Particularities of hull shape of offered high-nautical gliding boat at gas cavity

Hull of offered high-nautical gliding boat at gas cavity (see Fig. 1 and 2) has V-shape bottom 1 and sides 2 with two hard chines. Main hard chine 3 has a built-in spray deflector 4 that has the shape of step located between its inner 5 and outer 6 edges and is directed away from hull centre line (CL) relative to the above located hull plating. Main hard chine 3 extends lengthwise the total hull length and rises in its bow in S-shape path almost till the upper deck 7 level. Auxiliary chine 8 located close to the running water line 9 extends from its stem 10 till the main hard chine 3 in place of its entering into the water. At the level of auxiliary chine 8, hull stem possesses a sharp step that detaches its inclined forward upper part 11 from its almost vertical bottom part 10. In bow, keel line 12 is smoothly bent downward. Buttocks 13 of stern part of the bottom 1 in the space between the spray deflectors 4 and main hard chine 3 (including the keel line) are also bent downwards.

Auxiliary chine 8 has a shape of step 15 directed towards the CL relative to the above located hull plating. A part of hull bow located above the auxiliary chine 8 is pushed forward over the stem 11 line. At this, one observes creation of ram-shape projection 16 that has evenly convergent water lines 17 and frames 18 in the form of isosceles triangles delineated by straight lines or by weakly convex curves with the vertex directed downwards and located at the hull keel line 12. Ram-shape projection 16 upper edge 19 is a smooth extension towards the bow of steps 15 surfaces of auxiliary chines 8 of both boat sides. Auxiliary chines 8 edges and buttocks 20 of ram-shape projection 16 upper edge 19 are inclined towards the bow relative to running WL 9 plane. Steps 15 surfaces of auxiliary chines 8 smoothly turn into sides 2 surfaces at the bow. In the area limiting by stem upper part 11, auxiliary chine 8 outer edge and main hard chine 3 inner edge, these surfaces form cavities 21 with cone surface having the top in the point 22 of intersection of auxiliary chine 8 edge with main hard chine 3 inner edge.

Hull bottom 1 is provided with a special triangle groove. On the side of boat hull and sides, the bottom groove is limited by the side skegs 23 that enlarge in direction to the bow. Astern, it extends till the transom 24. Top 25 of triangle bottom groove is formed by the intersection of brake-constitutive rims 26 with side skegs 23 and is situated in bow. In front of the groove, there is a so-called bottom cylindrical insert 27. At the drawing, this insert 27 has a horseshoe-shape and on the side of bow and sides it is limited by the line 28. The line 28 is equidistant along the hull by side skegs 23 brake-constitutive rims. Keel line segment 29 located within the cylindrical insert 27 coincides with the tangent to the stern edge of its bow section bent downwards.

At this, angle of slop towards the bow of auxiliary chine 8 edge and of buttocks 20 of ram-shape projection 16 upper edge 19 to the plane of running WL 9 is chosen according to the following: firstly, when ram-shape projection 16 passes through the wave at maximum boat speed, at its upper edge 19, auxiliary chines 8 steps 15 of both sides 2 and lower surfaces of cone side cavities 21, there must be a total hydrodynamic force, secondly, the vertical component of this force has an approximate value of total extra buoyancy force that hull bow acquires after immersion into the wave.

At this, stem upper part 11 located above the auxiliary chine 8 can be inclined either towards or backwards.