SI22949A - Vessel with hull for top hull navigation speed - Google Patents

Abstract

Thanks to its specifically designed underwater part the vessel with hull for top hull navigation speed results in a minimum resistivity of water, while apart from that (also due to its shape) it enables a highly efficient operation of the propeller. Due to this the vessel attains in the displacement mode the so-called top hull speed, this is a speed, which exceeds the theoretical maximum speed based on the length of the water line or wave speed of the waterline wave length. The aforementioned underwater part of the hull is thus designed to achieve a single goal - to minimize the hydrodynamic resistivity, which results in the slightly decreased initial stability (this is stability at smaller inclination angles). This can be if required (for example under extreme weather conditions) substantially increased by filling the ballast tank (with water) so that the vessel submerges additionally, while again, thanks to the design features of the hull apart from increasing the displacement, it substantially changes its submerged part, while the consequence of both is a major increase in stability.

Description

The invention relates to the hull of a power-driven vessel, which, thanks to its specifically shaped underwater part, causes minimal water resistance and also (due to its shape) enables the operation of a high-efficiency propeller. As a result, the vessel achieves, in the displacement mode of navigation, the so-called super-hull velocity, that is, the speed exceeding the theoretical maximum speed, conditioned by the length of the water line or. wave velocity wave length of the waterline. The underwater hull section is thus designed to achieve a single objective - the lowest possible hydrodynamic resistance, which gives it a slight decrease in initial stability (i.e. stability at low tilt angles). This can, if necessary (eg in extreme weather conditions) be substantially increased by filling (with water) the ballast tank, so that the vessel is further submerged, again due to the hull design characteristics, in addition to increasing the displacement , significantly changes its underwater part, both of which result in a drastic increase in stability.

As is well known to those skilled in the art, the hydrodynamic resistance of a vessel in displacement mode is the sum of two different types of resistance: resistance due to the formation of waves and friction between the surface of the underwater hull and water. While the resistance due to the formation of waves (at a certain speed of navigation) depends on the size of the displacement and on the shape of the underwater part of the hull, the friction depends on the surface roughness and its size. As far as hydrodynamic resistance is concerned, the ideal shape of the underwater part of the hull should therefore have a hydrodynamic (droplet) circular cross-sectional shape (to minimize the wetted surface) at a given displacement. However, since the circular transverse shape does not offer any hull stability, this design is not applicable to (surface) vessels. The other extreme, that is, the hull with high stability, is provided by the transverse shape of the rectangle, with the width of the waterline (as large) as possible compared to the hull draft. Such a hull, however, has a large wetted surface and associated friction with respect to the displacement. Therefore, the optimal cross-sectional shape of the hull is somewhere between the two extremes, depending on the type and purpose of the vessel.

In order to minimize hydrodynamic resistance, the vessel according to the invention has the shape of the underwater hull part closer to the first of the aforementioned forms, due to the slightly reduced initial stability of the vessel. The latter can be substantially increased by immersing the hull further in the water with the help of a built-in water ballast. Due to the specific shape of the hull of the vessel according to the invention, its stability is significantly increased, because in such a position the cross section of the underwater hull is greatly altered - its width on the water line is greatly increased, which significantly increases the stability of the vessel.

The invention will be described in detail in the embodiment and shown in the drawings showing:

FIG. 1 is a side view of the hull of the vessel of the invention

FIG. 2 is a cross-section along line A-A of FIG. 1;

Fig, 3 is a cross-section along line B-B of Figs. 1;

FIG. 4 is a cross-section along line C-C of FIG. 1.

According to the design and functional characteristics of the hull (3) of the vessel according to the invention, there are two parts: the lateral, upper part (3.1) and the lower part (3.2), which are separated by the longitudinal hinge (3.3). The difference between the two parts of the hull mentioned is most evident in its cross-section. While the lateral part (3.1) of the hull has a substantially constant width, the width of the lower part (3.2) decreases sharply with depth (from the joint (3.3) in the downward direction), most just below said joint, where the contour has a concave curvature (3.4), and the tangent of said contour is essentially horizontal at the point where it touches the joint (3.3), which is especially pronounced for the front of the hull. During (normal) navigation, only the greater part of the lower part (3.2) of the hull is in the water. Therefore, the water line (WLi) runs below said joint (3.3), where the hull is significantly narrower than above the joint (3.3). The shape of the lower part (3.2) of the hull is subordinate to the basic objective - to give as little hydrodynamic drag as possible in the displacement mode. Therefore, it has the following characteristics:

cross sections near the V-shaped bow;

strongly rounded, relatively deep cross-sections in the central part of the torso; slightly rounded, shallow cross sections in the stern of the hull.

Due to these design features, the lower part (3.3) of the hull has a pointed bow, a narrow waterline (WLi), a small (depending on the volume of the underwater part of the hull) wetted surface and a laid passage (5) of the underwater part of the hull in the overhead aft, combined with a small displacement (which of course requires a correspondingly low weight of the vessel), all of which guarantee a small hydrodynamic resistance. Said pointed bow provides, in addition to that described, a soft immersion of the bow into waves, said concave hull part just below the joint (3.3), in particular due to the said almost horizontal part adjacent to the joint, preventing water from splashing onto the deck of the vessel. The aforementioned narrow waterline (WLi) interacts with the rounded hull in cross section (which provides a minimum wetted surface area with respect to displacement), although it does not provide the vessel with much initial stability. Therefore, a classically designed hull with such underwater part would have good hydrodynamic properties (small hydrodynamic resistance), but at the expense of vessel stability. The hull would therefore not have the optimum shape. In the case of the hull of the vessel of the invention, the described hull extension (said concave hull section together with the hinge (3.3)) just above the waterline (WLi) plays its role here. This part of the hull is submerged at a slight inclination of the vessel, with a dramatic increase in the stability of the vessel. Of course, the vessel according to the invention has significantly greater stability if the hull is more immersed in water. For this purpose, the vessel according to the invention has a water ballast tank installed. When said tank is filled with water, the hull of the vessel according to the invention is further submerged so that the water line (VVL2) extends above the joint (3.3). In this position, however, said waterline has a substantially greater width than waterline (WLi), which, and of course due to increased displacement, also increases the stability of the vessel. In such a recessed position, the vessel according to the invention is positioned primarily for the convenience of the crew (to rock as little as possible) when the vessel is stationary at anchorage or in port, as well as for greater safety while navigating the extremely turbulent sea.

It is well known that the hydrodynamic resistance of the hull significantly affects the fuel consumption. In addition, fuel consumption also depends on the utilization rate of all elements in the drive chain, from the propulsion engine to the propeller. One of the reasons for the reduced efficiency of the propeller or the reduced utilization of its propulsion force lies in the obliquely positioned shaft of the propeller and thus the propeller. Many of the engine-built vessels, for various reasons, have said shafts sloping downwards from the bow towards the stern. The problem is particularly pronounced in vessels where the propeller is located below the hull and must therefore be positioned quite deep (in order not to reach the hull of the vessel with blades), the deeper the larger the diameter of the propeller. The damage is twofold: the sloping draft on the propeller reduces its efficiency, and the flow of water through the propeller is reduced.

The hull of the vessel according to the invention also solves this problem - namely, it allows horizontal positioning of the propeller under the hull - by having a groove or tunnel (3.5) formed along the rear of the hull symmetry along which the propeller extends with the outside of the blades. The tunnel (3.4) also allows for the smooth flow of water, which even channels it, to the propeller.

Due to the low hydrodynamic resistance of the hull and also due to the high utilization of the propeller, the navigation of the vessel according to the invention in the upper position (when the ballast tank is empty) is extremely economical in terms of fuel consumption, ie the vessel achieves significantly higher, so-called over-hull velocity in displacement mode. The prototype vessel according to the invention has a line length of 10 m with a relatively low engine power, a speed of 10 knots in displacement mode, which is much higher than the theoretical speed of 7.4 knots with respect to the length of the water line.

Claims (5)

PATENT APPLICATIONS 1. Vessel with hull for buoyancy mode in displacement mode, which can be reached by buoyancy thanks to an underwater hull designed to create extremely low hydrodynamic resistance during navigation and to allow good utilization of the propeller, so that the resistance is optimally designed with as small as possible wetted surface, characterized in that, according to the design and functional characteristics of the hull (3) of the vessel according to the invention, there are two parts: the lateral, upper part (3.1) and the lower part (3.2) separated by a longitudinal joint (3.3) ) of the hull, the difference between the two parts of the hull being most visible in its cross-section: while the lateral part (3.1) of the hull is substantially constant in height, the width of the lower part (3.2) decreases with depth (from the hinge (3.3)). downwards) sharply decreases, most just below said joint, where the contour of the cross section has a concave curvature, and the tangent of said contour is essentially horizontal in the point (5.2) at which it touches the joint (3.3) on, which is especially true of the front of the hull. A vessel according to the first claim, characterized in that during (normal) navigation, only a large portion of the lower hull portion (3.2) is in water, that is, the water line (WLi) runs below said joint (3.3), where the hull is substantially narrower than the hull. above it. Vessel according to the first and second claims, characterized in that the hull extension just above the waterline (WLi), that is, the concave hull part together with the hinge (3.3) serves to increase the stability of the vessel during its inclination, since this hull part is already small. It sinks the slope of the vessel, increasing its stability momentum. A vessel according to the first and second claims, characterized in that it has a built-in water ballast tank by which the vessel can be submerged so that the water line (Wl_2 extends above the joint (3.3) and in this position has the waterline is substantially larger than the waterline (WLi), which, and of course, due to increased displacement, also increases the stability of the vessel. Vessel according to the first claim, characterized in that, along its rear end, a groove or tunnel (3.5) is formed on the hull symmetry, into which the propeller extends with the outer part of the blades, thus allowing the horizontal placement of the propeller under the hull, thereby providing good the utilization of the propeller, in addition, the tunnel (3.5) also allows a smooth flow of even sewage to the propeller.