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	KORT NOZZLES
		The Kort nozzle is a shrouded, ducted propeller assembly for marine propulsion.
		Kort nozzles may be fixed, with directional control coming from a rudder set in the water flow, or pivoting, where their flow controls the vessel's steering
		A "Kort Nozzle" is referred to as an accelerating nozzle and is generally a MARIN 19a profile or a MARIN 37 profile.
	www.solarnavigator.net /kort_nozzle.htm (2380 words)

	Kort Propulsion Co Ltd
		Kort engineers therefore have the expertise to provide powering and performance estimates for every application from 100mm diameter propellers for an ROV thruster to 4000mm and above for commercial vessels.
		Kort is employed by many owners, shipyards and designers at the design stage to ensure vessel performance meets specification.
		Kort are often asked to supply propulsion and manoeuvring equipment packages in addition to Kort nozzles and propellers.
	www.kortpropulsion.com /kort_nozzles_propellers.htm (297 words)

	Kort nozzle at AllExperts
		The Kort nozzle is a shrouded, ducted propeller assembly for marine propulsion.
		Kort nozzles may be fixed, with directional control coming from a rudder set in the water flow, or pivoting, where their flow controls the vessel's steering
		A "Kort Nozzle" is referred to as an accelerating nozzle and is generally a MARIN 19a profile or a MARIN 37 profile.
	en.allexperts.com /e/k/ko/kort_nozzle.htm (270 words)

	Tugboat - Encyclopedia, History, Geography and Biography
		Thrust is sometimes enhanced by the installation of Kort nozzles.
		The Kort nozzle is a sturdy cylindrical structure around a special propeller having minimum clearance between the propeller blades and the inner wall of the Kort nozzle.
		The thrust:power ratio is enhanced because the water approaches the propeller in a linear configuration and exits the nozzle the same way.
	www.arikah.com /encyclopedia/Tug (728 words)

	Kort Ship
		Kort was one of the original inventors of the nozzle back in the 1930s.
		Specifically, the key parameters for the inner surface were the diffusor angle, the longitudinal position of the propeller in the nozzle, and the inner diameter relative to the propeller diameter.
		Although these nozzles are working comfortably at what was considered the upper limit of 12 to 15 knots, the question remains whether or not even higher speeds with nozzles are possible.
	www.workboat.com /archives/03jul/bgkortship.htm (1488 words)

	Office of Boating Safety Boating Articles
		The Kort Nozzle has been on larger vessels for many years but has only recently been adapted to smaller vessels in the form of a modification to conventional outboard drives.
		The Kort nozzle is most commonly used on relatively slow, non-planing workboats where additional drag is not a significant consideration.
		The water intake grate is flush with the bottom of the hull and the nozzle moves or uses moveable deflectors to obtain steering, reverse, and/or stopping.
	www.uscgboating.org /articles/boatingview.aspx?id=67 (1642 words)

	Rudders
		Since the pressure on the outer part of the nozzle remains relatively unchanged, there is a resulting differential in pressure, which acting on the projected annulus of the nozzle, gives the additional forward thrust.
		This additional thrust is transmitted direct from the kort nozzle to the hull via the nozzle supports,so that no additional force acts on the propeller and shaft thrust block.
		In the case of nozzle rudders,when helm is applied, the increased thrust has an athwartship component which has powerful steering effect, so that hard over angles of 25' (or 30' in special cases) are sufficient to provide effective steering ahead during a crash stop and,provided the hull is a reasonable design, astern.
	www.marineengineering.org.uk /navarch/navrudmain.htm (1673 words)

	Marine Nozzle Tests
		One was fitted with an open propeller, one with a Kort nozzle and a Kaplan propeller, and the third with a Rice Speed Nozzle and Rice Skewed Kaplan.
		The Rice Thrust Nozzle is based on the Rice Speed Nozzle profile and was especially developed for tug work to maximize efficiency with both forward and astern thrust.
		The Kort nozzle's biggest draw back is the high drag coefficient which is successfully addressed with the more efficient Rice Speed Nozzle.
	www.olds.com.au /marine/nozzles/tests.html (428 words)

	Standard Nozzle Shapes by Harrington Marine
		The aft portion of this style of nozzle is approximately equal to the center diameter, and is most often used when greater free-running speed is required.
		This nozzle will generate the greatest amount of forward thrust of the three main nozzle forms.
		A compromise in form between the straight Type 19A and the double-flared Type 37, this nozzle is built with a taper in the aft portion to minimize or eliminate cavitation during periods of reverse thrust without any significant loss of forward thrust.
	www.harringtonmarine.com /stdnozzleshapes.htm (233 words)

	Great Lakes Boating magazine
		The Kort Nozzle has been on larger vessels for many years but has been adapted to smaller vessels in the form of a modification to conventional outboard drives.
		The Kort nozzle is most commonly used on relatively slow, non-planing workboats where additional drag is not a significant consideration.
		The water intake grate is flush with the bottom of the hull and the nozzle moves or uses moveable deflectors to obtain steering, reverse, and/or stopping.
	www.greatlakesboating.com /archives/2005/06/propeller_safeg.html (1430 words)

	National Mississippi River Museum & Aquarium
		Ludwig Kort of Hanover, Germany, began to experiment with shapes and sizes of propeller guards and in 1930, obtained a United States patent for the Kort nozzle.
		The Kort nozzle was rapidly adopted by the towing industry.
		The number of towboats with the Kort nozzle went from 161 in the 1930s, to over 1,500 in the 1970s and 1980s.
	www.mississippirivermuseum.com /achievement/dawson.cfm (283 words)

	Marine Propulsion Inc - Kort Propulsion Inc. (Kort Nozzles)
		The majority of Kort nozzles, either fixed or steerable units, are fitted on tugs.
		Various combinations of nozzles are in service, including twin steering nozzles - with and without independent steering controls - triple screw steering nozzles and a number of units fitted with patented Hannan slots.
		The cross section of the nozzle is, in effect, the same shape as an aeroplane wing but instead of 'lift', a forward thrust is produced.
	marinepropulsion.net /kort/nozzle.htm (288 words)

	Rudders & Korts (Site not responding. Last check: 2007-10-26)
		Korts, as their called, are different looking from those used on other vessels.
		And then there are Korts - That don't have such additions, and their shapes can vary greatly from what you might be used to seeing.
		Korts must always be mounted in place, using waterproof glue, like a 50/50 Epoxy - I use, to insure they stay solid and don't break loose....
	oldriverbillzumwalt.members.ktis.net /rudders-korts.htm (1884 words)

	Marine Propulsion Inc - Kort Propulsion Inc. (Kort Nozzles)
		The majority of Kort nozzles, either fixed or steerable units, are fitted on tugs.
		Various combinations of nozzles are in service, including twin steering nozzles - with and without independent steering controls - triple screw steering nozzles and a number of units fitted with patented Hannan slots.
		The cross section of the nozzle is, in effect, the same shape as an aeroplane wing but instead of 'lift', a forward thrust is produced.
	www.marinepropulsion.net /kort/nozzle.htm (308 words)

	Log Broncs and Mini-Tugs P
		The necessary alterations were made to the design, and Slape and his crew set out to build their first nozzle to Wilskey's specs.
		With the nozzle (and the helm) hard over at 35 degrees we didn't have enough lateral stability to handle the increased sideways thrust," Wilskey admitted.
		He is a longtime member of the American Truck Historical Society and regularly tows the five-ton tugs to the docks with his highly-modified 1972 International truck with its GM V-6-53 diesel and twin turbos.
	www.angelfire.com /or/petermarsh/beaver.htm (1334 words)

	ductprop
		A ducted propeller is a propulsion device consisting of a conventional open propeller surrounded by a duct or nozzle.
		Kort Nozzle ducted propellers have been widely used in tugboats and trawelers where the propeller is small and heavily loaded.
		The advantage of using a ducted propeller for these vessels is that the flow is accelerated and thus an improvement in propulsive efficiency is obtained In addition the duct shares a fair proportion of the thrust and thereby reduces the propeller loading.
	members.tripod.com /~V_BALA/ductprop.htm (763 words)

	PropGuard - Technical Information - How PropGuard works
		The nozzle consists of a ring of aerofoil section which forms a nozzle surrounding the propeller.
		The suction of the propeller causes an acceleration of flow in the mouth of the nozzle and hence a drop of pressure in this region.
		Since the pressure on the outer part of the nozzle remains relatively unchanged, there is a resulting differential in pressure, which acting on the projected annulus of the nozzle, gives the additional forward thrust.
	www.propguard.co.nz /technical.html (337 words)

	New Page 1
		To obtain unparalleled performance, the sectioned nozzle is combined with triple rudders, stators, and a skewed propeller in an Integrated Propulsion Unit.
		The NautiCAN Nozzle accelerates 15-20% more water through the propeller improving bollard pull and low speed thrust by 8-12% when compared to the 'Kort' nozzle.
		Nozzle equipped vessels resist turning due to momentum of water flow through the nozzle.
	www.nautican.com /products2.htm (297 words)

	MAKING A MODIFIED CORT NOZZLE FOR SMALL AUXILLARY MOTORS
		The Kort nozzle idea is an airfoil shaped ring around the propeller that increases thrust and controllability of the propeller both forward and reverse.
		My research revealed a more recent innovation of the Kort nozzle idea showing that a plain Kort nozzle is not as efficient as was thought due to internal cavitation pressures.
		Impressions are that the nozzle does make for an increase of thrust, and a greater torque load on the engine with a resulting increase in hull speed at lower throttle settings.
	www.duckworksmagazine.com /04/s/articles/kort/index.htm (1683 words)

	How a Marine Nozzle works
		As we already know, as the propeller blades rotate in the water, they generate high-pressure areas behind the each blade and low pressure areas in front, and it is this pressure differential that provides the force to drive the vessel.
		Because of this pressure difference, a force P (Figure 4) is created on the external surface of the nozzle that is always perpendicular to this surface.
		Due to the design of the outside trailing end part of the nozzle, the horizontal component of this force P creates an additional forward thrust on the nozzle; increasing the total thrust of the vessel.
	www.olds.com.au /marine/nozzles/nozzles.html (508 words)

	Rice Speed Nozzles more efficient than Kort 19a Nozzle
		The Test: To demonstrate the advantages of the Rice Speed Nozzles over the 19a Kort Nozzle and Open Propeller, a series of tests was performed.
		Three 72 foot Trawlers of 365 Hp, 1800 RPM with 6:1 reduction gear, each performing the same work, were used to measure the fuel consumption, free-running speed and bollard pull.
		Tests show the Rice speed nozzle uses 7% less fuel than the 19a Kort nozzle and 23% less fuel than an open propeller.
	www.propellerpages.com /?c=nozzles&f=Speed_Nozzle_Tests (370 words)

	Cascade General Installs High-Speed Kort Nozzle On Factory Trawler
		The ship put into Grays Harbor, where a diver found the Kort nozzle had de-laminated, peeled back and seriously bent the blades on the CP propeller.
		The replacement, a Rice Speed Nozzle produced in Mazatlan, Mexico, uses a full, stainless steel liner for durability and a long foil section to minimize drag.
		To ensure precise alignment, it was positioned with the aid of a rotating pointer mounted in the tailshaft.
	www.casgen.com /pr/pr990004.htm (441 words)

	Chapter 4
		Elevate and align the Kort nozzle to the height of the motor and proceed to drive the Kort nozzle onto the APU motor.
		When the Kort nozzle is fully seated on the motor, fasten the Kort nozzle to the motor using the eight 3/4-10 UNC hex head cap screws and 3/4-inch lock washers.
		The wedges are jammed in between the outer edge of the propeller blades and the inside of the Kort nozzle to stop propeller rotation.
	www.supsalv.org /manuals/uwsh/chap04/chap4Home.html (9775 words)

	The Advantages of Reservoir Runner Electric Outboard Motors
		The nozzle is a hydrodynamically shaped, cast aluminum, ring that surrounds the propeller and increases the volume and flow of water through it, much like a fan jet on an airliner.
		A Kort Nozzle also surrounds and protects the propeller from damage and renders it safe around swimmers and wildlife.
		The Kort Nozzle used on Reservoir Runner electric outboards provides even more steering control due to its directed stream of water; the turning radius of a boat with an outboard motor incorporating a Kort Nozzle is 20% smaller than one with an open propeller.
	www.qis.net /~jmgraham/advantag.htm (889 words)

	Madison MHD Dynamo Experiment (Site not responding. Last check: 2007-10-26)
		These are tabletop water shots using two left-handed, square-pitch, 5 inch kort nozzles, each a distance 8cm from the equatorial plane.
		After correcting the Kort Nozzles - they had become loose (could not come completely loose due to being keyed and held in with a slip ring = but were causing vibrations).
		Kort nozzles with 0.5" high fins with 1" spacers and 0.2" spoiler.
	aida.physics.wisc.edu /internal/experiments.html (2109 words)

	Rudders Kort Nozzle & Bow Thrusters:Model-Boats
		The nozzle can be swivelled around thevertical axis and the resultant flow of water can be directed in lieu of the vessel's rudder.
		If the servo travel is geared up to a ratio of 2:1 the swivel range of the nozzle is in the region of 180°, although the actual value will vary according to theservo you are using.
		Marx Kort Rudder 1775~With 2 marine props 40 and 50 mm Ø.
	www.westbourne-models.com /x2437.html (1139 words)

	:: STRAUHS ::
		Considerable gains of thrust and fuel economy can be achieved by using Kort nozzles.
		Tugs with Kort nozzles can achieve up to 40% more bollard pull in relation to that of a conventional propeller.
		The Kort nozzle also offers greater final speed and fuel economy.
	www.strauhs.com.br /ingles/helices_n.asp (372 words)

	Increasing propulsive efficiency
		The action of the screw within a nozzle with a small clearance between the tips of the prop blade and the walls of the nozzle (clearance about 1/100 of prop diameter) is to eliminate or reduce trailing vortices which cause loss of efficiency and cavitation at the blade tips
		From an operational point of view there are problems with cavitation around the inner section of the nozzles although from what I have seen this is not particularly severe.
		The advantage of this system over the full duct or kort nozzle is that it does not suffer from the same cavitation damage on the inner surface.
	www.marineengineering.org.uk /navarch/navpropeffmain.htm (744 words)

	September 2003, Heddle Marine and a tour of Hamilton docks.
		The props rotate inside the nozzle and this focuses the force and can be considered to increase thrust.
		The propellor shaft is seen on the left leading into the nozzle.
		There are also sacrificial anodes on the nozzle and shaft support.
	www.boatnerd.com /shiphotos/story-photos/2003/2003-sept-hamilton-page-2.htm (601 words)

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