Kitchen rudder

The Kitchen Rudder is the familiar name for "Kitchen's Patent Reversing Rudders", a combination rudder and directional propulsion delivery system for relatively slow speed displacement boats which was invented in the early 20th century by Admiral Jack Kitchen of the British Royal Navy. 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 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 Patent 3249/1914 and US Patent 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 (compare this with an outdrive or an outboard motor for direction of thrust of an unenclosed propeller where the propeller itself pivots).

Modern equivalent include certain types of pump jets or the jet drive.

While not strictly Kitchen rudder technology, the "clamshell" thrust reverser on some aircraft jet engines is an aeronautical derivative of the device. The picture of the aircraft shows the clamshells deployed directing thrust forwards. This is equivalent to the Kitchen rudder in the "full astern" position.

Operation

The operation of the Kitchen Rudder is performed with the propellor engaged, even when the boat is stationary. [cite web |url=http://www.proboat-digital.com/proboat/200608/?pg=63 |title=Rudders, Medium to Rare |publisher=Professional Boatbuilder |accessdate=2007-10-12 |month=August |year=2006 |last=Dave |first=Gerr] The rudder is controlled by a small wheel on the tiller.cite web |url=http://www.defence.gov.au/news/navynews/editions/4916/pdf/RN8.pdf |format=pdf |title=New lease of life for 65-year-old navy cutter
last=Dunning |first=Steve |accessdate=2007-10-12 |publisher=Reserve News (Royal Australian Navy) |date=2006-09-07 |quote=A small wheel attached to the tiller is used to control two curved metal plates that surround the propeller enabling the boat to go ahead, go astern or remain stationary without any change of engine speed or reversing of the propeller.]

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.

ee also

*Azipod
*Kort nozzle
*Pleuger rudder
*Reverse thrust
*Rudder
*Sterndrive

Notes

External links

* [http://www.hmsconway.org/relics_artifacts.html Description near the foot of the article under Pinnace]
* [http://www.pcez.com/~artemis/SLAkitchen.gifKitchen Rudder - Diagrams]
* [http://www.boatdesign.net/forums/showthread.php?t=418&highlight=Kitchen+rudder Kitchen Rudder - Discussion and diagrams]
* [http://patimg2.uspto.gov/.piw?Docid=04895093&idkey=NONE Manoeuvring device for boats: United States Patent 4895093] , expiring in fall 2007
* [http://www.boatdesign.net/forums/attachment.php?attachmentid=279&d=1031890494 Special rudders and manoeuvering devices]