Patent AU-2018436895-A1 (AU)
Title: Stabilized hull of a monohull motor boat, which surfs on a water cushion and has a deeply submerged supporting blade
Inventor: VODOPIANOV IGNAT MIKHAILOVICH
IPC: B63B39/06
Filed: 2018-12-06
Abstract: The invention relates to boat building and can be used in the building and modification of sea-going high-speed monohull motor boats having a single hull that travels in surfing mode on a water cushion. Claimed is a stabilized hull of a monohull motor boat, which glides in a surfing fashion on a water cushion and is provided with a deeply submerged water-displacing supporting blade, said hull having an overall width of not more than 50% of its length and having, along the entire length of the bottom part thereof, a bottom surface that extends downward in a direction from the bow to the stern, wherein the tip of the bow projects above the waterline by a distance equal to not less than 25% of the width of the hull, and below the tip of the bow there is a tall wave-penetrating stem. In the front 40% of the length of the hull, the bottom surface has a downwardly extending shape that smoothly transitions into the bottom surface of the stern portion of the hull and is inclined relative to the waterline by an angle of not less than 5 degrees when the boat is stationary; in the rear 60% of the length of the hull, the bottom surface has a downwardly extending shape and is inclined relative to the waterline by an angle of not more than 5 degrees when the boat is stationary, the bottom surface having a substantially flat shape in cross section and being submerged below the waterline across 70% or more of its length, the submerged portion constituting a "surfing surface" that glides on a water cushion when the boat is in motion and supports not more than 70% of the full unladen weight of the boat. Below its bottom surface, the hull is provided with a vertically oriented deeply submerged water-displacing supporting blade, which runs longitudinally along the full length of the boat and is symmetrical about the centreline thereof, said supporting blade having a narrow shape and low wave/hydrodynamic resistance, the ratio of the length of the supporting blade to its width being not less than 20 times, the water displacement of the supporting blade corresponding to 30-0% of the full unladen weight of the boat, and the height of the supporting blade (excluding the stem) being not less than 20% of the maximum width of the hull, ensuring that the bottom edge of the supporting blade is well submerged relative to the waterline. The supporting blade has a wave-penetrating profile, a tall wave-penetrating stem that extends heightwise to the bow tip of the underside of the hull, sharp rear and front profiles, a smooth middle profile, and a triangular shape in cross section throughout its entire length, the smallest angle of said triangle being at the bottom, and the supporting blade being at its widest at between 40 and 60% of its length, placing the centre of buoyancy of the supporting blade at between 40 and 60% of its length and in the upper third thereof. The manoeuvreable hull of a displacement-type craft, which is stabilized in choppy seas and glides on a water cushion, opens up broad possibilities in terms of the building of sea-going high-speed boats. Above all, it provides a fundamental improvement in running stability, eliminates rolling/pitching and yawing in open seas, and also increases load-carrying capacity and fuel efficiency by comparison with planing hulls.