US3548772A - Shape of the stern for a very large ship - Google Patents

Shape of the stern for a very large ship Download PDF

Info

Publication number
US3548772A
US3548772A US752564A US3548772DA US3548772A US 3548772 A US3548772 A US 3548772A US 752564 A US752564 A US 752564A US 3548772D A US3548772D A US 3548772DA US 3548772 A US3548772 A US 3548772A
Authority
US
United States
Prior art keywords
ship
propeller
hull
stern
line
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US752564A
Other languages
English (en)
Inventor
Kinya Tamura
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Mitsubishi Heavy Industries Ltd
Original Assignee
Mitsubishi Heavy Industries Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Mitsubishi Heavy Industries Ltd filed Critical Mitsubishi Heavy Industries Ltd
Application granted granted Critical
Publication of US3548772A publication Critical patent/US3548772A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • 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
    • B63B1/08—Shape of aft 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 length of [54] ii fi ggg fi mg A VERY LARGE SHIP the inclined section amounts to about 10 to 20 percent of the length between the forward and after perpendiculars of the [52] US. 114/57 ship.
  • the propeller shaft extends through the hull above the [51] I t. (I B63b 1/08 inclined bottom and the path of travel of the propeller blades [50] Field ofSeu-ch 1 14/57 is above the prolongation of the line of the inclined bottom.
  • the present invention is directed to the shape of the stern of a very large ship in the range of 200,000-500,000 d.w.t. and, more particularly, it is directed to the configuration of the bottom of the ship at the stern.
  • the propeller In the case of normal-sized ships, as a rule, the propeller is located as far below the surface of the water as possible in order to avoid the propeller intersecting the surface of water in the ballaste'd condition.
  • a main engine of large capacity it is necessary to increase the rake angle of the propeller shaft, particularly, where an aft engine is employed
  • the propeller of such a large ship is designed, its propulsive efficiency, which consists of a hull efficiency and.
  • the primary object of the present invention is to provide a large ship in the 200,000-500,000 d.w.t. range with a shaped bottom at its stern end which will increase the hull efficiency while decreasing its construction cost.
  • 'Another object of the invention is to provide the ship with an upwardly inclined bottom at its stem end.
  • the inclined portion of the bottom is arranged to extend from a point in the vicinity of the forward end of the engine room to the stern.
  • the propeller shaft is arranged to pass through the hull of the ship at a point above its inclined bottom with the blades of the propeller traveling in a path located above the prolongation of the line of the upwardly inclined bottom of the ship.
  • Still another object of the invention is to locate the propeller relative to the bottom of the ship so that it is sufficiently high enough to be disposed in the zone of the following wake. In this way the following wake can be utilized to increase the propulsion performance of the ship even though the propeller is too small for the hill.
  • the engine room is reduced in length which decreases the required volume and results in lowered construction costs.
  • the sagging moment of the ship in its loaded condition is reduced due to the decrease in the volume in the engine room and, further, the submerged depth of the hull is diminished which shortens the water line length of the ship and thereby effects a reduction in both its eddy resistance and its reference length.
  • Another object of the invention is to incline the propeller shaft upwardly relative to the base line of the ship. In this way the height of the double bottom required for the support of the engine is reduced and the construction costs of the ship are cut down.
  • a further object of the invention is to employ a direction stabilizing plate along the upwardly inclined bottom of theship to increase its stability and to reduce the area of the rudder which also contributes to a more economical construction for the ship.
  • the present invention is directed to a large-sized single screw ship in the 200,000-500,000 d.w.t. range, in which the bottom of its hull at the stem end is inclined upwardly from a position spaced a considerable distance. forwardlyof the stern.
  • the point at which the bottom of the ship commences to be inclined upwardly is located near the forward end of the engine room and extends for a length of approximately 10 percent to 20 percent of the length between the forward and after perpendiculars of the ship.
  • the propeller shaft extends through the hull of the ship above its inclined bottom and the radially outer edges of the propeller blades are located in a path of travel positioned above the prolongation of the upwardly inclined line of the bottom of the ship.
  • a direction stabilizing plate is provided along the upwardly inclined bottom to the stern of the ship. Further, a shoe piece for the ship's rudder can be secured to the direction stabilizing plate. Moreover, an auxiliary section of the direction stabilizing plate can be fixed to the hull rearwardly of thepropeller and above the rudder.
  • FIG. 5 is a schematic side view of a stern of a very large ship in the 200,000-500,000 d.w.t. range;
  • FIG. 6 is a view taken along line A-A in FIG. 5 showing the contour curves of the following wake of the ship;
  • FIG. 7a is a schematic side view of the stern of a conventional type ship having a bottom in accordance with the present invention.
  • FIG. 7b is a view ofthe buttock line of the ship shown in FIG. 7a;
  • FIG. 70 is a body plan of the rear half of the ship shown in FIG. 7a;
  • FIG. 8d, 8e and 8f are views similar to FIG.'8a, 8b and 8c exhibiting another ship of the Mariner-type;
  • FIG. 9a is a schematic side view of the stern of a ship similar to that shown in FIG. 5, however, disclosing another embodiment of the present invention.
  • FIG. 9b and 9c are views similar to 7b and 7c;
  • FIG. 10 is a sectional view taken along line 3-8 in FIG. 9;
  • FIG. 11 is a sectional view taken along the line C-C in FIG. 9-
  • FIG. 12 is a schematic side view of still another embodiment of the present invention.
  • FIG. 13 is a sectional view taken along line D-D in FIG. 12;" and FIG. 14 is a graphical illustration of the comparison of tank tests made on two models, one embodying the present invention.
  • FIG. 1 the stern of a conventional ship is illustrated com-.-.
  • the upper half of the full line 017 has a configuration generally similar to that shown for the stern of the ship in FIG. 1, however, the lower portion of the full line, that is, extending below the propeller shaft 05 diverges away from the propeller 04 providing a wider space than that indicated in FIG. 1.
  • the diameter D of the propeller is in the range of 50-70 percent of the full draft d of the ship. If, while under propulsion, the propeller 04 intercepts the surface of the water the propulsion efficiency of the ship is reduced. When such a condition exists the intake of air into the propeller causes it to idle. Further, solid objects floating on the surface of the water may damage the propeller. Accordingly, it is usually desirable to locate the propeller as far below the surface of the water as is possible in order to avoid the occurrence of such defects even in the ballasted condition.
  • the propeller is connected through a propeller shaft 05 to the main engine and, if the main engine of such a relatively large capacity it may not be possible to install it normally within the hull.
  • the propeller shaft is inclined rearwardly and downwardly at an angle 0, with respect to the horizontal line 05, as shown in FIG. 1, which permits the installation of the main engine, though usually the propeller shaft 07 is positioned in parallel relationship with the base line 06 of the ship.
  • the rake angle 0, of the propeller shaft 05 is about 2 (35/1000 in grade) and is especially large in the cases of aft engine ships, such as tankers and ore carriers.
  • the value of 1, is usually about 2 percent of the distance L that is, the distance between the forward and after perpendiculars.
  • the water line length L equals I. plus 1 it is adopted as the reference length of the hull construction and has to be reduced as much as possible in order to reduce the construction costs. In most instances 1, is fixed at a value below 2 percent.
  • the ratio of D/d that is, the diameter D of the propeller to the the draft d of the ship is reduced to about 40 percent or less by increasing the draft.
  • the height of the main engine is small relative to the size of the hull, then owing to the large draft of the vessel an unoccupied space is left above the engine.
  • the holds of the ship become far heavier than that of the engine room, and the sagging moment of the hull is increased.
  • the propeller 04 and its shaft 05 are located as far below the load draft line as possible, see FIG. 5 in order to make the height of the engine bed from the base line as low as possible from the view point of the reduction of construction cost.
  • the contour curves 012 show the equiwake lines and the numerals described on the curves show the values 'of wake, which are measured on the plane perpendicular to the center line of the hull at the propeller position.
  • wake is defined by where V, is ship speed, and V, is longitudinal component of local water speed relative to the ship.
  • dash lines 014 indicate the direction of a streamline in a plane perpendicular to the center line of the hull.
  • FIGS. 7a to 13 Embodiments of the present invention are illustrated in FIGS. 7a to 13.
  • FIG. 7a a conventional type stern of a single screw ship utilizing an aft engine is shown.
  • the bottom of its main hull is inclined upwardly from a point 4 near the forward end 3 of the engine room 2.
  • the forward end 3 of the engine room is positioned forwardly of the after perpendicular AP by approximately l020 percent of L,,,,.
  • the angle a of the upgrade of the bottom of the ship is in the range of 2l0.
  • the sloping portion of the bottom of the ship between the point 4 and the line AP, corresponding to the axis 7 of the rudder 6, is shown as a straight line or it may be a slightly curved line.
  • a propeller shaft 8 can be provided along the horizontal line 10, which is parallel with the base line 5 of the ship, and extends through the center of the propeller, or it may be inclined rearwardly and upwardly with respect to the horizontal line 10.
  • the tangent of the angle B of the upgrade is in the range of 10/ l000--60/ 1000.
  • the propeller 9 Because of the inclined bottom of the ship the propeller 9 is raised relative to the water level and is moved into a region in which the value of the following wake is greater, and, as a result, the propulsive performance of the ship is improved. Further, with the upward displacement of the propeller its shaft is also raised and, therefore, the engine can be shifted closer to the stern since a sufficient space is afforded between the engine and the walls of the engine room/Accordingly, the engine room can be decreased in length and the height of its double bottom reduced due to the upward inclination of the bottom. These changes in the construction of the ship effectively reduce its cost. Since the position of the engine within the ship is elevated the space above it is reduced and the sagging moment of the ship in its loaded condition is decreased.
  • FIG. 8a a ship having a Mariner-type stem is illustrated, and the stern portion of its bottom is shaped in accordance with the present invention.
  • the bottom of hull 1a is inclined upwardly from the forward end of the engine room, not shown, and is disposed in diverging relationship with the base line So toward the stern of the ship.
  • the line 7a corresponds to the after perpendicular AP, and also operates as the axis of the rudder 6a.
  • a propeller 9a extends rearwar'dly from the hull and is located above the prolongation of the upwardly sloping bottom of the ship indicated by the line 19a. Similar to the showing in FIGS. 2a and 2b, the stems of the ships in FIGS.
  • FIG. 8a and 8d have different configurations, one is shown by full lines 170 in FIG. 8a, in which the lower portion is more widely spaced from the propeller than its upper portion, and the other is shown in full lines 18a, in FIG. 8d disclosing the so-called bulbous stern.
  • FIGS. 8b and 8c and 8e and 8f show further illustrations of the aft portions of the ships illustrated in .FIG. 8a and 8d, respectively indicating the buttock line and body plan of the rear half of the hull.
  • the bottom of the stern portion of the ship disclosed in FIG. 80 is shaped in accordance with the present invention.
  • a direction or course stabilizing plate 12 is positioned along the upwardly inclined bottom of the ship 11.
  • the inclination of the bottom of the ship 1 1 is similar to that previously'described.
  • the direction stabilizing plate 12 is shown extending to the rear end of the shoe piece 13 for the rudder 14, while the embodiment shown in FIG. 12 has the direction stabilizing plate 12 extending rearwardly of the shoe piece to the after end of the rudder 17.
  • an auxiliary stabilizing plate 15 is provided on the hull above the rudder.
  • a propeller 16 is disposed betweenthehull and the rudder.
  • direction stabilizing plate 12 By means of the direction stabilizing plate 12 the stability of a large-sized ship is maintained and a decrease in the size of the rudder is achieved.
  • the direction stabilizing plate as reinforcement for the shoe piece 13the shoe piece itself becomes stronger and more simple in construction.
  • Another advantageous feature of the direction stabilizing plate 12 is its use in placing the hull in a ship building berth or as a supporting member for the hull in a dry dock.
  • FIGS. 10 and 11 the arrangement of the direction stabilizing plate 12 is shown along the bottom ofthe hull and with relationship to the shoe piece 13 below the rudder 14.
  • FIG. 14 the results of tank testsare shown which were performed to prove the advantages of the present invention.
  • the bottom of the ship has an inclined upgrade of 3.5%! with the point of inclination commencing forwardly of the after perpendicular by a distance of about 15 percent of the total length between the after and forward perpendiculars.
  • an aft engine is disposed upwardly toward the stern so that the propeller shah passes through the hull above the inclined portion of the bottom.
  • the propeller shaft is lifted and space is provided between the engine and the walls of the engine room.
  • the direction stabilizing plate which permits very large ships in the200,000--500,00 0 d.w.t. range, to be maintained on course, and in a stable condition with rela- -tive ease while reducing the-rudder costs, As mentioned previously the direction stabilizing plate is also useful in supporting the ship during construction or when it is located in dry dock.
  • a large-sized single screwship comprising a hull having a I stem end, the bottom of said hull being inclined upwardly to its stem end from a location spaced forwardly from the stem end, a propeller shaft extending through said hull at its stem end, and a propeller mounted on said shaft with the radially outer dges of the blades of said propeller located in a path of 3.
  • a ship according to claim 1. wherein the bottom of said 7 hull is inclined upwardly from a point forward of the after'perpendicular for a distance ranging between 10 percent to 20 percent of the length between its perpendiculars.
US752564A 1967-08-30 1968-08-14 Shape of the stern for a very large ship Expired - Lifetime US3548772A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP5516267A JPS47940B1 (de) 1967-08-30 1967-08-30

Publications (1)

Publication Number Publication Date
US3548772A true US3548772A (en) 1970-12-22

Family

ID=12991032

Family Applications (1)

Application Number Title Priority Date Filing Date
US752564A Expired - Lifetime US3548772A (en) 1967-08-30 1968-08-14 Shape of the stern for a very large ship

Country Status (8)

Country Link
US (1) US3548772A (de)
JP (1) JPS47940B1 (de)
DE (1) DE1781128C3 (de)
FR (1) FR1577059A (de)
GB (1) GB1206209A (de)
NL (1) NL142363B (de)
NO (1) NO127337C (de)
SE (1) SE351606B (de)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3898946A (en) * 1972-09-29 1975-08-12 Jan Zadrozny Sea-going high-commercial-speed displacement vessel
CN113799914A (zh) * 2021-10-29 2021-12-17 广州文冲船厂有限责任公司 一种船艉结构及船舶

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP6718546B1 (ja) * 2019-06-25 2020-07-08 ゴールドウィン シッピング リミティッド 船舶

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3898946A (en) * 1972-09-29 1975-08-12 Jan Zadrozny Sea-going high-commercial-speed displacement vessel
CN113799914A (zh) * 2021-10-29 2021-12-17 广州文冲船厂有限责任公司 一种船艉结构及船舶
CN113799914B (zh) * 2021-10-29 2023-01-06 广州文冲船厂有限责任公司 一种船艉结构及船舶

Also Published As

Publication number Publication date
FR1577059A (de) 1969-08-01
DE1781128C3 (de) 1974-01-31
SE351606B (de) 1972-12-04
NO127337C (no) 1979-06-26
GB1206209A (en) 1970-09-23
NL6812437A (de) 1969-03-04
DE1781128B2 (de) 1973-07-05
DE1781128A1 (de) 1971-07-29
NL142363B (nl) 1974-06-17
JPS47940B1 (de) 1972-01-11
NO127337B (de) 1973-06-12

Similar Documents

Publication Publication Date Title
US4756265A (en) High speed boat lifting structures
US4550673A (en) Hull construction for seagoing vessels
US4903626A (en) Planing motor boat hull
JP3660683B2 (ja) 水面航行器
US6213824B1 (en) Method for reducing vessel draft
US4478166A (en) Boat
US5443026A (en) Boat hull with aft planing members
AU2022203357A1 (en) Inflatable motor boat
US3651775A (en) Hydrofoil system
US3548772A (en) Shape of the stern for a very large ship
CN111017129A (zh) 一种抗摇及加强航向稳定性的全回转拖轮
US4843993A (en) Ship having a stern screw and a method of operating the ship
US20080070455A1 (en) Boat hull structure
US3450090A (en) Hull form for boats
TW200925051A (en) Vessel provided with a foil situated below the waterline
US5317982A (en) Ship
US1088226A (en) Apparatus for traversing water or other fluid mediums.
CN113799914A (zh) 一种船艉结构及船舶
JP2812686B2 (ja) 滑水式双胴船
US2127475A (en) Ship's stern
US3550550A (en) Ocean-going barge
CN219948479U (zh) 节能提速船舶
US4563968A (en) Boat with improved hull
JPS6015750Y2 (ja) ノズル付き船舶
US20220250717A1 (en) Pontoon boat with hull extension