US3322090A - Ship stabilization system - Google Patents

Description

y 1967 F. v. PANGALILA 3,322,090

SHIP STABILIZATION SYSTEM Filed Feb. 7, 1966 4 Sheets-Sheet 1 FIG. I.

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INVENTOR Frans V PangaI/la ATTORNEYS y 1967 F. v. PANGALILA SHIP STABILIZATION SYSTEM 4 Sheets-Sheet 2 Filed Feb.

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INVENTOR Frans M Panga/i/a BY I TTORNEYS y 1967 F. v. PANGALILA SHIP STABILIZATION SYSTEM 4 Sheets-Sheet 3 Filed Feb. '7, 1966 FIG. 7.

INVENTOR Frans i ll Panga/i/a BY I mfiww w ATTORNEYS SW/ TCH TRANDUCER G YROS COPE May 30, 1967 F. v. PANGALILA SHIP STABILIZATION SYSTEM 4 Sheets-Sheet 4 Filed Feb.

Frans l! Panga/i/a ATTORNEYS United States Patent ()fiice 3,322,096 Patented May 30, 1967 3,322,090 SHIP STABILIZATION SYSTEM Frans V. Pangalila, Staten Island, N.Y., assignor to John J. McMuilen Associates, Incorporated, New York, N.Y., a corporation of New York Filed Feb. 7, 1966, Ser. No. 525,426 18 Claims. (Cl. 114-125) The present invention relates generally to ship stabilization and more particularly to an improved apparatus for applying a restoring moment to a ship by the movement of fluid within a tank.

Ships of practically every type encounter the problem of undesirable ship motion caused by the surface condition of the water. Depending upon the type and size of the ship and the operating conditions to which the ship is to be subjected, various hull designs are selected to counteract the tendency of the Water to impart motion to the ship. Due to the great number of variables present and since cyclic wave motion can cause a gradual increase in the energy of motion of the ship, hull design provides only a limited effect in controlling the ship motion. Other attempts to minimize ship motion in response to wave action include the provision of stabilization systems which are capable of applying a restoring moment to the ship when it is subjected to the motion. Particular emphasis has been made with respect to improving systems for minimizing roll. Ballast tanks connected by piping and the like have been employed in order to transfer water in a manner to generate a restoring moment. Such systems encounter the difficulty of maintaining the proper phasing between the restoring moment and the motion imparted to the ship. Efforts to employ volumes of air above liquid ballast for controlling the ballast have resulted in massive systems which were uncertain as well as excessively noisy in operation. Efforts have also been directed to providing the ship with fixed or movable fin members extending from the hull beneath the waterline and adapted to generate restoring moments from the hydrodynamic forces on the fins accompanying the motion of the ship. In certain applications, controlled fins have been effective in controlling the roll of the ship but only at the expense of coupled-systems employing massive fin members and operating machinery.

Present day efforts in the art include stabilization systems employing the free-surface principle of operation, and although quite successful, they usually include tanks having specially shaped configurations, and/or substantial internal structure involving large amounts of material that is costly both in terms of money and in weight. This, of course, requires special machinery for making the tanks and, in many cases, reworking of the ships structure to accommodate such tanks. Further, present day designs are limited in adjustability of stabilization. That is, prior art stabilization systems are usually designed for a specific application or size vessel. Once'installed, they are not adaptable for a different application Without major remodeling involving great expense in terms of time and money to the ship owner.

The present invention is an improvement over the prior art in that it has built-in versatility while maintaining simplicity of design.

In the principal embodiment of the invention, the ship stabilizing system includes a tank entirely passive in design and containing a quantity of fluid having a free surface. The longitudinal axis of the tank is adapted to extend substantially horizontally and substantially at right angles to the axis about which the ship is to be stabilized.

Mounted Within the tank is a deflecting plate secured vertically and disposed so that it converges toward one tank wall while diverging from the oposite wall. Thus,

the plate is so oriented with respect to the walls parallel to the longitudinal axis of the tank, that an oblique angle is formed therebetween. With the plate mounted in the tank at an oblique angle, the fluid moves in part with a gradually decreasing width. In this manner, the effective longitudinal dimension of the tank is changed and, therefore, the frequency can change. Thus, in response to smaller rolls of the ship, the fluid can flow back immediately without having to first reach one or the other tank ends.

The plate may assume a variety of shapes and constructions, all designed to efi'iciently adapt to varying conditions of the sea and best suit the needs of various ships.

Thus, other embodiments include smoother or hydrodynamically designed tanks, plates and/or the additions of guide plates in the tanks for smoother fiow of the stabilizing liquid.

Another embodiment includes pivotally mounting the plate to the tank bottom to adjust the oblique angle thereof. The plate can either be adjusted to a position to provide a tank tuned for optimum stabilizing characteristics for a particular ship or weather condition encountered, or include a powered control and sensing mechanism to automatically adjust the oblique angle and tune the tank as the ship rolls.

A further embodiment includes cutting holes in the plate for controlling the tuning and damping effects of the plate. The holes may be of a permanent nature, or their efiect may be controlled by adjusting their total area, or their total number as depicted in still further embodiments.

In a further embodiment, the tank is converted to a semi-active stabilizing system by including in addition to the deflecting plate, a powered water-moving device such as propellers immersed in the liquid driven at a constant speed, or to an active system wherein the speed of the propellers is controlled by a sensing mechanism.

Accordingly, it is a primary object of this invention to provide a ship stabilizer of simple design which is capable of applying a restoring moment to a ship.

Another object of this invention is to provide a ship stabilizer employing essentially one internal component position within an enclosed tank containing a stabilizing liquid having a free surface.

A further object of this invention is to provide a passive ship stabilizer that can be converted to a semi-active stabilizing system that is relatively simple in design, and does not require complicated and cumbersome additional structure.

A yet further object of the present invention is to provide a passive ship stabilizer that can be converted to an active ship stabilizer of simple design that can automatically adjust and tune itself to ship roll.

Yet another object of this invention is to provide a passive ship stabilizer that is controllably tunable for various sea and weather conditions.

It is still a further object of this invention to provide a ship stabilizer that is versatile and easily adaptable to ships or boats of various sizes.

An even further object of the preseint invention is to provide a ship stabilizer that is self-contained and does not require major alterations in the ships structure for installation.

A still more obvious object of this invention is to provide a ship stabilizer which is compact and reasonably light in Weight.

Other objects and features of the invention will become apparent in the following specification, claims, and drawings in which;

FIG. 1 shows a plain view of the invention containing the tank and the oblique plate;

FIGS. 2a, b and show side elevations of the various profiles that the plate in FIG. 1 may assume;

FIGS. 3a, b and 0 show plan views of various modifications of the embodiment disclosed in FIG. 1;

FIGS. 4a, and b show a semi-active system by including an additional mechanism to control directional movement of the stabilizing liquid;

FIG. 5 shows the plate having holes cut in it and a control mechanism for varying the area of said holes; and

FIG. 6 shows the plate with holes cut in it having a control mechanism for varying the number of holes exposed on said plate;

FIG. 7 shows an active or semi-active embodiment of the invention.

Referring to FIG. 1, a tank 10 has its longitudinal axis substantially horizontal and at right angles to the axis about which the ship is to be stabilized. Mounted within the tank partially filled with stabilizing liquid is a deflecting plate 11 secured vertically and disposed so that the end portions converge toward opposite tank walls, thereby forming an oblique angle therebetween. As the ship rolls, most of the stabilizing liquid is channeled in a converging path formed by the plate and respective side wall and tank 10. In this manner, the liquid moves substantially in a circular path as indicated by the arrows.

Referring to FIG. 2a, a side elevation of FIG. 1, taken along lines 2-2, shows plate 11 running the full height of tank 10. 7

Referring to FIG. 2b, the static level of stabilizing liquid 20 is slightly above or higher than the height of plate 11. In this embodiment, there is a constant spillover of stabilizing liquid from one channel to the other in response to ship roll. It is obvious from this embodiment that the stabilizing liquid would reach the tank ends more quickly since part of the liquid would be taking a short cut over plate 11.

FIG. 2c shows a compromise between the two heights shown in FIGS. 2a and 2b. In FIG. 20, plate 11 begins with a height approximately equal to the static level of the liquid at the end portions and gradually rises to the full depth of the tank at its mid-portion. In this way, the plate is tuned to provide spillover of the stabilizing liquid during more violent rolls of the ship, where more rapid cross-transfer of the liquid would most likely be needed.

FIGS. 3a and 3b show other configurations in which FIG. 1 may take. In FIG. 3a, the side of tank 10 assume the form of a parallelogram, while plate 11 runs approximately at right angles to the roll axis of the ship.

In FIG. 3b, the tank as shown with rounded corners,

and the cross-section of plate 11 has a flattened S shape for smoother flow of stabilizing liquid 20. Guide plates 11" may be added to aid still further in the smoother flow of the liquid. It should be noted that the feature shown in FIG. 3b may be incorporated either singly or in combination with any of the other embodiments disclosed herein.

FIG. 30 has oblique plate 11 mounted on a vertically disposed rotatable axle 12 located at its mid-portion for adjustment of the oblique angle. By adjusting the oblique angle, the tuning and dampening effects of plate 11 and thus, the stabilizing effects of tank 10, may be controlled. Accordingly, plate 11 is adjusted to an angle that provides optimum stabilizing characteristics for a particular ship or weather condition encountered. The embodiment shown in FIG. 3c may be converted to a fully active stabilizing system that automatically controls or adjusts the oblique angle of plate 11 as a function of ship roll. This is done by switching in a sensing and control apparatus connected to axle 12 of plate 11. A gyroscope 30 is connected to a transducer 32. Transducer. 32 puts out an electrical signal, the voltage of which is directly proportional to the magnitude of ship roll, to control a motor 36 through an amplifier 33 and switch 34. Switch 34 is used to disconnect or connect the sensing mechanism to the control mechanism.

Referring to FIG. 4a, two one-way flap valves are connected, each of which extends from a respective side of plate 11 to an adjacent side wall of tank 10 to maintain the flow of stabilizing liquid 20 in a circular path in a manner to be explained and as indicated by the arrows 6. Flap valves 40 and 42 are for-med from a plurality of horizontally mounted pivotal slats that open and close in only one direction. The slats overlap one another in single fashion when the valves are closed, and swing open in response to gravity and liquid force to present a plurality of ladder-like horizontal openings that have a dampening effect on stabilizing liquid 20 flowing therethrough.

Arrows 8 indicate the direction of roll experienced by tank 10 in FIG. 4a. Thus, when the ship rolls starboard,

as shown, flap valve 40 opens to allow free passage of the stabilizing liquid, while flap valve 42 located on the reverse side of plate 11 is forced closed by the combination of gravity and the liquid force' against it. When the ship rolls to port or in the opposite direction from that shown by arrows 8, valve 42 will open while valve 40 will be held closed. Thus, referring to FIG. 4b, the liquid is forced to flow along one side of tank 10 during roll in one direction and flow along the other side of tank 10 during roll in the opposite direction, resulting in a circular path as indicated by arrows 6.

FIGURE 5 shows plate 11 having holes 16 cut therearea of the holes. By controlling the area of the holes, a

tuning and damping may be changed according to cargo carried or prolonged sea conditions.

FIGURE 6 shows a variation of FIG. 5. Instead of controlling the area of the holes, the number of holes can be controlled to achieve the same result. Thus, control mechansim 18 operatively attached to shutters 16 slide on tracks 19 to block or unblock holes 21.

Although the embodiments depicted in FIGS. 5 and 6 are passive in nature, i.e., the control mechanism preadjusted and tuned for optimum stabilization, they may be easily converted to fully active systems by switching in a sensing mechanism (not shown) similar to the one disclosed in FIG. 3c.

Referring to FIG. 7, a pair of propellers are inserted between respective side walls of tank 10 and plate 11. The embodiment shown in FIG. 7 forms a semi-active stabilization system when propellers 50 and 52 are driven at a constant rate causing stabilizing liquid 20 to move in a circular path as described with reference to FIG. 4;

The embodiment in FIG. 7 may be converted into a fully active system by switching in, via switch 34, the sensing mechanism made up with gyroscope 30, transducer 32, amplifier 33, and similar in operationto the one disclosed in FIG. 3. Thus, propellers 50 and 52 rotate as a function of the sensing mechanism which is controlled by the roll motion made by the ship, e.g., the greater the roll of the ship, the greater the speed of the propellers.

'Under thepassive stabilizing mode of operation, the

' dimension together with the level of the liquid. The size and type cargo the ship carries might best aid is considering the size tank to be constructed.

Referring to FIG. 1, tank 10 operates by stabilizing liquid 20 in tank 10 moving in part'with'a gradually de-,

creasing width. In so doing, the effective longitudinal dimension of tank 10 is changed and, therefore, the frequency can change. Therefore, with gentle rolls, liquid 20 in tank may impart a stabilizing effect without having to flow to one end or the other of the tank.

The height of plate, 11 in tank 10 determines the dampening effect on the liquid which in turn determines the'magnitude of the stabilizing moment produced. In FIG. 2a, greater dampening takes place which results in the production of a smaller stabilizing moment. In FIG. 2b, the reverse occurs with a greater stabilizing moment produced because of the decrease in liquid dampening by plate 11, while in FIG. 2c, a combination of the two results. Thus, in FIG. 2c, with more gentle rolls, a stabilizing effect similar to FIG. 2a is produced, while with more violent rolls, greater stabilizing moments similar in efiect to FIG. 2b are produced. The type ship employed or personal preference will determine which plate (FIG. 2a, b or c) is used.

Under the semi-active mode of operation, the same tuning parameters exist that existed for the passive stabilizing system except that the volume or level of the liquid is less critical. FIG. 4, and FIG. 7 with the sensing mechanism disconnected are examples of the ship stabilizing system according to the present invention operated in the semi-active mode.

In FIG. 4, a semi-active system is created when the ship roll in combination with flap valves 40 and 42 cause liquid 20 to be damped and flow in a circular motion in a manner described hereinabove. Because of the structure of the present invention, the liquid can flow in a circular path around the oblique plate (as opposed to merely a to and for movement) without any detrimental eiTect to the systems operation. Thus, simple one-way flap valves (40 and 42) can he and are utilized to aid in providing the required dampening effect on the liquid as it flows through the valves nozzle-like horizontal openings. The tuning efiect of the valves in the system is described in the operation description directly below with regard to the semi-active mode of operation for the propellers of FIG. 7.

In FIG. 7, the propellers driven at a constant speed to maintain the liquid in a circular movement around the plate during all phases of ship motion form a semi-active stabilization system. Again, because the structure of the present invention allows circular movement of the liquid, simply constructed propellers that operate at a constant speed requiring no speed adjustment mechanisms or reversing mechanisms are used.

During no roll periods, there are no upsetting moments produced on the ship because any force created at one end of tank 10 by the moving liquid is cancelled at the other end of tank 10. During extended periods of no roll activity by the ship, the liquid ceases its circular movement in FIG. 4 by being damped out, and the power to the propellers in FIG. 7 may be cut off.

In operation, if the ship rolls starboard, all the liquid flows starboard. But plate 11 in combination with the flap valves of FIG. 4, and plate 11 in combination with the propellers of FIG. 7, cause the liquid to decelerate on the aft side of the tank and accelerate at the fore side. Thus, by referring to FIGS. 4b and 7, essentially no motion is produced on the aft side of tank 10, and tuned motion is produced on the fore side. If the ship then rolls to port, essentially no motion is produced on the fore side of tank 10, and tuned motion is produced on the aft side.

Thus, because of the circular movement of the liquid, tuning of the tank in a semi-active mode of operation as disclosed in FIGS. 4 and 7 is accomplished simply and efiiciently without having to resort to complicated and/or other machinery that would otherwise prove necessary to control the liquid movement and tune a semi-active (or active) ship stabilization system.

Under the active mode of operation, the same tuning parameters apply that applied to the semi-active mode of operation. The active mode of operation allows the stabilization system according to the present invention to be totally sensitive and responsive to the motions of the ship.

In FIGS. 3(0), 5, 6 and 7, upon switching in the sensing mechanism, described hereinabove, any roll motion by the ship is picked up by the sensing mechanism and is automatically reacted to by the respective control mechanisnis shown. In FIG. 30, the angle of plate 11 is changed; in FIGS. 5 and 6 (sensing mechanism not shown) the area and number of holes in plate 11 are changed respectively; and in FIG. 7, the speed of the propellers changes. The aforementioned changes produce either greater or less dampening on the stabilizing liquid which result in constant tuning of the system to stabilize against the initiating causes. Thus, by the addition of relatively standard sensing and control equipment, the passive and/or semi-active stabilization systems according to the present invention are easily and efliciently converted to fully active stabilization systems.

While there has been disclosed what at present are considered to be the preferred embodiments of the invention, it is to be understood that changes and modifications can be made therein without departing from the essential spirit and scope of the invention as presented in the appended claims.

What is claimed is:

1. A passive stabilization system for a ship comprising a tank having a bottom, first and second sides, and two ends and having its longitudinal axis mounted transversely to the roll axis of said ship, said tank partially filled with a predetermined amount of liquid, an elongated upstanding plate means having a first and second end, said plate means mounted in said tank with its longitudinal dimension extending generally longitudinally in said tank and with said ends terminating short of said tank ends, said first end of said plate spaced closer to said first side of said tank than to said second side, and said second end of said plate spaced closer to said second side than to said first side so that an oblique angle is formed between said plate and either of said tank sides.

2. The apparatus as claimed in claim 1 wherein said plate means has a height extending at least above the static level of said liquid partially filling said tank.

3. The apparatus as claimed in claim 1 wherein the static liquid level partially filling said tank is at least slightly above the height of said plate means.

4. The apparatus as claimed in claim 1 wherein said plate means has a height whose end portions extend substantially equal to the static level of said liquid partially filling said tank and whose midportion extends the full depth of said tank.

5. The apparatus as claimed in claim 1 wherein said plate means has a longitudinal cross-section in the shape of a flattened S.

6. The apparatus as claimed in claim 1 wherein said plate means additionally includes as part of the structure thereof guide plate means hydrodynamically shaped and mounted within said tank for cooperating with said liquid.

7. The apparatus as claimed in claim 1 wherein said tank includes rounded corners.

8. The apparatus as claimed in claim 1 including a pair of unidirectional liquid flow means each inserted vertically in said tank and extending perpendicularly from the side walls of said tank to the elongated side surfaces of said oblique plate adjacent said tank side walls, said means placed so as to allow said liquid to flow in a circular movement around said plate.

9. The apparatus as claimed in claim 8 wherein said unidirectional liquid flow means comprises a plurality vertically spaced and horizontally displaced pivotal slats that swing open and closed in only one direction, said slats being in overlapping configuration in the closed position and forming a plurality of ladder-like horizontal openings in the open position.

10. The apparatus as claimed in claim 1 wherein said plate means is pivotally mounted to the tank bottom so that said oblique angle is adjustable.

11. The apparatus as claimed in claim 10' further i-n eluding means to automatically adjust said oblique angle as a function of ship roll.

12. The apparatus as claimed in claim 1 wherein said plate means includes a plurality of openings at both ends and spaced equidistant from the mid-line of said plate means.

13. The apparatus as claimed in claim 12 wherein said plate means includes shutter means for controlling the number of openings exposed.

14. The apparatus as claimed in claim 13 further including means for operating said shutter means in response to ship roll.

15. The apparatus as claimed in claim 12 wherein said plate means includes means for controlling the area of said openings.

16. The apparatus as claimed in claim 15 further including means for operating said area controlling means in response to ship roll.

17. The apparatus as claimed in claim 1 further includ! ing powered water-moving means at least partially immersed in said liquid to control the liquid movement in a predetermined manner. 7

18. The apparatus as claimed in claim 17 wherein said power means operates in response to ship roll.

No references cited.

MILTON BUCHLER, Primary Examiner.

T. M. BLIX, Assistant Examiner.

Claims (1)

1. A PASSIVE STABILIZATION SYSTEM FOR A SHIP COMPRISING A TANK HAVING A BOTTOM, FIRST AND SECOND SIDES, AND TWO ENDS AND HAVING ITS LONGITUDINAL AXIS MOUNTED TRANSVERSELY TO THE ROLL AXIS OF SAID SHIP, SAID TANK PARTIALLY FILLED WITH A PREDETERMINED AMOUNT OF LIQUID, AN ELONGATED UPSTANDING PLATE MEANS HAVING A FIRST AND SECOND END, SAID PLATE MEANS MOUNTED IN SAID TANK WITH ITS LONGITUDINAL DIMENSION EXTENDING GENERALLY LONGITUDINALLY IN SAID TANK AND WITH SAID ENDS TERMINATING SHORT OF SAID TANK ENDS, SAID FIRST END OF SAID PLATE SPACED CLOSER TO SAID FIRST SIDE OF SAID TANK THAN TO SAID SECOND SIDE, AND SAID SECOND END OF SAID PLATE SPACED CLOSER TO SAID SECOND SIDE THAN TO SAID FIRST SIDE SO THAT AN OBLIQUE ANGLE IS FORMED BETWEEN SAID PLATE AND EITHER OF SAID TANK SIDES.

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