United States Patent [191
`Dolengowski
`
`[11] Patent Number:
`[45] Date of Patent:
`
`4,890,568
`Jan. 2, 1990
`
`[54] STEERABLE TAIL BUOY
`(75]
`Inventor: George A. Dolengowski, Bellaire,
`Tex.
`[73] Assignee: Exxon Production Research
`Company, Houston, Tex.
`[21] Appl. No.: 236,107
`[22] Filed:
`Aug. 24, 1988
`Int. Cl.4 .............................................. B63B 21/00
`[51]
`[52) u.s. Cl ..................................... 114/246; 114/253;
`114/163
`[58] Field of Search ............... 114/162, 163, 242, 244,
`114/246, 253
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`1,717,286 6/1929 Ward ................................... 114/163
`3,125,980 3/1964 Anderson ............................ 114/235
`3,469,552 9/1969 Patrick ................................ 114/246
`3,560,912 2/1971 Spink et al ................... : ............ 340/
`3,605,674 9/1971 Weese ............................. 114/235 B
`3,710,749 1/1973 Duryea ................................ 114/163
`3,774,570 11/1973 Pearson ............................... 114/235
`3,896,756 7/1975 Pearson eta! .................. 114/235 B
`4,033,278 7/1977 Waters ................................ 114/245
`4,063,213 12/1977 Itria et al .................................. 340/
`4,087,780 5/1978 Itria eta!. ........................... 340/7 R
`4,130,078 12/1978 Cholet ................................. 114/244
`4,290,124 9/1981 Cole ...................................... 367/18
`4,323,989 4/1982 Huckabee eta! . .................. 367/181
`4,350,111 9/1982 Boyce, II ............................ 114/245
`
`4,404,664 9/1983 Zachariadis ........................... 367/19
`4,463,701 8/1984 Pickett et al ........................ 114/245
`4,506,352 3/1985 Brandsaeter eta!. ................. 367/21
`4,574,723 3/1986 Chiles eta! ......................... 114/253
`4,729,333 3/1988 Kirby eta!. ......................... 114/244
`4,763,126 8/1988 Jawetz ................................... 441/16
`
`FOREIGN PATENT DOCUMENTS
`2047406B 9/1983 United Kingdom .
`Primary Examiner-Sherman D. Basinger
`Assistant Examiner-Stephen P. Avila
`Attorney, Agent, or Firm-Sheila M. Luck
`[57]
`ABSTRACf
`A remotely controllable tail buoy• for use in marine
`geophysical prospecting operations is disclosed. The
`tail buoy is attached to the trailing end of one or more
`seismic streamers towed by the vessel. The tail buoy is
`provided with rudders that are controlled by a steering
`mechanism and communication system. The communi(cid:173)
`cation system collects and processes radio signals emit(cid:173)
`ted from a radio transmitter located on the towing ves(cid:173)
`sel. The processed signals control the steering mecha(cid:173)
`nism which includes a hydraulic pump for directing
`fluid into a hydraulic cylinder. The fluid flow rotates
`the rudders. The tail buoy will travel toward the direc(cid:173)
`tion that the rudders are turned and thus avoid hooking
`or entangling of the tail buoy on other like tail buoys or
`structures.
`
`15 Claims, 2 Drawing Sheets
`
`74
`
`10
`
`./
`
`.,/ '
`
`76
`
`~ 72A
`
`728
`
`~ 72[
`
`16
`
`I
`
`20
`
`20
`
`22A
`
`=----1'
`
`20
`J
`
`l
`
`20
`I
`};
`
`20
`)
`0
`
`<::::::;:>
`\
`24A
`
`228
`I =t'
`248
`
`22C
`I =?
`'zt.c
`
`1
`
`ION 1008
`
`

`

`00
`0'\
`Ol
`~ =
`...
`...
`....
`
`~ a
`
`N
`9,
`.........
`
`~
`
`~
`
`~ ?
`
`.........
`N
`
`~ a ~ a
`
`•
`rJ.l
`~
`
`22[
`
`24A
`
`22A
`
`~4[
`
`22[
`
`248
`
`·~
`
`228
`
`~
`
`24A
`
`22A
`
`20
`
`20
`
`LU
`
`L(J
`
`20
`
`20
`
`12[
`
`128
`
`20
`
`20
`
`12A
`
`20
`
`12[
`
`----
`
`---------=---=---~=
`
`-
`
`--
`
`20
`
`12A
`
`16
`
`24
`
`FIG.2
`
`//
`
`14
`
`c-._)
`16
`
`FIG. I
`
`2
`
`

`

`U.S. Patent
`
`Jan. 2, 1990
`
`Sheet 2 of2
`
`4,890,568
`
`F/G.3
`
`26
`
`48
`
`f
`4
`
`30
`
`32
`
`FIG.4
`
`r ·
`I
`
`60
`
`68
`\
`
`34
`
`36
`
`REHOTE
`CONTROLLER
`
`RADIO
`
`74
`
`72
`
`BATTERY
`
`"\
`
`\
`
`3
`
`

`

`1
`
`STEERABLE TAIL BUOY
`
`4,890,568
`
`FIELD OF THE INVENTION
`This invention relates generally to marine towing
`operations. More specifically, but not by way of limita(cid:173)
`tion, it relates to a steerable tail buoy for use while
`gathering marine seismic data using one or more seismic
`streamers.
`BACKGROUND OF THE INVENTION
`In recent years the search for oil and gas has moved
`offshore. In order to locate potential offshore oil and
`gas reservoirs, it has been necessary to develop new
`devices and techniques for conducting marine geophys- 15
`ical prospecting operations. Due to the hostile environ(cid:173)
`ment in which they are conducted, such operations are
`typically quite difficult and costly to perform.
`The primary method for conducting marine geophys(cid:173)
`ical prospecting operations involves the use of towable 20
`marine seismic sources and seismic receiver cables. The
`basic principles of this prospecting method are well
`known to those skilled in the art. The seismic source(s)
`introduce seismic signals into the body of water. The
`signals travel downwardly through the water, across 25
`the water-floor interface, and into the subterranean
`geological formations, and are, to some e.xtent, reflected
`by the interfaces between adjacent formations. The
`reflected signals travel upwardly through the geologi(cid:173)
`cal formations and the body of water to a seismic re- 30
`ceiver cable located near the surface of the body of
`water. The seismic receiver cable typically contains a
`number of hydrophones spaced along its length which
`record the reflected signals. Analysis of the signals
`recorded by the hydrophones can provide valuable 35
`information concerning the structure of the subterra(cid:173)
`nean geological formations and possible oil and gas
`accumulation therein.
`Seismic
`receiver cables, commonly known as
`"streamers", are usually towed below the water surface. 40
`The streamers are preferably of neutral buoyancy and
`can be balanced by filling them with a liquid having a
`specific gravity less than 1 to add flotation, or by re(cid:173)
`moving excess liquid or taping lead strips to the outer
`surfaces of the streamers to reduce flotation. As is well 45
`known to those skilled in the art, a properly balanced
`streamer should maintain approximately the same depth
`along its entire length while it is being towed. Balancing
`the streamer is often a difficult process as it is possible
`for the streamers to be 6 kilometers (3.7 miles) long or 50
`more.
`The depth of the streamers during tow is usually
`controlled by winged devices known as "birds" which
`are attached to the streamers typically every 300 to 500
`meters (about 1000 to 1600 feet). The birds are provided 55
`with remote depth controls which enable them to main(cid:173)
`tain the streamer at a uniform running depth or to raise
`or lower the streamer. A typical bird looks like a tor(cid:173)
`pedo, being about 0.6 meters (2 feet) long, with two
`short winglike fms. It usually separates into halves, 60
`along its length, and is hinged on one side so that it can
`be opened and clamped onto the cable. One example of
`a bird is described in U.S. Pat. No. 3,605,674 which
`issued on Sept. 20, 1971 to Weese.
`At the trailing end of the streamer, away from the 65
`vessel, a tail buoy is attached to the streamer, typically
`by a rope. The tail buoy enables the vessel operators to
`determine and mark the approximate location of the end
`
`2
`of the streamer. It also serves as a warning device for
`other vessel operators to indicate that a streamer is
`being towed. The tail buoy is usually a catamaran raft
`provided with tubular floats, lights and radar reflectors.
`5 The rope, which may range in length from 30 to 300
`meters (about 100 to 1000 feet), allows the tail buoy to
`float on the surface of the water without raising the
`trailing end of the streamer.
`In recent years, it has become feasible to tow a plural-
`to ity of streamers, laterally spaced apart, behind a single
`vessel. As a result, a greater survey area may be cov(cid:173)
`ered in a shorter period of time, resulting in a lower
`overall survey cost. When a plurality of streamers are
`towed behind a single vessel, paravanes, being attached
`to the lead end of each streamer, are often used to later(cid:173)
`ally seperate the lead end of each streamer. One exam-
`ple of a paravane is described in U.S. Pat. No. 4,463,701
`which issued Aug. 7, 1984 to Pickett, et al. A remotely
`controlled paravane is disclosed in U.S. Pat. No.
`4,729,333 which issued Mar. 8, 1988 to Kirby, et al.
`A particular difficulty has arisen when towing a plu(cid:173)
`rality of streamers. In routine turns, all streamers nor(cid:173)
`mally tow in concentric circles. However during de(cid:173)
`ployment or repair of the streamers or in non-routine
`turns such as slow speed turns or sharp turns, it is ·com(cid:173)
`mon for the streamers to cross and become tangled. It is
`possible to prevent entanglement of the streamers by
`diving one streamer while surfacing the other with the
`aid of the remotely controllable birds. Although this
`keeps the streamers from tangling, the tail buoys, which
`at all times remain on the water's surface, are likely to
`cross and become hooked, or the ropes that connect the
`buoys to the streamers may become tangled. Unhooking
`the tail buoys or untangling the ropes requires the use of
`a small auxiliary boat, if available. Otherwise, the
`streamers and ropes must be reeled toward the vessel to
`be untangled by the vessel operators.
`Another difficulty arises when data is being collected
`near an offshore structure. As one or mor!! streamers are
`towed behind a vessel, the wind and water current may
`cause the trailing end of the streamer to feather out-
`wardly from the vessel's path. If data is being collected
`along a path near an offshore structure, the wind and
`current may push the streamer and tail buoy into the
`structure. As a result the buoy or the streamer may
`become damaged or they may become hooked to the
`structure.
`Accordingly, in marine seismic exploration the need
`exists for a remotely controllable tail buoy which can be
`attached to a seismic streamer so as to indicate the ap(cid:173)
`proximate location of the trailing end of the streamer,
`and which can be remotely steered away from other tail
`buoys attached to other streamers or from offshore
`structures and other obstructions in order to prevent
`~angling of the tail buoys or damage to the tail buoys or
`streamers.
`
`SUMMARY OF THE INVENTION
`The present invention is a remotely controllable tail
`buoy that may be directed from a remote location such
`as from a towing vessel to prevent damage to the tail
`buoys, hooking of the tail buoys or tangling of the ropes
`when one or more streamers are being towed by the
`towing vessel. Additionally, the inventive tail buoy may
`be used when towing one or more streamers to direct
`the trailing ends of the streamers away from offshore
`
`4
`
`

`

`4,890,568
`
`3
`structures or other obstructions which could damage
`the streamers.
`In a preferred embodiment, the tail buoy is provided
`with two or more rudders, a steering mechanism and a
`communication system. The rudders are adapted to 5
`rotate substantially simultaneously about generally ver(cid:173)
`tical axes to control the course of the tail buoy. The
`rotation of the rudders are controlled by the steering
`mechanism and the communication system. The steer(cid:173)
`ing mechanism controls the rudder position based on 10
`signals received by the communication system from a
`remote transmitter on the vessel. The communication
`system includes a two-way radio receiver tuned to the
`same frequency as the remote transmitter for receiving
`radio signals emitted from the remote transmitter. The 15
`signals are processed by a remote controller which is
`preferably a microprocessor-based controller and data
`acquisition system. The processed signals control the
`steering mechanism which includes a hydraulic pump.
`The pump directs flow to a hydraulic cylinder causing 20
`the rudders to turn. Then, as the vessel continues to
`move, the tail buoy will travel toward the direction that
`the rudders are turned thereby avoiding other tail buoys
`or offshore structures.
`The tail buoy design preferably includes a single 25
`tubular float and an anti-roll weight. The tubular float
`provides all necessary buoyancy for the tail buoy while
`the anti-roll weight keeps the buoy in an upright or
`vertical position. This design lessens the probability that
`the tail buoys will hook if one buoy floats into another's 30
`path.
`The steerable tail buoy of the present invention may
`include additional peripheral equipment such as rudder
`position sensors, relative positioning instrumentation
`and navigational instrumentation. The navigational in- 35
`strumentation may be acoustic based, radio based or
`optical based instrumentation. Data from these sensors
`and instruments may be continuously transmitted to the
`vessel and fed into a computer located on board the
`vessel. The computer would continuously monitor the 40
`precise location of the tail buoy and initiate any neces(cid:173)
`sary actions to adjust the course of the tail buoy.
`DESCRIPTION OF THE DRAWINGS
`The actual operation and advantages of the present 45
`invention will be better understood by referring to the
`following detailed description and the attached draw(cid:173)
`ings in which:
`FIG. 1 is a plan view of a vessel towing three stream(cid:173)
`ers with the inventive tail buoys attached to ends of the 50
`streamers.
`FIG. 2 is a side view of a vessel towing two stream(cid:173)
`ers, illustrating that one streamer has been lowered to
`avoid entanglement with the other streamer during a
`repair operation and the other streamer has been raised 55
`to the surface of the water.
`FIG. 3 is a perspective view of the inventive tail
`buoy.
`FIG. 4 is an internal diagram along line 4--4 of FIG.
`3 which illustrates a preferred embodiment of the tail 60
`buoy's st~ering mechanism, communication system and
`power source.
`While the invention will be described in connection
`with the preferred embodiments, it will be understood
`that the invention is not limited thereto. On the con- 65
`trary, it is intended to cover all alternatives, modifica(cid:173)
`tions, and equivalents which may be included within the
`spirit and scope of the invention.
`
`4
`DESCRIPTION OF THE PREFERRED
`EMBODIMENT
`FIG. 1 illustrates a plan view of vessel 10 which is
`moving in the direction of the arrow and is towing three
`streamers 12A, 12B, and 12C in a body of water 14. In
`normal operation, streamers 12A, 12B, and 12C are
`towed at a constant depth of approximately 3 to 15
`meters (10-50 feet) below the surface of water 14. Outer
`streamers 12A and 12C are maintained separated later(cid:173)
`ally from .streamer 12B by paravanes 16. The total dis(cid:173)
`tance between streamers 12A, 12B, and 12C can be
`varied from approximately 50-300 meters (160-1000
`feet). For illustration purposes only, seismic source 18 is
`shown directly behind vessel 10. The most common
`seismic source used today is an air gun array. Other
`seismic sources include water guns, explosive gas guns,
`steam, small explosives and marine vibrators. Spaced
`along the length of each streamer 12A, 12B, and 12C are
`remotely controllable birds 20. Birds 20 are typically
`used to control the depth of streamers 12A, 12B, and
`12C. However, as illustrated in U.S. Pat. No. 3,605,675
`to Weese, birds 20 also have been designed to control,
`although to a limited extent, lateral movement of
`streamers 12A, 12B, and 12C. At the far end of stream(cid:173)
`ers 12A, 12B, and 12C, attached by ropes 22A, 22B, and
`22C, are the inventive tail buoys 24A, 24B, and 24C
`disclosed herein. Tail buoys 24A, 24B, and 24C are used
`to indicate the approximate location of the ends of
`streamers 12A, 12B, and 12C and warn boat operators
`and others that one or more streamers are being towed.
`FIG. 2 illustrates the particular problem to be solved
`by steerable tail buoy 24 of the present invention. For
`purposes of simplification, streamer 12B and seismic
`source 18 are not included in FIG. 2. During a repair
`operation using an auxiliary boat (not shown), to avoid
`tangling of streamers 12A and 12C, streamer 12A is
`raised to or near the surface of water 14 and streamer
`12C is lowered by about 18 to 30 meters (60-100 feet) by
`birds 20. As the repairs are being made, streamers 12A
`and 12C may cross paths due to wind or surface cur(cid:173)
`rents but they will not tangle due to vertical separation.
`However, since tail buoys 24A and 24C remain on the
`surface of water, they may hit one another, become
`hooked, or ropes 22A and 22C may tangle.
`FIG. 3 illustrates a perspective view of a preferred
`embodiment of steerable tail buoy 24. The major com(cid:173)
`ponents shown include tubular float 26, frame 28, anti(cid:173)
`roll weight 34, actuator housing 36, rudders 38, mast 40
`with light 42 and radar reflector 44, tow bridle 46 and
`solar panel 48, if desired. Float 26 provides sufficient
`buoyancy to maintain tail buoy 24 on the surface of
`body of water 14 during operation. Preferably the buoy(cid:173)
`ancy is provided by one tubular float 26, rather than a
`plurality of floats in order to reduce the possibility of
`one tail buoy getting hooked to another by reducing the
`number of components on the tail buoy. Float 26 should
`be designed to provide low drag when towed while
`maintaining adequate hydrodynamic stability. Many
`designs are feasible, however a cylindrical float with
`hemispherical ends may be preferred. Frame 28 is at(cid:173)
`tached to the bottom of float 26 by one or more support
`legs 30. Support legs 30 extend downwardly from float
`26 and attach to base plate 32. Attached to base plate 32
`is anti-roll weight 34 which reduces rolling of tail buoy
`24 due to rudder lift or sea state. Anti-roll weight 34 can
`be a lead pipe or any other object of sufficient weight to
`reduce rolling of tail buoy 24. The weight tends to
`
`5
`
`

`

`4,890,568
`
`5
`lower the center of gravity, reducing rolling in a man(cid:173)
`ner similar to ballast in a ship's keel. If a plurality of
`floats are used, anti-roll weight 34 may not be needed.
`Actuator housing 36, being attached to the bottom of
`float 26, contains the tail buoy steering mechanism and 5
`communication system which will be further described
`in connection with FIG. 4. Rudders 38 are substantially
`vertical, wing-shaped plates of either uniform or vaned
`size and shape. Although any number of rudders may be
`used, a preferred embodiment has at least two rudders 10
`to allow tail buoy 24 to move laterally while continuing
`to face the general towing direction of vessel10. Rud(cid:173)
`ders 38 are connected to tail buoy 24 by rudder shafts
`50. In a preferred embodiment rudder shafts 50 extend
`vertically through rudders 38 and upwardly into actua- 15
`tor housing 36, where they are fixedly attached to tiller
`arms 52 (see FIG. 4). In a preferred embodiment, the
`lower end of rudders shafts 50 are rotatably attached to
`base plate 32 of frame 28 for added strength to prevent
`shafts 50 from twisting or bending. Rudders 38 are fixed 20
`to rudder shafts 50 so that rotation of the rudder shafts
`50 will rotate the rudders 38. Alternatively, rudder
`shafts 50 and rudders 38 may be integrated into single
`components, each component forming one shaft 50 and
`one rudder 38. The angular position of rudders 38 is 25
`controlled by the steering mechanism (see FIG. 4)
`which is in actuator housing 36. Connected to mast 40 is
`light 42, radar reflector 44 and radio antenna 76. Light
`42 aids in visual detection of tail buoy 24; radar reflector
`44 aids in radar detection of tail buoy 24; and radio 30
`antenna 76 (further described with FIG. 4) receives and
`transmits signals from vessel10 or from another remote
`location. Tow bridle 46 is the connection on which to
`tie rope 22. In a preferred embodiment as illustrated in
`FIG. 3, one end of tow bridle 46 is attached to frame 28 35
`near actuator housing 36 and the other end is attached
`near anti-roll weight 29. This connection will provide
`towing stability particularly when tail buoy 24 is pro(cid:173)
`vided with a single tubular float 26. Tow bridle 46 may
`be made of any suitable shape and material, including 40
`flexible material such as a rope or chain, having suffi(cid:173)
`cient strength to tow buoy 24 without breaking. Solar
`panel 48 is an optional device intended to supplement
`battery 78 (see FIG. 4) through the utilization of solar
`energy. The output of solar panel48 is related to avail- 45
`able sunlight and therefore is dependent on the time of
`day and weather. Marine worthy solar panels are com(cid:173)
`mercially well known and will not be further described.
`Actuator housing 36 is sealed against water penetra(cid:173)
`tion. Within actuator housing 36 is the steering mecha- 50
`nism for turning rudders 38, the communication system
`which provides a communication link between opera(cid:173)
`tors on vessel10 and tail buoy 24, and battery 78 which
`supplies the necessary power to run the communication
`system and the steering mechanism. FIG. 4 illustrates a 55
`preferred embodiment of the elements within actuator
`housing 36.
`Referring to FIG. 4, the steering mechanism in a
`preferred embodiment includes tiller arms 52, connect(cid:173)
`ing rod 66, hydraulic cylinder 62 with piston rod 68, 60
`hydraulic pump 58 with flexible fluid conduits 60, and
`motor 56. FIG. 4 illustrates four tiller arms for purposes
`of illustration; however, it will be understood that there
`is one tiller arm for each rudder 38. Tiller arms 52 are
`generally elongated and are connected to rudder shafts 65
`50. Opposite the connection to rudder shafts 50, tiller
`arms 52 are pivotally attached to connecting rod 66 in
`series. As connecting rod 66 moves, tiller arms 52 will
`
`6
`simultaneously rotate rudder shafts 50, thereby causing
`rudders 38 to rotate simultaneously.
`Connecting rod 66 may be moved in a number of
`ways. In a preferred embodiment, as illustrated in FIG.
`4, hydraulics are used. Receiving electrical power from
`battery 78, motor 56 powers hydraulic pump 58. Hy(cid:173)
`draulic pump 58 directs hydraulic fluid (not shown)
`through one of the fluid conduits 60 into hydraulic
`cylinder 62 which is pivotally mounted on one end 64 to
`actuator housing 36. The pressure of the hydraulic fluid
`in cylinder 62 causes piston rod 68 to move. Piston rod
`68 is pivotally attached to extension 54 on one of the
`tiller arms 52 opposite the connection to connecting rod
`66. As piston rod 68 moves, it causes tiller arm 52 to
`rotate about the axis of rudder shaft 50 and move con(cid:173)
`necting rod 66. This results in simultaneous rotation of
`rudder shafts 50 and rudders 38. Fluid conduits 60 are
`constructed using a flexible material or joints 70.
`Motor 56 is preferably a low voltage (12 volt for
`example) reversible DC motor. Battery 78 may be sup(cid:173)
`plemented or recharged by solar panel 48 (see FIG. 3).
`Pump 58 may be a bidirectional pump which works in
`combination with an internally piloted, double check
`valve (not shown). Pump 58 is capable of pumping the
`hydraulic fluid into either side of hydraulic cylinder 62
`through fluid conduits 60. The double check valve
`hydraulically locks rudders 38 into place when pump 58
`is turned off. When pump 58 is turned on, cracking
`pressures of the check valve are overcome allowing
`fluid to flow, thereby affecting rotation of rudders 38.
`As an alternative, pump 58 may be a non-reversable
`pump where hydraulic fluid flow may be directed into
`either side of hydraulic cylinder 62 by using a solenoid(cid:173)
`operated, normally closed, 4-way, 3-position control
`valve (not shown). As a second alternative, rotation of
`rudders 38 could be achieved by using an electro(cid:173)
`mechanical push-pull actuator (not shown). If used, the
`electric actuator would replace hydraulic cylinder 62,
`the control valve (if used), and pump 58. However, due
`to low mechanical efficiency, the electric push-pull
`actuator will result in high power consumption. Other
`methods for actuating the rudders will be apparent to
`those skilled in the art.
`The tail buoy communication system includes radio
`72, remote controller 14 and antenna 76 (see FIG. 3). In
`a preferred embodiment radio 72 is a two-way radio
`capable of sending and receiving signals transmitted
`through antenna 76 over radio waves. Remote control(cid:173)
`ler 74 is a microprocessor-based controller and data
`acquisition system, such as Motorola's microprocessor,
`Model 6805. It decodes and executes commands trans(cid:173)
`mitted to radio 72 over radio waves from a two-way
`radio (not shown) by a master controller (not shown),
`each being on vessel 10. In addition, remote controller
`74 regulates the average charge rate of battery 78 by
`automatically switching solar panel 48 (see FIG. 3) on
`or off as needed. TypicallY, the communication system is
`contained within actuator housing 36, however antenna
`76 may extend outside actuator housing 36 (see FIG. 3)
`for improved reception.
`The communication equipment (not shown) on vessel
`10 includes a two-way radio, an antenna, a master con(cid:173)
`troller, a CRT screen and a power source. The two-way
`radio on vessel 10 is preferably capable of transmitting
`and receiving signals through the vessel antenna to and
`from radio 72 on tail buoy 24. The signals received by
`the vessel radio on vessel 10 are input to the master
`controller which analyzes the signals received and dis-
`
`6
`
`

`

`4,890,568
`
`35
`
`7
`plays the status of tail buoy 24 on the CRT screen. In a
`preferred embodiment, the master controller is a porta(cid:173)
`ble personal computer.
`To summarize, if the vessel operator determines that
`the location of tail buoy 24 relative to other buoys or 5
`offshore structures is not acceptable, the vessel operator
`initiates a rudder change command by requesting a new
`rudder setting through signals transmitted from the
`vessel radio to radio 72 on tail buoy 24. When a rudder
`change command is received by radio 72, such com- 10
`mands are electronically input to remote controller 74.
`Remote controller 74 executes the command by turning
`on motor 56. Motor 56 supplies operating power to
`hydraulic pump 58. Pump 58 directs hydraulic fluid into
`hydraulic cylinder 62 causing piston rod 68 to move, 15
`thereby moving rod 66 from side to side. Such move(cid:173)
`ment causes tiller arms 52 to turn rudders 38. Changing
`the direction of rudders 38 will cause tail buoy 24 to
`move in a new direction, thereby changing the location
`of tail buoy 24 relative to other tail buoys or offshore 20
`structures. A feed-back system (not shown) capable of
`reading the rudder position, measured in degrees, pro(cid:173)
`vides rudder position data to remote controller 74
`which turns motor 56 off after the new rudder setting is
`reached. Remote controller 74 confums that all rudder 25
`changes are executed by signaling back through radio
`72 and the vessel radio to the master controller a confir(cid:173)
`mation after the change is complete. In addition, remote
`controller 74 may periodically update the vessel opera(cid:173)
`tors through the master controller and the CRT screen 30
`on the following data regarding tail buoy 24: rudder
`position, battery voltage, battery current, solar panel
`voltage, solar panel current, motor current, electronic
`reference voltage, sea water intrusion, and hydraulic
`line pressures from pressure transducers (not shown).
`The present invention and the best modes contem(cid:173)
`plated for practicing the invention have been described.
`It should be understood that the invention is not to be
`unduly limited to the foregoing which has been set forth
`for illustrative purposes. Various modifications and 40
`alternatives of the invention will be apparent to those
`skilled in the art without departing from the true scope
`of the invention. Accordingly, the invention is to be
`limited only by the scope of the appended claims.
`What I claim is:
`1. A remotely controllable tail buoy for use in marine
`towing operations, said tail buoy being attached to an
`object being towed by a vessel in a body of water so as
`to indicate the approximate location of said object, said
`tail buoy comprising:
`a buoyant float;
`at least two substantially vertical and substantially
`parallel rudders each rotatably attached by a shaft
`to said buoyant float and extending generally
`downwardly into said body of water;
`a communication system adapted to receive and de(cid:173)
`code signals transmitted from said vessel; and
`a steering mechanism being electrically attached to
`said communication system and operatively at(cid:173)
`tached to said shafts so that said steering mecha- 60
`nism will respond to said signals that are received
`and decoded by said communication system by
`simultaneously rotating said shafts, thereby shifting
`the angular orientation of said rudders relative to
`the course of said vessel causing said tail buoy to 65
`change directions.
`2. The tail buoy of claim 1 further comprising an
`anti-roll weight attached to said buoyant float and gen-
`
`8
`erally positioned below said buoyant float in said body
`of water, said anti-roll weight having sufficient weight
`to reduce rolling of said buoy.
`3. The tail buoy of claim 1 further comprising a
`power source capable of providing sufficient electrical
`power to operate said communication system and said
`steering mechanism, said power source being electri(cid:173)
`cally connected to said communication system and said
`steering mechanism.
`4. The tail buoy of claim 1 wherein said steering
`mechanism shifts said angular orientation of said rud(cid:173)
`ders hydraulically.
`5. A remotely controllable tail buoy for use in marine
`towing operations to indicate the approximate location
`of an object being towed in a body of water by a vessel
`having a vessel communication system, said tail buoy
`being attached to said object by a rope, said tail buoy
`comprising:
`a buoyant float;
`at least two substantially vertical and substantially
`parallel rudders each rotatably attached by a shaft
`to said buoyant float and extending generally
`downwardly into said body of water in such a
`manner that said rudders will control the course of
`said tail buoy, said rudders being adapted to be
`simultaneously rotatable about said shafts;
`a buoy communication system capable of receiving
`and decoding signals transmitted from said vessel
`communication system;
`a steering mechanism being electrically attached to
`said buoy CO!fiillUnication system and operatively
`attached to said shafts so that said steering mecha(cid:173)
`nism will respond to said signals received and de-
`coded from said vessel communication system by
`simultaneously rotating said shafts, thereby shifting
`the angular orientation of said rudders relative to
`the course of said vessel causing said tail buoy to
`change directions; and
`a power source capable of providing sufficient elec(cid:173)
`trical power to operate said communication system
`and said steering mechanism, said power source
`being electrically connected to said communica(cid:173)
`tion system and said steering mechanism.
`6. The tail buoy of claim 5 wherein said steering
`mechanism controls said rotation of said rudders hy(cid:173)
`draulically.
`7. The tail buoy of claim 5 wherein said power source
`comprises a battery.
`8. The tail buoy of claim 7 wherein said power source
`further comprises a solar panel mounted on the upper
`surface of said buoyant float and adapted to supplement
`the electrical power provided by said battery.
`9. The tail buoy of claim 5 wherein said buoy commu-
`55 nication system comprises:
`a radio receiver adapted to receive signals over radio
`waves transmitted from said vessel communication
`system; and
`a microprocessor-based controller electrically at(cid:173)
`tached to said radio receiver, said microprocessor(cid:173)
`based controller being capable of decoding said
`signals received by said radio receiver into com(cid:173)
`mands and causing said commands to be executed
`by said steering mechanism to control and adjust
`the angular position of said rudders.
`10. The tail buoy of claim 5 further comprising an
`anti-roll weight attached to said buoyant float and gen(cid:173)
`erally positioned below said buoyant float in said body
`
`45
`
`50
`
`7
`
`

`

`4,890,568
`
`9
`of water, said anti-roll weight having sufficient weight
`to reduce rolling of said buoyant buoy.
`11. A remotely controllable tail buoy for use in ma(cid:173)
`rine towing operations, said tail buoy being attached by
`a rope to an object being towed by a vessel in a body of 5
`water so as to indicate the approximate location of