RU2827118C2 - High-speed boat (gliding vessel) hull with improved running characteristics - Google Patents

Abstract

FIELD: shipbuilding.

SUBSTANCE: invention relates to ship building, particularly, to hull of high-speed boats. High-speed boat hull has hard-chine lines with angles of external deadness of at least 14°. In the aft part, the bottom is made with a break at the keel line, which forms a flat section of the bottom adjacent to the transom, perpendicular to the centre plane (CP) and which is an equilateral triangle with a base on the transom, which is symmetrical relative to the CP, equal to 0.05 to 0.15 of the width of the body along the bow on the transom, and apex on the keel line located at distance of 3−4 theoretical spacings from the transom. Controlled interceptors extending across the incident flow are installed along the aft edge of the bottom from the keel to the bows with possibility to change its extension below surface of bottom from 0 to maximum value equal to 0.01 to 0.03 of width of body along bow on transom, in order to change angle of running trim.

EFFECT: maximum reduction of resistance to movement and increase of hydrodynamic quality at optimal for each speed of movement of interceptor extension.

2 cl, 3 dwg

Description

The invention relates to shipbuilding and concerns the hull of high-speed boats (planing vessels).

High-speed planing boats and vessels of various purposes are known with moderate and increased deadrise hulls and with deep-V hulls, the main feature of which is a large deadrise of the bottom (more than 10°), which remains constant from midship to transom (see Handbook of Small-Tonnage Shipbuilding, Sudostroenie Publishing House, Leningrad, 1987). The deadrise angles of the bottom from transom to midship are in the range from 10 to 30°. As a rule, such hulls have longitudinal slats on the bottom. The disadvantage of such hulls is that, while providing sufficient seaworthiness when moving at high speeds, they require significant power-to-weight ratio due to the relatively low hydrodynamic quality of such hulls compared, for example, with unseaworthy hulls with a small deadrise.

It is known that the hydrodynamic quality of planing hulls with the above-mentioned deadrise of more than 10° at high Froude numbers for displacement Fro can be increased by introducing horizontal flat elements into the bottom design, which increase the load-bearing properties of the hull, which is manifested in an increase in the lifting force and the floating of the hull at high speeds, due to which the wetted surface of the hull and the frictional resistance associated with it can be reduced.

It is also known that the hydrodynamic quality of planing hulls at high Froude numbers increases with the displacement of the center of mass in the direction from the midship to the transom (to the stern), while at lower Froude numbers a significant deterioration in the hydrodynamic quality is observed in the area of the so-called "drag hump". In such cases, to reduce the resistance to movement and increase the hydrodynamic quality at speeds in the area of the "drag hump", it is common to control the boat's running trim angle by using transom plates or transom interceptors (both fixed and controllable).

The purpose of the present invention is to develop a hull for a high-speed boat (planing vessel) which, while maintaining a large (more than 14°) deadrise of the bottom from midship to transom, would provide a reduction in resistance to movement and an increase in hydrodynamic quality both at high Froude numbers, characteristic of maximum speeds, and at lower Froude numbers in the region of the "resistance hump".

To achieve the stated goal, the proposed housing has the following set of significant differences, explained by the drawings in Fig. 1 and Fig. 2:

- in the aft part of the hull the bottom is formed with a break at the keel line, which forms a flat section of the bottom 1 adjacent to the transom, perpendicular to the DP and representing an equilateral triangle symmetrical relative to the DP with a base along the line of intersection with the transom, equal to 0.05 to 0.15 of the width of the hull along the cheekbone on the transom Bctr and the apex on the keel line, which has an extension towards the bow from its base by 3-4 theoretical spaces (by 0.15-0.20 of the length along the KWL _CWL );

- on the transom along the aft edge of the bottom from the keel to the cheekbones, controlled interceptors 2 are installed, extending across the oncoming flow, with the ability to change their extension below the bottom surface from 0 to a maximum value equal to 0.01 to 0.03 of the hull width along the cheekbone on the transom B _Ctr , in order to change the running trim angle and achieve maximum reduction in resistance to movement and increase in hydrodynamic quality with an optimal extension of the interceptors for each speed of movement.

In addition, in order to reduce the wetted surface of the hull, reduce the washout of the side above the chines by spray jets and improve the hydrodynamic quality of the hull due to the increase in the lifting force (dynamic support force), longitudinal chines 3 (two or three branches on each side) can be additionally installed on the bottom between the keel and the chine, and a chine bend 4 can be formed so that from the inner, closest to the DP, break line to the chine, the frame branches are perpendicular to the DP or are deflected downwards as they move away from the DP and approach the chine. Similarly, the chine bend can be formed in the form of an overhead splash guard running along the chine along its entire width or partially extending beyond the chine line outward. In this case, the width of each longitudinal chine and the bent section of the bottom along the edge of the chine is from 0.02 to 0.03 of the hull width along the chine B _C .

The result of the implementation of the proposed invention is as follows:

- the triangular flat section of the bottom adjacent to the transom reduces the resistance to movement and increases the hydrodynamic quality of the hull at high Froude numbers (at Fr _G >3.5 for the tested model) due to the reduction of the wetted surface of the hull due to the increase in the angle of running trim and ascent, causing an increase in the lifting force (dynamic support force);

- at lower speeds in the area of the "drag hump" (at 1.0<Fr _G <3.0 for the tested model), especially when the boat's center of mass is shifted to the stern (advantageous from the point of view of increasing the hydrodynamic quality at high Froude numbers), the optimal extensions of the transom interceptors for each speed are used to reduce the resistance to movement and increase the hydrodynamic quality of the hull;

- between the above speed ranges (at 3.0<Fr _G <3.5 for the tested model), the resistance to movement and the hydrodynamic quality of the proposed hull differ slightly from the hull with increased deadrise without the proposed changes;

- additional installation of longitudinal ribs and formation of a chine bend (or installation of an overhead splash guard along the chine) also contribute to reducing resistance to movement and increasing hydrodynamic quality in the above-mentioned ranges of movement speeds due to a reduction in the wetted surface of the hull and an increase in lift (dynamic support force).

The effect of reducing the resistance to movement and increasing the hydrodynamic quality of the hull of a high-speed boat (planing vessel) made in the proposed manner was experimentally confirmed during towing tests of a model with a relative abscissa of the center of mass X _G /L _CWL = 0.339 in an experimental tank in the range of Froude numbers 0.25 < Fr _G < 4.1. On the model in the original version and the version modified in the proposed manner, longitudinal chines were installed and the cheekbone was bent as described above. The results of the towing tests in the form of dependencies on the Froude number for displacement Fr _G of the relative resistance of the model R _m / (ρ⋅ (B _C ) ³ ) in the original and modified versions are shown in Fig. 3. The positive effect of the above-mentioned triangular flat section of the bottom adjacent to the transom manifests itself at high speeds at Fr _G > 3.5 and is expressed in a decrease in resistance to movement as the speed further increases. In this case, the resistance decreases by 5% already at Fr _G = 4.0. The effect of the optimal extension of the transom interceptors at lower speeds in the area of the "resistance hump" is present at Froude numbers for displacement 1.0 < Fr _G < 3.0. In this case, the maximum reduction in the resistance is ~ 18% at 1.5 < Fr G < 2.0. In the intermediate range of speeds at 3.0 < Fr _G < 3.5, the resistance to movement of the proposed hull is practically no different from the original.

The proposed hull of a high-speed boat (planing vessel), using the tested model as an example, has lower resistance to movement and higher hydrodynamic quality when moving at high speeds at Fr _G >3.5 and in the region of the "resistance hump" at 1.0<Fr _G <3.0 with approximately equal resistance to movement in the intermediate range of speeds at 3.0<Fr _G <3.5, which distinguishes it favorably from a conventional hull.

Claims (2)

1. A hull for a high-speed boat with sharp-chine contours with external deadrise angles of at least 14°, characterized in that in the aft part the bottom is made with a break at the keel line, which forms a flat section of the bottom adjacent to the transom, perpendicular to the centerline plane (CP) and representing an equilateral triangle symmetrical relative to the CP with a base on the transom equal to from 0.05 to 0.15 of the hull width along the chine on the transom, and a apex on the keel line located at a distance of 3-4 theoretical frames spaces from the transom, while along the aft edge of the bottom from the keel to the chines, controllable interceptors are installed that extend transversely to the oncoming flow, with the ability to change their extension below the bottom surface from 0 to a maximum value equal to from 0.01 to 0.03 of the hull width along the chine on the transom, in order to change the running trim and achieving maximum reduction in resistance to movement and increase in hydrodynamic quality with optimal extension of interceptors for each movement speed. 2. The hull of a high-speed boat according to paragraph 1, characterized in that in order to reduce the wetted surface of the hull and the washing away of the side above the cheekbones by spray jets, as well as to improve the hydrodynamic quality of the hull by increasing the lifting force on the bottom between the keel and the cheekbone, longitudinal slats can be additionally installed and a cheekbone bend can be formed by deflecting downwards to the horizontal or below the branches of the frames in front of the edge of the cheekbone or in the form of an overhead splash guard running along the cheekbone, extending beyond the line of the cheekbone outward, wherein the width of each longitudinal slat and the bend of the bottom along the edge of the cheekbone is from 0.02 to 0.03 of the width of the hull along the cheekbone.