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
• • 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
  • B63B1/042—Hydrodynamic or hydrostatic features of hulls or of hydrofoils deriving lift mainly from water displacement with single hull the underpart of which being partly provided with channels or the like, e.g. catamaran shaped
• • 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
  • B63B1/063—Bulbous bows
• • 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

• This invention relates to a hull shape having a sharp bow and bulb, and a broad, essentially squarily cut off stern, in and below the design waterline, in which the waterline in the stern end of the hull is essentially perpendicular to the centre line of the hull shape and the waterline is shifted gradually toward the stern with increasing draught from the ground plane approximately midships, so that an approximate sloped plane positioned through the respective waterlines thwart ships make a broad end in the stern.
• a vessel of this type is described in European patent 0,134,767 (Ramde) .
• Ramde's solution comprises sinusoidal waterlines in the area between the bow and stern of the vessel. The sinusoidal lines stretching over half a period from the least separation defined by the minimum value of the sinusoidal shape to the largest separation defined by the maximum value by the vessels stern.
• the hull shape defined by Ramde's patent gives the vessel a number of advantages compared to conventional hull shapes, as it has been possible to improve the vessels dead weight tonnage, lateral stability, manoeuvrability and sailing characteristics and to reduce the strains on the hull beams both when sailing in quiet waters and against the waves.
• the performance of the hull shape according to the present embodiments of the inventions at sea is improved so that the pitch and heave properties of the hull is reduced when compared to the movements of conventional hulls, as well as the earlier Ramform hull. Also, these movements are damped so that the improved hull does not show such large movements, while the resistance to propulsion of the improved hull is reduced at the same time. Also, according to the invention, a very even, essentially homogeneous two dimensional water flow is obtained under the hull and passed the stern, resulting in very low turbulence and very smooth sailing. In addition the invention implies an improved position of the propulsion to take advantage of the smooth water flow. In Norwegian patent application 95.1511 Ramde has tried to improve these properties of the vessel even further.
• a hull according to the invention is provided with a sloped plane having an angle being under approximately 14 degrees between the basis line and the centre plane, and the a line stretching from the (squarily cut off) stern end to another point on the surface at 0.2-0.3L from the stern, L being the length of the ship at the waterline (dwl) .
• a bulb at the bow continuous to meet an upward tilting element essentially under the design waterline and extending close to the surface of the design waterline.
• a displacement type ship is provided with a hull according to the invention, having squarily cut off in the longitudinal direction and convex waterlines, and having at the bottom of the stern part a sloped plane between the basis plane and the stern, said sloped surface making an angle with the basic plane and extending tangentially into the base plane at approximately L/2, and the angle of the sloped surface is relative to the base plane and a line connecting a first point in a longitudinal section in parallel to or equal to the centre section at the lower edge of the straight ended stern, and another point in the same section as the first in the sloped plane at 0,2L.
• the angle of the sloped surface is 14°.
• a ship of the displacement type is provided with a hull according to the invention, having an essentially squarily cut off longitudinal and convex waterlines comprising a sloped plane at the bottom of the ship, formed between the base plane and the stern, the sloped plane extending tangentially into the base plane at approximately L/2.
• a ship of the displacement type is provided with a hull according to the invention, comprising squarily cut off longitudinal and convex waterlines comprising a sloped plane at the bottom of the ship, formed between the base plane and the stern, the sloped plane extending tangentially into the base plane at approximately L/2, with a bulb which at the cross section in the middle between the forward perpendicular and the a cross section through an upper part of the bulb has a larger breadth than hight and with a rounded upper surface and a V-shape down toward the base plane.
• the length of the bulb measured from the forward perpendicular up to the cross section corresponding to the upmost part of the bulb is in the range of 0.1 to 0.12 Bmax, and the cross section of the bulb in the middle of this length has a width/depth relationship being approximately 1.8.
• a ship of the displacement type is provided with a hull according to the invention, having an essentially squarily cut off longitudinal and convex waterlines comprising a sloped plane at the bottom between the base plane and the stern of the ship, the sloped plane extending tangentially into the base plane at approximately L/2.
• Figure 1 is a horizontal projection of a hull formed according to an embodiment of the invention.
• Figure 2 is an elevation of the hull according to figure 1.
• Figure 3 is an elevation of the bottom of the hull according to figure 1.
• Figure 4 is an elevation of a hull with two keels.
• Figure 5 illustrates the same hull shape as figure ty , as seen from the side.
• Figure 6 is an elevation of a hull according to a preferred embodiment of the invention.
• Figure 7 illustrates the same hull shape as figure 6 in a horizontal projection.
• Figure 8 illustrates the hull shape in figures 6 and 7 as seen from one side.
• a hull 10 is provided having more rounded lines than conventional hull shapes, which is evident from the expression for the length/displacement ratio L/V 13 , where L is the length of the hull at the design waterline (dwl) corresponding to the depth at summer free board (see figure 2) and V is the displacement volume of the hull at the design waterline.
• L/V 13 is 3,7 or lower.
• this embodiment results in a hull width being such that the L/B ratio is between 2 and 2.5.
• the preferred ratio has been found to be approximately 2.1.
• B is the maximum width of the hull at the stern by the design waterline (dwl) .
• the height of the metacentre of the hull 10 is in this embodiment multiplied relative to the conventional hull shapes having the same length.
• the displacement distribution in the longitudinal direction becomes an approximate Rayleigh distribution.
• This type of distribution is obtained in the present embodiment with the essentially squarily cut off convex waterlines (figure 3: dwl, 1,2, 3) with extreme or stationary points 12 and 14 at the ends of the hull both afore and astern, while the basis lines for the waterlines (0 dwl , 0 X , 0 2 , 0 3) from (G) is shifted astern with increasing draught so long that an essentially sloped plane (S) , which may be straight, is defined.
• the plane (S) further comprises the stern half of the hull 10 and allows for the use of different propulsion means or positioning devices.
• a ratio Bl/tl is defined at a cross section through the hull 10 under the design waterline (dwl) at a distance 0.15L from the stern, where Bl is the width an the design waterline (dwl) and tl is 25%T of the draught (T) measured from the same water line. According to this embodiment the ratio Bl/tl approximately equals 18.
• the hull parameter e equals approximately 1.1 or less.
• LCF - LCB 0.083 L.
• Figure 2 shows an embodiment of the hull according to the invention under the design waterline (dwl) in a vertical section in which it is shown that the base lines is essentially squarily cut off.
• convex waterlines (O dwl , C 0 2 , 0 3 ) along a sloped, essentially plane surface (S) being combined with the base plane (G) at approximately L/2, and being astern with increasing draught.
• the distance between the area centre of gravity (LCF) and the buoyancy centre (LCB) for the hull 10 at the depth of the design waterline (dwl) is approximately equal to 0.083L.
• the essentially plane surface (S) is in some embodiments a curved surface with a very large radius .
• FIG 3 the hull shape of figure 2 is shown in a horizontal projection with the waterlines dwl, 1,2,3 and G in the example with a triangular shape 9 afore in the ship.
• Figures 4 and 5 illustrates an embodiment of the invention comprising two skegs or keels 300. These keels contributes in stabilizing the roll and pitch movements and increasing the directional stability and displacement of the ship, and also provides a possibility for laying the whole ship in the keels in dock, e.g. for maintenance. The arrangement of the keels will especially, when the ship is at rest, contain a large volume of water in addition to the displacement of the ship. This increased mass will substantially reduce the roll and pitch movements of the ship. As is evident from figure 5 the keels 300 will preferably stretch in the vertical direction down to the base plane G. In figure 5 the vessel is also provided with a tongue shaped bulb 100 of a per se known type.
• the keels 300 stretches astern to a position in front of the ship propellers.
• the keels preferably ends at a distance from the stern corresponding to approximately 4-7% of the ship length. Preferably 5%, but this will to some degree depend on the steering and propulsion systems of the vessel.
• Figures 6, 7 and 8 show an especially preferred embodiment of the hull 10 according to the invention, and which, with proper scaling of the drawings, is the basis of the prototype of the hull being tested. In the figures the hull also has a bulb 100.
• Figure 6 shows the bow part of the hull in perspective using frame profiles and waterlines
• figure 7 illustrates, using waterlines, the hull as a whole
• figure 8 shows a side elevation of the hull with longitudinal profiles.
• the hull 10 is shown with keels 300, in a manner similar to figure 5.

Priority Applications (1)

Applications Claiming Priority (2)

Publications (1)

Family

ID=19902277

Family Applications (2)

Family Applications Before (1)

Country Status (3)

Cited By (2)

Families Citing this family (4)

Citations (2)

Family Cites Families (1)

• 1998
  • 1998-07-21 NO NO983369A patent/NO983369L/no not_active Application Discontinuation
• 1999
  • 1999-07-16 WO PCT/NO1999/000239 patent/WO2000007873A1/no not_active Application Discontinuation
  • 1999-07-16 AU AU56582/99A patent/AU5658299A/en not_active Abandoned
  • 1999-07-16 WO PCT/NO1999/000238 patent/WO2000007872A1/no active Application Filing
  • 1999-07-16 AU AU56583/99A patent/AU5658399A/en not_active Withdrawn

Patent Citations (2)

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events