Patent application title: Jet drive system powered by a 4-cycle engine to propel shallow water boats
Gary Allen Jarnot (Sauk Rapids, MN, US)
Shawn Everett Kroll (St. Cloud, MN, US)
IPC8 Class: AB63H11107FI
Class name: Marine propulsion jet drive direction control for fluid jet
Publication date: 2011-11-10
Patent application number: 20110275257
One embodiment of a boat or watercraft that is fitted with a jet drive
system powered by a 4-cycle engine and positioned in such a way that will
enable the boat to be propelled and maneuvered in extremely shallow water
and launched for use by a minimum of one person.
1. A jet pump drive system that is affixed centrally to the lowest point
of the transom in the stern portion of a buoyant water-proof vessel for
conveying human beings with or without cargo, comprising a hull, keel,
bow, and transom (i) as to mate with the discharge opening of the water
intake and discharge chute (ii) allowing the pump to pull water through
the water intake and discharge chute when sufficient power is supplied to
it from 4 cycle engine (iii) to move said vessel, comprising i. a vessel,
boat or watercraft manufactured using but not limited to aluminum,
fiberglass, plastic, rigid inflatable materials or other rigid
water-proof buoyant materials for use in water, in combination with, ii.
an apparatus functioning as a water intake and discharge chute for
channeling and supplying the flow of water to the jet pump, and iii.
using but not limited to a 4-cycle engine commonly used in the power
equipment industry, but for which an electric motor utilizing a
battery(ies) may be substituted, and iv. a torque conversion means that
couples the jet pump drive shaft to the crank shaft of the engine affixed
centrally and in accordance with the jet pump drive shaft location
whereby there is created a large volume of water through a directional
nozzle, utilizing the Archimedes screw principal, creating sufficient
power for nautical propulsion that will function in deep or extremely
shallow water by means of said jet-drive system, and v. where with water
intrusion being deterred, the jet pump drive shaft penetrates the water
intake and discharge chute (ii) to allow the jet pump drive shaft (1) to
be accelerated inside the hull (i) by said engine (iii), and vi. thereby
combining an engine (iii) and apparatus (ii) to provide nautical
propulsion by means of said jet-drive system (1) with a steering and
control of direction means to propel a vessel in shallow or deep water.
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BACKGROUND OF THE INVENTION
 1. Field of the Invention
 This invention generally relates to jet-propelled watercraft, specifically utilizing a 4-stroke engine and a simplified drive system for shallow water use.
 2. Prior Art
 The idea of jet propelled system for boats dates back to the late 1920's as seen in U.S. Pat. No. 1,716,400 by John Arthur Weis. In 1974, U.S. Pat. No. 3,797,447, inventor Robert Stubblefield perfected the inboard propulsion system. In recent years, a jet propulsion system has become popular and used primarily in jet skis and jet boats. A jet pump is comprised of a steel impeller, a drive shaft, a directional nozzle that connects to the steering cable tab on the discharge nozzle directing the flow of water through the nozzle which provides direction for the boat/apparatus to which the jet pump is attached. With large engines and costly construction, production and use of the jet boat is limited. Outboard motors are subject to damage caused by obstructions such as rocks and logs below the waterline of the boat. Therefore there is a need for an improved john boat with a jet drive incorporating features that allow for mass production and wide multi-use applications at a low cost.
 This invention embodies a john or duck boat fitted with a transom mounted jet propelled system that will allow it to navigate in the shallowest of waters (4-7 inches) allowing access to rivers, lakes, and even flooded streets during hurricane and flood disasters. This will give exceptional maneuverability for search, patrol and rescue operations, and will provide recreational opportunities for hunting and fishing enthusiasts. An objective of this invention is to provide these benefits at a significantly reduced cost from that of conventionally produced construction. This jet-propelled boat utilizes an air-cooled horizontal shall 4-cycle engine. Exhaust is not expelled into the water. No oil is required to be mixed with the fuel, making the boat more convenient to use. The 4-cycle engine is attached to the jet pump using a drive and driven clutch system and belt. The boat can be launched and docked by one person of average strength. The boat is controlled by simple one-hand operation. An advantage of a jet-propelled system is reduced maintenance due to less exposed moving parts.
 FIG. 1 is: an overhead view of an aluminum john boat with the jet drive system, intake and discharge chute, the 4-cycle motor, operator seat base, and steering lever with a throttle grip.
 FIG. 2 is: a side view of the boat featuring the housing attached to the boat transom that protects the jet pump and prevents water back splash, a 4-cycle motor, operator seat and steering mechanism, and intake and discharge chute.
 FIG. 3 is: a cross-section view of the motor in conjunction with a means of torque conversion attached to the jet pump drive system with a seal and bearing carrier to support it and to prevent water from entering the boat.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
 As shown in FIG. 1, an aluminum john boat configured with a jet propulsion system (4) commonly found in jet-ski/watercraft applications. The rider steers the jet-propelled boat (12) using a simple steering lever (6) with a throttle grip (11).
 The transom of all john boats is manufactured with roughly an 80 degree angle to accommodate outboard motors. To accomplish this invention, we begin by molding a 90 degree transom (7) which will allow the jet pump (4) to be mounted to the transom (7) and be positioned perpendicular to the bottom of the boat.
 As illustrated in FIG. 3, on the keel portion of the john boat (8) a custom aluminum intake cylinder (3) will direct water from a hole cut in the keel on the stern portion of the boat (18). This intake cylinder will direct water through a hole cut into the transom of the boat (7) into the jet pump (4) to provide propulsion. FIG. 2 shows an aluminum housing (20) attached to the transom of the boat (7) that protects the jet pump (4) and prevents back splashing.
 FIG. 1. shows a jet pump (4) mounted and sealed to the transom (7) thus also attaching it directly to the intake cylinder (3) by four bolts and a rubber gasket (23).
 As seen in FIG. 3, the jet pump drive shaft (13) is positioned through a seal and bearing carrier (14) in the bow portion of the custom intake cylinder (3). This seal and bearing carrier (14) will provide support for the jet pump drive shaft (13) as well as stop any water from entering boat.
 Adequate torque to the jet pump is accomplished using a comet series clutch system (2) as seen in FIG. 1. The driven portion of the clutch (15) is attached to the jet pump drive shaft (13) by means of a key way and set screws (9) as seen in FIG. 3. This secures the driven clutch (15) to the jet pump shaft (13). The drive portion of a comet series clutch (16) transfers power from the four cycle engine (1) to the driven clutch (15) using a symmetric belt system (25).
 As seen in FIG. 3, a standard four cycle small engine (1) is mounted to the top of the rear bench seat (9) by four bolts (2). The drive portion of the comet series clutch (16) is attached to the motor drive shaft (26).
 As illustrated in FIG. 1, steering control is performed by the user pushing or pulling on a custom made lever (6). This lever pivots on a shaft connected to the seat base plate (5). A basic water craft control cable (10) connects the steering lever (6) to the directional nozzle of the jet pump (17). This will allow the boat to steer left or right by means of water being pushed through jet pump nozzle (17). Motor speed is controlled by a throttle mechanism (11) attached to the steering lever (6).
 As illustrated in FIG. 1, a seat base is constructed using a 14 inch×14 inch aluminum plate (5) welded to the support braces of the keel portion of the hull. The seat (21) is supported by an aluminum seat post (24) and aluminum triangle supports (24).
CONCLUSION, RAMIFICATIONS, AND SCOPE
 A jet-drive system has hitherto been applied successfully in small aluminum boats. A simple combination of the following concepts will be successful:  1. A simple mass-produced 4-stroke motor  2. A custom-manufactured intake and sealed bearing carrier;  3. A mass-produced jet pump;  4. A mass-produced drive and driven clutch system  5. A grate positioned across the water inlet that will prevent ingress of debris from entering the pump.
 Accordingly the reader will see that, according to one embodiment of the invention, there is provided an inexpensive, environmentally friendly, commercially mass produced 4 cycle motor mounted to a drive and driven clutch system connected through a custom-manufactured intake and sealed bearing carrier attached to a mass-produced, commercially available jet pump. Various features and aspects of the disclosed embodiments can be combined with or substituted with one another in order to form varying modes of the disclosed invention. It is intended that the scope of the present invention hereto disclosed should not be limited by the particular disclosed embodiments described above. Numerous details of the construction may be altered or omitted without departing from the spirit of this invention.
 Ramifications: Elements that can be eliminated or duplicated include but are not limited to other sized engines mounted to the drive and driven clutch system and the john boat itself can be changed in size, being made larger or smaller. Additionally, the boat could be colored in camouflage for use in shooting sports such as duck hunting, or can be painted to denote a rescue boat or a boat suitable for jet-skiing or pageantry. Heavy-duty materials could be used, provided they are water proof.
 Scope: Thus, the scope of the invention should be determined by the appended claim or claims and their legal equivalents, and not solely by the examples given.
Patent applications in all subclasses Direction control for fluid jet