and, eventually, into the water preceding the path of the watercraft  20 . 
         [0045]    Referring to  FIG. 7  illustrates the deployment of one or more submunitions  10  in advance of a watercraft  20 . One or more of the submunitions  10  is launched into the water in front of a watercraft  20  (any impeller-propelled watercraft  20  such as a Jet Ski, etc.) by a propulsion mechanism  32  from, for example, a law enforcement vehicle (e.g. boat  30 , helicopter, airplane, from land, etc.). 
         [0046]    Referring to  FIGS. 8 and 9 , one of the submunitions  10  entering the intake  21  of a watercraft  20  (in  FIG. 8 ) then adhering to a blade  27  of an impeller  26  of a watercraft (in  FIG. 9 ) is shown. The intent is for one or more of the submunitions  10  to clamp onto the blade  27  of the impeller  26  (see  FIG. 9 ) of the watercraft  20 . Once one or more submunitions  10  clamps onto the blade  27  of the impeller  26 ; the submunition(s)  10  move with the blade  27  of the impeller  26  as it rotates, causing imbalance and cavitation within the impeller cavity  30 . In  FIG. 8 , the watercraft  20  driven by a person  25  (perhaps a criminal or a person with a medical condition) is moving at a high rate of speed and the submunition  10  is floating in the path of the watercraft  20 , then the submunition  10  is hit by the hull of the watercraft  20  and submerges, recovering to enter the intake  21  of the watercraft  20  within the propulsion shroud  30  where, as in  FIG. 9 , the submunition after being hit by the blade  27  of the impeller  26  holds onto the blade  27  of the impeller  26  causing cavitation within the propulsion shroud  30 . The cavitation and imbalance reduces the output thrust  28 / 28 ′ from a high output thrust  28  (see  FIG. 8 ) to a low output thrust  28 ′ (see  FIG. 9 ). The low output thrust  28 ′ allows a small amount of maneuverability and low speed so that the watercraft  20  has difficulty escaping the law enforcement vehicle (e.g. boat  32 ). 
         [0047]    Equivalent elements can be substituted for the ones set forth above such that they perform in substantially the same manner in substantially the same way for achieving substantially the same result. 
         [0048]    It is believed that the system and method as described and many of its attendant advantages will be understood by the foregoing description. It is also believed that it will be apparent that various changes may be made in the form, construction and arrangement of the components thereof without departing from the scope and spirit of the invention or without sacrificing all of its material advantages. The form herein before described being merely exemplary and explanatory embodiment thereof. It is the intention of the following claims to encompass and include such changes.