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Publication numberUS3593533 A
Publication typeGrant
Publication dateJul 20, 1971
Filing dateOct 23, 1968
Priority dateOct 23, 1968
Publication numberUS 3593533 A, US 3593533A, US-A-3593533, US3593533 A, US3593533A
InventorsLamar Washington
Original AssigneeOcean Recovery Corp Of America
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Underwater collecting and lifting device
US 3593533 A
Abstract  available in
Previous page
Next page
Claims  available in
Description  (OCR text may contain errors)

United States Patent [72] Inventor Lamar Washington 68 Rogers St.

Cambridge. Mass. 02142 1211 Appl. No. 769,843 [22] Filed Oct. 23,1968 [45] Patented July 20, 1971 [54] UNDERWATER COLLECTING AND LlFTlNG DEVICE 7 Claims, 2 Drawing Figs.

[52] US. Cl 61/69, 37/56, 73/4256, ZZZ/386.5 [51] lnt.C1 ..B63c 11/00, G01n1/14, E02f3/88 [50] Field of Search 37/54, 56, 58, 195; 61/69; 175/5,6,226; 222/3865, 216; 73/4256 [56] References Cited UNITED STATES PATENTS 687,830 12/1901 Kirk 37/56 X 813,935 2/1906 Avery, Jr. 37/56 958,615 5/1910 Fitzgerald et a1. 61/69 975,534 11/1910 King. 4, 61/69 1,097,722 5/1914 Lake 37/56 UX 2,735,589 2/1956 Milster et a1 222/3865 2,927,776 3/1960 Hildebrandt et a1 175/226 3,063,507 11/1962 ONeill et a1 37/54 UX 3,343,422 9/1967 McSmith 73/4256 3,354,659 1 H1967 Lehmann 61/69 3,367,191 211968 Richard.... 73/4256 3,369,368 2/1968 Wilson 61/69 3,415,068 12/1968 Casey, al 37/56X Primary ExaminerRobert E. Pulfrey Assistant Examiner-Clifiord D. Crowder Attorney-Kenway, Jenney & Hildreth ABSTRACT: An underwater collecting and lifting device for use in obtaining material from below the earth's surface, such as the floor of the ocean, has a first chamber for raising and lowering the device in a body of water and a second chamber for collecting the material and transporting it. A diaphragm divides the second chamber into two compartments and is movable so as to change the volumes of the two compartments inversely to each other.

PATENTEI] JUL20|97| v 3,593, 583

sum 1 OF 2 UNDERWATER COLLECTING AND LIF'IING DEVICE BACKGROUND OF THE INVENTION Many devices have been proposed or used for obtaining benthic material, i.e., materials or objects on or below the water earth interface of a large body of water such as the ocean. Commonly such devices are linked to a surface station by a cable and are limited in size and load capacities. Limitation occurs because of the fact that the cable necessary to support extremely heavy weights must have an extremely large radius. The large radius greatly complicates winding and unwinding of such cables. Even where cable radii are not severely limiting factors, limitations occur due to the complicated and costly collecting devices commonly used to obtain samples from great depths.

SUMMARY OF THE INVENTION According to the invention, an underwater collecting and lifting device for use in obtaining objects from great depths is provided. The device has means defining a first chamber adapted to be filled with water to cause lowering of the device and means defining a second chamber for collecting objects such as benthic materials by the use of a pressure differential between the second chamber and a surrounding environment. Preferably the first and second chambers are mounted on means interlinking the means defining the two chambers.

The collecting device which comprises the means defining the second chamber is preferably divided into two compartments by a diaphragm constructed and arranged to be movable so as to increase the volume of one of the compartments while simultaneously decreasing the volume of the other compartment and vice versa. The collecting device can act to collect benthic materials and other sample objects and also to aid in causing the collecting and lifting device to pass downwardly in a body of water such as the ocean.

It is a feature of this invention that the novel and advantageous collecting device can be constructed at low cost with high reliability. The collecting and lifting device of this invention can be used without attachments of any kind to the surface of the body of water in which it is operated. Large volumes of sample materials can be obtained easily permitting large scale underwater sampling and/or mining.

Preferably the collecting and lifting device acts as a hoist in that the first chamber has a predetennined volume as compared wi th the volume of the second chamber so that extremely large and/or heavy loads contained within the second chamber can be raised to the surface when the first chamber is made buoyant. Buoyancy of the fist chamber is easily accomplished by filling the first chamber with a gas which displaces the water therein. Preferably displacement of the water is automatically carried out after means interconnected with the second chamber have been activated to cause a pressure differential between compartments of the second chamber whereby one of said compartments becomes enlarged and fills with material or objects to be collected.

In the preferred embodiment, the second chamber is carried on a mounting platform so that it can be easily removed from the means defining the first chamber as is desirable in certain operations.

Accordingly, it is an important object of this invention to provide a novel and improved underwater collecting device.

Another object of this invention is to provide an underwater collecting device in accordance with the preceding object which is mounted in a collecting and lifting structure which permits ease of lowering the device to great depths and raising of said device to the surface of a large body of water.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other features and objects of the present invention will be better understood from the following description when read in conjunction with the accompanying drawings in which:

DESCRIPTION OF PREFERRED EMBODIMENTS With reference now to the drawings, a preferred embodiment of the lifting and collecting device is illustrated generally at and has a first or major sphere 11 connected to a second or minor sphere 12 by a mounting and connection means 13 on which a control means 14 is positioned.

The major sphere 11 which acts to raise and lower the device is constructed of two hemispherical sections each having mating outwardly extending annular flanges l5 and 16 hen metically sealed together by a compression O-ring or gasket 17 preferably formed of a resilient rubber material. The

sphere ll defines a chamber 18 closed to the surrounding en vironment except at orifice 21 located at the lower portion of the sphere. Valve 22 .provides an upper passagewayv 23 between the chamber and the environment. Valve 22 can be any check valve which is normally closed but can be opened when desired.'The spring-loaded valve illustrated is preferably used and is maintained in place by a conventional grommet 23a. The passageway of the valve is closed through the use of a conventional plug 24 which is firmly urged in place as pressure within the chamber 18 increases.

The minor sphere I2 is formed as is sphere ll of two identig cal rigid, structurally strong hemispherical members and 12b each carrying an annular outwardly extending flange 26 and 27 having predrilled holes for mechanical connection together. An orifice 28 is provided for connection with a pump as will be described. A collection snout comprising a pipe 29 extends outwardly from the lower hemispherical member 120 defining a passageway 30 connected with the in terior of the sphere 12. A frustoconical check valve member 31 operates to close or open passageway 30 as will be described. The check valve member 31 has an attached rod with an encircling slip ring member 310 mounted on the inside of passageway 30 which prevents it from being raised off its seat (as shown in FIG. 2) beyond a predetermined distance. Other means for limiting travel of member 31 to prevent its misalignment or displacement in chamber 37 can be used.

A pipe 32 interconnects the interior of the sphere 12 with an outlet nozzle 33. Preferably a second check valve 34 is positioned at the outlet end 33. It is preferred that the outlet end 33 extend above the uppermost portion of the upper sphere 11 since in operation in water, the device 10 will be positioned as indicated in the drawing with spheres 11 and 12 symmetrical about a vertically extending central axis. The up perrnost position of the outlet end allows ease of connecting a suitable receptacle to the device to transfer materials from the collecting sphere 12 to a surface station.

A resilient rubber diaphragm 35 has an annular outer pot tion thereof clamped between flanges 26 and 27 to seal the in side of the sphere from the surrounding environment. The diaphragm 35 is capable of resiliently moving withiit the interior of the sphere 12 to define two entirely separated compart ments 36 and 37 of variable volume. Thus when the diaphragm is in its lowermost position as shown in FIG. 2, compartment 36 is substantially nonexistent while compartment 36 occupies substantially the entire volume of the sphere 12. However, the diaphragm is capable of movement wheii pressures in compartment 37 exceed those in compartment to an uppermost position adjacent the inside of hemispherical portion 12a. In FIG. 2, a small space is shown between portioii 12b and diaphragm 35 to aid in understanding of the int/em tion. However, in the lowermost position, diaphragm 35 abuts the portion 12b and is thus supported against rupture due to excessive pressure as is the case when the diaphragm is in its uppermost position.

The mounting and connection means 13 has a disc-shaped flat, platform 40 which mounts aseries of supporting rods 4i attached thereto at first ends and engaging flanges 26 and 27 at second ends as best shown in H6. 2. Preferably rods 41 are uniformly spaced about the circumference of the sphere 12. In the preferred embodiment, four rods 41 are used although the number and size of the rods can vary. The rods 41 are anchored by bolts 43 which have underlying washers 44 and screw-threaded shanks 45 passing through the platform 40 or flanges 26, 27 screw-threaded into female threaded ends of the rods as best shown in F IG. 2. Preferably the Rods 46 are identical to rods 41 and mount the major sphere on the platform 40. In the preferred embodiment, four rods 46 are used.

Also mounted on the platform 40 is a control box 14 which is connected with the minor sphere at orifice 28 by pipe 50 and interconnected with the major sphere at orifice 20 through pipe SL The control box preferably includes a gasgenerating mechanism of any conventional type for generating gas when desired and passing it through pipe 51 into the chamber 18. The generated gas is used to remove water from the chamber 18 and render the entire lifting and collecting device buoyant.

Another part of the control box is a conventional fluid pump which is used to pump water or other fluids to or from compartment 36.

Turning now to the method of operation of this invention, the device starts its operational cycle at the interface between the atmosphere and the surface of the ocean or other body of water. Valve 22 preferably at the top of the major sphere 11 is opened and water enters through the opening 21 decreasing the buoyancy of the device [0. simultaneously, in the minor sphere 12, the upper compartment 36 is flooded through pipe 50 with water pumped from the control box. Fluids in compartment 37 are removed through end 33. The flooding results in the diaphragm 35 being distended downwardly and allows water to fill the entire minor sphere with compartment 36 encompassing substantially the entire sphere. The device 10 then starts to accelerate downwardly maintaining its position as shown in the drawing as the gravitational force overcomes the buoyant force due to the entrance of water into chamber 18 and compartment 36. The device comes to rest on the interface between the water and the ocean floor with the snout 29 in the benthic material to be collected.

A second operational phase now begins. The water inside the upper compartment 36 of the minor sphere 12 is rapidly pumped out through pipe 50 and the diaphragm 35 rises since the pressure in compartment 36 becomes lower than the pressure in compartment 37 and pipe 32. A pressure differential, between the external ocean and the minor spheres compartment 37, causes the compartment 37 to be filled with benthic material. As the benthic material rises in the snout, it opens the valve 31 whose density is preferably greater than that of the benthic material so that a self-closing system is formed when the flow of benthic material ceases. In the second operational phase, valve 34 which is preferably a conventional pressure-sensitive, normally closed valve is closed. Valve 34 is opened either manually or by a pressure differential when the pressure at the inside of pipe 32 is greater than that of the surrounding ocean.

When the minor sphere is filled so that the pressure dif ferential across valve 35 diminishes, the valve 31 closes and the entire system enters its third operational phase. After compartment 37 is filled with the benthic material, the gas generator within the control mechanism 14 is activated and forces gas to enter into the chamber 18 and displace the water contained therein to give the device 10 a net positive buoyancy. The valve 22 is closed as it can be opened only when the external pressure is greater than that inside the major sphere or it is manually opened. The locked valve 22 retains the gas and prevents its escape. Thus, when the camber 18 is filled with gas, the water therein displaced and the sphere 12 is filled substantially with the benthic material, there exists a system which has collected material from beneath the water-ocean interface and which is capable of delivering the material to the surface by positive buoyancy. The device returns quickly to the surface.

When the device 10 is ascending, certain types of benthic material may expand due to a reduction in pressure in the surrounding sea as higher levels are reached. Thus, the benthic material may flow up pipe 32. When the valve 34 is an internally activated pressure-sensitive check valve it can open and allow excess benthic material to flow over the side of the device 10. Since the major sphere 11 is open to the external ocean through opening 21, a flux exists to counteract and equalize internal and external pressures. Therefore, the structure of the device 10 is such that an increase or decrease of external pressure is no threat to the physical integrity of the system. Of course water samples or other materials can be collected by the device 10 above the water-ocean interface if desired.

Once at the surface, the benthic material collected in the collecting sphere 12 can be removed by pumping water into the compartment 36 to expand the compartment 36 while reciprocally contracting the volume of compartment 37 forcing the collected material through pipe 32 and out the end 33 into a suitable receptacle such as a land station, ship or another pipe.

Although the size, weight and dimensions of the lifting and collecting device 10 can vary greatly, the size of the sphere l l is always directly related to the size and weight of the sphere l2 and the weight of the material to be collected. Thus, the sphere 11 must be sufficiently large to create a buoyant force when the sphere 12 is filled with benthic material. The minor sphere may be only 1 foot in diameter with volume of 0.52 cubic foot of benthic material when loaded. In a larger device 10, such as one that might be used for mining materials from the ocean bed, the minor sphere 12 could for example be I00 feet in diameter with a volume of 5.2Xl0 cubic feet.

In a specific example, if we assume the benthic material to be collected to have a density of pounds per cubic foot, the minor sphere having a diameter of 100 feet would weigh about 5 X l 0 pounds or 26,200 tons. Since the purpose of the major sphere is to provide positive buoyancy to the entire device 10 when fully loaded, there is a need for a calculation of the minimum size of the major sphere which is determined as follows.

In making the calculation to determine the size of the major sphere 11, the weight of the gas used to displace the water in the major sphere must be considered. At standard temperature and atmospheric pressure conditions, the density weight of a gas is about 1.3 grams per liter. At depths of several thousand feet at which the device 10 is capable of operating, tens of atmospheres increase the pressure which compresses the gas to a density weight of a third of the density weight of water or to about 20 pounds per cubic foot.

Another factor which must be taken into account is temperature as there exists a temperature gradient between the surface and the lower interface. However, since the proportion is based on absolute (Kelvin) temperature, the factor does not vary significantly when compared to the pressure factor and can be ignored for first order approximations.

In determining the minimum size needed for a steel major sphere l 1, the following formulas and weights are used:

Volume of a sphere= Volume of a shell: (4)(1r)(1) ((AT) Weight of water=64 pounds per cubic foot Weight of benthic material 100 pounds per cubic foot.

For a minor sphere of radius of 50 feet and steel shell thickness of one-half inch (one twenty-fourth of a foot), the

buoyancy function is dependent upon the radium of the major sphere, the radius of the minor sphere having been fixed. For

this approximation, the associated equipment, including platforms, pumps, connectors, etc.. will be disregardedv Buoyancy as :1. function of radius (r) (1r) (4/3) tr) '(64-20) l-(ir) (4) (1/24) r )(64 490) -"(1r) (4/3) (50) The radius (r) should be such that B(r) is positive. For our first order approximation, 60 feet radius percent over the radius of the minor sphere) is enough for the entire system, fully loaded, to be delivered a net positive vuoyancy when the major sphere has a steel shell thickness of one-half inch.

While specific embodiments of the present invention have been shown and described, it should be understood that many variations thereof are possible. For example the spheres can be integral units rather than formed of two-part hemispheres. ln some cases, cylindrical or other shaped chambers may be used although the spherical shape is preferred to increase the strength of the chambers. During the second operational phase, the velocity of flow through the snout must be great enough to establish and maintain two-phase flow in order to take in the benthic material. Otherwise, only water will be taken into the compartment 37. The velocity of flow through the snout is a function of its cross-sectional area and of the pump capacity in gallons per minute.

The spheres are preferably made of high-strength steel materials although various other structurally strong materials can be used. It is a feature of this invention that pressures on the spheres are minimal during descent and rising since the spheres are filled with fluid when lowered and can be filled with a sample material collected (minor sphere) and a gas under pressure (major sphere) when raised. Thus, the spheres do not have to withstand high unbalanced outside pressures. Although platform 40 is provided with the specific connection means shown, other types of devices can be used to connect the spheres together. Similarly, the particular discharge pipe 32 can vary as can the snout 29 and the particular valves shown. in some cases, a mechanically operated auger can be positioned within the snout to aid in collection of benthic materials.

In some cases, it may be desirable to attach a guiding cable to the device 10 from the surface of the body of water although this is not necessary. Similarly it may sometimes be desirable to mount the control means 14 on a surface station or surface vessel and control gas generation and pumping from the surface. However, conventional pumps and gasgenerating apparatus can be used mounted directly on the platform as shown and sequenced for timed operations which can be predetermined to determine the length of time of each phase of operation of the device 10.

lt is also possible to use the collection means exemplified by the sphere 12 with other means for positioning at a site where sample objects and materials are to be collected. it is also possible to surround the device 10 above the snout 29 with a hydrodynamically shaped casing to aid in effecting lowering of the device 10 by gravity substantially along a vertical axis coincident with the axis of the snout 29.

The sphere 12 can also be used for depositing material underwater. 34 locked, chamber 37 can be filled with cement, valve 34 locked, the sphere lowered underwater, valve 3] opened by suitable means and gas or water pumped into chamber 36 to force the cement out snout 29. Alternatively, the material to be deposited can be forced out of end 33 in the device 10.

The diaphragm is preferably of rubber although any material having sufi'icient strength and resiliency can be used. in face, the diaphragm 35 need not be elastic or resilient in the sense of an ordinary rubber diaphragm. In some cases, a folded resilient or rigid plastic sheet or other means can be used as long as it is capable of being moved to vary the compartments 36 and 37 inversely proportioned to each other with the compartments being hermetically sealed.

In view of the many modifications possible, which will be apparent to those skilled in the art, this invention is to be limited only by the spirit and scope of the appended claims.

what I claim is: 1 I

l. A submergeable underwater collecting and lifting device comprising A. a first chamber having a normally closed venting valve at a nonnally uppermost end thereof and having a fluid passage at an opposite end thereof,

B. a materials collecting and storing second chamber mounted with and normally below said first chamber,

C. a diaphragm element dividing said second chamber into first and second compartments normally vertically arranged with said second compartment above said first compartment,

D. a normally closed pressure-responsive valved port for controlling the passage of material between the environment of said device and said first compartment of said second chamber, and

E. control means carried with said chambers for selectively releasing buoyant fluid to said first chamber and for selec-.

tively pumping liquid into and out of said second compartment for charging the volume of said first compartment.

2. A collecting and lifting device as defined in claim 1 further comprising overflow and evacuating port means coupled at one end thereof with said first compartment .of said second chamber and having a second end normally disposed above said one end thereof.

3. An under water collecting and lifting device as defined in claim 1 in which said venting valve opens in response to a greater pressure outside said first chamber than within it, and in which said valved port opens in response to a pressure outside said first compartment greater than the pressure within it,

4. A submergeable chambered device for carrying material in an underwater environment and for transferring material between the chamber interior thereof and the environment outside it, said device comprising A. a first chamber for controlling the buoyancy of said B. a materials transferring and storing second chamber mounted with said first chamber,

C. a diaphragm element dividing said second-chamber into first and second compartments normally of relative volumes such that there is a minimal pressure differential thereacross,

between said environment of said device and said first compartment of said second chamber in response to the pressure differential between the interior of said first compartment and said environment, and I E. control means carried with said chambers for selectively releasing buoyant fluid to said first chamber and for selectively pumping liquid into and out of said second compartment for changing the volume of said second compartment inversely relative to the volume of said first compartment. I 5. A device as defined in claim 4 in which said control means withdraws fluid from said second compartment to draw said diaphragm increasingly into said second compartment and produce a pressure differential across said valved port, thereby opening said valved port for drawing material from the environment into said first compartment.

6. A devices defined in claim 4 A. in which said valve means in said first chamber comprises a pressure-responsive valve for venting buoyant fluid from said first chamber in response to a greater pressure outside said first chamber than within it, and B. further comprising a port for passing ballast fluid between said first chamber and said environment. 7. A device as defined in claim 4 in which the volume of said first chamber more buoyant than said second chamber such that said device normally maintains an orientation in water with said first chamber above said second chamber.

(5/63) 11' r '1 r" r r 'JLLMIMC l l in CF COurihC'llON Patent No. 3 593,533 Dated July 20, 1971 Invent fl Lamar Washington It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 6 3, before "is substantially" change Column 3, line 8, delete "screw-threaded" and insert therefor -and--.

Column 3, line 9', delete "Preferably the".

Column 3, line 43, after "snout 2 9 insert --embedded--. v

Column 4, line 41, change "5xxlO to -'-5x1O Column 4, line 70, after "per cubic foot" delete "steel". I

Column line 73, "radium" should be "radius- Column 5, line 14, "vuoyancy" should be --buoyancy--.

Column 5, line 38, after "Although" insert --a--.

Column 5, line 64, delete 34 locked" and insert therefor --Thus-- I I Column 5 line 72, "faee" should be --fact--.

(5/00) W m m 1 a m (Ii-Ll? l I}: iCA. J. E O (JOEL- 13C l lON Patent; No. 3 Dated July 20 1971 Invent0r(s) Lamar Washington It is certified that: error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 6,- line 25,-"charging" should be --changing--.

Column 6', line 25, after (volume of said" insert ---second compartment invei'sely relative to the volume of said". v I l i h Column 6., line 68 -"devices should be Signed and sealed this 3rd day of October- 1972.

(SEAL) Attest:

EDWARD IKFLE'I'CHER ,JR. ROBERT GQTTSCHALK Uttestitg, Officer Commissioner of Patents J

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US687830 *May 2, 1900Dec 3, 1901J W RobertsSubmarine dredger and gold-saving machine.
US813935 *Aug 1, 1904Feb 27, 1906Thaddeus Avery JrSubmarine dredge.
US958615 *Dec 14, 1909May 17, 1910William George FitzgeraldSubmarine device for dredging and other similar purposes.
US975534 *Feb 18, 1909Nov 15, 1910Robert Owen KingMethod and apparatus for wrecking bodies sunk in water.
US1097722 *Jul 10, 1913May 26, 1914Simon LakeSubmarine dredging apparatus.
US2735589 *Jun 21, 1950Feb 21, 1956 Portable device for
US2927776 *Mar 7, 1958Mar 8, 1960Jersey Prod Res CoCoring apparatus
US3063507 *Aug 7, 1958Nov 13, 1962Neill OMethod and apparatus for offshore drilling
US3343422 *Aug 12, 1965Sep 26, 1967Dwight G McsmithPipette safety device
US3354659 *Sep 27, 1965Nov 28, 1967Wolfgang Lehmann GuentherDeep-submergence foundation vehicle
US3367191 *Oct 22, 1965Feb 6, 1968Richard Joseph DWater sampling apparatus
US3369368 *May 11, 1967Feb 20, 1968Union Carbide CorpDiving structure
US3415068 *Apr 18, 1966Dec 10, 1968Sam R. Casey Jr.Submarine device
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3722444 *Apr 20, 1971Mar 27, 1973Komatsu Mfg Co LtdStructure of under-water vehicle
US3812922 *Feb 16, 1972May 28, 1974B StechlerDeep ocean mining, mineral harvesting and salvage vehicle
US3815267 *Sep 15, 1972Jun 11, 1974Ihc Holland NvMethod and apparatus for sucking up material from the bottom of a body of water
US4041944 *Jul 21, 1975Aug 16, 1977Rhodes William ABody fluid transfusion and displacement apparatus and method
US4150503 *Jan 17, 1977Apr 24, 1979Pierre LespinasseApparatus for excavation and earth removal from aquatic bottoms
US4159692 *Oct 25, 1977Jul 3, 1979Dye Jr Wayne KMethod of submerging floatation bodies and apparatus for performing same
US4345461 *Nov 30, 1979Aug 24, 1982Lezgintsev Georgy MApparatus for taking bedrock samples from bottom of deep-water basins
US4480569 *Jan 12, 1983Nov 6, 1984Veen Abraham V DContainer for ground material removed by a ground working device from the bottom of a watercourse
US5535635 *Dec 30, 1994Jul 16, 1996Mcfarland Pump Co.Composite sample storage and measurement system
US7225690 *Jul 31, 2003Jun 5, 2007A+ Manufacturing, LlcMulti-cavity sample cylinder with integrated valving
US7555965 *Mar 14, 2007Jul 7, 2009A+ Manufacturing, LlcMulti-cavity sample cylinder with integrated valving
US20130081388 *Nov 19, 2010Apr 4, 2013Purenco AsWave powered buoyancy control system for floating wave power plants
U.S. Classification405/185, 73/864.31, 222/386.5, 37/313, 73/864.62
International ClassificationB63B22/24, E02F7/00
Cooperative ClassificationB63B2207/04, B63B2211/02, B63B22/24, B63B2207/02, E02F7/005, B63B2025/085
European ClassificationE02F7/00B, B63B22/24