Field of the invention

The present invention relates to the boat building, in particular to monohull vessels with a small waterline area which are useful preferably as small vessels for recreational, traveling and commercial voyages. In general, such a small vessel is up to 20 meters long and carries up to 12 persons.

Background art

Widely known are monohull vessels of so called water displacement type. Such a monohull vessel has a wide entire hull with a sufficiently large waterline area. The hull is partly submersed in the water, and the submersed part creates a lift force which supports the vessel on the water surface. A vessel moving through a body of water displaces the water by pushing it aside with its bow. In that motion the body of water, on passing along the hull, fills an emptied volume behind the stern of the vessel. In such a way, the moving vessel involves particles of the water in a vibratory motion which due to the elastic properties of the water surface propagates in the form of waves.

Hence, the moving vessel forms the bow divergent waves, stern divergent waves and stern transverse waves , all of which together form a powerful wave system. Depending on the relation between the wavelength and hull length, the pattern of interaction between the bow waves and the stern waves varies. As the velocity of vessel movement increases the wave formation becomes stronger. The vessel's engine spends up to 30 - 45% of its power for such a wave formation.

Last years, to reduce the wave formation, the vessels with a small waterline area were begun to construct (US, 3,447,502). Such vessels realize the so called "reversal effect", that is decreasing the wave resistance at the expense of re moval o f the water displacement volumes from the surface water body. Such vessels comprise more than one (preferably two) submersed pontoon parts under water surface and an upper platform above the water surface, where the last is bound to the pontoon parts through longitudinal supports which divide the vessel into an above-water part and an under-water part that are not bound with each other. In other words, such a vessel in fact is a multihull vessel, and in most cases - the three-hull vessel which comprises two underwater parts and one above-water part. The lift force of such a vessel is provided by the under-water part, and its waterline passes across the supports and has a small waterline area. An advantage of such a vessel, in comparison with an usual water-displacement mono-hull vessel, is that due to a small water-line area it ensures a little wave formation to reduce the wave resistance to the movement of the vessel. As a result, the vessel moves "as if it would fly over waves".

However, a shortage of the vessel of this type is that its weight virtually is 1 ,3 - 1 ,5 times the weight of an usual vessel because its under-water pontoon part (pontoons and supports) does not serve as the useful area of the vessel.

To eliminate this shortage is the object of the present invention. Thereto the invention is aimed at the creation of a vessel which due to its constructive features would reduce the wave formation and at the same time would provide sufficiently large useful area inside the vessel, and additionally would be able to assure a stability and a reduction of the resistance to the movement of such vessels with various propeller types.

Summary of the invention

This object of the invention is achieved in a vessel which comprises a hull that includes an above-water part consisting of a bottom and walls forming an internal space of the above-water part, and a pontoon part positioned under the above-water part, as well as a ballast system, where according to the invention the pontoon part is arranged in the central portion of the bottom along the longitudinal axis of the vessel and is bound with the bottom, the internal space of the pontoon part being communicated with the internal space of the above-water part, and the common room of the pontoon part being such that the waterline of the vessel passes along the pontoon part near the bottom of the above-water part.

In one of the preferable embodiments of the present invention, the pontoon part can in the cross section of the central portion have substantially a form of a rectangle with rounded angles in the lower portion, where the long walls of this rectangle are directed perpendicularly to the longitudinal axis of the vessel, and the width/length relation of the rectangle is selected in the range of from about 0,4 - 0,5.

It is desirable the space of the pontoon part to make so that the waterline of the vessel distances from the bottom in the range of from about 0,5 - 0, 10 of the length of said rectangle.

In another preferable embodiment of the present invention the pontoon part is desirable to make in a rounded form.

Additionally, the bottom of the vessel could be made in such a way that the cross section of the above-water part be flat and parallel to the waterline, and the portion of its connection with walls have a rounded form.

Further, it is desirable that the bottom of the above-water part in the cross section be made with a slope relative to the waterline, providing a V- form cross section of the above-water part, the bottom be made with a slope to the stern of the vessel, and the portion of the connection on the bottom with the walls have a rounded form.

It is preferable the ballast system in such a vessel to arrange in the pontoon part.

Brief description of the drawings

Further objects and features of the present invention will be described below in more details with references to the drawings in which:

Fig. 1 is a general side view of a vessel with a flat bottom,

Fig. 2 is a plan view of the vessel,

Fig. 3 is a cross section view of the vessel with a flat bottom,

Fig. 4 is a view of the vessel, equipped with a sail propeller, with a side inclined state,

Fig. 5 is a view of the vessel equipped with an engine propeller, Fig. 6 is a cross section view of the vessel of the Fig. 5 with a V-form bottom,

Fig . 7 is a view of the vessel in a mooring state with the pontoon part filled with the ballast water, and

Fig. 8 is a cross section view of the vessel with the pontoon part in a rounded form. Best mode for carrying out of the invention

As is shown in Fig. 1 , 2, the vessel of the invention comprises an above-water part 1 which consists of a bottom 2 with a slit 4 along the longitudinal axis 3 of the vessel, and walls 5 forming an internal space 6 of the above-water part 1. Besides, the vessel comprises a pontoon part 7 which is arranged in the central portion of the bottom 2 along the longitudinal axis 3 of the vessel and is integrally bound with the bottom 2 along the edges of the slit 4.

The internal space 8 on the pontoon part 7 communicates with the internal space 6 of the above-water part 1 , thus creating a common internal operating room of the vessel where required equipment, essentials and the like are kept.

According to the invention, the common room 9 of the pontoon part 7 is such that the waterline 10 of the vessel passes along the pontoon part 7 near the bottom 2 of the above-water part 1 of the vessel.

The pontoon part 7 (Fig. 2) comprises a central portion 11 , bow portion 12 and stern portion 13. In the plan view, the bow portion 12 and the stern portion 13 are sharp-pointed, while the central portion 11 has a rectangular form, wherein the cross section (Fig. 3) of the central portion 1 1 the pontoon part 7 has substantially the form of a rectangle with rounded angles 14 in the lower portion. The long sides 15 of this rectangle are positioned perpendicularly to the longitudinal axis 3 of the vessel; to increase stability of the vessel, the width B/length A relation of the rectangle may be selected in the range of from 0,4 - 0,5.

Additionally, to provide a high stability of the moving vessel and to reduce the wave resistance, the waterline 10 of the vessel should lie at the distance D from the bottom, which amounts to approximately 0,05 - 0,10 of the length A of the rectangle.

In another embodiment of the invention, the central portion 11 of the pontoon part 7 in the cross section (Fig. 8) is made preferably in the rounded form, for instance in the form of a ring bound from above with the edges of the slit 4 in the bottom 2. That is, as a matter of fact the pontoon part 7 on the outside has a form of a tube sharp-pointed at the bow and stern portions. Having such a form, the pontoon part 7, when its volume is equal to a corresponding volume of the variant with a rectangular cross section, has a smaller external wetted surface, due to which the vessel requires a less powered propeller for its motion.

The bottom 2 of the above-water part 1 of the vessel in the cross section of the above-water part 1 (Fig. 3) is rectilinear and parallel to the waterline, while the portion 16 of its communication with the walls 5 is made in the rounded form.

According to other embodiments of the invention illustrated in the Figs.

5, 6, the bottom 2 in the cross section of the above-water part 1 is made positioned with an inclination relative to the waterline 10 of the vessel, thus providing a V-form of the cross section of the bottom 2 of the above-water part 1 . The angle of inclination a is limited by the interval from 18° - 20°. Besides, the bottom 2 is carried out with an inclination (the angle β which amounts approximately to 5° - 10° ) relative to the stern of the vessel.

According to the invention, it is desirable to arrange in the pontoon part 7 a ballast system 17 which services, for instance, for pumping-in and pumping-out some amount of the water 18, as it is shown in the Fig. 7, or other ballast which can be placed preferably into the lower portion of the pontoon part 7 of the vessel.

It is to note that in the stage of projection of the vessel, all equipments, devices etc. are kept in the internal operating room of the vessel which includes the internal space 6 of the above-water platform and the internal space 8 of the pontoon part. The most heavy equipment should be located in the pontoon part 7, thus providing a higher moment of restitution of a normal position of the vessel after its healing, and achievement of the higher stability of the vessel, particularly when its movement is provided by a wind propeller.

Before going out into a wide water area taking into consideration the load of the vessel and the presence of the waves on the water surface, the pontoon part 7 is filled with the water 8 or other ballast by means of the ballast system 17 or kept unloaded so that the waterline of the vessel on the upper portion of the pontoon part 7 under the bottom would be at the level described above, and then begin a movement through the water.

The rounded angles of the joints of the bottom 2 with walls 5 of the above-water part 1 and the rounded angles of the sides of the pontoon part 7 decreases the so called "wetted surface" of the vessel and the wave formation at contacting with water, thus lowering a required power of the propeller.

Investigations carried out by the author, revealed that during the movement of the vessel the submersed pontoon part 7 creates a low wave in the region of the bow portion 12 of the pontoon part 7 (as shown by a dotted line in Fig. 1 , Fig. 3, and Fig. 6), the height D of which depends on the relation between the width B of the rectangular section of the pontoon part 7 and the length A on the long side (Fig. 3). At the speed of the vessel in the range of from 25-30 km/h, which corresponds approximately to the speed of the vessel with a sail propeller, an optimum relation ranges from approximately 0,4 - 0,5.

The vessel can be equipped with both the wind and screw propellers (not shown). It is understood that with a wind propeller, heeling of the moving vessel should be greater because of the increased heeling moment created by the soil system, and as a result the vessel will touch sometimes the water with its edges (Fig. 4) to insure stability of its position.

At increased speed of the vessel (of the order of 50-60 km/h that corresponds approximately to the speed of the vessel with a screw propeller (motor vessel) and plane bottom 2 (Fig. 3), a phenomenon of repeated blows to the bottom 2 can arise, which becomes stronger at presence of waves on the water surface. For such conditions, the bottom 2 should be made inclined relative to the waterline 10, using a V-shape cross section (Fig. 6) of the above-water part 1. Besides, taking into account such cases, the bottom 2 (Fig. 5) should be made inclined relative to the stern in the longitudinal direction of the vessel to insure so called "glide effect" which enables to reduce resistance to the movement of the vessel.

On mooring, the lower portion of the pontoon part 7 (Fig. 7) is filled by means of the ballast system 17 until the bottom 2 lies on the water surface. 4

7

Thus, the offered design of the small vessel according to the invention allows to reduce a wave formation and at the same time provides a sufficiently large useful area inside the vessel. Additionally to this, depending on the used types of the propellers, the proposed optimal embodiments of the invention enable to insure stability and to reduce resistance to the movement of the vessel.