WO2009053762A2

WO2009053762A2 - Ship with longitudinally extending foils, inclined keel, and lift producing blades at the stern

Info

Publication number: WO2009053762A2
Application number: PCT/GR2008/000063
Authority: WO
Inventors: George Sioutis
Original assignee: George Sioutis
Priority date: 2007-10-26
Filing date: 2008-10-27
Publication date: 2009-04-30
Also published as: WO2009053762A3; GR1006197B

Abstract

Cruising vessel with the capacity of sailing at high speeds with a reduced consumption of fuel because of the highly efficient hull thereof that extends in between lateral sides (A, B) and comprises in combination frames (3) with a minimally resistant arcuate curvature at the bow and a progressively increasing inversely turned configuration downstream the bow and with longitudinally extending foils (4) at the bow that lead within the boundaries of the hull a large part of the wave mass created during propulsion of the ship, a central longitudinal inclined keel (2) extending at progressively decreased depth from the bow till the stern so as to form a progressively broadening cavity (10) of an inverse V cross-section from approximately the middle of the ship up to the stern that leads into equivalently progressively decreased hydrostatic pressure being exerted upon the water mass entrapped within the boundaries of the hull of the ship, and lift producing blades (5) on either side of the stern that contribute towards lifting of the stern equivalently with the lifting of the bow during propulsion of the ship and towards the achievement of a constantly horizontally sailing ship that is progressively raised as speed increases and the wetted surface respectively decreases.

Description

SHIP WITH INCLINED KEEL AND PROGRESSIVELY TURNED FRAMES

THE FIELD OF THE ART

The invention pertains to the field of sea transport and proposes a cruising vessel provided with a hull of high performance. THE PRIOR ART

The effort to obtain optimally high speeds of cruising vessels in combination with an optimally low consumption of energy has been the object of continuing research. The solution of this problem is related with the reduction of the overall resistance being encountered during propulsion of the vessel and is of the utmost importance in the development of sea transport and in the same time in the protection of the environment and of energy resources.

A category of vessels that constitutes a percentage exceeding 90% of the total of cruisers is those vessels with a planning hull of various types. This technology is broadly applicable in small cruising vessels used for recreational activities and in vessels of a special mission, such as those of the port authority or of the navy. The following disadvantages are observed in the vessels with a planning hull of the prior art: a) The existence of an upper limit of speed beyond which a further increase of speed necessitates a disproportionate increase of the power supplied and of fuel consumption and of a maximum final upper limit beyond which speed increase is technically not achievable. This is due to the fact that progressive increase of speed leads to a disproportionate increase in the overall resistance imposed during movement of the ship. The wave making resistance built up during movement of the ship is the most substantial part of such overall resistance in ships of this type and it might reach at a proportion of 60-70% of the power required for overcoming frictional resistance. Frictional resistance largely depends on the wetted surface and on the hydrostatic pressure exerted thereupon. The abovementioned frictional and wave making resistances are the principal resistances encountered during propulsion of vessels of this category and it is these resistances that are taken into account for the design and building of such vessels with the calculation of the power required for the propulsion thereof. The wave making resistance that disproportionately increases as speed is increased leads into a lifting of the bow that results in a distortion of the initial geometrical characteristics of the hull, whereby the sharp edge through which the ship penetrates water mass becomes a highly resistant surface. b) Lifting of the bow of the vessel that is due in the abovementioned disproportionately increasing resistance with the increase of speed and the consequent deformation of the initial geometrical characteristics of the hull, since bow lifting results in the advantageous pointed edge vessel's surface of intrusion into the sea being transformed to a resistant surface area.

The lifting of the bow that leads beyond others to a disproportionate fuel consumption and to the existence of the abovementioned upper limit beyond which speed increase is at the first place rendered economically disadvantageous and eventually technically impossible, is more pronounced in small recreational cruisers that might even risk to overturn since such vessels present rather limited stability, whilst they also provide very restricted exploitable spaces. Bow lifting in combination with even light waving leads in the vessel being subjected to strokes, thereinafter being unable to cruise smoothly even at low speed. This is the reason that the planning hull of the prior art is not broadly applicable in ship building of commercially exploitable vessels and is mainly confined in the building of ships for private use or of ships with a special mission that have to perform short term traveling either for recreational purposes or for performing their special mission respectively. c. The breaking up of sea water around and externally of the vessel, as well as the creation of wave making resistance that also breaks up around the vessel constitute a substantial energy loss that does not contribute into increasing the speed of the vessel or else into an economically optimum efficiency in the propulsion thereof.

The abovementioned disadvantages are encountered with no exception in all vessels with a planning hull of the prior art, such planning hull being characterized by frames that lead into a vessel with an almost planar bottom with a slight inclination towards the central longitudinal axis that results to a configuration of a slightly discernable V section, such V section being opened at an oblique angle approximating 180° with the apex of the V section oriented at a direction towards the sea bottom.

The object of the present invention is to advantageously overcome the abovementioned disadvantages of the prior art of vessels with a planning hull and to propose a novel hull design that will be broadly applicable and that will succeed in an advantageous change of the resistances that the vessel encounters as its speed increases, thereby arriving at a super fast cruising vessel and at the possibility of broadening the field of application of such technology with the proposed highly efficient planning hull in large commercially exploitable vessels. Specifically, it is an object of the present invention to disclose a highly efficient planning hull that exhibits the following advantageous characteristics: a. An improvement in the geometrical characteristics of the planning hull as speed of the vessel is increased, such improvement being attained with a stern lifting that follows the corresponding lifting of the bow as speed increases, thereby resulting in a substantially horizontally cruising vessel at any value of speed whatsoever. Such proportionate bow and stern lifting leads on the one hand to a reduction of the wetted surface (reduction of frictional resistance) and on the other hand to elimination of the phenomenon of conversion of the sea intruding pointed edge form of the vessel's surface into a surface resisting such intrusion into the sea that is encountered in the prior art, thereby effecting a pointed edge sea intrusion at any speed whatsoever. As a result of the advantageous geometrical lines of sailing obtained, the abovementioned upper limit in the increase of speed encountered with planning hull vessels of the prior art is eliminated and super fast cruising vessels are provided in which speed increase does not result in a disproportionate increase in fuel consumption. b. Advantageous management of a large part of the resistant waves that is led underneath , « the vessel and within the boundaries of the hull, wherein by means of a gradual reduction of hydrostatic pressure along the hull due to the configuration of the same, a laminar flow is obtained of the water mass entrapped therein with flow characteristics substantially different from those of the water mass around the exterior of the vessel. An improved ^■ dynamic stability and a capacity of the vessel being capable of cruising under even more adverse weather conditions under which traveling of vessels of this category of the prior art is not allowed are being obtained as a result of such differentiated flow conditions underneath the hull.

The highly efficient hull proposed in the present invention by means of which are obtained the abovementioned advantages is characterized by the combination of progressively turned frames that give rise to a hull configuration with a clearly observed V section, such V section being reverse in comparison to the slightly discernable V section of hulls of the prior art, the apex of the V section being directed towards the sea and not towards the vessel as is the case with planning hull vessels of the prior art. The hull of the invention is also characterized by the central inclined keel that longitudinally extends at a progressively reduced depth from the bow to the stern so as to render a V section of correspondingly progressively increased sectional area and therefore a progressively broadening cavity originating from approximately the middle of the vessel up to the stern, such progressively broadening cavity correspondingly resulting in a gradually reduced hydrostatic pressure being exerted onto the water mass entrapped within the boundaries of the hull. The hull of the invention further comprises an arrangement of lift producing blades mounted at the stern that perform lifting of the stern corresponding to the lifting of the bow during propulsion of the vessel, thereby leading to a horizontally cruising vessel, the vessel being thereby gradually raised upwardly as speed increases and its wetted surface being accordingly reduced, thereby leading to the optimization of exploitation of the energy consumed as cruising speed is increased.

Another object of the invention is to provide by means of an arrangement of guiding foils at the bow portion on either side of the aforementioned inclined keel the ability of creation of the necessary conditions for the guidance of a large part of the wave mass produced during propulsion of the vessel within the boundaries of the hull and the exploitation of the energy of this wave mass through differentiation of the flow entrapped within the boundaries of the hull from the flow externally surrounding the vessel thereby producing energy of lifting of the vessel and reducing the wetted surface and eliminating resistant areas and eventually obtaining propulsion of the vessel with a lower fuel consumption at an unlimitedly increasing speed.

These and other characteristics and advantages of the invention will be made clear in the detailed description hereinafter.

BRIEF DESCRIPTION OF DRAWINGS

The invention will be made clear to those skilled in the art with reference to the accompanying drawings, in which an embodiment of the invention is presented in an indicative and non restrictive manner.

Figure 1 presents an illustrative preferred embodiment of the vessel of the invention in perspective focusing in the highly efficient hull thereof.

Figure 2 presents a corresponding view of the vessel of Figure 1 in perspective with an illustration of its theoretical shipbuilding frames. Figure 3 presents a view of the rear of the vessel, wherein appears the supporting means of the rear lift producing blades and is distinguished the frame at which the creation of a progressively widening inverted V section is initiated.

Figure 4 presents a side view of a ship adapted to transporting passengers and vehicles with the hull of high efficiency of the invention.

Figure 5 presents the ship of Figure 4 with an illustrative superstructure as used in the experimental specimen of the basic application study, results of which are presented in the detailed description hereinafter.

Figure 6 presents a diagram of the frames in the experimental specimen of the ship of the invention.

Figure 7 presents the hydrostatic diagram of the ship of Figure 6 wherein are illustrated the hydrostatic curves thereof.

Figures 8 and 9 present a photograph of a side view and of a rear side view respectively of the experimental specimen of the ship of the invention as it functions under real life conditions maintaining horizontal sailing at increased speed, being uniformly raised from the bow up to the stern in comparison to its immersion when it is found at rest.

Figures 10a and 10b respectively present photographs of experimental specimens of a ship with planning hull of the prior art and of the ship of the invention as they function under real conditions and more specifically in the beginning of movement and after having developed a speed that, in as much as the ship of the prior art is concerned, causes elevation of the bow, whilst in the ship of the invention it causes a uniform elevation from the bow till the stern thereby resulting in the ship sailing with substantially reduced wave making.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

By reference hereinafter to the accompanying drawings we will present the invention through illustrative, preferred, but not restrictive embodiments thereof.

The hull of the ship 1 of the invention is contained in between longitudinally extending planar lateral surfaces A and B underneath the exterior lateral surfaces A' and B' of the ship respectively. In the vessel depicted in Figure 1 or 2 is distinguished the longitudinally extending central keel 2 with a bow end 2a which is characterized by that it is inclined in relation to the horizontal level and its inclination is such that, with the ship horizontally oriented, its bow end portion is located at a depth greater than the stern portion thereof. The section of frames 3 in the bow portion follows a minimally resistant arcuate curvature and thereafter follows a progressively increasing inversely turned configuration so that, following the bow portion of the hull, a V-section channel 10 is being formed, such V section being inversely oriented in comparison to the hulls of this type of the prior art wherein a lightly configured V-section is formed with the apex of the V-section directed towards the sea bottom. In the present invention on the contrary the apex of the V-section is directed towards the ship and the channel 10 being shaped downstream the bow is progressively widening up to the stern of the ship. According to a preferred embodiment of the invention, the cross-section V is shaped, as illustrated in Figure 3 and also partially shown in Figure 1, from a zig-zag line A1-A2-A3 extending from lateral side A and B1-B2-B3 extending from lateral side B of the hull. With this configuration is shaped suitably the channel of V cross-section so that might be suitably supported an arrangement of lift producing blades, whilst its hydrodynamic characteristics are optimised. As appears indicatively in Figures 1-3 a pair of lift producing blades 5 that are being mounted at the overlying hull portion by means of supports 5a are provided at both sides of the stern. Alternatively the pair of blades 5 can be replaced by a single blade that runs through the span of the stern in between lateral surfaces A and B of the hull (application suitable for smaller ships), whilst in connection with the study of application of each specific ship being built they are being precisely determined the technical characteristics of the lift producing stern blade arrangement used in order to render the desired lifting outcome.

Lift producing blades 5 are aimed at achieving a lifting of the stern that is proportional with the lifting of the bow that is effected as speed is increased, thereby achieving a horizontally sailing vessel and it is in no way related with other applications of such blades that may serve aims of regulating inclinations, etc. Thus, during propulsion of the ship, despite the lifting of the bow that is created by the developing wave making resistance, sailing is constantly maintained at horizontal level because of the counteracting force applied by the lift producing blades 5 at the stern. As the speed of the vessel increases greater lifting forces develop for the vessel as a whole, thereby leading at the vertical elevation thereof, i.e. reduction of wetted surface area and improvement of sailing lines or reduction of frictional and wave making resistances. The design of the frontal portion with frames 3 following an arcuate curved configuration and the perpendicularly oriented guiding foils 4 result in a large portion of the water mass emanating from the resistance of waves being led within the widened V-sectioned channel 10 wherein due to the consequent fall of hydrostatic pressure it is defused underneath the vessel. The result of the above is that a large part of the energy of resistant waves that was lost around the vessel with unfavourable results of imposing increased power and fuel consumption requirements in the propulsion of the vessel is now being beneficially used since it leads into further elevation of the vessel that travels thereupon. Thus the guidance of sea water mass inside channel 10 and the progressive reduction of the hydrostatic pressure thereof that takes place therein because of the progressively increasing V-section necessarily create laminar flow conditions, such flow being independent from the flow around the vessel and providing substantial elimination of the resistances due to developing vortices.

As shown in Fig. 1 and 2, longitudinally extending guiding foils 4 are being provided on either side of the bow portion, which are adapted to guide a large part of the waves being created during propulsion of the vessel within the boundaries of the hull. These longitudinal foils 4 (vertical bilge strake) preferably have a morphology such as to follow the curvature of the hull and their length, height and possibly the number thereof are probably associated with the study of application in each particular ship. According to a preferred embodiment of the invention, a recessing step 6 is being formed in between the sides A' and B' of the vessel 1 and the corresponding lateral sides A and B of the hull thereof (Figure 1, 3),-- which contributes in the reduction of wetted surface area during elevation of the vessel (it is located above water-line) and mainly acts so as to counteract upon the growth of capillary phenomena of water that develop at high speeds because of the affinity and because of their covering a substantial part of the sides of the vessel leading towards further resistance being built up.

BASIC STUDY OF PROPOSED APPLICATION

The hereinabove described and hereinbelow claimed design and innovative technical characteristics of the ship with an inclined keel and progressively turned frames of the invention was implemented through applying scientific data of shipbuilding studies, was tested in practice and the conclusions of the study and of the behaviour of the experimental specimen confirmed the reliability of the advantages presented by the proposed ship that were exposed hereinabove. Because of non existence of comparable data, the design and the basic study for the ship were performed in a generic manner and were henceforth confirmed with the manufacture and operation of a specimen at a scale of 1:120 in real sailing conditions. The basic dimensions of the ship studied with a scope of shipbuilding were: Overall Length of ship 100 m.

Maximum Width (moulded) of conventional ship 27 m. Sailing Width 25 m. Lateral height at main deck 14 m. hi Figure 6 are portrayed the naval lines of the ship of the study, wherein appear the theoretical frames and the auxiliary normality controlling curves (a, b, c). The areas and volumes of the ship were calculated through using the analytic method of Simpson's Rule with the results enlisted herein below:

RESULTS OF CALCULATION OF WATER-LINE SURFACES

RESULTS OF CALCULATION OF HULL VOLUME AND OF UPPER CENTRE OF BUOYANCY OF THE KEEL

RESULTS OF CALCULATION OF WATER-LINE SURFACES

^■ ~ 5 -

In Figure 7 is portrayed the hydrostatic diagram of the ship with the corresponding curves of the ship studied as follows:

• The displacement curve is portrayed with numeral 1 and its scale is Im=I 500 ton.

• The vertical locus of the Center of Buoyancy is portrayed with curve 2 at a scale of

10 1 :2 in m.

• The longitudinal locus of the Center of Buoyancy is portrayed with curve 3 and at a scale of 1 : 100 in m from the median section.

• The water-line surface area is portrayed with curve 4 and at a scale of 1 m = 500 m². • The weight of immersion in ton/cm is portrayed with curve 5 and at a scale of lm=10 ton.

• The wetted surface is portrayed with curve 6 and at a scale of 1 m = 1000 m².

• The weight of the ship was determined through rough estimation via the method of comparison with similar ships, maximized as follows:

LIGHT WEIGHT

DEAD WEIGHT

As shown herein above the ready made steel ship prior to its loading has a weight that corresponds to a displacement of 4250 ton.

The corresponding applicable waterline of the hydrostatic diagram is the waterline 2.7 that has a height of 4.75 m. After adding the Dead Weight we have a total displacement of 5386 ton with applicable waterline 3 in the hydrostatic diagram that corresponds to a height of 5.2 metres.

The immersion of the specimen during cruising at an elevated condition exhibits a wetted surface reduced by a percentage of approximately 20% at the maximum speed.

Assuming that a reduction of 15% is achieved with the vessel, the applicable waterline is the waterline 2.52 that corresponds to a wetted surface of 2650 m .

Determination of Speed

According to Froude's law of mechanical similarity, the speed of ship is related to the speed of the specimen by the following relation:

U=V^, where U= The speed of the ship

V= The speed of the specimen L= The length of the ship 1 = The length of the specimen. The speed of the specimen was measured to be around 4 m/s. The length of the ship at the waterline is 93 m, whereas the length of the specimen is 0.77m. The result of calculations in the above formula gives a speed of the ship 44.32 m/s/0.514 = 82.07 knots.

Approximate method of determination of power

The resistances that are basically encountered during sailing of a ship are the frictional resistance, the wave-making resistances and the air-resistance.

According to Froude's formula where we enjoy a rather high precision in the calculation of the resistance, i.e. R_f =FSV¹ ^⁵, where:

Rf- The frictional resistance in Newtons F - A constant dependent on the length

S - The wetted surface, which during sailing amounts to 2,650 m². V - The speed of the ship in m/s =25.70 (20.57 m/s at 40 Knots) Consequently for a speed of the ship of 50 Knots: Rrl.428 X 2,650 X 374.22 = 1416123.30 N = 1416.80 KN The power is 1416.80 X 25.70 = 36411 KW.

The wave making resistance is created during intrusion of the ship in water, whereby an increased pressure is exerted mainly at the bow, such increased pressure resulting in lifting of the bow and a consequent expansion of the wave. The wave created has all the characteristics of a wave, i.e. height, width, frequency. In other words it is the interposing of an obstacle/surface in the movement of water that forces the latter to deviate from linear flow. Also because of the pressure it is possible that the bow is lifted upwardly and the resistant surface increases thereby resulting in the creation of still larger waves. The wave making resistance in conventional cruisers may reach up to 50-70% of the power required to be consumed for the frictional resistance.

The most important advantage of the ship presented herein is that it does not exhibit resistant surfaces at any speed whatsoever. The creation of wave (pressure) that begins to form becomes the object of exploitation by the ship itself contributing in the lifting thereof, as it is defused underneath the ship thereby creating a further propulsive tendency elirninating the tendency of pressure increase at the bow. ^* -

Taking into account the above and the behaviour of the specimen we take the wave making resistance to amount at 25% and the air resistance at 10% (rather than at 35% that is developed in conventional cruising vessels). The 35% of the power of frictional resistance is 12743KW. Consequently the total horsepower of the steel ship is 49154 KW for a speed of 50 Knots, whereas for the speed of 40 Knots it is 32712KW.

For a ship made from aluminium we correspondingly have for 50 Knots a power requirement of 37077 KW and for the speed of 40 Knots 24692 KW, whilst the immersion is 3.93 m.

As far as the approximate verification of the values assumed, we take into consideration that the specimen moves with two engines of obligatory choice that provide an overall power of 229 W; the displacement of the specimen is 5.5 Kg and the immersion thereof is 6.5 cm. For the speed achieved the ratio of displacement/power is 5.5/229=0.024.

The immersion of 0.065 m in the specimen corresponds to the ship object of the study having an immersion of (0.065 X 120) =7.8 m with the applicable waterline 4.46 that corresponds to a wetted surface of 3600 m², i.e.

Rrl.428 X 3600 X 1011.68=5200.84 KN X 25.7=133,661,7 KW X 35% = 46781.50 = 180443.20 KW.

The displacement/power coefficient is 5386/180443.20=0.029. The differentiation at the third decimal is considered to be within the framework of approximation because of the sizes measured.

From the above results that the proposed hull achieves:

A. Reduction of power by at least 10% in comparison with existing similar cruising vessels at the speed of 40 Knots.

B. Optimal exploitation of power in combination with the speed that it can develop because the wetted surface is decreased as speed is increased and iat the same time sailing lines are improved. This parameter provides the possibility of developing super-fast ships independently of the size thereof.

C. Improved dynamic stability because of the different flow conditions around and underneath the ship, thereby also providing better sailing conditions under adverse weather conditions.

It must hereby be noted that the above description of the invention was made by reference to an illustrative example of application in which it is not limited. Thus any change or modification regarding the shape, morphology, dimensions, materials and accessories used in the manufacturing and assembly process, as long as they do not constitute a new inventive step and do not contribute in the technical development of what is already known, must be considered part of the aims and scope of the present invention.

Claims

1. Cruising vessel with a highly efficient hull extending between lateral surfaces (A, B) underneath corresponding lateral surfaces (A', B') of the vessel, said hull characterized by that it comprises in combination: a. minimally resistant frames (3) with an arcuate curvature and longitudinally extending foils (4) on either side of the bow portion that create the essential conditions for the guidance of a large portion of the wave mass formed during propulsion of the vessel within the boundaries of the hull, b. a central inclined keel (2) longitudinally extending at progressively decreasing depth from an ending (2a) at the bow up to the stern and frames (3) with a progressively increasing inversely turned configuration downstream the bow so as to create a progressively widening V-sectioned cavity (10) with the apex of the V-section oriented in the direction of the vessel, said cavity (10) extending from approximately the middle of the vessel up to the stern and consequently creating proportionately progressively decreasing hydrostatic pressure of the water mass entrapped within the boundaries of the hull, and c. an arrangement of lift producing blades (5) installed at the stern that contribute in the lifting of the stern equivalently with the lifting of the bow during propulsion of the vessel, thereby resulting in the achievement of constant horizontal sailing of the vessel that is progressively lifted upwardly as speed increases and the wetted surface correspondingly decreases, thereby leading to an optimisation of exploitation of the energy consumed as sailing speed is increased.

2. Cruising vessel with a highly efficient hull according to the above claim 1, characterized by that the V-cross-section of said cavity (10) is formed by zig-zag lines (Al- A2-A3) extending inwardly from lateral hull surface (A) and (B1-B2-B3) inwardly from lateral hull surface (B) with lower portions (Al, Bl) of lateral hull surfaces (A₅ B) shaped with an inwardly and upwardly oriented curvature.

3. Cruising vessel with a highly efficient hull according to the above claim 1, characterized by that said arrangement of lift producing blades (5) comprises one single stern lift producing blade, which extends throughout the span of the stern between surfaces (A) and (B) of the hull or a pair of co-planar lift producing blades (5) mounted at both sides of the stem, wherein said arrangement of lift producing blades (5) is mounted at that overlying hull portion by means of supports (5a).

4. Cruising vessel with a highly efficient hull according to the above claim 1, characterized by a recessing step (6) being formed in between the sides (A', B') of the vessel and the corresponding lateral sides (A, B) of the hull thereof, wherein recessing step (6) results in the span of the hull being determined by the distance between surfaces (A, B) thereof is smaller than the span of the vessel being determined by the distance between surfaces (A', B') thereof, thereby averting development of capillary phenomena in the flow of water along the sides of the vessel and of the resistance to the propulsion of the vessel associated with such phenomena.

5. Cruising vessel with a highly efficient hull according to the above claim 1, characterized by said longitudinally extending foils (4) at the bow portion of the hull being arranged so as to follow the curvature of the hull.

6. Cruising vessel with a highly efficient hull according to the above claim 1, characterized by the exploitation of the energy of the waves being formed during propulsion of the vessel through differentiation of the flow of the water mass entrapped within the boundaries of the hull of the vessel from the flow externally surrounding the vessel and through controlled laminar flow of said entrapped water mass thereby producing energy of lifting of the vessel, reducing the wetted surface, eliminating resistant areas and eventually obtaining propulsion of the vessel with a lower fuel consumption at an unlimitedly increasing speed.