US3392694A - Ship stabilization means - Google Patents

Description

July 16, 1968 A. l. APPLETON SHIP STABILIZATION MEANS Filed March 17. 1967 C'OMPU TE R DI VER TER CONTROL MOTOR Un t S es a n 3,392,694 SHIP STABILIZATION MEANS Arthur I. Appleton, Northbrook, Ill. Appleton Electric Co., 1701 W. Wellington, Chicago, lll. 60657) Filed Mar. 17, 1967, Ser. No. 623,952 6 Claims. (Cl. 114--122) ABSTRACT OF THE DISCLOSURE Ship stabilization means incorporating an inlet duct into which water flows and from whence it isdistributed between downwardly directed outlet ducts spaced on opposite lateral sides of the ship by flow diverter means carried within the ducting system and controlled 'bysensing means including a gyroscope'and/or wave height detection means.

Background of the invention This invention relates generally to means for inhibiting or restraining the undesirable movements (such as rolling and pitching) of a watercraft at sea, and more particularly to a system of ducts and control means therefor which divert water and expel it from given locations relative to the ship to thereby counteract the effect thereon of an uncalm sea;

Considerable effort has been spent in the past on Ways of inhibiting or preventing those movements of a water vessel that result in passenger discomfort, yet very little of this effort has been sufliciently successful to warrant its adoption into conventional designs or existing ships. While some shipshave enjoyed nominal success with laterally extendable stabilizing fins, perhaps the most publicized recent thinking along these lines involves the use of hydrofoils. Although thisapproach i undoubtedly effective, it generally requires substantial change to the traditional concepts of ship design. Yet, it would appear the conventionally designed ship will be with us for a long time.

United States Patent 2,098,531 to W. L. Baze is an example of a system for braking the rolling or pitching of a ship, and it is similar in some respects to the present disclosure. This patent describes apparatus for supplying water beneath the low side of the vessel to effect a righting couple. However, the system 'as presented exhibits many inherent problems which diminish its effectiveness.

For example, the Baze patent shows a plurality of separate ducts of which each includes its own inlet and outlet, and each duct requires its own separatevalving. Because of the positioning of each duct the reaction force set up by the change in momentum of the water passing therethrough includes at least one component which would create a moment on the vessel tending to rotate it about a vertical axis whenever there is present a difference of flow in the ducts along opposite sides of the ship. Therefore, while the flow does help to offset roll, it also creates a new undesirable movement. Another and very serious disadvantage of the Baze structure resides in the means for operating the valves which is shown therein as a pendulum connected within a controlling linkage. As a result, the flow in the various duct work is controlled entirely as a function of the angle of the ship relative to a vertical and longitudinal plane. Thus, the control system is neither anticipatory nor can it take into account any other parameters such as wave frequency and height, as well as the ships inertia, which causes the ship to assume an unusual roll pattern. In addition to the above, the pendulum is subject to its own natural frequency as Well as a portion of the water force which is exerted on it through the control mechanism, all of these acting to decrease its effectiveness.

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As will become apparent, the present invention solves these problems.

Summary of the invention In its preferred form, the present inventionsolvesthe above described problems by incorporating improved sensing means capable of anticipating the undesirable movements of the ship so as to better counteract them. Herein these sensing means include a gyroscope and/or water elevation sensing means which can be supplied to a computer or more directly implemented to properly divert water in the proper proportions to each side of the ship and thereby provide a restraining force tending to offset those forces which would otherwise create a roll condition. The present invention, in its preferred form, further contemplates a specific arrangement of duct worlc which not only minimizes a tendency of the vessel to r0- tate or pivot in a horizontal plane, but also requires only a minimum of material in achieving this endjHerein this is accomplished by utilizing a single central duct into which water naturally or forceably flows and from which it is internally diverted to the appropriate side of the ship by diverter means controlled by the aforementioned sensing means. The diverter means are preferably arranged such that a single element controls flow in each of two ducts.

While the accompanying drawing is shown to assist in an understanding of one preferred form of the invention, this showing is not intended to limit the invention to the specific embodiment shown or to defeat that'purpose of a patent which is to protectively cover the inventive concepts contained therein. The appended claims are the chief aid toward this purpose as it is these that point out the scope of the invention.

Description of the drawings FIG. 1 is a plan view of a ship incorporating the principles of one preferred form of the invention;

FIG. 2 is a side elevation of the ship shown in FIG. 1;

FIG. 3 is an enlarged fragmentary and cross section view of a portion of the duct work containing the diverter means and also shows one form of the diverter means used therein;

FIG. 4 is the view similar to FIG. 3 and shows'an alternate form of diverter; and

FIG. 5 is a schematic diagram of one arrangement of the control means for the flow diverter.

Description of the preferred embodiment Referring now to the drawings in more detail, the invention is shown installed in and forming a part of an ocean-going vessel shown in outline form at A and having a water line as at B. Rigidly mounted within vessel A is a complex of water handling duct work or duct means r' shown generally at 10. This duct means includes a forward portion or main trunk 11 extending generally down the middle of the vessel in plan view from its front end C to its central portions. The forwardmost end 12 of main trunk 11 opens forwardly of the craft at its bow and is spaced below the water line B to providean inlet for water. Also forming a part of the duct means 10, and connected into the rear end 13 of main trunk 11, is a first branch 15 and a second branch 16. Branches 15 and 16 diverge laterally relative to one another, each extending to a different side of the vessel. Near their laterally outermost end, each branch includes a generally downward and slightly laterally outwardly directed segment 17 which is connected to outlet means shown here in the form of an opening in the lower side of the ship. Outlet 18 permits an outflow from branch 15, and outlet 20 permits an outflow from branch 16. Thus, water normally will enter duct means 10 only by way of open 3 ing 12, and this water will normally exit by way of outlets 18 and 20.

As will be understood, forward movement of the vessel causes an inflow of water into opening 12 and a resulting outflow of water from one or both of the branches 15 and 16 through the outlets 18 and 20 respectively. Means are provided for dividing the outflow in any desired proportion between branches 15 and 16, and herein these means comprise diverter means 21. Diverter means 21 can take any desirable form and is shown in FIGS. 1 and 3 as a pivotal member or element which functions similar toa valve. This pivotal member may assume any intermediate position between a first extreme where all water flowing through main trunk 11 is diverted to branch 15, and another extreme where all water flowing through trunk 11 is diverted through branch 16. By adjusting the position of the diverter valve between these extreme positions, different proportions of flow between the branches is ttai'iable. The diverter is preferably located at that location about which the ship tends to pivot. This location wiLl herein be broadly termed the ships center of resistance, and it is shown in FIG. 1 of the drawings generally at 22.

In FIG. 4 there is shown a modified form of diverter means 21 which is translatable from side to side to effect the division of water flow.

Means are provided for controlling the position of the diverter, and herein the means are shown schematically in FIG. as a diverter control motor 25. Diverter control motor 25 is in turn controlled by a computer 26 which is fed information from a gyroscope 27 and/or a pair of pressure transducers 28 and 30 mounted on opposite lateral sides of the vessel and below its water line.

In discussing the operation of the system described, we will assume the wave action is such that, at a given in stant, the water level on the starboard side of the ship is higher than the water level on the port side. This condition not only tends to lift the starboard side and permits the port side to lower, but the difference in water pressure on each side tends to push the entire vessel to port, both reactions acting in a vertical and transverse plane passing generally through the ships center of resistance. Under these conditions, the sensing means will cause diverter means 21 to divert the bulk of the water flowing through main trunk 11 into branch 16. For simplicity, we will assume diverter means 21 to be in its extreme position (best seen in FIG. 1) such that all of the water is diverted into branch 16.

It will be apparent that the flow of water through main trunk 11 creates substantially no reactions on the ship. However, the change in lateral momentum of this water as it is channeled through duct 16 and out of outlet 20 causes a lateral reaction on the ship tending to push it to starboard. Since the diverter is positioned generally at the location of the ships center of resistance, this reaction opposes the wave created force in substantially the same transverse plane. Thus, a resistance is supplied with negligible accompanying rotative moment.

This same flow of water through the ductwork l0 and out of outlet 20 also undergoes a change in vertical momentum, this change exerting an upward reaction on the branch 16. Thus, a lift is exerted on the port side of the ship tending to offset its downward rolling condition, and again this lift is exerted in substantially the same transverse plane as the forces which produce the rolling condition. Therefore, they produce substantially no undesirable moments.

As the wave condition changes such that the water level on the port side exceeds the water level on the starboard side, the sensing means causes the diverter to shift toward its other extreme position via the control system. Obviously, moving the diverter 21 to its other extreme position will exert a force tending to lift the other side of the vessel, and positions of the diverter therebetween (or between its extreme positions) provides varying degrees of lift on each respective side of the vessel. Thus it can be seen that the position of the diverter 21 determines the relative amount of lift applied on either side of the vessel as well as the amount of lateral push thereagainst. It will be understood that the configuration of the duct means 10 not only minimizes the amount of ducting required by incorporating a single inflow duct, but also, its configuration serves to diminish the adverse effect of the change in momentum reactions. Of course, the angle of the outflow outwardly and downwardly from outlets 18 and 20 depends upon the spacing therebetween as well as upon the design of the specific vessel. Some designs might incorporate variable inclination outlet nozzles while others might be fixed to expel the water directly downward in order to gain a maximum anti-roll condition.

Computer 26 signals the diverter control motor which continuously varies the position of diverter means 21 to best offset the tendency for the vessel to roll. Computer 26 is fed with information gained by gyroscope 27, this information preferably including not only deviation from a vertical longitudinal plane, but also the roll frequency. The computer can thus be programmed to anticipate the movements of the vessel from this information and can thereby best control the diverter control motor to supply the right lift at the right time to most effectively inhibit the rolling condition. An alternate system, or one that can be used in combination with the gyroscope 27, is that of installing a pair of pressure transducers on opposite sides of the vessel and well below its water line. Since the movement of the ship is largely dependent on the water level on each side thereof, each pressure transducer senses the water level on its own side and supplies this information to the computer which makes use of it in determining its output signal.

As will be appreciated, both of these sensing systems acting in combination will provide substantial information to the computer which in turn regulates the righting effort by means of the flow diverter.

In some installations, it may be desirable to additionally include means, such as the impeller shown at 31, to create a forced flow of water through the main trunk 11. Thus stability may be achievable even when the vessel is standing still or moving at low speeds. Particularly with a forced flow, certain applications might preferably direct the exodus of water at a substantial angle from the vertical by means of fixed or variable inclination outlets in order to assist in propelling the ship.

The diverter system described above lends itself particularly well to the use of impeller 31. Irrespective of the position of diverter 21, whether this be at one of its two extreme positions or somewhere therebetween, water forced through main trunk 11 can exit through at least one of the two outlets. Thus, impeller 31 can pump continuously and will experience a substantially constant load under a given ship speed. This is to be contrasted with the above referred to Baze patent which appears to suggest a separate pump in each of his ducts. The Baze system would therefore require not only a plurality of pumps, but these pumps would probably have to be set up to alternately start and stop in conjunction with the starting and stopping of flow through each of the laterally spaced ducts. The probably necessary start and stop control for each motor, as well as the adverse effects of the momentum of each pump in starting and stopping at short periodic intervals, is avoided by the present disclosure.

Although the figures show only one main trunk and a single outlet opening on each side of the ship, it will be apparent that additional duct work and outlet openings at other strategic points can be incorporated to inhibit other undesirable movements, such as pitching, or to suit a given ship design. For example, a pitching condition can be inhibited by longitudinally spacing the water outlets.

Also, particularly in the adaptation of an existing ship where it is not feasible to install the duct work internally, the duct work can be mounted externally of the ship with the flow diverter positioned at the bow thereof.

I claim as my invention:

1. In a water vessel, stabilization means for counteracting certain of the discomforting movements resulting from an uncalm sea, comprising: water duct means carried by said vessel, said duct means extending rearwardly from the bow of said vessel and having inlet means opening in a forward direction thereof below the vessels water line for accepting an inflow of water therein, said duct means including a plurality of water conducting and diverging branches, each of said branches having separate and spaced water outlet means directed generally downwardly away from said vessel for expelling water therefrom, movable diverter means associated with said duct means for variably apportioning the inflow of water therethrough between said outlet means, and means sensitive to said discomforting movements for varying the position of said diverter means responsive thereto whereupon the relative flow through said outlet means assists in counteracting said discomforting movements.

2. Stabilizing means for counteracting the roll of a Water craft, comprising: duct means carried by said craft, said duct means including a forward main trunk portion having an inlet below the ships Water line and opening forwardly relative to said water craft to assist the inflow of water therein, said duct means also including first branch and second branch connected into the rear end of said main trunk portion and forming a junction therewith, each of said first branch and second branch diverging laterally from the other to a laterally outwardly positioned outlet, said outlet being arranged to expel water generally downwardly therefrom beneath said water craft, movable flow diverter means at said junction for apportioning the flow of water between said first branch and said second branch, and control means sensitive to the tendency of said water craft to roll for controlling movement of said flow diverter means whereupon the relative amount of outflow between said first branch and second branch inhibits a rolling condition of said water craft.

3. The water craft stabilizing means as set forth in claim 2, wherein said control means includes water level sensing means laterally spaced on said water craft below its water line for sensing the relative water level on each side of the craft.

4. The water craft stabilizing means as set forth in claim 2, wherein said control means includes means sensitive to the inclination of the water craft relative to the vertical.

5. The water craft stabilizing means as set forth in claim 2, wherein said duct means includes bends to channel the water flow therein to each outlet, said bends being located and arranged such that the horizontal reaction component set up by said flow passes generally through the water crafts center of resistance.

6. The water craft stabilizing means as set forth in claim 2, including means for forcibly driving water through said main trunk.

References Cited UNITED STATES PATENTS 11/1937 Baze 114-122 11/1966 Field et al 114-122

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