Title:
HYDROJET PROPULSION OF BOATS
United States Patent 3625176


Abstract:
A system for and a method of propelling boats by hydrojets. The illustrative embodiment employs a single engine driving a pump provided with a central water inlet and with two longitudinally extending discharge conduits which are equally spaced on opposite sides of the centerline of the boat. The rear, discharge ends of the conduits are disposed below the waterline when the boat is at rest. Connected to the conduits adjacent their rear ends by selectively operated valves are upper branch conduits which provide jets for driving the boat when it is planing and the discharge ports of the branch conduits are then under water. The boat is also provided with jet means for reversing the boat and for maneuvering it at slow speeds, as during docking.



Inventors:
MOELLERING KARL
Application Number:
04/819682
Publication Date:
12/07/1971
Filing Date:
04/28/1969
Assignee:
KARL MOELLERING
Primary Class:
International Classes:
B63H11/00; (IPC1-7): B63H11/00
Field of Search:
114
View Patent Images:
US Patent References:
3121994Hydraulic jet marine engine1964-02-25Aldropp
3102389Hydrojet propulsion and control means for boats1963-09-03Pedersen et al.
2467022Marine propulsion and steering device1949-04-12Forlano
1665053Propelling mechanism for boats1928-04-03Carpio



Primary Examiner:
Blix, Trygve M.
Claims:
I claim

1. A hydrojet system for propelling a boat, comprising a pump, means for driving the pump, an inlet conduit for feeding water to the pump, a first discharge conduit leading from the pump to a first, lower rearwardly directed discharge port at the rear end of the boat for driving the boat forwardly at low speed, a second upper discharge conduit which conducts water from the pump and leads to a second, higher rearwardly directed discharge port at the same, rear end of the boat for driving the boat forwardly at high speed, and valve means for selectively directing water discharged by the pump into a selected discharge conduit.

2. A system according to claim 1, wherein the second conduit branches from the first conduit at a location forwardly of the first discharge port, and wherein the valve means are disposed at said location.

3. A system according to claim 1, wherein the first discharge port is disposed below the waterline of the boat when the boat is at rest and moving forwardly at slow speed, and the second discharge port is disposed above such waterline when the boat is at rest and moving forwardly at slow speed, but is submerged when the boat is moving forwardly at high speed.

4. A system according to claim 1, comprising two similar further discharge conduits having ports on opposite sides of the boat and directed somewhat forwardly, and means for selectively directing water from the pump into said further discharge conduits to slow and reverse the boat.

5. A system according to claim 4, comprising selectively operated valve means for closing each of said further discharge conduits against the flow of water outwardly therethrough.

6. A system according to claim 1, comprising two similar first conduits, second conduits, and a valve means for each associated set of first and second conduits, said sets of discharge conduits and their discharge ports being markedly spaced laterally of the boat.

7. A system according to claim 6, wherein the sets of conduits and ports are disposed at equal distances on opposite sides of the longitudinal centerline of the boat, and the pump and means for driving it are disposed on such centerline.

8. A hydrojet system for propelling a boat, comprising a pump, means for driving the pump, an inlet conduit for feeding water to the pump, a first discharge conduit leading from the pump to a first, lower discharge port at the rear of the boat, a second upper discharge conduit which conducts water from the pump and leads to a second, higher discharge port at the rear of the boat, and valve means for selectively directing water discharged by the pump into a selected discharge conduit, a deflector mounted rearwardly of the first discharge port for directing the jet issuing from the first discharge port to steer the boat at low speeds, and a rudder disposed laterally of the first discharge port to steer the boat when the boat is being driven at high speed.

9. A hydrojet system for propelling a boat, comprising a pump, means for driving the pump, an inlet conduit for feeding water to the pump, a first discharge conduit leading from the pump to a first, lower rearwardly directed discharge port at the rear end of the boat for driving the boat forwardly at low speed, a second upper discharge conduit which conducts water from the pump and leads to a second, higher rearwardly directed discharge port at the same, rear end of the boat for driving the boat forwardly at high speed, valve means for selectively directing water discharged by the pump into a selected discharge conduit, a deflector mounted rearwardly of the first discharge port for directing the jet issuing from the first discharge port to steer the boat at low speeds, and a rudder disposed laterally of the first discharge port to steer the boat when the boat is being driven at high speeds.

Description:
This invention relates to a system for and a method of propelling boats by one or more hydrojets. The invention is particularly concerned with a system and method in which the vertical positioning of the line of thrust of the jet or jets may be changed as the boat passes from slow-speed to high-speed operation, thereby producing an increased efficiency of thrust.

The invention has among its objects the provision of a hydrojet propulsion system and method of improved efficiency.

A further object of the invention is the provision of a hydrojet propulsion system and method wherein the vertical positioning of the line of thrust of the jet or jets may be changed during the operation of the boat.

Another object is the provision of a system and method wherein a single pump supplies a plurality of jet creating conduits disposed symmetrically laterally of the boat.

A still further object is the provision of a novel system and method of steering a hydrojet propelled boat, during its slow-speed forward operation, its high-speed forward operation, and its operation in reverse.

The above and further objects and novel features of the invention will more fully appear from the following description when the same is read in connection with the accompanying drawings. It is to be expressly understood, however, that the drawings are for the purpose of illustration only, and are not intended as a definition of the limits of the invention.

In the drawings, wherein like reference characters refer to like parts throughout the several views,

FIG. 1 is a view in side elevation of a boat provided with an illustrative jet propulsion system in accordance with the invention; and

FIG. 2 is a fragmentary view in bottom plan of the boat of FIG. 1, the bow portion of the boat being broken away, the view being taken from line 2--2 of FIG. 1.

Turning now to the drawing, there is there shown a boat, in this instance of the twin-hulled catamaran type, which is provided with two similar hulls 13 disposed in parallel side-by-side relationship and connected by a central body. Within the body there is supported an engine 9 with its output shaft on the centerline of the boat and extending forwardly to a pump 11, here shown to be of the turbine type, which it drives. The pump is also located on the centerline of the boat. The inlet port of the pump faces forwardly, and is connected by a short straight conduit to an inlet port 10 provided with a self-cleaning screen disposed at a marked angle with respect to the vertical, as shown, the port 10 being located centrally between the hulls 13 and so disposed as to lie below the waterline at all times. The location of port 10 between the forward ends of the twin hulls 13 aids the flow of water into the port, both by reason of the normal forward motion of the boat and the curved contours of the forward confronting surfaces of the hulls which lead the water into the port.

The pump 11 has two similar discharge ports which are located at equal distances from the centerline of the boat with their axes lying generally in a horizontal plane when the boat is at rest. Connected to the discharge are two similar parallel first discharge conduits 12 likewise disposed at equal distances on opposite sides of the centerline of the boat with their axes lying generally in a horizontal plane. Conduits 12 terminate rearwardly in similarly laterally spaced discharge ports 14 through the transom of the boat. The discharge ports 14 are so located that they are beneath the waterline at all times. Thus the inlet conduit, pump, and discharge conduits are filled with water at all times, making the propulsion system immediately ready to operate upon the starting of the engine. Centrally between the discharge ports 14 there is located a conventional rudder 15 which is employed to steer the boat when it is being propelled forwardly at high speeds in a manner to be described. The rudder 15 may also be employed to supplement the action of the jet deflectors used in conjunction with the high-speed jet-propelling system.

Steering of the boat at slow speeds is normally effected by means of deflectors 18 which are mounted on vertical stub shafts journaled on the boat centrally of each of the discharge ports 14. The deflectors 18 are symmetrical on both sides of such stub shafts. The two stub shafts are connected so that the deflectors always remain parallel; a linkage, schematically shown at 23, connecting the deflectors may be operated by mechanical means, or may be of either the conventional hydraulic or electrical types wherein a command device, such as a hydraulic cylinder or selsyn motor, is connected to the tiller or steering wheel and a slave device such as a hydraulic cylinder or selsyn motor, respectively, is connected to the deflectors 18. Steering of the boat may also be performed or aided, during low speed operation of the boat, by the rudder 15, above described, or by the side conduits 21, the ports 22 thereof, and the further deflectors 24, to be described.

When the boat is propelled forwardly at high speeds, the bow tends to rise and the stern to sink so that the longitudinal axis of the boat lies at a marked angle with respect to the waterline. Under such conditions, the thrust upon the boat caused by the jets issuing from the ports 14 is not advantageously employed. It is accordingly an object of the present invention to provide means for shifting the line of thrust of the boat-propelling jets under high-speed operation of the boat from that provided by ports 14 to one in which the boat is thrust much more efficiently.

The illustrative jet-propelling system is accordingly provided with two similar second jet discharge ports 17 through the transom of the boat, the two ports 17 being shown as lying at the same height and as lying vertically above the respective ports 14. The upper discharge ports 17 are connected to the respective conduits 12 forwardly of but close to the ports 14 by curved conduits 16, the conduits 16 being selectively placed in operative communication with the conduits 12 by valves 19. Valves 19 are shown as being of the clapper or vane type, the vane or deflector of each valve being pivoted at its rear end at the separation point of conduits 12 and 16 so as to turn about a horizontal axis between an upper position, in which conduits 16 are cut off from the pump 11, so that all of the water in the respective forward portion of the conduit 12 flows through its jet 14, and an upper position in which all of such water flows through the respective conduit 16 and discharge port 17. The vanes or deflectors of the valves 19 are connected by means not shown for simultaneous operation from their upper to their lower positions at the same angular speed. Such operation of the valves 19 may be effected mechanically by a suitable control device which is positioned so as to be immediately available to the operator of the boat at the steering wheel or tiller. Alternatively, the valves 19 may be actuated by conventional remote control devices such as the hydraulic or electrical means described above in connection with the control of deflectors 18. Preferably, the control of the valves 19 is effected by a remote control means linked to the engine accelerator throttle. In such system, a remote control device at the boat operator's end is connected to the accelerator throttle; the connection to the throttle and command and slave devices of the remote control being so constructed and arranged that for a throttle setting corresponding to zero to a predetermined intermediate speed of the engine the vanes of the valves 19 remain in their upper positions, and that for throttle settings corresponding to an engine speed in excess of such intermediate engine speed to maximum engine speed the vanes of valves 19 are turned to lie in their lower position.

The boat is caused to move rearwardly by the selective discharge of water from the conduits 12 through conduits 21 communicating with ports 22 on the opposite sides of the boat beneath the slow-speed waterline. Conduits 21, which are similar, are inclined forwardly at a small angle, for example 15°. with respect to a transverse vertical plane through the boat. The inner ends of conduits 21 are closed off from conduits 12 by valves 20 which are shown as having vanes or deflectors, the rear ends of which are pivoted on vertical pivot pins mounted at the separation point of the conduits 12 and 21. The ports 22 are closed during operation of the boat in a forward direction by cover plates 24 which are mounted at their forward edges on vertical pivot pins. When the plates 24 are swung open they may be stably maintained in such position by releasable latch means, not shown. Alternatively, the plates 24 may swing freely on their pivots, the forward motion of the boat maintaining them closed when the valves 20 are closed, and the jets of water from conduits 21 maintaining them open when valves 20 are open. In either case the plates 24 when opened extend outwardly and forwardly from their pivots and serve as maneuvering deflectors.

The valves 20 are shown as being connected by a schematically illustrated linkage 28. Linkage 28 is such that the valves 20 may be opened and closed simultaneously in the reversing of the boat, but may be operated individually and in the desired degree as during the docking of the boat. Alternatively, the valves may at all times be operated individually.

Although a limited number of embodiments of the invention have been illustrated in the accompanying drawings and described in the foregoing specification, it is to be especially understood that various changes, such as in the relative dimensions of the parts, materials used, and the like, as well as the suggested manner of use of the apparatus of the invention, may be made therein without departing from the spirit and scope of the invention, as will now be apparent to those skilled in the art. Thus although the illustrative hydrojet propulsion system employs two lower and two upper discharge ports, it is to be understood that a single-lower and a single-upper discharge port may be employed. Further, the number of lower and upper discharge ports need not be the same. Also, although the hydrojet propulsion system of the invention is shown installed in a catamaran-type boat, it is to be understood that the system of the invention may be applied to water craft of all types.