Location of overboard person or object or of water-chemical interface

I claim:

1. Apparatus for determining the approximate location, on the upper surface of a body of water, of a perceived boundary between a target chemical released in the water and the ambient water, the apparatus comprising one or more location-indicating instruments, each of which comprises:

a free-floating body designed to be placed in and to float in an upright position on the upper surface of a body of water;

an activatable Satellite Positioning System (SPS) signal antenna and receiver/processor that, when activated, receives SPS signals from two or more SPS satellites and determines the location of the SPS antenna, the SPS receiver/processor and antenna being contained on the free-floating body;

an activatable location transmitter and transmitter interface that, when activated, continually receives from the SPS receiver/processor a location signal representing the SPS-determined location of the SPS antenna and transmits this location signal at a selected frequency, with the transmitter and transmitter interface being contained on the free-floating body;

activation means for activating the SPS receiver/processor and location transmitter; and

a power supply connected to the SPS antenna, the SPS receiver/processor, the transmitter and the transmitter interface, and the activation means, to provide operating power;

where each free-floating body is deposited approximately on a perceived boundary between the target chemical released in the water and the surface of the ambient water.

2. The apparatus of claim 1, wherein at least one of said location-indicating instruments further comprises:

a chemical analyzer, positioned on said free-floating body to be in contact with a liquid in which said body floats, that determines and issues an output signal representing the local concentration of said target chemical in this liquid, wherein said transmitter interface also receives the chemical analyzer output signal and causes said location transmitter to transmit this chemical analyzer signal at a selected transmitter frequency.

3. The apparatus of claim 1, wherein said activation means includes an immersion switch that is contained on said free-floating body and is electronically activated by immersion in water.

4. The apparatus of claim 1, wherein said activation means comprises:

an activation signal transmitter and associated power supply that transmits an SPS receiver/processor activation signal and is located on a structure near where a person or object has fallen into the water; and

an activation signal receiver, contained on said floatable object, to receive the SPS receiver/processor activation signal and to activate said SPS receiver/processor and said location transmitter in response to receipt of this activation signal.

5. The apparatus of claim 1, wherein said activation means includes a manually operable switch that, when switched to an active state, activates said SPS receiver/processor and said location transmitter, this switch being contained on said free-floating body.

6. The apparatus of claim 1, further comprising a visually perceptible flag, visually perceptible light or other visually perceptible indicia attached to said floatable object so that, when said free-floating body floats in an upright position in the water, at least a portion of the flag, light or other indicia is visible above the upper surface of the water.

7. The apparatus of claim 1, further comprising a drogue attached to said free-floating body and unfurled in the water to encourage said free-floating body to move at approximately the same velocity and in approximately the same direction as the local water current.

8. A method for determining the approximate location, on the upper surface of a body of water, of a target chemical in the water, the method comprising the steps of:

providing one or more free-floating bodies designed to be placed in and to float in an upright position on the upper surface of a body of water, with each flee-floating body containing or being attached to:

an activatable Satellite Positioning System (SPS) signal antenna and receiver/processor that, when activated, receives SPS signals from two or more SPS satellites and determines the location of the SPS antenna, the SPS receiver/processor and antenna being contained on the flee-floating body;

an activatable location transmitter and transmitter interface that, when activated, continually receives from the SPS receiver/processor a location signal representing the SPS-determined location of the SPS antenna and transmits this location signal at a selected frequency, with the transmitter and transmitter interface being contained on the flee-floating body;

activation means for activating the SPS receiver/processor and location transmitter; and

a power supply connected to at least one of the SPS antenna, the SPS receiver/processor, the transmitter, the transmitter interface and the activation means, to provide operating power; and

positioning the flee-floating body or bodies in a selected pattern in the water approximately on a perceived boundary between the target chemical released in the water and the surface of the ambient water.

9. The method of claim 8, further comprising the step of activating said SPS receiver/processor and location transmitter at the time said flee-floating body is positioned in the water.

10. The method of claim 8, further comprising the step of attaching a visually perceptible flag, visually perceptible light or other visually perceptible indicia to said free-floating body so that, when said free-floating body floats in an upright position in the water, at least a portion of the flag, light or other indicia is visible above the upper surface of the water.

11. The method of claim 8, further comprising the step of attaching a drogue to said free-floating body and unfurling the drogue in the water to encourage said free-floating body to move at approximately the same velocity and in approximately the same direction as the local water current.

12. The method of claim 8, further comprising the step of positioning a chemical analyzer on said free-floating body to be in contact with a liquid in which said free-floating body floats, that determines and issues an output signal representing the local concentration of said target chemical in this liquid, wherein said transmitter interface also receives the chemical analyzer output signal and causes said location transmitter to transmit this chemical analyzer signal at a selected transmitter frequency.

13. The apparatus of claim 7, wherein said free-floating body is not appreciably affected by local wind currents.

14. Apparatus for determining the approximate location, on the upper surface of a body of water, of a person or other object that has fallen into the water, the apparatus comprising:

a flee-floating body designed to be placed in and to float in an upright position on the upper surface of a body of water;

an activatable Satellite Positioning System (SPS) signal antenna and receiver/processor that, when activated, receives SPS signals from two or more SPS satellites and determines the location of the SPS antenna, with the SPS receiver/processor and antenna being contained on the flee-floating body;

an activatable location transmitter and transmitter interface that, when activated, continually receives from the SPS receiver/processor a location signal representing the SPS-determined location of the SPS antenna and transmits this location signal at a selected frequency, the transmitter and transmitter interface being contained on the flee-floating body;

an activation device, attached to the flee-floating body, for activating at least one of the SPS receiver/processor and location transmitter when the fleefloating body is at least partly immersed in water, the activation device comprising an immersion switch, which is activated by immersion of the switch in water and which transmits a signal that activates the location transmitter, transmitter interface and SPS receiver/processor to cause the transmitter to transmit a selected signal that includes the present location of the SPS antenna; and

a power supply connected to at least one of the SPS antenna, the SPS receiver/processor, the transmitter, the transmitter interface and the activation device, to provide operating power,

where the free-floating body is designed to be placed in the water adjacent to, but separate from, a person or other object that has fallen into the water.

15. The apparatus of claim 14, further comprising a manually operable switch that, when switched to an active state, activates at least one of said SPS receiver/processor and said location transmitter, this switch being contained in or on said free-floating body or on a structure near said free-floating body.

16. The apparatus of claim 14, further comprising a visually perceptible flag, visually perceptible light or other visually perceptible indicia attached to said free-floating body so that, when said free-floating body floats in an upright position in the water, at least a portion of the flag, light or other indicia is visible above the upper surface of the water.

17. The apparatus of claim 14, further comprising a drogue attached to said free-floating body and unfurled in the water to encourage said free-floating body to move at approximately the same velocity and in approximately the same direction as the local water current.

Description Submit all comments and votes

FIELD OF THE INVENTION

This invention relates to marine safety equipment, and more particularly to communication of the location of a person or other object that has fallen overboard, or the location of objects or of boundaries of abnormal substances in the water, using location information provided by satellites.

BACKGROUND OF THE INVENTION

Persons travelling on a boat across a body of water are exposed to the possibility of falling overboard, and of drowning, in part because of confusion or an inability to determine the present location of the overboard person. If the boat from which the person falls overboard is a small keel boat, the boat master may be able to tum the craft around within a radius of 3-10 boat lengths after first becoming aware of the mishap; in a large keel boat, the distance required to turn is much larger because of the greater inertia of the large keel boat. The upper surface of a large body of water, such as a fiver, lake, sea or ocean, is seldom flat and often manifests a sequence of peaks and troughs ("swells") that serve to hide the exposed or above-water portion of the overboard person in the water. A large body of water is often perturbed by surface current that can carry a person or object in the water in an arbitrary direction at a rate greater than 3 feet per second. In such an instance, knowledge of the point of entry into the water of the overboard person is of little help in locating the person five minutes after the overboard incident. Thus, it is often crucial to determine the present location of the overboard person so that a boat or other watercraft can quickly return to that location and search for and retrieve the overboard person. Several workers in this field have developed approaches to (1) advise the boat's occupants of the overboard incident or (2) indicate the location where the overboard incident occurred or (3) assist in retrieval of the overboard person, once that person is located.

Sunken vessel locator apparatus that operates only if the vessel is submerged is disclosed in U.S. Pat. No. 3,686,656, issued to Richards. The apparatus includes a water-responsive switch and alarm with a water-tight battery is attached to the vessel and generates a distinctive sound underwater when the switch senses that it has become submerged. The distinctive sound might be used to determine the direction from which, but not the location of, the alarm that produces the sound.

Lieb discloses an alarm system, including a portable transmitter attached to the body of a person to be monitored, that is activated upon its immersion in water, in U.S. Pat. No. 3,810,146. The transmitter issues a distinctive signal that is sensed by a nearby receiver that activates an alarm to indicate that the monitored person (for example, a non-swimmer) is immersed in water. The transmitter switch is activated by electrical bridging of two electrodes through immersion of the volume between the electrodes in water or another liquid with relatively high electrical conductivity. The alarm system does not indicate the location of the monitored person in the water.

An alarm system that operates in a similar manner to that of Lieb is disclosed by Antenore in U.S. Pat. No. 4,079,364. The alarm system is automatically released from the wearer's body upon immersion in water and floats on the top surface of the water. The alarm is received above the water.

A Man Overboard Package, allegedly arranged to provide lifesaving apparatus for a person who has fallen overboard into water from a boat, is disclosed in U.S. Pat. No. 3,886,612, issued to Schnirel et al. The Package includes a rocket and rocket launcher that carries the remainder of the apparatus (inflatable life rings, etc.) to a position adjacent to the overboard person in the water. The Package provides no means of locating the overboard person, except for a line of length at most 600 feet that is dropped between the boat and the overboard person by the rocket and launcher.

U.S. Pat. No. 4,305,143, issued to Simms et al, discloses a Man Overboard sensor and rescue system. Part of the apparatus is worn on a person's clothing and is activated by immersion in water. This part of the apparatus, when activated, emits ultrasonic waves that are carried underwater to and sensed by a receiver carried on a boat. This receiver than activates an audible alarm or visual display, indicating that a person has fallen overboard, and may also cause flotation equipment and a marker buoy to be discharged from the boat. The marker buoy may or may not be adjacent to the person overboard, and the buoy's location would have to be found by line of sight visual searching.

Man Overboard rescue apparatus for use on a sailboat is disclosed by McDonald in U.S. Pat. No. 4,343,056. After a person has fallen overboard and been located, a lifeline and attached life ring is tossed to that person, and the person is pulled to the boat by a boom structure attached to a mast on the sailboat. A similar invention, disclosed in U.S. Pat. No. 4,599,073 by Fryer et al, uses a flotation sling to lift the overboard person into the boat. Beckly, in U.S. Pat. No. 4,599,074, discloses a Man Overboard retrieval device including a boom attached to the bow or other exposed portion of a boat, to be used to reel an overboard person into the boat. U.S. Pat. No. 4,747,797, issued to Hindle, discloses Man Overboard retrieval apparatus including an inflatable ring or small boat, part of which converts to a sling to haul the overboard person out of the water and into the boat. Wilson et al, in U.S. Pat. No. 4,843,994, disclose use of a specially configured boat fender as an auxiliary float, to be thrown to a person who has fallen overboard from a boat. None of these apparati provides a means for locating the overboard person so that a boat can move to that location.

Otaka discloses a system for automatically stopping a boat when the sole crewperson on the boat falls overboard, in U.S. Pat. No. 4,630,205. The (sole) crewperson wears a radio transmitter that transmits a signal continuously at a certain intensity when that person is aboard the boat. The transmitted signal is attenuated or stops altogether when the crewperson falls overboard, and the resulting absence of signal causes the boat to stop. In another embodiment, the on-board system computes the accumulated time since the crewperson fell overboard and causes the boat to maneuver to return to the approximate location where this overboard incident occurred. The radio transmitter worn by the crewperson can transmit a rescue signal when the overboard incident occurs, but this signal contains no information on the location of the crewperson or the transmitter.

A liquid immersion switch that is activated when the switch wearer falls overboard from a boat is disclosed by Boe in U.S. Pat. No. 4,714,914. An alarm delay circuit is built in so that momentary or transitory immersion of the switch in water or another liquid will not activate the switch. The alarm signal carries no information on the location of the person overboard.

Rowland et al, in U.S. Pat. No. 4,813,025, discloses a person location and water safety system in which each person on board a boat wears a transceiver. A central station interrogates each transceiver in a fixed sequence, using both radio waves and ultrasonic waves, and each transceiver responds by a signal that is distinctive for that transceiver. The "round trip time" for the interrogation signal and response signal indicates the distance of the person wearing that transceiver from the central station. If the wearer falls overboard, the transceiver responds with a radio wave or an ultrasonic wave, according as the transceiver is above the water or submerged in water; and the central station senses and distinguishes between arrival of these two kinds of response signals. The central station uses an angie discrimination antenna to determine the direction from which the response signal arrives and uses the signal round trip time to determine approximately the location of the transceiver, and thus of the wearer. This system appears to require line of sight communication, above the water line or below the water line, between the central station and an individual transceiver. The Rowland et al patent also discusses several earlier patents that disclose water immersion alarm systems for boating safety, none of which provides adequate information on location of the alarm or the wearer in the water.

A portable military target locator using a Global Positioning System (GPS) is disclosed by Ruszkowski in U.S. Pat. No. 4,949,089. A rifle-laser rangefinder located at a known GPS position on the ground is used to determine the present location of a moving target, such as a tank on the ground, relative to the rangefinder. This information, together GPS-determined information on the rangefinder's location, is transmitted to another vehicle, such as an aircraft on a search-and-destroy mission. The rangefinder apparatus must remain at a known, fixed position and relies upon line-of-sight contact with the target.

U.S. Pat. No. 5,006,831, issued to de Solminihac, discloses positioning of an acoustic signal transmitter on the underside of a boat, for use in a Man Overboard situation. A boat occupant wears an alarm pack including an acoustic sensor. If the boat occupant falls overboard, the alarm pack receives the acoustic signal and causes, by remote control, the boat to jettison a beacon with its own signal into the water, to mark the approximate position of the person who has fallen overboard. The beacon may enter and reside in the water at some distance from the person in the water, and the beacon provides only line of sight visual information on this person's approximate location.

Stetson, in "When a crewmember falls overboard", Sail, Feb. 1993, pp. 48-54, discusses how a boat should attempt to return to the location where a crewmember has just fallen overboard, using a jib or tacking and gybing to execute a sequence of 12 steps to bring .the boat back to that location. Although a small keel boat may be able to turn and return in 3-10 boat lengths, a big keel boat typically will require much more room, and the line of sight to the overboard crewmember may be lost for some time interval. A method, other than line-of-sight contact, for keeping track of the overboard crewmember's present location in the water is not discussed.

What is needed is an approach: (1) that can instantly advise the boat's occupants that an overboard incident has occurred; (2) that can continually advise the boat's occupants of the approximate present location of the overboard person; (3) that does not require line-of-sight contact and constant vigilance in order to maintain such contact; (4) that does not require expenditure of great amounts of resources, such as electrical power, to obtain information on the present location of the person overboard; and (5) that is relatively compact and can be easily carried by a boat occupant or on a boat; (6) that can be used for measuring or indicating the location and/or rate of movement of a boundary between two dissimilar liquids, such as oil and water, on the surface of a body of water; (7) that can be used for real time studies of ocean currents, tides, or movement of other bodies of water, such as rivers; (8) that can be used to mark the present location of fishing nets that are set out on an ocean or sea and returned to at a later time; and (9) that can be extended to search-and-retrieval for overboard persons or objects using aircraft or other vessels.

SUMMARY OF THE INVENTION

These needs are met by the invention, which provides a floatable object, such as a Man Overboard Pole ("MOP") or similar apparatus, that is thrown into the water near the overboard person and that continually advises the boat's occupants of the present location of the MOP and overboard person by radio waves that do not require line-of-sight contact. The boat, or any other nearby watercraft or other structure that can respond to the incident, receives this radiowave signal on a selected channel and can return to the indicated present location of the MOP and overboard person by matching its present location with the indicated present location of the MOP. If a water current carries the overboard person away from that person's entry point into the water, the MOP will follow the same course, even if the overboard person has not reached out to grasp the MOP.

The invention combines an activatable Satellite Positioning System (SPS) signal antenna and receiver/processor and an activatable radio transmitter with a MOP so that the location of the MOP, and thus of the overboard person, can be determined without requiring sighting of a visually perceptible signal, such as a flag or a strobed light. The SPS receiver/processor and radio transmitter on the MOP would be activated before or at the time the MOP is thrown overboard to mark the approximate location where the overboard person entered the water. The boat carries a second activatable SPS signal antenna and receiver/processor and an activatable radio receiver that is tuned to the frequency band on which the radio transmitter will broadcast.

When a person falls overboard, the SPS receiver/processor and radio transmitter on the MOP are activated as the MOP is thrown overboard. Thus, electrical power is not drawn by the apparatus until the apparatus is activated for use in an overboard incident. The SPS signal receiver/processor determines the location of the SPS antenna, this location information is passed through a transmitter interface to the transmitter, and the transmitter begins to broadcast a distress signal giving the coordinates of this location. At this time, if not before, the SPS receiver/processor and radio receiver on board the boat or another nearby watercraft are activated, and the radio receiver begins to receive and display or store the SPS-determined location coordinates of the MOP. The SPS-determined location coordinates of the SPS antenna on board the boat are also found and compared with the location coordinates of the MOP broadcast by the transmitter. The boat can thus promptly rerum to the locale of the MOP and search for the person who has fallen overboard, without requiring line-of-sight contact and without assuming that the overboard person and the MOP have remained motionless in the water.

Activation of the SPS receiver/processor and location transmitter on the MOP can be implemented by (1) a water immersion switch on the MOP, (2) a manually operable switch on the MOP, (3) a radiowave activation signal of a selected frequency that is transmitted from the boat or another nearby structure, or (4) any other suitable activation instrument.

To facilitate location of the MOP itself in this locale, the MOP can optionally include a visually perceptible flag and/or strobing light. Any other boat in the vicinity of the locale where the person has fallen overboard can also participate in the search, if this second boat carries a radio receiver th