US3362369A - Form of the hull of a low speed, full form ship - Google Patents

Form of the hull of a low speed, full form ship Download PDF

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Publication number
US3362369A
US3362369A US539166A US53916666A US3362369A US 3362369 A US3362369 A US 3362369A US 539166 A US539166 A US 539166A US 53916666 A US53916666 A US 53916666A US 3362369 A US3362369 A US 3362369A
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United States
Prior art keywords
hull
condition
ship
ballasted
full
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Expired - Lifetime
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US539166A
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English (en)
Inventor
Taniguchi Kaname
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MESSRS MITSUBICHI JUKOGYO KABU
MESSRS MITSUBICHI JUKOGYO KK
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MESSRS MITSUBICHI JUKOGYO KABU
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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 
    • B63B1/00—Hydrodynamic or hydrostatic features of hulls or of hydrofoils
    • B63B1/02—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement
    • B63B1/04—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement with single hull
    • B63B1/06—Shape of fore part
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T70/00—Maritime or waterways transport
    • Y02T70/10—Measures concerning design or construction of watercraft hulls

Definitions

  • the hull has forward and after perpendiculars and a bottom, and the portion of the fore edge of the stem intersecting the water surface in the loaded condition projects rearwardly of the portion of a substantially vertical fore edge of the stem intersecting the water surface in the ballasted condition, by a substantial distance which is between 2% and 5% of the length between the forward and after perpendiculars.
  • the full form ship is designed to have a block coefficient of at least 0.75 and a Froude number of less than 0.2 in the loaded condition, with the fore draft in the ballasted condition being between 30% and 50% of the fore draft in the loaded condition.
  • the forward perpendicular is located rearwardly of that point on the fore edge of the stem which is at a height from the bottom of the hull of between 40% and 60% 'of the loaded fore draft.
  • This invention relates to ship hulls and, more particularly, to a novel hull for a slow speed, full form ship, such as a tanker, a bulk carrier, an ore carrier, etc., having a block coefficient in excess of about 0.75 and a Froude number less than 0.2, operating as frequently in the ballasted condition as in the full load condition, but infrequently in an intermediate or partially loaded condition.
  • ballasted condition is fully as important as the full load condition. Consequently, it is highly desirable to provide, in the case of full form ship of the mentioned types, a hull having improved performance, with respect to propulsion in both the ballasted and the full load conditions of the ship.
  • a so-called bulbous bow is known.
  • a bulbous bow is provided for preventing, though not fully, a bow wave from arising.
  • the case of a tanker or a bulk carrier however, the
  • the hull resistance of a ship consists of wave making resistance and viscous resistance.
  • the wave making resistance depends on the mutual interference of wave systems arising chiefly at a bow, a forward shoulder, an after shoulder, and a stem.
  • the so-called Froude number is used as a measure of the relative speed of a ship, defined by taking into consideration the wave making resistance. The reason for this is that the Froude number is physically significant in indicating a degree of the interference among wave systems arising at the above-mentioned parts.
  • a cylindrical section and a run or stern section may be determined so that the designed displacement and length can be obtained taking into account the initially designed entrance section.
  • designing of a hull in accordance with the hullform separation principle of the present invention requires far less data on systematic tests for the best possible hull shape than does the conventional design procedure in which wave making resistance is considered dependent upon the mutual interference of wave systems arising chiefly at a bow, a forward shoulder, an after shoulder, and a stern. It has been confirmed by the results of trial runs that the propulsive resistance of the best hull shape obtained by the present invention is, on an average, less than that obtained by the conventional design method when hulls having the same dead weight tonnage and designed for operation at the same speed are compared.
  • the design according to the hull-form separation principle was used first to improve the propulsive performance in the full load condition.
  • the propulsive performance in the ballasted condition was not improved as much as the full load condition.
  • the speed in the ballasted condition is generally 1.0 to 1.2 knots greater than the speed in the full load condition.
  • the propulsive performance of which was substantially improved in the full load condition the difference in speed in the both conditions was equal to only about 0.6 knot.
  • an entrance in the ballasted condition must be longer than an entrance in the full load condition.
  • an object of the present invention is to provide a hull for a slow speed, full form ship which has a maximum propulsive performance in both the fully loaded condition and the ballasted condition without raising the construction cost of the ship.
  • Another object of the invention is to provide a hull for low speed, full form ships which has a novel form of entrance providing maximum propulsive efficiency in both the fully loaded condition and in the ballasted condition.
  • a further object of the invention is to provide a hull for a low speed, full form ship in which the entrance, in the ballasted condition, is substantially longer than the entrance in the fully loaded condition.
  • Yet another object of the invention is to provide a hull for a low speed, full form ship, as thus described, in which, when the fore draft in the ballasted condition is 0.4 to 0.6 the loaded draft, the forward perpendicular is situated behind the point where the approximately vertical forward edge of the stem intersects the water surface by from 22 to 5% of the length between perpendiculars.
  • FIG. 1 is a partial side elevation view of the fore part of the hull of a ship illustrating the comparison between a hull shape in accordance with the present invention and a conventional hull shape;
  • FIG. 2 is a plan view of water lines of the hull section shown in FIG. 1 in both the fully loaded and the ballasted condition;
  • FIG. 3 is a diagram illustrating a comparison of the propulsive performance of a hull in accordance with the present invention and a conventional hull;
  • FIG. 4 is a schematic plan view of the conventional hull form of a low speed, full form ship
  • FIG. 5 is a graph diagrammatically illustrating, in the case of a tanker, the relation between speed and wave making resistance
  • FIG. 6 is a graph diagrammatically illustrating the results of studies upon which the present invention is based.
  • a low speed, full form ship is schematically shown in plan as generally comprising three parts. These parts are a cylindrical part 01 whose cross sectional shape is substantially constant, an entrance or prow section 02 and a run or stern section 03. The junctions of the cylindrical part 01 with the entrance and run sections are called, respectively, a forward shoulder 04 and after shoulder 05. As mentioned above, wave making resistance hitherto has been regarded as dependent upon the mutual interference of wave systems arising chiefly at the bow 06, forward shoulder 03, after shoulder 05 and stern 07.
  • wave making resistance is noticeable substantially only at the entrance section 02 but is negligible at the run or stern sections 03 as Well as along the cylindrical part 01, and the interference of such wave resistances is also negligible.
  • FIG. 5 the relation between speed and wave making resistance in the case of a 67,000 d.w.t. tanker is shown.
  • Four kinds of points are plotted, indicating the results of resistance tests of four large-size model ships which differ respectively from each other in the shape of their run sections but which have similar entrance sections.
  • values indicating the wave making resistance of the several ships are substantially equal to one another. This indicates that wave making resistance depends substantially only on the entrance section.
  • FIG. 6 Data from the research, upon which the present invention is based, are shown, by way of example, in FIG. 6.
  • the abscissae represent the degree of fullness of entrance expressed non-dimensionally
  • the ordinates represent a length d which is equal to the difference in length when an entrance in the ballasted condition is made longer than the entrance in the fully loaded cndition so that the speed in the ballasted condition may be, at the normal output of a main engine, as much as one knot higher than that in the full load condition. It is assumed that a ratio m of displacement in the ballasted condition to that in the full load condition is equal to 0.5.
  • FIG. 1 an entrance of a ship having ahull designed in accordance with the present invention is indicated at 1 in full lines.
  • a broken line 2 and a dash dot line 3 indicate parts of conventional entrance sections.
  • the full line 1a represents that water line of a hull designed in accordance with the present invention and corresponding to a load water line 4 such as shown in FIG. 1.
  • Full line 1b represents that water line of a hull designed in accordance with the present invention corresponding to a ballasted water line 5 when the hull is trimmed by the stern.
  • the broken line 2b of FIG. 2 represents the water line of the conventional entrance section 2, shown in FIG. 1, corresponding to the ballasted water line 5.
  • the dash dot line 3a of FIG. 2 represents that water line of the conventional entrance 3, shown in FIG. 1, corresponding to the load water line 4.
  • the lower part of the fore edge of the stem coincides with the dash dot line 3.
  • An upper part of the fore edge of the stern represented by a curve running from point F to point A where the fore edge intersects the load water line 4, coincides with the broken line 2 indicating a conventional hull shape.
  • An intermediate part of the fore edge of the stem is shown by the combination of two fair curves, one of which runs from point A to point B while the other of which runs from point B to point C.
  • a hull in accordance with the present invention may be obtained, based on the conventional hull form 3, by moving backward, by a distance d, that part of the entrance which is situated above the load water line 4.
  • the distance d is chosen to be from 2% to 5% of the length Lpp between perpendiculars, and the height h from the bottom of the ship to the point C is fixed to be 0.4 to 0.6 times as much as the load draft H. The reason for the selection of these values will be apparent hereinafter.
  • a double or dual entrance consisting of an upper entrance and a lower entrance which differ in length from each other. It has been proven by tank tests, conducted using a large-sized model ship, that, using a dual entrance, any interference between the upper entrance and the lower entrance was substantially non-existent, and that desirable characteristics for both the loaded condition and the ballasted condition were maintained. By way of example, data of these tests are indicated hereinafter.
  • the shaft horsepower is represented on one coordinate axis and the speed on the other.
  • This diagram shows the propulsive performances in the fully loaded and in the ballasted conditions, with the performances of a hull designed in accordance with the present invention being compared with those of a conventionally designed hull.
  • the performance of the hull designed in accordance with the present invention is illustrated by the curves 1 shown in full lines, assuming that a is 4% of Lpp.
  • the performance of a conventionally designed hull is shown by broken lines 2 and dash dot lines 3, respectively.
  • the value d has been determined to be from 2 to 5% of the length beween perpendiculars. If the distance d is smaller than 2%, then the aimed effect of the present invention is not appreciable. Also, if d is larger than 5%, then the buoyancy of the hull part below the load water line is gradually increased. Accordingly, the hull portions near point A have to be reinforced so as to withstand the increased buoyancy. As a result, a decrease in the hull weight or a reduction of the material required cannot be obtained, while the cost of the ship increases. Moreover, the longer the horizontal distance from the point A to the point C, the less the usefulness of the ship becomes because of difficulties in maneuvering and docking the ship.
  • the fore edge CD of the stern in the ballasted condition, extends perpendicularly as shown in FIG. 1.
  • the fore edge may assume the form of either a straight line inclined at a small angle to the vertical or a smooth curve radius of whose curvature is large.
  • a hull for a low speed, full form ship having forward and after perpendiculars, a stem including a fore edge having a substantially vertical portion, and a bottom; the portion of the fore edge of said stem intersecting the water surface in the loaded condition projecting rearwardly of the substantially vertical portion of the fore edge of said stern, which intersects the water surface in the ballasted condition, by a substantial distance.
  • a hull for a low speed, full form ship as claimed in claim 1, in which said forward perpendicular is located rearwardly of that point on the fore edge of said stem which is at a height from said bottom of between 40% and 60% of the loaded fore draft by a distance of between 2% and 5% of the length between said perpendiculars; the portion of the fore edge of said stem extending downwardly from said point being substantially vertical.
  • a bull for a low speed, full form ship as claimed in claim 7, in which said ship operates only in the loaded condition on in the ballasted condition, and has a block coefficient of at least 0.75 and the Froude number, in the loaded condition, of less than 0.2; the fore draft in the ballasted condition being between 30% and 50% of the fore draft in the loaded condition.
  • a hull for a low speed, full form ship having forward and after perpendiculars, a stem and a bottom; said ship having a block coefficient of at least 0.75 and a Froude number, in the loaded condition, of less than 0.2 and operating only in the loaded condition or in the ballasted condition; the fore draft in the ballasted condition being between 30% and 50% of the fore draft in the loaded condition; said forward perpendicular being located rearwardly of that point on the fore edge of said stern which is at a height from said bottom of between and of the loaded fore draft, by a distance of from 2% to 5% of the length beween said perpendicular-s; the portion of the fore edge of said stem extending downwardly from said point being substantially vertical.

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  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • Ocean & Marine Engineering (AREA)
  • Placing Or Removing Of Piles Or Sheet Piles, Or Accessories Thereof (AREA)
  • Vibration Prevention Devices (AREA)
  • Silicon Compounds (AREA)
  • Other Liquid Machine Or Engine Such As Wave Power Use (AREA)
US539166A 1965-04-08 1966-03-31 Form of the hull of a low speed, full form ship Expired - Lifetime US3362369A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP40020782A JPS5112915B1 (pl) 1965-04-08 1965-04-08

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US3362369A true US3362369A (en) 1968-01-09

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US (1) US3362369A (pl)
JP (1) JPS5112915B1 (pl)
GB (1) GB1126372A (pl)
NL (1) NL148841B (pl)
NO (1) NO127699B (pl)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3443544A (en) * 1967-07-13 1969-05-13 Vladimir Nikolaevich Begizov Shape of ship's bow
US3455262A (en) * 1967-11-14 1969-07-15 Schiffswerft Neptun Rostok Veb Bulbous bow construction of a vessel
US3653352A (en) * 1969-05-16 1972-04-04 Nippon Kokan Kk Hull form of a ship provided with a cylindrical bow
EP1855937A4 (en) * 2005-03-09 2011-08-17 Ulstein Design As PREVENTION ARRANGEMENT FOR A DISPLACEMENT SHIP
US9908589B1 (en) 2016-04-26 2018-03-06 Stephen Lee Bailey Hull shape for improved powering and seakeeping

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3180299A (en) * 1960-02-01 1965-04-27 Inui Takao Ship hull form
GB1033968A (en) * 1962-08-09 1966-06-22 Algonquin Shipping & Trading Low resistance, high block coefficient hull form
US3302603A (en) * 1963-10-15 1967-02-07 Exxon Research Engineering Co Ship's hull construction
US3306243A (en) * 1964-09-17 1967-02-28 Exxon Research Engineering Co Cargo ship hull

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3180299A (en) * 1960-02-01 1965-04-27 Inui Takao Ship hull form
GB1033968A (en) * 1962-08-09 1966-06-22 Algonquin Shipping & Trading Low resistance, high block coefficient hull form
US3302603A (en) * 1963-10-15 1967-02-07 Exxon Research Engineering Co Ship's hull construction
US3306243A (en) * 1964-09-17 1967-02-28 Exxon Research Engineering Co Cargo ship hull

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3443544A (en) * 1967-07-13 1969-05-13 Vladimir Nikolaevich Begizov Shape of ship's bow
US3455262A (en) * 1967-11-14 1969-07-15 Schiffswerft Neptun Rostok Veb Bulbous bow construction of a vessel
US3653352A (en) * 1969-05-16 1972-04-04 Nippon Kokan Kk Hull form of a ship provided with a cylindrical bow
EP1855937A4 (en) * 2005-03-09 2011-08-17 Ulstein Design As PREVENTION ARRANGEMENT FOR A DISPLACEMENT SHIP
EP2530008B1 (en) 2005-03-09 2017-04-05 Ulstein Design & Solutions AS A vessel with an improved foreship arrangement
US9908589B1 (en) 2016-04-26 2018-03-06 Stephen Lee Bailey Hull shape for improved powering and seakeeping

Also Published As

Publication number Publication date
NO127699B (pl) 1973-08-06
GB1126372A (en) 1968-09-05
NL6604796A (pl) 1966-10-10
NL148841B (nl) 1976-03-15
JPS5112915B1 (pl) 1976-04-23
DE1506189A1 (de) 1969-10-30

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