USA As Represented by Secretary of the Navy

Scott Gowing

Young T Shen

Frank B Peterson

Thang D Nguyen

Edward S Ammeen

William G Day

Timothy W Coats

The invention is directed to an apparatus for mitigating the load impact on a surface watercraft and passengers therein, during high speed travel. The hull includes a damping cavity for mitigating the load impact on the surface watercraft. The damping cavity is positioned on a dry portion of an undersurface of the hull between a forward end and an aft end of the hull. The damping cavity includes a porous plate on the undersurface, and a deck plate within the hull body. The deck plate and the porous plate are separated by a gap, and an inflatable bladder may be positioned in the gap between the plates.

Permeable hull to mitigate impact load in water

A high-speed water vessel including a steering arrangement for reducing cavitation and its effects. The arrangement includes a twisted rudder pair located downstream of a high-speed propulsor. The rudder pair may also be contoured at a bottom portion thereof. The propulsor has at least one propeller having a propeller diameter. In operation, the propulsor produces a slipstream that contracts with distance from the propeller. To avoid the effects of cavitation, the twisted rudder pair is positioned outside and adjacent to the slipstream diameter, with the rudders of the rudder pair separated by a distance that is less than the diameter of the propellers. The rudders of the rudder pair may be in a substantially parallel orientation with respect to each other. In gas turbine applications, the rudder pairs may be rotated towards each other to produce a rudder bucket for producing a negative thrust for stopping the high-speed water vessel.

Rudders for high-speed ships

A hydrofoil stabilizer fixed to an underwater hull and provided with a pair of pivotally deflectable control flaps through which surface lift on the stabilizer is controlled, is provided with trailing edge tabs on both of the flaps that are pivotally deflected in the same direction to further offset and thereby improve recovery from surface jam inducing lift force on the stabilizer which adversely affects maneuvering control.

Control tab assisted lift reducing system for underwater hydrofoil surface

The inventive apparatus exercises control of the water flow which is discharged from a marine waterjet propulsor. Typical inventive embodiments comprise plural horizontal and plural vertical blade-like structures which together describe an open-ended, box-like rectilinear configuration characterized by at least two adjacent channels. Every vertical blade-like structure includes, at its aft end, a &ldquo;steering&rdquo; flap which is pivotable about a vertical axis. Some inventive embodiments advance marine craft reversing by implementing one or more bucket-like devices behind the inventive apparatus. According to many inventive embodiments, every vertical blade-like structure (other than the two laterally extreme vertical blade-like structures) has a steering flap attributed with lengthwise severability (as if severed by a vertical plane) into two sub-flaps, each sub-flap itself being pivotable about the same vertical axis; in cooperation therewith, the marine craft is reversed by implementing plural &ldquo;backing&rdquo; flaps (included in the bottom-side horizontal blade-like structure or structures) which are each pivotable about a horizontal axis. The inventively coordinated movements and dispositions of the flaps, sub-flaps and/or bucket-like devices effect steerable and/or reversible maneuverability of the marine craft. Utilization of the present invention is especially efficacious in the context of waterjet propulsion systems wherein the water flow is discharged underwater; underwater-discharge marine waterjet propulsion, practically unknown but theoretically recognized for its potential benefits, is rendered a real and viable option by the present invention.

Steering and backing systems for waterjet craft with underwater discharge

Cavitation of a hydrofoil element, such as the rudder of a marine vessel, om exposure to a body of water during onset flow at different angles to the chordal axis of the rudder profile, is suppressed by a tab on the lower end tip of the rudder. Such tab has external surfaces thereon which affect flow separation relative to the rudder so as to suppress or delay cavitation.

Rudder tab for suppression of tip vortex cavitation

The quantity of gases dissolved in liquids is determined by introducing a quid sample into a hollow cylinder with a plunger, retracting the plunger to create a void space into which gases originally dissolved in the liquid sample diffuse, compressing the gases into a reduced volume, measuring the absolute pressure of the gases, and calculating the amount of gases originally dissolved in the liquid from the absolute pressure, the temperature, the vapor pressure of the liquid at the prevailing temperature, the volumes of liquid and the final volume of the gas, by using the ideal gas law.

Growing community of inventors

North Potomac, MD, United States of America

Scott Gowing