US3334608A - Method and apparatus for establishing draft and trim of a vessel - Google Patents

Method and apparatus for establishing draft and trim of a vessel Download PDF

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Publication number
US3334608A
US3334608A US542516A US54251666A US3334608A US 3334608 A US3334608 A US 3334608A US 542516 A US542516 A US 542516A US 54251666 A US54251666 A US 54251666A US 3334608 A US3334608 A US 3334608A
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Prior art keywords
draft
trim
tanks
vessel
ship
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US542516A
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English (en)
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Nemoto Hirotaro
Shibata Kiyoshi
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IHI Corp
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Ishikawajima Harima Heavy Industries Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B39/00—Equipment to decrease pitch, roll, or like unwanted vessel movements; Apparatus for indicating vessel attitude
    • B63B39/12—Equipment to decrease pitch, roll, or like unwanted vessel movements; Apparatus for indicating vessel attitude for indicating draught or load
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
    • B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING 
    • B63B11/00—Interior subdivision of hulls
    • B63B11/04—Constructional features of bunkers, e.g. structural fuel tanks, or ballast tanks, e.g. with elastic walls

Definitions

  • This invention relates to a method and an apparatus for attaining and maintaining the values of draft and trim of a ship hull at a predetermined Value, and in particular to a method and apparatus in which the values of the draft and trim of the ship hulls are automatically calculated and controlled.
  • the draft and the trim of a ships hull are determined by the loading of the ship.
  • the ship both tends to increase draft or sinks, or to slant.
  • the change in the state of a ship may be considered in two stages under the assumption that the angle of inclination remains relatively small in magnitude. In the first stage the ship sinks vertically in proportion to the magnitude of the loading, and in the second stage the ship is slanted while maintaining a constant displacement.
  • the final displacement of the ship does not guarantee the desired level of draft and trim, the trim being the difference between the draft in the fore perependicular of the ship and the draft in the aft perpendicular of the ship. If the loading is continued in the second state of sinking in an effort to correct the value of the trim, the displacement of the ship will increase and the ship will sink beyond a required level of draft of displacement.
  • the present invention provides for separate tanks displaced along the hull of the ship which control the trimming of the vessel by letting liquid into or out of the tanks.
  • the predetermined level which is automatically computed on the basis of either of the drafts at stern, or the draft in the midship and the trim, the charge or discharge of the fluids to the corresponding tanks is suspended.
  • FIG. 1 is a schematic view in side elevation of the interior of an oil tanker illustrating features of the present invention
  • FIG. 2 is a top plan view of the vessel shown in FIG. 1, showing in schematic form the various piping arrangements by which liquid is passed between the two tanks;
  • FIG. 3 is a schematic view of a vessel showing the various design points which are used in the analysis of the inventive method and apparatus;
  • FIG. 4 is a schematic of the fore portion of a vessel showing one type of remote draft indicator
  • FIG. 5 is a schematic cross-section of a vessel showmg another example of remote draft indicator.
  • FIG. 6 is a block diagram of the apparatus of the present invention.
  • an oil tanker having a hull 1 in which are disposed liquid tanks 2, 3 and 21 each of which 1s supplied with liquid from a main pipeline 4 by means of pipes branching from the main pipeline.
  • the branchmg pipes in each tank are equipped with a bell mouth 22 and valves 6, 7 and 23.
  • Main pipeline 4 is generally led to the upper deck through a a pump room 24 aft the cargo tanks.
  • tanks 2 and 3 are spaced apart from each otherin the fore and aft sections of the vessel. Tanks 2 and 3 may be used as the two tanks for controlling the trim and draft.
  • TPC is the weight required to sink the hull parallel to the base line by one unit of draft
  • MTC is the value of moment required to initiate a unit trim to the hull at the water line
  • I is the horizontal distance from the point of intersection 12 to the center of gravity of the sea water ballast W (which is negative if the center of gravity is forward of the intersection 12 and positive if it is aft of intersection 12);
  • H is the vertical distance between the water line 8 and 10, that is the depth which the hull has sunk
  • t is the value of the trim, i.e. the difference between the fore draft and the aft draft expressed in units of length. Therefore, we have:
  • 1 W ZW TPC and MTC Intersection 12 is referred to as the center of floatation at the water line 10 and can be assumed to be invariable when the angle of inclination is small.
  • the triangles defined by points 16, 17 and 18, and by points 11, 12 and 15 are similar triangles, so that the horizontal distance between the intersections 11 and 12 may be expressed by:
  • L is the length between perpendiculars which is an idiomatic phrase used in naval architecture meaning the distance between aft perpendicular and fore perpendicular, and often referred to as the length of the ship. This distance is shown as a horizontal distance [0 between the points 16 and 18 in FIG. 3.
  • L- I 1 W/TPC' L-MTC Accordingly, the horizontal distance 10 between intersections 11 and 12 is independent of W, and since the intersection 12 is invariable at the water line 10 as shown above, intersection 11 is invariable regardless of the value of W.
  • intersection 11 moves to some extent in response to the water line since MTC, TPC and I all change with the position of the water me. 1
  • L is the horizontal distance between points 16 and 18;
  • lb corresponds to la when the above condition is in existence.
  • the liquid supply to the tank will cause a change in the slanting of the ship floating on the water. Even in case there is no slanting, the ship will sink by the weight of the liquid supplied.
  • the change of position of the ship may occur in the following ways:
  • the water line 10 shows the condition involved in (a)
  • water line 9 shows the condition involved in (b).
  • the values of dB and dA may be calculated from these values at each moment by means of the above equations.
  • FIG. 4 illustrates one embodiment of an aero-type remote draft indicator.
  • a pipe 16 in which lower end 46 terminates at the bottom of the hull 1, is open to the water.
  • Another air pipe 41 which is open at the lower end thereof, is installed within opening 46.
  • Compressed air is passed first through a flow controller 42 and is forced out by a nozzle 43 at the lower end 46 of the pipe 41.
  • the compressed air which exhausts from nozzle 43, is collected in pipe 40, with the result that the equivalent volume of sea water in the pipe 441 is in turn forced out through lower end 46.
  • the upper end of pipe 40 is closed, and a pipe 44 of relatively smaller diameter extends laterally from the upper end of pipe 40, to a manometer 45 located in the control room.
  • FIG. 5 shows another example of a remote draft indicator.
  • a pipe 51 is installed through the outer side of hull 1 and extends from the bottom to the top of the hull as shown.
  • the lower end of pipe 51 is open to the sea near the bottom of hull 1, while the upper part of pipe 51 is equipped with a sound transducer 52 which is constructed to transmit a downwardly directed sound wave, and also receives the reflected sound waves.
  • a transmitter 53 housed in the controll room is electrically connected to transducer 52.
  • pipe 51 has an opening 55 for the escape of air at the upper part thereof, sea water easily occupies pipe 51 to the level of the sea water outside when the ship is afloat.
  • Transducer 52 which receives the signals from transmitter 53, transmits the sound waves downwardly at preselected intervals of time.
  • a portion of the transmitted signal waves are reflected by the surface of the water in the pipe at level 54 and are reflected to transducer 52 having a corresponding time lag.
  • Transducer 52 receives the reflected sound Waves and transmits these waves to a receiver housed in the control room.
  • the level 54 of the surface of the water then prevailing in the pipe can be determined. This time lag may be directly read out by suitable means which are well known in the art, and which are therefore not further described herein.
  • the remote draft indicators shown in the embodiments of FIGS. 4 and 5, are only two examples of many possible embodiments of draft indicators.
  • the methods for transmitting the remote draft data may be found in the combination of these shown or in the use of hydraulic pulse, etc. In the present invention any one of these methods may be applied, as shown in FIG. 6.
  • Placing remote draft indicators, such as 61 and 62, in the fore and aft sections of the vessel provide indications of the respective drafts from which the trim may be easily calculated.
  • the value of d may be obtained from another draft indicator set up at the midship dA and dB may be calculated from these values through the above equations.
  • a comparator circuit 64 in the computer which compares the calculated values of dA and dB against the predetermined values from a draft and trim reference source 65 produces an electrical signal when these signals are equal, which operates to close the valve 7 at the mouth of the aft tank 3, via a valve 7 control unit 66 and leads 67 and 68, preventing further loading of tank 3.
  • the computer will produce a signal to stop the loading of fore tank 2, by closing the valve 6 of the mouth of tank 2, via a valve 6 control unit 69, the lead 67 and a lead 70, when the calculated value of dB has reached the predetermined value dBo, that is, when the draft at the position at the second intersection point of the center of rotation of the aft tank has reached the value dBo.
  • valve 6 will be closed first, and then valve 7, once the value of dAo has been reached.
  • the draft d at the mid-ship part will first reach its predetermined value do. In this case the loading will be stopped when d has reached do regardless of the values of the drafts dA and dB.
  • the operation described above will be performed in the reverse order.
  • similar effect can be obtained by using the cargo oil instead of sea Water as ballast.
  • the inventive method is applicable to the loading and unloading of water ballast to the tanks of ships in general, including bulk carriers, as well as in the above mentioned reference for use on oil tankers.
  • the present invention provides a method and apparatus for attaining a predetermined value of draft and trim in the final state of ship loading by making use of an automatic calculation of parameters, which is efiicient in application in loading operations and the like.
  • a method for establishing and maintaining the draft and trim of a vessel comprising the: steps of varying an amount of liquid in each of at least two tanks disposed separately in the hull of said vessel, simultaneously establishing the level of liquid in each of said tanks, comparing the instantaneous values of midship draft and trim against predetermined values thereof, controlling the flow of liquid into said tanks to maintain the amount of liquid in each of said tanks when the established value of draft and trim corresponds to the predetermined value thereof.
  • a method as claimed in claim 1, wherein the step of establishing the liquid level comprises discharging liquid from said tanks.
  • a method as claimed in claim 1, wherein the step of establishing the liquid level comprises charging liquid into said tanks.
  • Apparatus for establishing draft and trim in a vessel having at least two tanks separately disposed in the hull of said vessel comprising measuring means for measuring the values of draft and trim of the vessel, valve means controlling the flow of liquid to and from each of said tanks, reference means for providing predetermined values of draft and trim, comparator means connected to said measuring means and to said reference means for comparing the measured values of draft and trim with the predetermined values thereof, and control means connected between said comparator means and said valve means for controlling said valve means when the measured values of draft and trim correspond to the predetermined values thereof.
  • measuring means comprises means for producing an electrical signal proportional to the measured value of midship draft and trim.
  • valve means is closed thereby maintaining the amount of liquid in said tank when said comparator means produces said third signal.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • Ocean & Marine Engineering (AREA)
  • Loading And Unloading Of Fuel Tanks Or Ships (AREA)
  • Filling Or Discharging Of Gas Storage Vessels (AREA)
US542516A 1963-03-16 1966-04-14 Method and apparatus for establishing draft and trim of a vessel Expired - Lifetime US3334608A (en)

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JP1437763 1963-03-16

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US (1) US3334608A (enrdf_load_stackoverflow)
GB (1) GB1029725A (enrdf_load_stackoverflow)
NL (1) NL6402719A (enrdf_load_stackoverflow)
SE (1) SE342791B (enrdf_load_stackoverflow)

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3916811A (en) * 1974-08-29 1975-11-04 Sun Oil Co Pennsylvania Tide compensation system
US3922985A (en) * 1970-01-16 1975-12-02 Ferris F Hamilton Submarine tanker for transportation of liquid cargo
US4347574A (en) * 1978-10-11 1982-08-31 Parsons Ward H Method of and apparatus for determining with precision the payload of a water borne vessel
US4534217A (en) * 1983-01-07 1985-08-13 Tate & Lyle Public Limited Company Measuring the draft of a vessel
US4964437A (en) * 1989-12-15 1990-10-23 Energy Transportation Group, Inc. Apparatus and method for control of oil leakage from damaged tanker
US5121766A (en) * 1991-07-10 1992-06-16 Energy Transportation Group, Inc. System for control of oil leakage from damaged tanker
WO1993025433A1 (en) * 1992-06-15 1993-12-23 Den Norske Stats Oljeselskap A.S. Method for offshore loading of a tanker and construction of said tanker
US5385110A (en) * 1990-09-07 1995-01-31 Bennett Marine, Incorporated Of Deerfield Beach Boat trim control and monitor system
US6347461B1 (en) * 1999-12-07 2002-02-19 Northrop Grumman Corporation Portable draft measurement device and method of use therefor
US6836746B2 (en) 2002-04-01 2004-12-28 Control Stuff, Inc. Method and apparatus for calculating the payload on a water-borne vessel
US20130323005A1 (en) * 2012-06-03 2013-12-05 Conveyor Applicant Systems LLC System for conveying drill cuttings
CN106741706A (zh) * 2017-01-11 2017-05-31 江苏科技大学 一种船舶姿态及吃水测量装置及其测量方法

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113044176A (zh) * 2021-04-22 2021-06-29 中海油田服务股份有限公司 一种勘探船舶姿态和吃水的调整方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2751921A (en) * 1953-08-10 1956-06-26 Honeywell Regulator Co Control apparatus
US3128375A (en) * 1959-04-28 1964-04-07 Sintef Apparatus for calculation of depth, trim, bending moment and shearing stress in a loaded ship

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2751921A (en) * 1953-08-10 1956-06-26 Honeywell Regulator Co Control apparatus
US3128375A (en) * 1959-04-28 1964-04-07 Sintef Apparatus for calculation of depth, trim, bending moment and shearing stress in a loaded ship

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3922985A (en) * 1970-01-16 1975-12-02 Ferris F Hamilton Submarine tanker for transportation of liquid cargo
US3916811A (en) * 1974-08-29 1975-11-04 Sun Oil Co Pennsylvania Tide compensation system
US4347574A (en) * 1978-10-11 1982-08-31 Parsons Ward H Method of and apparatus for determining with precision the payload of a water borne vessel
US4534217A (en) * 1983-01-07 1985-08-13 Tate & Lyle Public Limited Company Measuring the draft of a vessel
US4964437A (en) * 1989-12-15 1990-10-23 Energy Transportation Group, Inc. Apparatus and method for control of oil leakage from damaged tanker
US5385110A (en) * 1990-09-07 1995-01-31 Bennett Marine, Incorporated Of Deerfield Beach Boat trim control and monitor system
US5121766A (en) * 1991-07-10 1992-06-16 Energy Transportation Group, Inc. System for control of oil leakage from damaged tanker
AU673363B2 (en) * 1992-06-15 1996-11-07 Den Norske Stats Oljeselskap A.S. Method for offshore loading of a tanker
WO1993025433A1 (en) * 1992-06-15 1993-12-23 Den Norske Stats Oljeselskap A.S. Method for offshore loading of a tanker and construction of said tanker
RU2122959C1 (ru) * 1992-06-15 1998-12-10 Ден Норске Статс Ольесельскап А.С. Способ загрузки танкера нефтью в открытом море и танкер для загрузки нефтью в открытом море
US6347461B1 (en) * 1999-12-07 2002-02-19 Northrop Grumman Corporation Portable draft measurement device and method of use therefor
US6836746B2 (en) 2002-04-01 2004-12-28 Control Stuff, Inc. Method and apparatus for calculating the payload on a water-borne vessel
US20130323005A1 (en) * 2012-06-03 2013-12-05 Conveyor Applicant Systems LLC System for conveying drill cuttings
US9169089B2 (en) * 2012-06-03 2015-10-27 Conveyor Application Systems Llc System for conveying drill cuttings
CN106741706A (zh) * 2017-01-11 2017-05-31 江苏科技大学 一种船舶姿态及吃水测量装置及其测量方法
CN106741706B (zh) * 2017-01-11 2019-02-26 江苏科技大学 一种船舶姿态及吃水测量装置及其测量方法

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Publication number Publication date
GB1029725A (en) 1966-05-18
SE342791B (enrdf_load_stackoverflow) 1972-02-21
NL6402719A (enrdf_load_stackoverflow) 1964-09-17

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