The Kitchen rudder is the familiar name for "Kitchen's Patent Reversing Rudders", a combination

rudder A rudder is a primary control surface used to steer a ship, boat, submarine, hovercraft, aircraft, or other vehicle that moves through a fluid medium (generally air or water). On an aircraft the rudder is used primarily to counter adve ...

and directional propulsion delivery system for relatively slow speed displacement boats which was invented in the early 20th century by John G. A. Kitchen of Lancashire, England. It turns the rudder into a directional thruster, and allows the engine to maintain constant revolutions and direction of drive shaft rotation while altering

thrust Thrust is a reaction force described quantitatively by Newton's third law. When a system expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction to be applied to that sys ...

by use of a control which directs thrust forward or aft. Only the rudder pivots; the propeller itself is on a fixed shaft and does not. "Kitchener gear" or "Kitchener rudder" have been common misnomers for the Kitchen rudder. It is held under British Provisional Patent No. 3249/1914 and US Patent No. 1186210 (1916) and has been improved with the design in US Patent 4895093 (1990).

Description

The rudder consists of a pair of slightly conical (usually but not always - designs vary), semi-cones mounted on a pivot either side of the propeller with the long axis of the cone running fore and aft when the helm is midships. They are pivoted about a vertical axis such that the cone may close off the propeller thrust aft of the propeller, directing the thrust forwards and thus creating motion astern. In addition to the "jaws" of the cone being controlled the direction of thrust is also controlled by rudder direction. In this way, it is unlike the

azimuth thruster An azimuth thruster is a configuration of marine propellers placed in pods that can be rotated to any horizontal angle (azimuth), making a rudder unnecessary. These give ships better maneuverability than a fixed propeller and rudder system. Ty ...

s used on many medium and large vessels, or the

outboard motor An outboard motor is a propulsion system for boats, consisting of a self-contained unit that includes engine, gearbox and propeller or jet drive, designed to be affixed to the outside of the transom. They are the most common motorised method ...

s or

stern drive A sterndrive or inboard/outboard drive (I/O) is a form of marine propulsion which combines inboard power with outboard drive. The engine sits just forward of the transom while the drive unit (outdrive or drive leg) lies outside the hull. Opera ...

s used by some small boats, since these all use the directed thrust to avoid the need of a rudder altogether. Modern equivalent include certain types of

pump jet A pump-jet, hydrojet, or water jet is a marine system that produces a jet of water for propulsion. The mechanical arrangement may be a ducted propeller ( axial-flow pump), a centrifugal pump, or a mixed flow pump which is a combination of bot ...

s or

Kort nozzle A ducted propeller, also known as a Kort nozzle, is a marine propeller fitted with a non-rotating nozzle. It is used to improve the efficiency of the propeller and is especially used on heavily loaded propellers or propellers with limited di ...

. While not strictly Kitchen rudder technology, the "bucket" on some aircraft jet engines is an aeronautical derivative of the device. When the deflectors are deployed, directing thrust forwards, they are equivalent to the Kitchen rudder in the "full astern" position.

Operation

The operation of the Kitchen rudder is performed with the propeller engaged, even when the boat is stationary. The rudder is controlled by a small wheel on the

tiller A tiller or till is a lever used to steer a vehicle. The mechanism is primarily used in watercraft, where it is attached to an outboard motor, rudder post or stock to provide leverage in the form of torque for the helmsman to turn the rudder. ...

Neutral

The engine is brought up to speed with the drive to the propeller engaged and with the Kitchen rudder in the "neutral" position. This is a position where an equal quantity of thrust is aimed forward and aft. Each vessel will have a unique "neutral" position.

Moving ahead

The Kitchen gear is opened up to direct an increasing proportion of thrust aft. As the balance changes the vessel will move ahead.

Moving astern

The Kitchen gear is closed to direct an increasing proportion of thrust forward. As the balance changes the vessel will move astern.

Notes

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External links

Description near the foot of the article under PinnaceKitchen Rudder - DiagramsKitchen Rudder - Discussion and diagrams Manoeuvring device for boats: United States Patent 4895093
expiring in fall 2007
Special rudders and manoeuvering devicesU.S. patent 1,186,210

U.S. patent 4,895,093
Propellers Marine propulsion Fluid dynamics