A low-cost viscous-drag-reducing cladding for a ship's hull comprising airbags whose outer surfaces are adapted to be water repelling. Each airbag comprises a plenum that comprises substantially open space, which does not obstruct the flow of air through it. The airbags are inflated with compressed air to a pressure higher than the adjoining hydrostatic pressure. The airbag material comprises a reinforcing fabric, which is adapted to withstand the forces encountered during operation, and is sealed with a sealant so as to be made substantially impermeable to air. The outer water-repelling surface of each airbag is connected to a plenum by means of restrictor holes. Air flows from the plenum through the restrictor holes into the water-repelling layer.

The present disclosure relates generally to the field of facilitating a laminar flow and sound mitigation between a wetted hull of a vessel and surrounding fluid. More specifically, the present disclosure includes methods, systems, and apparatuses to facilitate providing and sustaining a laminar flow of a fluid across a vessel. A system for sustaining laminar flow of a fluid across a vessel comprising a main control unit. The main control unit comprises one or more air compressor units configured to generate air. An integrated longitudinal air distribution assembly is secured to a wetted hull of the vessel. The distribution assembly comprises a series of air dispersal modules configured to distribute the generated air across the wetted hull of the vessel to create at least one air layer between the wetted hull of the vessel and the fluid to sustain the laminar flow of the fluid across the vessel.

This disclosure relates to a ship hull microbubble system used to reduce frictional drag on a ship hull while traveling through water. The microbubble system includes a water pump connected to an ejector which intern draws and compresses air within the ejector body. While in the ejector the compressed air becomes entrained within the pumped liquid as microbubbles creating a multiphase fluid which is then ejected at suitable pressure from the ship hull below the waterline through dedicated hull openings. The ejected air liquid multiphase fluid then creates plurality of microbubbles within the below water boundary layer reducing frictional drag generated by the hull as it travels through water. This disclosure has advantages when compared to related art through minimizing ship structure modifications, reducing wear on the ballast pump, operational autonomy from the ballast system, reducing the systems area footprint, independent control of the air injection rate, simplifying the installation through reducing existing pipework modifications and removing the need for riser pipes and additional tanks.

The present invention is a device to reduce the skin friction drag on the hull surface of a marine vehicle. The device is in a form of a channel having a wider portion facing an incoming water stream (inlet) and a narrower portion (outlet) installed over an air orifice on the hull surface, forming an array of channels. A stream of water, generated by a marine vehicle motion, enters the channels and creates a low pressure region that pulls the air into the stream of water through the air intake holes, creating a stream of air bubbles. This structure increases water flow velocity close to each air orifice, creates larger turbulent components passing through and over each channel, injects more bubbles, and avoids dispersion of air bubbles to improve the existing skin friction drag.

Disclosed herein are a method and a system for forming an air layer over a portion of an engineered surface, wherein the air layer is formed with a reduced flux and preferentially steering gas away from, or toward, a specific location by way of a hydrophobic surface, a hydrophilic surface, and/or a structured surface. Moreover, disclosed are a method and a system for recovering or separating a portion of the gas or other fluid layer.

A watercraft system including one or more air passageways and/or one or more water passageways is provided. The air passageways may extend from an upper surface of the watercraft, through the body of the watercraft, to an underneath surface of the watercraft. The water passageways may extend from an underneath forward or side portion on the watercraft, through the body of the watercraft, to a rear portion of the watercraft. The air and/or water passageways may be constricting from the inlets to the outlets so that the air and/or water is accelerated through the passageways during use of the craft. In this way, the release of the accelerated air and/or water decreases the craft's drag and provides the craft a forward thrust.

A marine vessel hull, and marine vessels comprising at least one such hull, comprising a non-entrapment hull having at least one longitudinally vented transverse step, each longitudinally vented transverse step comprising a transverse step, and one or more longitudinal steps extending forward therefrom. Each longitudinal step portion has a cross-sectional profile defining a cutout into the hull relative to a line defined by a deadrise angle of the hull. The cutout defines a vertical rise starting from the line defined by the deadrise angle and a run tilted outwardly upward at a non-horizontal angle less than the deadrise angle and that extends to an intersection with the line defined by the deadrise angle.

A marine vessel (100) comprising: propulsion means (118, 134); a hull section (102); a body section (104) connected to said hull section via at least one stanchion (106, 108, 110, 112); and the body section and the hull section being movable relative to each other via said at least one stanchion.

A viscous-drag-reducing cladding for a ship's hull whereby the wetted area of the hull is reduced by interspersing air between the hull surface and the water. A substantial portion of the submerged area of the ship's hull comprises densely packed air pockets. The dimension of the air pocket is less than twice the capillary length of water. Each air pocket is supplied with pressurised gas by means of a restrictor. The pressurised air is supplied to each air pocket by means of a network of corrugated channels.

Systems, methods and apparatuses are provided for the reduction of hydrodynamic frictional drag. These systems, methods and apparatuses can include a vessel surface having an external layer and a plurality of dimples, wherein the external layer comprises a hydrophilic material, and wherein each of the dimples includes an inner surface having a superhydrophobic coating. The dimples can be configured to maintain an air-water interface as one or more fluids flow over the vessel surface. In some embodiments, a pressure reservoir can be coupled with the dimples, and can include an acoustic speaker to vibrate the air-water interface.