US3789445A

US3789445A - Buoy construction

Info

Publication number: US3789445A
Application number: US00198138A
Authority: US
Inventors: L Frazier
Original assignee: US Department of Navy
Current assignee: US Department of Navy
Priority date: 1971-11-12
Filing date: 1971-11-12
Publication date: 1974-02-05
Anticipated expiration: 1991-02-05

Abstract

A vertically disposed tube having valves at each end and suspended in the ocean for the purpose of creating dynamic system stability. When the valves are closed, water is trapped in the tube and forms a large mass which is added to the system. If both valves are open, water flows freely through the tube with no vertical stability added to the system.

Description

United States Patent 1191 Frazier Feb. 5, 1974 BUOY CONSTRUCTION 3,092,852 5/1963 Devereaux 9/8 R 3,434,422 3/1969 Mannin 9/8 P [75] invent: Vane Ventura, 3,521,594 7/1970 Field et al 114/125 Cahf' 3,464,071 9/1969 Starratt 9/8 R [73] Assignee: The United States of America as 2586828 2/1952 Keeran 9/8 R 3,029,767 4/1962 Donnan 114/121 "epresemed by the Secretary the 3 711 821 1/1973 Dale 9/8 R x Navy, Washington, DC.

[22] Filed: Nov. 12, 1971 Primary Examiner-George E. A. Halvosa Assistant ExaminerGregory W. O'Connor [2]] Appl' l98138 Attorney, Agent, or Firm-Richard S. Sciascia; J. M.

St. Amand [52] US. Cl. 9/8 R, 114/125 [51] Int. Cl B631) 21/52 57 ABSTRACT [58] Field of Search... 9/8 R, 8 P; 114/0.5 T, 0.5 R,

, A vertically disposed tube having valves at each end 114/125, 12l,6l/46.5

and suspended 1n the ocean for the purpose of creat- [561 CM 135551 1 33323551; 111; m in lrfil i 11?; UNITED STATES PATENTS mass which is added to the system. If both valves are 3,512,493 5/1970 Hallanger 9/8 R open water flows freely through the tube n0 ver- 3,299,398 1/1967 Hersey et a1. 9/8 R tica] Stability added to the System 3,377,810 4/1968 Crumley 61/465 X 3,191,202 6/1965 Handler 9/8 R 2 Claims, 4 Drawing Figures Patented Feb. 5, 1974 F ig.

BUOY CONSTRUCTION BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates in general to buoy systems and more particularly to systems for imparting dynamic stability to oceanographic data gathering devices and the like.

2. Description of the Prior Art In the specific concept of imparting dynamic stability to oceanographic data gathering systems which must of necessity remain substantially as placed for considerable periods of time, there is little relative information set forth in the prior art. There is in fact no suitable art relating to the particular structural arrangement of the present invention. The sketchy information that is available relates to devices that would either add excessive weight to the system and have only fair reliability during actual use or large plates, called damping plates, mounted in a horizontal position at right angles to the lower end of a vertically suspended cable have been used extensively in this connection. Large flat plates, when deployed in situ, have a virtual water mass associated with the dynamics of the plates motion and associated medium Reynolds number. Vertical retrieval of such plates is difficult if rapid recovery is desired. Helicopter retrieval was anticipated for the system employing the vertical tube described herein. Horizontal flat plates cannot be recovered in a normal helicopter recovery operation.

SUMMARY OF THE INVENTION The invention comprises a vertically disposed tube suspended at a particular depth to impart dynamic stability to oceanographieal data gathering systems or the like. The tube has valves at each end and when in the closed position, the entrapped water forms a large mass added to the system which resists transverse movement. However, when both valves are open, water flows freely into and out of the tube imparting no vertical mass or stability to the system. Moreover, when the valves are open the device may be easily retrieved with little weight added to the system.

OBJECTS OF THE INVENTION It is an object of the present invention to provide dynamic stability to oceanographical data gathering systems by attaching a large mass thereto and suspending the same at a particular depth.

Another object of the present invention is to provide apparatus attached to a floating structure which creates mass and hence stability at a particular depth but which adds little out of water weight to the structure.

Still another object is to provide apparatus which adds dynamic stability to oceanographic data gathering devices and is both easy to fabricate and reliable in operation.

Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings wherein:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view showing the invention suspended in position below a structure floating on the ocean with a line extending below the device to data gathering equipment not shown.

FIG. 2 is an enlarged elevational view showing the invention with the valves at both ends in closed and open position.

FIG. 3 is a plan view taken along line 3-3 of FIG. 2.

FIG. 4 is an elevational view of the invention showing the bails at both ends.

DESCRIPTION OF THE PREFERRED EMBODIMENT The cylindrical buoy 12 in FIG. 1 has a certain crosssectional area, A, and a certain length, 1, below the water line. The length, 1, depends on displacement of the mass, m, its weight, and the displacement and weight of the float. While the effects of the cable are not necessarily negligible they have been neglected in order to simplify this analysis.

The buoyant force, F,,, is the area, A, time 1 times the density of sea water, 'y minus the weight of the buoy, W,,, which is the density of the buoy, 7 times the buoy volume, or: F,, Al'y W,,.

The force, Fm, due to the mass, m, is mg minus the mass volume times the density of sea water 7 for the particular depth, or

' l We know that F,, F for equilibrium.

It is not the intent here to expound the physics of the system at length; however, the system behaves dynamically like a classical spring mass system. That is, the restoring force is proportional to the displacement distance.

If a wave front passes the buoy, the additional submerged length of buoy, Al, times the area, A, times y causes a small force, AF, to pull upward on the buoymass system, or

AF AAl'y As Al varies for the same A and 'y,,. the force, AF, varres.

The force AF may also be expressed as a hydrostatic pressure head change acting on the lower surface of the buoy. For simplification of presentation the AF attributable to the Archimedean principle of additional submerged volume was used.

If all of the water drag forces and mass inertial forces are considered, as they affect the systems motion, a second order differential equation may be written, describing that motion.

Wherein X is equivalent to distance, is the first derivative of X with respect to time, and X is the second derivative of X with respect to time. Each of the co'efficients, A, B, C and D are defined by the systems physical parameters and the parameters of the environment to which the system is subjected; in this case the environment being the ocean.

The effects of the various physical properties affecting the systems motion may be separated and studied individually.

The coefficient, A, defines the system's behavior as a function of changes in velocity. in other words, A is the acceleration coefficient and is mass dependent.

The coefficient, B, defines the systems behavior as a function of position change with time. In other words, B is the velocity coefficient and is drag dependent.

The coefficient, C, defines the systems behavior as a function of position. in other words, C is the position coefficient and is dependent on system stiffness.

The coefficient, D, defines the amplitude behavior of the forcing function. This function is dependent on the surface wave action in this case. However, for other forces of interest there are appropriate terms which may be inserted in an equation to define the system response to these other forces.

With increases in overall system weight, D generally increases. A way to get around this D-to-weight dependence is to increase the length of the buoy and change the buoy diameter. The enclosed area of the buoy which cuts the waters surface (wetted area) has the most effect on system response to surface wave action of any of the system parameters. As a system becomes large, the length of the buoy must become extreme if the wetted area is to be maintained. Ideally this approach is all right; however, practically it is very difficult and expensive to deploy, retrieve, and maintain.

The present invention was devised as a means of overcoming all of the aforme'ntioned obstacles.

Referring to the drawings there is shown a buoyant body floating on the ocean surface. A cylindrical buoy l2 mounting a transmitter 14 is positioned at a shallow depth below the buoyant body 10 and a tube 16 is vertically disposed at a particular depth below the body 10. The tube is the portion of the system which imparts dynamic stability thereto. A support cable 18 connects the buoyant body 10 to the cylindrical buoy l2 and to the tube 16. From the latter a separate cable 19 supports oceanographical equipment or the like used in obtaining data. it will be noted that buoyancy is added to cable 18 by the floats 20 a, b, c, d and to cable 19 by floats 21 a, b, c, d and by large float 22. An electric line 24 is attached to buoyant body 10, and to transmitter 14 as well as buoy l2, tube 16 and the oceanographical equipment not illustrated. Line 24 is the means of gathering data on the ocean floor or at specified depths.

As stated above tube 16 is the means of imparting stability to the system. It includes

valve end closures

26 and 28 mounted at each end of the tube 16 and preferably of the butterfly variety. The valves may be of any suitable type but are preferably of the butterfly variety and are swivel mounted by the

support element

30 and 32 respectively and have the weights 34 attached on one under side thereof to force the valves to an open position when released from the closed position.

It will be noted that the upper valve end closure 26 is held in the closed position by a latch 36 attached at the upper end of vertical rod 38 and is adapted to have one end hook around pin 42 located on the upper surface of the valve end closure 26. The opposite end of latch 36 is attached to rod 44 which is designed to operate in and out of solenoid 46. The vertical rod 38 is positioned in

mounts

48, 50, S2 and 54 and is operatively attached to latch 56 which in the closed position is hooked around the adjacent pin 58 located on the under surface of valve end closure 28. Thus when the solenoid 46 is operated, the rod 44 rotates both latch 36 and rod 38 which releases valve end closure 26. Rod 38 when rotated also rotates latch 56 attached to the lower end thereof out of engagement with pin 58 and releases valve end closure 28.

It is stressed that other methods of opening the

valve end closures

26 and 28 may be employed in place of the solenoid and

rod

46 and 44 arrangement as defined herein.

A pair of

balls

60 and 62 are connected to the top of tube 16 and an equivalent pair of

bails

64 and 66 are also attached to the bottom of said tube 16 substantially as shown in FIG. 4. The support cable 18 is in turn connected to

bails

60 and 62 at the top of tube 16 whereas cable 19 is connected to

bails

64 and 66.

Thus it is clear that when the

valves

26 and 28 are closed, the tube 16 becomes a barrel and when the valves are open it reverts to a tube again.

The tube 16 is employed primarily in an oceanographic data gathering system wherein a large mass must be suspended at a considerable depth. The mass is essential to gain the required system dynamic stability. It should be noted that the suspended mass concept as defined herein is also readily adaptable for use with other deep ocean programs and systems.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

I claim:

1. A stabilizing device for fluid borne suspension systems which device may rapidly be changed so as to impose a maximum or a minimum mass resistance to movement of a portion of said system comprising:

an elongated tube;

a pair of butterfly closure valves mounted at both the upper and lower ends of said elongated tube;

means attached to said tube for opening and closing said closure valves said means including;

a rotatable rod vertically oriented and mounted adjacent the external side of said tube;

a rotatable latch mounted at both the top and bottom ends of said rotatable rod each of said latches adapted to latch around a pin mounted at one end of the upper and lower closure valves and;

a solenoid operated rod attached to one end of the latch positioned on the upper end of the rotatable rod;

thus when the closure valves are closed, the tube acts like a barrel adding a large mass to the system but when open the tube adds no effective mass to the system because water flows freely through the tube.

2. The device as defined in claim 1 wherein the butterfly closure valves have weights positioned on the under surfaces of both the upper and lower closure valves in order to force the valves open when released by said upper and lower latches.

Claims

1. A stabilizing device for fluid borne suspension systems which device may rapidly be changed so as to impose a maximum or a minimum mass resistance to movement of a portion of said system comprising: an elongated tube; a pair of butterfly closure valves mounted at both the upper and lower ends of said elongated tube; means attached to said tube for opening and closing said closure valves said means including; a rotatable rod vertically oriented and mounted adjacent the external side of said tube; a rotatable latch mounted at both the top and bottom ends of said rotatable rod each of said latches adapted to latch around a pin mounted at one end of the upper and lower closure valves and; a solenoid operated rod attached to one end of the latch positioned on the upper end of the rotatable rod; thus when the closure valves are closed, the tube acts like a barrel adding a large mass to the system but when open the tube adds no effective mass to the system because water flows freely through the tube.