Europaisches Patentamt J European Patent Office © Publication number: 0 678 445 A1 Office europeen des brevets

EUROPEAN PATENT APPLICATION

© Application number: 95105964.1 © Int. CI.6: B63B 1/04

@ Date of filing: 21.04.95

® Priority: 21.04.94 US 230640 Rogestien No. 4 N-3189 Horten (NO) © Date of publication of application: 25.10.95 Bulletin 95/43 0 Representative: Altenburg, Udo, Dipl.-Phys. et © Designated Contracting States: ai DE DK GB NL Patent- und Rechtsanwalte Bardehle Pa9enberg Dost Altenburg © Applicant: PETROLEUM GEO-SERVICES AG " . . . Drammensvn. 302 Frohwitter . Geissler & Partner, N-1324 Lysaker (NO) Postfach 86 06 20 @ Inventor: Ramde, Roar D-81633 Munchen (DE)

© configuration.

© A new hull configuration providing provided with a slope surface forming an angle of for homogenous flow of water under the stern includ- below about 14° between the base line of the ing side-hull bulges that are relatively constant in near mid-ship and a line extending from that point to size from the bow to mid-ship and tapering off to another point on the surface to about 0.2L from the about zero at the stern. Additionally, the hull is stern, where L is the length of the ship.

oo CO FIG. 1

Rank Xerox (UK) Business Services (3. 10/3.09/3.3.4) 1 EP 0 678 445 A1 2

BACKGROUND OF THE INVENTION: and heaving. The earlier Ramde patent taught the use of This invention relates to ship hull designs, and certain relationships which have been found to be in particular to hulls made of the sinusoidal water- non-optimal. Also, other differences have been line variety, an example of which is described in 5 found that make substantial improvements in the European Patent 0 134 767 B1, issued to Ramde, performance of designed according to the incorporated herein by reference. Hereinafter, such earlier Ramde patent, as well as curing problems a hull may be referred to as a "Ramform" hull. found in the use of such ships. Such a hull, in comparison to conventional hull designs makes it possible to improve a vessel's w SUMMARY OF THE INVENTION: deadweight , transverse stability, naviga- tional and sailing properties and to reduce stresses The seagoing properties of the hull configura- on the hull whether the vessel is sailing in tion of the present embodiments of the invention quiet water or into the waves. are improved, such that the hull's pitching and As explained in the Ramde patent, at given 75 heaving movements are reduced, compared to the main dimensions of length, breadth and depth to movements of conventional hulls travelling at the the design , conventional hull configura- same rate of speed, as well as the previous Ram- tions can obtain greater deadweight tonnage by form hulls, and these movements are also retarded increasing the fullness of the underwater portion of such that the improved hull does not exhibit cor- the hull, thereby increasing the total displacement. 20 respondingly large movements until the wave To improve the transverse stability of a convention- length/hull length ratio is more than twice as large, ally formed hull, expressed as a higher initial while at the same time the improved hull's resis- metacenter, the breadth of the hull can be in- tance to propulsion is reduced to a similar degree. creased to obtain a greater moment on inertia at Also, the present invention provides for very the waterline, optionally also raising the volumetric 25 smooth, substantially homogeneous, two-dimen- center of gravity of the underwater hull. sional flow of water under the hull and past the However, changes of this nature (increasing stern, resulting in very low turbulence, and very displacement and beam), as demanded for trans- quiet running. Further still, the present invention verse stability and speed increase, will eventually provides for an improved propulsion placement to result in an unacceptable increase in a conven- 30 take advantage of the smooth water flow. tional vessel's resistance to propulsion in quiet According to various embodiments of the waters as well as in heavy waves. present invention, there is provided a ramform-type To improve the seagoing properties of a con- hull with a sloped surface forming an angle of ventional hull configuration, expressed as the ves- below about 14 degrees between the base line of sel's angular movements about a transverse axis 35 the ship near the centerplane and a line extending (pitching), vertical movements (heave), accelera- from the transom stern to another point on the tions and the amount of increase in propulsion surface at about 0.2L from the stern, where L is the resistance compared to the resistance in quiet length of the ship. Further in accordance with var- seas, one seeks to alter the vessel's natural fre- ious embodiments there is provided a Ramform- quency of pitching and heaving so that this fre- 40 type hull with a Froude number of between about quency, insofar as possible, does not coincide with 0.1 and below about 0.35, and a bulge on each the frequency of the wave lengths which the vessel side of the hull is formed near the bottom of the encounters. ship, being relatively constant in size from the bow In the case of conventional hull designs, struc- to midship and tapering off to about zero at the tural alterations result in only slight improvements 45 stern. Further in accordance with embodiments of in the seagoing properties of the vessel, and ex- the invention, the two bulges continue beyond the treme pitching and heaving movements and a great bow to merge into an upward tilting member sub- increase in the resistance to propulsion will occur stantially below the design waterline and extending when the ship is sailing into the waves when the to about the surface of the design waterline. prevailing wave length is approximately equal in 50 According to still a further embodiment of the in- the ship's length at the waterline. vention, there is provided a ship of a displacement Depending on the type vessel and its rate of type with a Ramform type hull, having squarely cut speed, such synchronous movements always make off longitudinally approximately sinusoidal water- it necessary for a conventional ship to reduce lines; a sloped surface at the bottom of the aft part speed or alter course in relation to the waves, 55 of the ship, formed between a base plane and the thereby altering the cycles of encounter with the stern of the ship; said sloped surface forming an waves so that the wave period does not coincide angle with the base plane and tangentially extend- with the natural frequency of the vessel's pitching ing into said base plane approximately at L/2; said

2 3 EP 0 678 445 A1 4 angle of said sloped surface related to the base section. According to still a more specific embodi- line and a line connecting a first point in a longitu- ment of the invention, the ship has an L/B ratio of dinal ship section parallel or equal to the center- between 1 .4 to less than 2, for example, 1 .8. plane section at the lower edge of the transom According to a still further embodiment of the stern and a second point in the same section as 5 invention, the ship includes a dieselelectric power the first one in the sloped surface at 0.2L. Accord- plant, which is arranged in a power station located ing to a specific embodiment, the angle of said at the forepart and uppermost deck of the ship, and sloped surface is about 12.5°. According to a still the ship further includes an increased deck area, further embodiment, the Froude-No. of the ship is which is prolonged up to the aftmost extension of between about 0.1 and about 0.3. io the fins, and which is supported by an extended According to still a further embodiment, there hull structure above the waterline with an open is prodded a ship of a displacement type with a transom stern. Ramform type hull having substantially squarely According to still a further embodiment of the cut off longitudinal and approximately sinusoidal invention, there is provided a ship of a displace- comprising; a sloped surface on the 15 ment type with a Ramform type hull, comprising a bottom of the ship, formed between a base plane squarely cut off longitudinally approximately and the stern of the ship; said sloped surface sinusoidal waterlines; a sloped surface at the bot- forming an angle with the base plane and tangen- tom of the ship, formed between a base plane and tially extending into said base plane approximately the stern of the ship; said sloped surface forming at L/2; and a bulge on each side of the hull ar- 20 an angle with the base plane and tangentially ex- ranged from the bow to the edge of the transom tending into said base plane approximately at L/2; stern According to a more specific embodiment, the bulges on each side of the hull arranged from said bulge is relatively constant in size in the range the bow to the edge of the transom stern terminat- from the bow to L/2 and continuously decreasing in ing at about the stern area of the ship by merging size from L/2 to nearly about zero towards the 25 into each other forming a tongue-like shape with a edge of the transom stern. Further, said bulge at flattened upper surface and raising up to about the the transversal midship section (L/2) has a maxi- waterline. mum normal distance related to the longitudinal The preceding embodiments are given by way centerline, which is larger by about 0.03 to 0.04 of example, only. No limitation of the invention is Bmax than the distance at the designed waterline. 30 intended by the inclusion of any particular feature According to still a further embodiment of the or combination in the preceding examples, as it will inventions, there is provided a ship of a displace- be clear to a person of ordinary skill that the ment type with a Ramform type hull, comprising invention lends itself to other embodiments. squarely cut off longitudinally approximately sinusoidal waterlines; a sloped surface at the bot- 35 DESCRIPTION OF THE DRAWINGS: tom of the ship, formed between a base plane and the stern of the ship, said sloped surface forming Figure 1 is a top plan view of a hull made an angle with the base plane and tangentially ex- according to an embodiment of the present inven- tending into said base plane approximately at L/2; tion. a bulb, which at the transverse cross section mid- 40 Figure 2 is a side elevation of the hull of Fig. 1. way between the forward perpendicular and a Figure 3 is bottom plan view of the hull of Fig. transverse section through the uppermost portion 1. of the bulb, has a width larger than a height with a Figure 4 is a side view of the aft portion of the flattened upper surface and which foremost upper hull of Fig. 1. range is raised up to about the waterline. According 45 Figure 5 is a bottom plan view of a hull made to a more specific embodiment, the length of said according to an embodiment of the present inven- bulb measured from the forward perpendicular up tion. to the cross section corresponding to the upper Figure 6 is a sectional view of one have of the most portion of said bulb ranges from between hull of Fig. 1 at L/2. about 0.1 to 0.12 Bmax, and the cross section of 50 Figure 7 is a side view of a hull made accord- said bulb at the middle of said length has a ing to an embodiment of the present invention. width/height ratio of about 1.7. Further in accor- Figure 7A is a cross section of an element dance with this embodiment, control surfaces are provided according to an embodiment of the arranged at each of the sidemost portion of the present invention. transom stern. For example, the control surfaces 55 Figure 8 is a side view of an the bow of a hull are fins, according to one embodiment, provided made according to an embodiment of the present with controllable flaps at their aft ends at about one invention. third of the longitudinal extension of their cross

3 5 EP 0 678 445 A1 6

Figure 8A is the principal cross section taken to an embodiment of the present invention, the axis through line A of Fig. 8. of the propeller is mounted to be substantially Figure 9 is a side view of a hull showing how parallel to the baseline of the ship, as seen in Fig. the bulb is formed as an integral part of bulge. 4. Figure 10 shows the diesel-electric power plant 5 Referring now to Figs. 2 and 3, according to a and the deck it is located upon. further embodiment of present invention, a ratio Figure 11 shows the increased deck area and B1/t1 is defined at a transverse section through the the extended hull supporting it. hull 10 below the design waterline (dwl) at a dis- Figure 12 shows the open transom stern. tance of about 0.15 L from the stern, wherein (B1) 10 is the beam at the design waterline (dwl) and (t1) DETAILED DESCRIPTION OF THE INVENTION: is the depth of the hull (measured from the same waterline). According to this embodiment, the ratio Referring now to Fig. 1, according to one em- B1/t1 is about 15. According to an alternative em- bodiment of the present invention, there is provided bodiment, the ratio B1/t1 is greater than the cor- a hull 10 with more rounded lines than conventional 15 responding ratio for a section at L/2 where the hull configurations, expressed by the term for lean- beam (B2) and depth (t2) are measured in the ness of line LA/1'3, where L is the length of the hull same way. at the design waterline (dwl) corresponding to the According to a further embodiment of the in- depth T to the summer (see Fig. 2), and vention a further hull ratio e = CP/CdW| is defined, V is the displacement volume of the hull at the 20 wherein CP is the hull's longitudinal prismatic co- design waterline. Further according to this embodi- efficient, expressed from the following equation: ment, LA/1'3 is about 3 or greater, but the specific resistance to propulsion compared to conventional Cp= V/(AL/2xL), hull configurations is not increased. At the same time, the present embodiment provides that the 25 and wherein CdW| = AdW|/LB, wherein L is the design hull beam B is such that the L/B ratio is between waterline, A is the area of a transverse section up about 1 and about 2, preferably between about 1 .4 to the waterline at L/2, V Is the displacement vol- and 1.9. The preferred ratio has been found to be ume to the design waterline, A dW| is the waterline about 1.8. According to this embodiment, B is the area, and B is the maximum beam at the waterline. maximum beam of the hull at the design waterline 30 According to this embodiment, the hull parameter e (dwl). According to this embodiment, the height of is about 1 or greater. the metacenter of the hull 10 is more than doubled Referring again to Fig. 1 according to a further in relation to conventional hull configurations of the embodiment of the invention, the design waterline's same length. areal center of gravity (LCF) is located around 0.2 According to a further embodiment of the in- 35 L aft of midship, and the improved hull's volumetric vention, the displacement distribution in the longitu- center of gravity (buoyancy) (LCB) at the depth of dinal direction approximates Rayleigh wave. Such a the design waterline (dwl) around 0.075 L forward wave is accomplished in the present embodiment of areal center of gravity, which may be expressed with substantially squarely cut off, approximately as LCF - LCB = 0.075 L. harmonic sinusoidal waterlines (Figure 2: dwl, 1, 2, 40 Referring now to Fig. 5, according to a further 3) with extremity or stationary points 12 and 14 at embodiment, hull 10 is configured in the region the ends of the hull fore and aft, while at the same from the stern post and forward to about 0.3 L be time the base lines of the waterlines (OdW|, d , O2, provided with turbulence-controlling appendages O3) from the design waterline (dwl) and at increas- (for example, fixed or flexible fin-like means (v)) in ing depths from this gradually are displaced in the 45 the streamline direction mounted approximately direction of forward propulsion, shortened so far perpendicular relative to the hull 10 and located that an approximately oblique surface (s), which approximately at the transition between the bottom may be straight, is defined. Further in accordance and sides of the hull. According to another exam- with this embodiment, surface (s) which comprises ple, the turbulence-controlling appendages are lon- the stern half of the hull 10 and permits utilization 50 gitudinal grooves in the form of pointed, rectangu- of various propulsion systems. lar or wave-like grooves (x) which decrease in One such propulsion system is disclosed in the depth in the direction of forward propulsion, and Ramde European '767 patent, wherein the propeller which, at about 0.3 L from aft, terminate in and (f) is shown substantially parallel to the approxi- coincide with the even portion of the oblique sur- mately oblique surface (s). Such a design was 55 face (s) and whose depth (d) will usually be about believed to afford advantages with that particular 0.02 B. non-conventional hull, to take advantage of water Referring again to Fig. 1, the hull 10 is shown flow parallel to the surface (s). However, according with the approximately harmonic sinusoidal water-

4 7 EP 0 678 445 A1 8 lines around the design waterline (dwl) with extrem- length (including the control surface flap 202). ity points around the hull's bow and stern ends According to still a further embodiment, seen in with, wherein the areal center of gravity (LCF) is Figs. 8 and 8A, a bulb 80 is provided at the bow of about 0.2 L aft of L/2 and where the length/breadth the hull, substantially below the waterline dwl. Ac- ration L/B of the design waterline is about 2. 5 cording to this embodiment, bulb 80 has a width Figure 2 shows the an embodiment of the larger than its height at the transverse cross sec- invention's hull below the design waterline (dwl) in tion midway between the forward perpendicular vertical section, where it is seen that the base lines and a transverse section through the uppermost are substantially squarely cut off. Further in accor- portion of the bulb. Such a bulb 80 further has a dance with this embodiment, there are approxi- 10 flattened upper surface 82 the foremost upper mately harmonic sinusoidal waterlines (0dW|, d , O2, range 84 of which is raised up to about the water- O3) along a sloped generally planar surface (s), line (dwl). which are displaced in the direction of forward Referring now to Fig. 9, an embodiment is propulsion of the vessel, and which coincide with shown in which bulb 80 is formed as an integral the base plane (g) at about L/2. Further, the dis- 15 part of bulge 100 and a corresponding bulge (not tance between the areal center of gravity (LCF) and shown) on the opposite side of the hull, which run the buoyancy center of gravity (LCB) of the hull 10 from the bow to the edge of the transom 700. In at the depth of the design waterline (dwl) is about this embodiment, the bulges terminating at about 0.075L. The generally planar surface (s) in some the stern area of the ship by merging into each embodiments takes the form of a curved surface 20 other forming a tongue-like shape 80 with a flat- with a very large radius, (for example between tened upper surface 82. about 3 and about 5 times the maximum beam, Further embodiments will occur to those of skill and in a specific embodiment, about 4) in the art, the above embodiments given by way of In Figure 3, the hull configuration of Figure 2 is example, only. shown in horizontal projection with the waterlines 25 dwl, 1, 2, 3 and g in the examples with a U-frame Claims at the bow end of the hull. According to alternative embodiments of the invention, other known frame 1. A ship of a displacement type with a Ramform forms are used. The embodiment of Figure 3 also type hull (10), a transom stern (700), a longitu- has a ratio between beam and depth for a section 30 dinal length of L, and defining a base plane around 0.1 5L from the stern and at L/2, where the and a design waterline plane (dwl), the ship respective beams and depths are designated B1 comprising: and B2 and ti and t2 . approximately sinusoidal waterlines; and According to still a further embodiment of the a surface extending from the transom stern invention, there is provided a bulge 100, as seen in 35 (700) at the design waterline plane (dwl) to the Fig. 6, running from the stern to the bow. Accord- base plane at about L/2 and defining an angle ing to such embodiment the bulge 100 has a between: maximum normal distance (d6) from the longitudi- the base plane and nal center line which is larger by between about an oblique plane, said oblique plane being 0.03 and about 0.04 of the maximum beam than 40 defined by: the distance (d62) between the centerline and the a line at the intersection of the transom hull at the design waterline (dwl) at L/2. stern (700) and the design waterline plane Referring now to Fig. 7, according to still a (dwl) and further embodiment of the invention, there is pro- a point located on said surface at about vided stabilizing fins 200, having a generally tear- 45 0.2L from the transom stern (700), drop cross-section (Fig 7A) and a control surface wherein, said angle is between about flap 202 as shown in Fig. 7A. According to one 12.5° and about 14.0°. such embodiment, the chord length of the stabiliz- ing fin (including the flap 202) is about 3% of L, 2. A ship of a displacement type with a Ramform and the control surface flap 202 has a chord length 50 type hull (10), a transom stern (700), a longitu- less than one percent of L. According to one em- dinal length of L, and defining a base plane bodiment, such fins 200 are places as close to the and a design waterline plane (dwl), the ship stern corners as is practical. In one embodiment, comprising: shown in Fig. 7, the trailing edge is in the plane of approximately sinusoidal waterlines; and the transom 700. In an alternative embodiment, (not 55 a surface extending from the hansom stern shown) the leading edge of the fin 200 is in the (700) at the design waterline plane (dwl) to the plane of the transom. According to a specific em- base plane at about L/2 and defining an angle bodiment, the fin 200 is about twice the chord between:

5 9 EP 0 678 445 A1 10

the base plane and stern (700) and the design waterline plane an oblique plane, said oblique plane being (dwl) and defined by: a point located on said surface at about a line at the intersection of the transom 0.2L from the transom stern (700); and stern (700) and the design waterline plane 5 a bulb (80), said bulb (80) comprising: (dwl) and an upper bulb surface (82), said upper a point located on said surface at about bulb surface (82) being substantially flat, 0.2L from the transom stern (700); and an uppermost portion of said upper bulb a Froude Number of between about 0.1 surface (82), said uppermost portion being lo- and about 0.35. io cated at about the design waterline plane (dwl), 3. A ship of a displacement with a Ramform type a cross-sectional width of said bulb (80), hull (10), a transom stern (700), a longitudinal said cross-sectional width being greater than a length of L, and defining a base plane, a lon- cross-sectional height of said bulb (80) at a gitudinal perpendicular center plane, and a de- is transverse cross-section, said transverse sign waterline plane (dwl), the ship comprising: cross-section being located midway between: approximately sinusoidal waterlines; and a first transverse forward perpendicular a surface extending from the transom stern plane located at a distance L (700) at the design waterline plane (dwl) to the from the transom stern (700), and base plane at about L/2 and defining an angle 20 a second transverse forward perpendicular between: plane passing through an uppermost point on the base plane and the bulb (80). an oblique plane, said oblique plane being defined by: 6. A ship according to one of the above claims, a line at the intersection of the transom 25 wherein a length of said bulb (80), from said stern (700) and the design waterline plane first transverse forward perpendicular plane to (dwl) and said second transverse forward perpendicular a point located on said surface at about plane, is between about 0.1 to about 0.12 0.2L from the transom stern (700), Bmax, and a bulge (100) in the hull (10), arranged 30 a cross section of said bulb (80) at the middle along a water-contacting portion of the hull of said length has a width/height ratio of about (10), from about the bow to about the transom 1.7. stern (700) wherein said bulge (100) is sub- stantially constant in size from about the bow 7. A ship according to one of the above claims, to about L/2 and continuously decreasing in 35 wherein a length of said bulb (80), from said size from about L/2 to about zero at the tran- first transverse forward perpendicular plane to som stern (700). said second transverse forward perpendicular plane, is between about 0.1 to about 0.12 4. A ship according to one of the above claims, Bmax. wherein the furthest normal distance from the 40 perpendicular center plane to a point on said 8. A ship according to one of the above claims, bulge (100) is between about .03 and about .04 wherein a cross section of said bulb (80) at the Bmax. middle of said length has a width/height ratio of about 1 .7. 5. A ship of a displacement type with a Ramform 45 type hull (10), a transom stern (700), a longitu- 9. A ship of a displacement type with a Ramform dinal length of L, and defining a base plane type hull (10), a transom stern (700), a longitu- and a design waterline plane (dwl), the ship dinal length of L, and defining a base plane comprising: and a design waterline plane (dwl), the ship approximately sinusoidal waterlines; and 50 comprising: a surface extending from the transom stern approximately sinusoidal waterlines; and (700) at the design waterline plane (dwl) to the a surface extending from the transom stern base plane at about L/2 and defining an angle (700) at the design waterline plane (dwl) to the between: base plane at about L/2 and defining an angle the base plane and 55 between: an oblique plane, said oblique plane being the base plane and defined by: an oblique plane, said oblique plane being a line at the intersection of the transom defined by:

6 11 EP 0 678 445 A1 12

a line at the intersection of the transom dinal length of L, and defining a base plane stern (700) and the design waterline plane and a design waterline plane (dwl), the ship (dwl) and comprising: a point located on said surface at about approximately sinusoidal waterlines; and 0.2L from the transom stern (700); and 5 a surface extending from the transom stern at least one stabilizing fin (200), located (700) at the design waterline plane (dwl) to the approximately at the transom stern (700) such base plane at about L/2 and defining an angle that turbulence at the stern of the hull (10) is between: reduced. the base plane and io an oblique plane, said oblique plane being 10. A ship according to one of the above claims, defined by: wherein said stabilizing fin (200) further com- a line at the intersection of the transom prises a control surface flap (202). stern (700) and the design waterline plane (dwl) and 11. A ship according to one of the above claims, is a point located on said surface at about wherein a first chord length of said stabilizing 0.2L from the transom stern (700); and fin (200) is about 3 percent of L, and a second a water-contacting bulge (100) on each chord length of said control surface flap (202) side of the hull (10) arranged from the bow to is less than about 1 percent of L. the edge of the transom stern (700), said 20 bulges (100) joining together at about the stern 12. A ship according to one of the above claims, of the ship defining a tongue-like shape with a wherein said stabilizing fin (200) is located at flattened upper surface, said flattened upper about the stern corners. surface located at about the design waterline plane (dwl). 13. A ship according to one of the above claims, 25 having an increased deck area, said deck area 17. A ship according to one of the above claims, extending to about the aftermost extension of equipped with a diesel-electric power plant lo- the fin (200). cated in the forepart of the ship.

14. A ship according to one of the above claims, 30 18. A ship according to one of the above claims, wherein said increased deck area is supported wherein said diesel-electric power plant is lo- by an extended hull (10) structure above the cated on the uppermost deck. design waterline plane (dwl). 19. A ship according to one of the above claims, 15. A ship of a displacement type with a Ramform 35 having an open transom stern (700). type hull (10), a transom stern (700), a longitu- dinal length of L, and defining a base plane 20. A ship according to one of the above claims, and a design waterline plane (dwl), the ship having an L/B ratio of between about 1.4 and comprising: about 2. approximately sinusoidal waterlines; and 40 a surface extending from the transom stern (700) at the design waterline plane (dwl) to the base plane at about L/2 and defining an angle between: the base plane and 45 an oblique plane, said oblique plane being defined by: a line at the intersection of the transom stern (700) and the design waterline plane (dwl) and 50 a point located on said surface at about 0.2L from the transom stern (700); and a propeller located such that the axis of said propeller is substantially parallel to the base plane of the ship. 55

16. A ship of a displacement type with a Ramform type hull (10), a transom stern (700), a longitu-

7 EP 0 678 445 A1

FIG. 1

« L *

A10 ~0.15L t ~0.075L — — * "(1 £ /2 dwl r

| LCB--

'1 g2 s °3

F/G. 3 EP 0 678 445 A1

FIG. 6

9 EP 0 678 445 A1 11 European Patent EUROPEAN SEARCH REPORT Application Number Office EP 95 10 5964

DOCUMENTS CONSIDERED TO BE RELEVANT Category Citation of document with indication, where appropriate, Relevant CLASSIFICATION OF THE of relevant passages to claim APPLICATION qnt.CI.6) X,D EP-A-0 134 767 (R. RAMDE) 1,2,9-11 B63B1/04 Y * the whole document * 5-8, 12-15

Y GB-A-1 295 211 (SASEBO HEAVY INDUSTRIES) 5-8 * figures *

Y US-A-3 934 531 (R.ALLEN) 12-14 * column 8, line 16 - line 19; figures *

Y US-A-4 550 673 (S.INGVASON) 15 * figures *

A DE-C-112 414 (O.KRETSCHMER) 1-3,5,9, 15,16 * figures *

GB-A-775 706 (E.MAIER) 3,4,16 * figures * TECHNICAL FIELDS SEARCHED (Int.CI.6) B63B

The present search report has been drawn up for all claims Place of March Date of completion of the tearch Fxaminer THE HAGUE 7 July 1995 Stierman, E CATEGORY OF CITED DOCUMENTS T : theory or principle underlying the invention E : earlier patent document, but published on, or X : particularly relevant if taken alone after the filing date Y : particularly relevant if combined with another D : document cited in the application document of the same category L : document cited for other reasons A : technological background O : non-written disclosure & : member of the same patent family, corresponding P : intermediate document document