Patent Publication Number: US-2020298942-A1

Title: Marine vessel and marine vessel imaging device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority to Japanese Patent Application No. 2019-051057 filed on Mar. 19, 2019. The entire contents of this application are hereby incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a marine vessel and a marine vessel imaging device. 
     2. Description of the Related Art 
     A marine vessel including an imager is known in general. Such a marine vessel is disclosed in Chinese Utility Model No. 204871490, for example. 
     Chinese Utility Model No. 204871490 discloses a marine vessel including an imager and an illuminator. The imager and the illuminator are both attached to an upper portion of a mast. That is, the imager is provided in the vicinity of the illuminator. When the imager is provided in the vicinity of the illuminator, power is easily supplied, to the imager, from a power source of power supplied to the illuminator. 
     However, in the marine vessel described in Chinese Utility Model No. 204871490, when the imager is provided in the vicinity of the illuminator, light of the illuminator appears in an image captured by the imager, which adversely affects the image. Although not explicitly described in Chinese Utility Model No. 204871490, the imager is conceivably provided in the vicinity of a navigation light. However, even in such a case, when the imager is provided in the vicinity of the navigation light, light from the navigation light appears in the image captured by the imager, and the image may be adversely affected. 
     SUMMARY OF THE INVENTION 
     Preferred embodiments of the present invention provide marine vessels and marine vessel imaging devices that significantly reduce or prevent the appearance of light from navigation lights in images captured by imagers. 
     A marine vessel according to a preferred embodiment of the present invention includes a vessel body including a navigation light, an imager provided in a vicinity of or adjacent to the navigation light, and a light shield provided between the navigation light and the imager so as to block light from the navigation light to the imager. 
     In a marine vessel according to a preferred embodiment of the present invention, with the structure described above, the light from the navigation light toward the imager is blocked by the light shield, and thus the appearance of light from the navigation light in an image captured by the imager is significantly reduced or prevented. Furthermore, the imager is provided in the vicinity of or adjacent to the navigation light, and thus power is also supplied to the imager by wiring that supplies power to the navigation light. That is, the wiring is shared, and thus the structure (the structure of the wiring) that supplies power is simplified. 
     In a marine vessel according to a preferred embodiment of the present invention, the imager is preferably provided at a position that overlaps the light shield in an upward-downward direction. Accordingly, a space in which the imager and the light shield are provided in a horizontal direction is reduced. 
     In such a case, the light shield is preferably provided at a position that overlaps the imager and the navigation light in a plan view. Accordingly, a space in which the imager, the light shield, and the navigation light are provided in the horizontal direction is reduced. Furthermore, the navigation light emits light substantially in the horizontal direction, and thus the imager and the navigation light overlap each other in the plan view such that the appearance of light from the navigation light in the image captured by the imager is significantly reduced or prevented. 
     A marine vessel in which the imager is provided at the position that overlaps the light shield in the upward-downward direction preferably further includes a navigation light mounting pole to which the navigation light is attached, the navigation light mounting pole extending in the upward-downward direction, and the imager and the light shield are preferably attached to the navigation light mounting pole above or below the navigation light. Accordingly, the imager and the navigation light are attached to the common navigation light mounting pole such that the imager is easily provided in the vicinity of or adjacent to the navigation light. 
     In such a case, the navigation light mounting pole preferably includes a mast light mounting pole to which a mast light of the navigation light is attached, the mast light mounting pole being provided at an upper portion of the vessel body, the light shield is preferably attached to the mast light mounting pole above the mast light, and the imager is preferably attached to the mast light mounting pole above the mast light. Accordingly, the imager is attached to the mast light mounting pole provided at the highest position of the marine vessel, and thus a wider range is imaged by the imager. 
     In a marine vessel in which the imager is attached to the mast light mounting pole above the mast light, the imager is preferably attached to the mast light mounting pole above the light shield such that an image captured by the imager does not include the light shield. Accordingly, an image of the surroundings of the marine vessel to be imaged is reliably captured over a wider range without being obstructed by the light shield. 
     In a marine vessel including the navigation light mounting pole, the imager preferably includes a single all-around imager that images an entire or substantially an entire circumference around the vessel body. Accordingly, the structure of the device is simplified as compared with a case in which a plurality of imagers image the entire or substantially the entire circumference around the vessel body. 
     In a marine vessel including the navigation light mounting pole, the light shield preferably has a disk shape that extends in a horizontal direction around the navigation light mounting pole. Accordingly, a distance from the navigation light to the outer peripheral end of the light shield is uniform, and thus the light shield uniformly blocks light in any horizontal direction. 
     In such a case, in a plan view, a diameter of the light shield is preferably larger than a diameter of the navigation light. Accordingly, the light shield and the navigation light reliably overlap each other in the upward-downward direction, and thus light is more reliably blocked by the light shield. 
     In a marine vessel in which the imager is provided at the position that overlaps the light shield in the upward-downward direction, the light shield is preferably attached below a port light and a starboard light of the navigation light, and the imager is preferably attached below the light shield. Accordingly, images in leftward and rightward directions in which a blind spot of the imager is likely to occur are reliably acquired without being obstructed by the light shield. 
     In a marine vessel in which the imager is provided at the position that overlaps the light shield in the upward-downward direction, the imager preferably includes a plurality of outer circumference imagers that image surroundings of the vessel body, the plurality of outer circumference imagers preferably do not image a same target, and in a horizontal direction, a sum of angles of views of the plurality of outer circumference imagers is preferably about 360 degrees. In general, when the surroundings of a marine vessel are imaged by a plurality of imagers and a composite image is created, it is necessary to perform calibration in order to match the overlapping of the captured images of the plurality of imagers. With the structure described above, the plurality of outer circumference imagers capture images of about 360 degrees around the marine vessel without overlapping each other, and thus a composite image of the entire or substantially the entire circumference around the marine vessel is easily acquired without performing calibration. 
     In a marine vessel according to a preferred embodiment of the present invention, the imager preferably includes two outer circumference imagers, an angle of view of each of the two outer circumference imagers is preferably about 180 degrees in the horizontal direction, and the two outer circumference imagers are preferably disposed to capture images in horizontally opposite directions. Accordingly, a blind spot of one of the two outer circumference imagers is reliably covered by the other of the two outer circumference imagers. 
     In a marine vessel according to a preferred embodiment of the present invention, the two outer circumference imagers preferably include a first outer circumference imager and a second outer circumference imager that captures an image in the horizontal direction opposite to that of the first outer circumference imager, the first outer circumference imager is preferably provided in a vicinity of or adjacent to a port light of the navigation light to capture an image in a leftward direction, or provided in a vicinity of or adjacent to a bow light of the navigation light to capture an image in a forward direction, and the second outer circumference imager is preferably provided in a vicinity of or adjacent to a starboard light of the navigation light to capture an image in a rightward direction when the first outer circumference imager is provided in the vicinity of or adjacent to the port light, and provided in a vicinity of or adjacent to a stern light of the navigation light to capture an image in a rearward direction when the first outer circumference imager is provided in the vicinity of or adjacent to the bow light. Accordingly, when the first outer circumference imager is provided in the vicinity of or adjacent to the port light and the second outer circumference imager is provided in the vicinity of or adjacent to the starboard light, the occurrence of blind spots of the marine vessel in the leftward direction and the rightward direction is significantly reduced or prevented. When the first outer circumference imager is provided in the vicinity of or adjacent to the bow light and the second outer circumference imager is provided in the vicinity of or adjacent to the stern light, the occurrence of blind spots of the marine vessel in a forward direction and a rearward direction is significantly reduced or prevented. 
     A marine vessel according to a preferred embodiment of the present invention preferably further includes power supply wiring that supplies power to the navigation light, and the power supply wiring preferably also supplies power to the imager. Accordingly, the power supply wiring supplies power not only to the navigation light but also to the imager. Therefore, the structure (the structure of the wiring) that supplies power is simplified as compared with a case in which dedicated wiring that supplies power to the imager is provided. 
     In a marine vessel according to a preferred embodiment of the present invention, the light shield and the navigation light are preferably separate from each other. Accordingly, the arrangement of the light shield with respect to the navigation light is adjusted. 
     In a marine vessel according to a preferred embodiment of the present invention, an upper surface of the light shield preferably includes an inclined surface that is inclined downward toward an end of the upper surface such that water does not accumulate thereon. Accordingly, adhesion of water to the imager that has accumulated on the upper surface of the light shield is significantly reduced or prevented. 
     In a marine vessel according to a preferred embodiment of the present invention, the light shield is preferably provided closer to the navigation light than the imager. Accordingly, the spreading of light emitted from the navigation light toward the imager is effectively significantly reduced or prevented. 
     In such a case, the light shield preferably contacts the navigation light and is preferably spaced apart from the imager. Accordingly, the spreading of light emitted from the navigation light toward the imager is more effectively significantly reduced or prevented. 
     In a marine vessel according to a preferred embodiment of the present invention, the imager is preferably provided at a position higher than a vicinity of a bow light of the navigation light. Accordingly, the imager is provided at a relatively high position, and thus a wide range is imaged by the imager. 
     In a marine vessel according to a preferred embodiment of the present invention, the light shield preferably includes a plate-shaped light-shielding plate. Accordingly, the light from the navigation light toward the imager is blocked by a simple structure. 
     A marine vessel imaging device according to a preferred embodiment of the present invention includes an imager provided in a vicinity of or adjacent to a navigation light provided in a vessel body, and a light shield provided between the navigation light and the imager so as to block light from the navigation light to the imager. 
     In a marine vessel imaging device according to a preferred embodiment of the present invention, with the structure described above, the appearance of light from the navigation light in an image captured by the imager is significantly reduced or prevented, similarly to the marine vessels according to preferred embodiments of the present invention described above. Furthermore, a structure (the structure of wiring) that supplies power is simplified. 
     The above and other elements, features, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side view showing a marine vessel according to a first preferred embodiment of the present invention. 
         FIG. 2  is a plan view showing the marine vessel according to the first preferred embodiment of the present invention. 
         FIG. 3  is a schematic view illustrating navigation lights of the marine vessel according to the first preferred embodiment of the present invention. 
         FIG. 4  is a side view showing a marine vessel imaging device of the marine vessel according to the first preferred embodiment of the present invention. 
         FIG. 5  is a plan view showing a marine vessel according to a second preferred embodiment of the present invention. 
         FIG. 6  is a side view showing a marine vessel imaging device of the marine vessel according to the second preferred embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Preferred embodiments of the present invention are hereinafter described with reference to the drawings. 
     First Preferred Embodiment 
     The structure of a marine vessel  100  according to a first preferred embodiment of the present invention is now described with reference to  FIGS. 1 to 4 . The marine vessel  100  is a small marine vessel, for example. 
     As shown in  FIG. 1 , the marine vessel  100  includes a vessel body  1  including navigation lights  6 , propulsion devices  2   a  and  2   b , a side thruster  2   c , and a marine vessel imaging device  3 . The vessel body  1  includes a cabin  11  at its upper portion and a bridge  12  at an upper portion of the cabin  11 . As shown in  FIG. 2 , an operation seat  4   a  and a marine vessel operation unit  5   a  provided in the vicinity of the operation seat  4   a  are provided inside the cabin  11 . An operation seat  4   b  and a marine vessel operation unit  5   b  provided in the vicinity of the operation seat  4   b  are provided in the bridge  12 . The operation seat  4   a  and the operation seat  4   b  have the same structure. The marine vessel operation unit  5   a  and the marine vessel operation unit  5   b  have the same structure. 
     In this specification, the term “front (forward)” refers to a direction indicated by “FWD” in the figures and the forward movement direction (the bow  1   a  side of the vessel body  1 ) of the marine vessel  100 . The term “rear (rearward)” refers to a direction indicated by “BWD” in the figures and the reverse movement direction (the stern  1   b  side of the vessel body  1 ) of the marine vessel  100 . Furthermore, the term “left (leftward)” refers to a direction indicated by “L” in the figures and the port  1   c  side of the vessel body  1 . The term “right (rightward)” refers to a direction indicated by “R” in the figures and the starboard  1   d  side of the vessel body  1 . The term “vertically” refers to a direction indicated by “Z” in  FIG. 1 . The term “upper (upward, above)” refers to a direction indicated by “Z 1 ” in  FIG. 1 , and the term “lower (downward, below)” refers to a direction indicated by “Z 2 ” in  FIG. 1 . 
     The propulsion devices  2   a  and  2   b  are outboard motors, for example. As shown in  FIG. 2 , the propulsion device  2   a  is attached to a left portion of the stern  1   b.  The propulsion device  2   b  is attached to a right portion of the stern  1   b.  The side thruster  2   c  is attached to a vertically lower portion (see  FIG. 1 ) of a hull  1   e  of the vessel body  1 , for example. The marine vessel  100  is movable and turnable in forward, rearward, leftward, and rightward directions by the propulsion forces of the propulsion devices  2   a  and  2   b  and the side thruster  2   c.    
     The marine vessel operation units  5   a  and  5   b  each include a steering operator, a remote control, and a joystick, for example. The marine vessel operation units  5   a  and  5   b  change the orientations and propulsion forces of the propulsion devices  2   a  and  2   b  and change the propulsion force generation direction and propulsion force of the side thruster  2   c  based on operations performed by a marine vessel operator. 
     The navigation lights  6  each have a cylindrical outer shape, and emit light in a predetermined angular range in a horizontal or substantially horizontal direction defined by a rule regarding the marine vessel  100 . The navigation lights  6  include, for example, a mast light  61  (a rear mast light), a port light  62 , a starboard light  63 , a bow light  64  (a front mast light), and a stern light  65 . The navigation lights  6  are able to notify another marine vessel of the presence and orientation of the marine vessel  100 . The luminous intensity of the navigation lights  6  is, for example, not less than 0.9 candela and less than 12 candela (for a trawler having a length of less than 50 meters, it is, for example, not less than 0.9 candela and less than 4.3 candela). 
     The mast light  61  is provided above a rear portion of a deck. Specifically, the mast light  61  is attached to a mast light mounting pole  71  provided at an upper portion of the vessel body  1 . The mast light mounting pole  71  extends upward (in an upward-downward direction) from the rear portion of the deck. The mast light  61  is provided at the highest position among all the navigation lights  6 . The central axis of the cylindrical mast light  61  is located coaxially with the central axis of the mast light mounting pole  71 . The mast light mounting pole  71  is an example of a “navigation light mounting pole”. 
     As shown in  FIG. 3 , the port light  62  is attached to a port light mounting pole  72  provided on the left side of the vessel body  1 . The starboard light  63  is attached to a starboard light mounting pole  73  provided on the right side of the vessel body  1 . The stern light  65  is attached to a stern light mounting pole  75  provided on the stern  1   b.  The bow light  64  is attached to a bow light mounting pole  74  provided on the bow  1   a.    
     The marine vessel imaging device  3  shown in  FIG. 4  supports the marine vessel operation of the marine vessel operator. For example, as shown in  FIG. 2 , the marine vessel imaging device  3  displays a captured image on a display  40  (see  FIG. 2 ) when the marine vessel operator operates the marine vessel operation unit  5   a  ( 5   b ) (operates the marine vessel) while being located on the operation seat  4   a  ( 4   b ) so as to complement the marine vessel operator&#39;s field of view (blind spot). 
     The marine vessel imaging device  3  includes an all-around imager  31  and a light-shielding plate  32 . The all-around imager  31  is an example of an “imager”. The light-shielding plate  32  is an example of a “light shield”. 
     The all-around imager  31  images the entire or substantially the entire circumference around the vessel body  1 . Specifically, the all-around imager  31  includes, for example, a single omnidirectional camera (360-degree camera) that captures a moving image. The omnidirectional camera captures 360-degree panoramic photographs in all directions, upward, downward, leftward, and rightward directions, and 360-degree moving images. 
     The all-around imager  31  (marine vessel imaging device  3 ) is provided in the vicinity of or adjacent to the mast light (navigation light  6 ). Specifically, the all-around imager  31  is attached to the mast light mounting pole  71  above the light-shielding plate  32  such that an image captured by the all-around imager  31  does not include the light-shielding plate  32  (the light-shielding plate  32  does not appear in an imaging range of the all-around imager  31 ). 
     The all-around imager  31  is provided at a position that overlaps the light-shielding plate  32  and the mast light  61  in the upward-downward direction. Furthermore, the all-around imager  31  is provided at a position higher than the vicinity of the bow light  64  in the upward-downward direction. 
     As shown in  FIG. 4 , the light-shielding plate  32  is provided between the mast light  61  (navigation light  6 ) and the all-around imager  31 . Thus, the light-shielding plate  32  blocks light from the mast light  61  to the all-around imager  31 . 
     The light-shielding plate  32  is separate from the mast light  61 . The light-shielding plate  32  contacts the mast light  61  from above and is spaced apart from the all-around imager  31 . That is, the light-shielding plate  32  is provided closer to the mast light  61  than the all-around imager  31 . 
     The light-shielding plate  32  is provided at a position that overlaps the all-around imager  31  and the mast light  61  in a plan view. Furthermore, the all-around imager  31  and the mast light  61  are provided inside the outer peripheral end of the light-shielding plate  32  in the plan view. 
     The light-shielding plate  32  is attached to the mast light mounting pole  71  above the mast light  61 , similarly to the all-around imager  31 . 
     The light-shielding plate  32  has a disk shape that extends horizontally around the mast light mounting pole  71 . The central axis of the light-shielding plate  32  is located coaxially with the central axes of the mast light  61  and the mast light mounting pole  71 . Note that the diameter D 1  of the light-shielding plate  32  (in the plan view) is larger than the diameter D 2  of the cylindrical mast light  61 . 
     The upper surface  32   a  of the light-shielding plate  32  includes an inclined surface that is inclined downward toward the outer peripheral end of the upper surface  32   a  such that water does not accumulate thereon. Even when liquid adheres to the inclined upper surface  32   a , the liquid is removed by flowing toward the outer peripheral end due to gravity. 
     The marine vessel  100  (see  FIG. 1 ) includes power supply wiring  8  that supplies power to the mast light  61  (navigation light  6 ). A power supply source of the power supply wiring  8  is a battery (not shown) provided in the marine vessel  100 . The power supply wiring  8  also supplies power to the all-around imager  31 . The power supply wiring  8  is branched before the mast light  61 , and electrically connects the battery to the mast light  61 , and the all-around imager  31  so as to supply power to both the mast light  61  and the all-around imager  31 . 
     According to the first preferred embodiment of the present invention, the following advantageous effects are achieved. 
     According to the first preferred embodiment of the present invention, with the structure described above, the light from the navigation light  6  toward the all-around imager  31  is blocked by the light-shielding plate  32 , and thus the appearance of light from the navigation light  6  in the image captured by the all-around imager  31  is significantly reduced or prevented. Furthermore, the all-around imager  31  is provided in the vicinity of or adjacent to the navigation light  6 , and thus power is also supplied to the all-around imager  31  by the wiring that supplies power to the navigation light  6 . That is, the wiring is shared, and thus the structure (the structure of the wiring) that supplies power is simplified. 
     According to the first preferred embodiment of the present invention, the all-around imager  31  is provided at the position that overlaps the light-shielding plate  32  in the upward-downward direction. Accordingly, a space in which the all-around imager  31  and the light-shielding plate  32  are provided in the horizontal direction is reduced. 
     According to the first preferred embodiment of the present invention, the light-shielding plate  32  is provided at the position that overlaps the all-around imager  31  and the navigation light  6  in the plan view. Accordingly, a space in which the all-around imager  31 , the light-shielding plate  32 , and the navigation light  6  are provided in the horizontal direction is reduced. Furthermore, the navigation light  6  emits light in or substantially in the horizontal direction, and thus the all-around imager  31  and the navigation light  6  overlap each other in the plan view such that the appearance of light from the navigation light  6  in the image captured by the all-around imager  31  is significantly reduced or prevented. 
     According to the first preferred embodiment of the present invention, the marine vessel  100  further includes the mast light mounting pole  71  to which the navigation light  6  is attached and that extends in the upward-downward direction, and the all-around imager  31  and the light-shielding plate  32  are attached to the mast light mounting pole  71  above or below the navigation light  6 . Accordingly, the all-around imager  31  and the navigation light  6  are attached to the common mast light mounting pole  71  such that the all-around imager  31  is easily provided in the vicinity of or adjacent to the navigation light  6 . 
     According to the first preferred embodiment of the present invention, the navigation light mounting pole includes the mast light mounting pole  71 , to which the mast light  61  is attached, provided at the upper portion of the vessel body  1 , the light-shielding plate  32  is attached to the mast light mounting pole  71  above the mast light  61 , and the all-around imager  31  is attached to the mast light mounting pole  71  above the mast light  61 . Accordingly, the all-around imager  31  is attached to the mast light mounting pole  71  provided at the highest position of the marine vessel  100 , and thus a wider range is imaged by the all-around imager  31 . 
     According to the first preferred embodiment of the present invention, the all-around imager  31  is attached to the mast light mounting pole  71  above the light-shielding plate  32  such that the image captured by the all-around imager  31  does not include the light-shielding plate  32 . Accordingly, an image of the surroundings of the marine vessel  100  to be imaged is reliably captured over a wider range without being obstructed by the light-shielding plate. 
     According to the first preferred embodiment of the present invention, the all-around imager  31  includes a single all-around imager  31  that images the entire or substantially the entire circumference around the vessel body  1 . Accordingly, the structure of the device is simplified as compared with a case in which a plurality of all-around imagers  31  image the entire or substantially the entire circumference around the vessel body  1 . 
     According to the first preferred embodiment of the present invention, the light-shielding plate  32  has a disk shape that extends in the horizontal direction around the mast light mounting pole  71 . Accordingly, a distance from the navigation light  6  to the outer peripheral end of the light-shielding plate  32  is uniform, and thus the light-shielding plate  32  uniformly blocks light in any horizontal direction. 
     According to the first preferred embodiment of the present invention, in the plan view, the diameter D 1  of the light-shielding plate  32  is larger than the diameter D 2  of the navigation light  6 . Accordingly, the light-shielding plate  32  and the navigation light  6  reliably overlap each other in the upward-downward direction, and thus light is more reliably blocked by the light-shielding plate  32 . 
     According to the first preferred embodiment of the present invention, the marine vessel  100  further includes the power supply wiring  8  that supplies power to the navigation light  6 , and the power supply wiring  8  also supplies power to the all-around imager  31 . Accordingly, the power supply wiring  8  supplies power not only to the navigation light  6  but also to the all-around imager  31 . Therefore, the structure (the structure of the wiring) that supplies power is simplified as compared with a case in which dedicated wiring that supplies power to the all-around imager  31  is provided. 
     According to the first preferred embodiment of the present invention, the light-shielding plate  32  and the navigation light  6  are separate from each other. Accordingly, the arrangement of the light-shielding plate  32  with respect to the navigation light  6  is adjusted. 
     According to the first preferred embodiment of the present invention, the upper surface  32   a  of the light-shielding plate  32  includes the inclined surface that is inclined downward toward the end of the upper surface  32   a  such that water does not accumulate thereon. Accordingly, adhesion of water to the all-around imager  31  that has accumulated on the upper surface  32   a  of the light-shielding plate  32  is significantly reduced or prevented. 
     According to the first preferred embodiment of the present invention, the light-shielding plate  32  is provided closer to the navigation light  6  than the all-around imager  31 . Accordingly, the spreading of light emitted from the navigation light  6  toward the all-around imager  31  is effectively significantly reduced or prevented. 
     According to the first preferred embodiment of the present invention, the light-shielding plate  32  contacts the navigation light  6  and is spaced apart from the all-around imager  31 . Accordingly, the spreading of light emitted from the navigation light  6  toward the all-around imager  31  is more effectively significantly reduced or prevented. 
     According to the first preferred embodiment of the present invention, the all-around imager  31  is provided at the position higher than the vicinity of the bow light  64 . Accordingly, the all-around imager  31  is provided at a relatively high position, and thus a wide range is imaged by the all-around imager  31 . 
     According to the first preferred embodiment of the present invention, the plate-shaped light-shielding plate  32  that blocks light is provided. Accordingly, the light from the navigation light  6  toward the all-around imager  31  is blocked by a simple structure. 
     Second Preferred Embodiment 
     The structure of a marine vessel  200  according to a second preferred embodiment of the present invention is now described with reference to  FIGS. 5 and 6 . In the second preferred embodiment, marine vessel imaging devices  230   a  and  230   b  are provided in the vicinity of or adjacent to a port light  62  and a starboard light  63 , respectively, unlike the first preferred embodiment in which the marine vessel imaging device  3  is provided in the vicinity of or adjacent to the mast light  61 . In the second preferred embodiment, the same or similar structures as those of the first preferred embodiment are denoted by the same reference numerals, and description thereof is omitted. 
     As shown in  FIG. 5 , the marine vessel  200  includes the marine vessel imaging devices  230   a  and  230   b . The marine vessel imaging device  230   a  (first outer circumference imager  231   a  described below) is provided in the vicinity of or adjacent to the port light  62 . The marine vessel imaging device  230   b  (second outer circumference imager  231   b  described below) is provided in the vicinity of or adjacent to the starboard light  63 . The first outer circumference imager  231   a  and the second outer circumference imager  231   b  are examples of an “imager”. 
     The marine vessel imaging device  230   a  includes the first outer circumference imager  231   a  and a light-shielding plate  232   a . The marine vessel imaging device  230   b  includes the second outer circumference imager  231   b  and a light-shielding plate  232   b . That is, the marine vessel  200  includes a plurality of outer circumference imagers (i.e., the first outer circumference imager  231   a  and the second outer circumference imager  231   b ) that image the surroundings of a vessel body  1 . 
     The plurality of outer circumference imagers (i.e., the first outer circumference imager  231   a  and the second outer circumference imager  231   b ) shown in  FIG. 6  do not image the same target (image different ranges). Furthermore, the two first outer circumference imager  231   a  and second outer circumference imager  231   b  are disposed to capture images in horizontally opposite directions. The angle of view A of each of the first outer circumference imager  231   a  and the second outer circumference imager  231   b  is about 180 degrees in a horizontal direction. Therefore, in the horizontal direction, the sum of the angles of view A (see  FIG. 5 ) of the plurality of (two) outer circumference imagers (the first outer circumference imager  231   a  and the second outer circumference imager  231   b ) is about 360 degrees. 
     The first outer circumference imager  231   a  (second outer circumference imager  231   b ) images half or substantially half the circumference around the vessel body  1 . Specifically, the first outer circumference imager  231   a  (second outer circumference imager  231   b ) includes a single 180-degree camera that captures moving images. The 180-degree camera captures 180-degree panoramic photographs in all directions, upward, downward, leftward, and rightward directions, and 180-degree moving images. 
     The light-shielding plate  232   a  is attached to a port light mounting pole  72  below the port light  62 . The first outer circumference imager  231   a  is attached to the port light mounting pole  72  below the light-shielding plate  232   a . The light-shielding plate  232   b  is attached to a starboard light mounting pole  73  below the starboard light  63 . The second outer circumference imager  231   b  is attached to the starboard light mounting pole  73  below the light-shielding plate  232   b.    
     The first outer circumference imager  231   a  is provided in the vicinity of or adjacent to the port light  62  to capture an image in the rightward direction. The second outer circumference imager  231   b  is provided in the vicinity of or adjacent to the starboard light  63  to capture an image in the leftward direction. 
     The remaining structures of the second preferred embodiment are similar to those of the first preferred embodiment. 
     According to the second preferred embodiment of the present invention, the following advantageous effects are achieved. 
     According to the second preferred embodiment of the present invention, the light-shielding plates ( 232   a ,  232   b ) are attached below the port light  62  and the starboard light  63 , and the first outer circumference imager  231   a  and the second outer circumference imager  231   b  are attached below the light-shielding plates  232   a  and  232   b . Accordingly, images are captured without being obstructed by the light-shielding plates, and the images in the leftward and rightward directions in which blind spots of the imagers are likely to occur are reliably acquired. 
     According to the second preferred embodiment of the present invention, the marine vessel  200  includes the plurality of outer circumference imagers (i.e., the first outer circumference imager  231   a  and the second outer circumference imager  231   b ) that image the surroundings of the vessel body  1 , the first outer circumference imager  231   a  and the second outer circumference imager  231   b  do not image the same target, and in the horizontal direction, the sum of the angles of view A of the first outer circumference imager  231   a  and the second outer circumference imager  231   b  is about 360 degrees. In general, when the surroundings of a marine vessel are imaged by a plurality of imagers and a composite image is created, it is necessary to perform calibration in order to match the overlapping of the captured images of the plurality of imagers. With the structure described above, the plurality of outer circumference imagers (i.e., the first outer circumference imager  231   a  and the second outer circumference imager  231   b ) capture images of about 360 degrees around the marine vessel  200  without overlapping each other, and thus a composite image of the entire or substantially the entire circumference around the marine vessel  200  is easily acquired without performing calibration. 
     According to the second preferred embodiment of the present invention, the angle of view of each of the first outer circumference imager  231   a  and the second outer circumference imager  231   b  is about 180 degrees in the horizontal direction, and the two outer circumference imagers (the first outer circumference imager  231   a  and the second outer circumference imager  231   b ) are provided to capture images in horizontally opposite directions. Accordingly, a blind spot of the first outer circumference imager  231   a  is reliably covered by the second outer circumference imager  231   b.    
     According to the second preferred embodiment of the present invention, the two outer circumference imagers include the first outer circumference imager  231   a  and the second outer circumference imager  231   b  that captures an image in a horizontal direction opposite to that of the first outer circumference imager  231   a , the first outer circumference imager  231   a  is provided in the vicinity of or adjacent to the port light  62  to capture an image in the leftward direction, and the second outer circumference imager  231   b  is provided in the vicinity of or adjacent to the starboard light  63  to capture an image in the rightward direction. Accordingly, when the first outer circumference imager  231   a  is provided in the vicinity of or adjacent to the port light  62  and the second outer circumference imager  231   b  is provided in the vicinity of or adjacent to the starboard light  63 , the occurrence of blind spots of the marine vessel  200  in the leftward direction and the rightward direction is significantly reduced or prevented. When the first outer circumference imager  231   a  is provided in the vicinity of or adjacent to a bow light  64  and the second outer circumference imager  231   b  is provided in the vicinity of or adjacent to a stern light  65 , the occurrence of blind spots of the marine vessel  200  in a forward direction and a rearward direction is significantly reduced or prevented. 
     The remaining advantageous effects of the second preferred embodiment are similar to those of the first preferred embodiment. 
     The preferred embodiments of the present invention described above are illustrative in all points and not restrictive. The extent of the present invention is not defined by the above description of the preferred embodiments but by the scope of the claims, and all modifications within the meaning and range equivalent to the scope of the claims are further included. 
     For example, while the marine vessel preferably includes outboard motors in each of the first and second preferred embodiments described above, the present invention is not restricted to this. The marine vessel may alternatively include inboard motors or inboard/outboard motors, or the marine vessel may alternatively include jet propulsion devices. 
     While the marine vessel imaging devices, the port light, and the starboard light are preferably indirectly attached to the vessel body via the navigation light mounting poles in the second preferred embodiment described above, the present invention is not restricted to this. In the present invention, the marine vessel imaging devices, the port light, and the starboard light may alternatively be directly attached to the vessel body, for example. 
     While the imagers are preferably provided in the vicinity of or adjacent to the port light and the starboard light in the second preferred embodiment described above, the present invention is not restricted to this. In the present invention, the imagers may alternatively be provided in the vicinity of or adjacent to the bow light and the stern light, for example. 
     While one imager is preferably provided in the first preferred embodiment described above, and two imagers are preferably provided in the second preferred embodiment described above, the present invention is not restricted to this. In the present invention, three or more imagers may alternatively be provided. 
     While the light-shielding plate(s) preferably has a disk shape in each of the first and second preferred embodiments described above, the present invention is not restricted to this. In the present invention, the light-shielding plate(s) may alternatively have a shape other than the disk shape such as a rectangular plate shape. In the preferred embodiments, the light-shielding plate(s) is used as a light shield(s) that significantly reduces or prevents the influence of the navigation light on the imager(s), but the light shield(s) is not necessarily limited to the light-shielding plate(s). For example, a light-shielding cover(s) or a light-shielding lens(es) may alternatively be used as the light shield(s) instead of the light-shielding plate(s). 
     While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims.