Marine propulsion – Screw propeller – With means effecting or facilitating movement of propulsion...
Reexamination Certificate
1999-11-05
2001-05-22
Morano, S. Joseph (Department: 3617)
Marine propulsion
Screw propeller
With means effecting or facilitating movement of propulsion...
C440S053000, C440S063000, C440S078000
Reexamination Certificate
active
06234854
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates generally to improved drive mechanisms for boats, especially for boats that are to be operated in shallow water, and boats incorporating such mechanisms.
(2) Description of the Prior Art
The prior art describes numerous types of drive mechanisms for boats, with the characteristics of any particular drive mechanism being determined, in part, by such factors as the boat size, and the environment in which the boat is to be operated. Drive mechanisms suitable for one boat size and/or environment may be unsuitable for another boat size and/or environment.
For example, small boats are often used in shallow water for various purposes, including hunting, fishing, oyster gathering, and other kinds of sporting and work activities. The drive mechanisms for such boats must be designed to be operable in this shallow water, and must also be resistant to damage for obstacles and debris often encountered in shallow water.
Some boats of this type, referred to herein as shallow draft boats, have been driven by above-water aircraft-type propellers or underwater jet drives. However, due to considerations of cost, ease of operation, and ease of repair, most shallow draft boats are propelled by an underwater or water-level propeller that is rotated through a drive shaft connected to an engine or motor.
The engine, drive shaft and propeller drive mechanisms can be configured in one of three ways. First, the engine can be mounted inside the boat with the drive shaft extending through the bottom of the boat to the propeller. This design adds to the draft of the boat, limiting its ability to operate in very shallow water, and prevents lifting of the propeller from the water if an obstacle is encountered.
Second, the mechanism can be mounted so that the drive shaft extends over the boat transom. In this configuration, the entire mechanism is usually designed to tilt or pivot, requiring movement of the engine to steer the boat. This mechanism does have the advantage that it can be readily removed from the boat for trailering, and to prevent fouling of the propeller by marine flora or fauna. A typical design of this type is illustrated in U.S. Pat. No. 4,676,756 to Rodrigue et al.
In a third design, the engine is mounted in the boat interior, and the drive shaft extends from the engine through the boat transom to the propeller. One section of the drive shaft may extend from the engine to the exterior of the boat transom, with a second drive shaft section extending from the first drive shaft section to the propeller. The distal end of the first section and the proximal end of the second section are connected by some flexible drive connection, so that the second drive section can be laterally pivoted to steer the boat. Typical examples of this type of mechanism are illustrated in U.S. Pat. No. 4,726,796 to Rivette, Jr., et al, and U.S. Pat. No. 2,996,035 to Torrey.
Drive mechanisms of this third type have the advantage of permitting the use of a larger engine, since movement of the engine during steering is not required. Thrust characteristics are also improved due to the alignment of the drive shaft. This mechanism can also be designed to lift when obstacles are encountered, preventing damage to the propeller and drive shaft. However, this mechanism, as described in the prior art, has significant disadvantages that limit its usefulness.
First, the drive shaft and attached propeller project a significant distance from the rear of the boat, rendering the boat difficult, and often hazardous, to launch, store and trailer. Prior art mechanisms, while permitting the mechanism to be raised slightly, do not allow the mechanism to be moved to a substantially vertical orientation that would avoid this problem.
Also, many prior art mechanisms are designed essentially for low-speed, non-planing uses. As a result, the user must travel at low speeds to reach the shallow water location, even when traveling through deep water. Steering mechanisms for prior art mechanisms of this type also tend to change the depth of the propeller in the water, altering the steering characteristics of the boat when the boat is being turned.
Modifications to prior art drive and steering mechanisms of this type to overcome these prior art deficiencies would significantly improve the performance of these mechanisms and boats incorporating the mechanisms, and their resultant commercial acceptance.
SUMMARY OF THE INVENTION
The present invention relates to a boat drive mechanism that overcomes the above disadvantages of prior art shallow water boat drives and to boats incorporating these improved drives.
While the present drive mechanism is designed primarily for use with a small, shallow draft boat, the drive mechanism will also find utility in larger boats. The boat may have a hull of various configurations, although the mechanism will normally be used with a boat having a flat-bottom hull. The boat may be formed of wood, aluminum, fiberglass, other materials commonly used to manufacture small boats, or combinations thereof. The boat will include a rear transom, preferably transverse to the longitudinal axis of the boat, through which the drive shaft of the drive mechanism extends.
In its broad aspects, the drive mechanism of the present invention is comprised of an engine, a rearwardly extending drive shaft having a forward end attached to the engine, a prop or propeller, a forward extending propeller shaft having a rear end attached to the propeller, a universal joint connecting the rear end of the drive shaft directly to the front end of the propeller shaft, a steering mechanism in operative communication with the propeller shaft for moving the shaft in a generally horizontal direction, and a lifting mechanism in operative communication with the propeller shaft for moving the propeller shaft in a vertical direction between a lowered position, and a raised, generally vertical position.
The drive mechanism will normally include other components including a stern tube or block that extends through the boat transom with the drive shaft extending through the stem tube to prevent leakage, a propeller tube surrounding the propeller shaft to protect the propeller shaft, upper and lower skegs extending from adjacent the rear end of the propeller tube to protect the propeller tube and propeller from encountered objects, and an anti-ventilation plate to minimize air entrainment from the surface down along the top of the propeller tube into the propeller.
The engine is an internal combustion engine containing modifications of known types to adapt the engine for marine use. As used herein, the term engine will be understood to include not only the internal combustion engine, but also its transmission and other operable components. The engine may be mounted in the lower part of the boat within a wide range of distances forward of the transom to suit the vessel layout and weight balance needs. Using a drop angle and/or drop center type marine transmission or a marine transmission modified to incorporate the characteristics of the aft end of the drive shaft and tube, the engine may be placed very near the transom.
The engine is connected to the propeller through a drive train comprised of a drive shaft having a front end connected to the engine, and a rear end; a propeller shaft having a rear end attached to the propeller, and a front end; and a universal joint connecting the rear end of the drive shaft to the front end of the propeller shaft. Unlike earlier drive trains in this type of drive mechanism, this universal joint serves as the only thrust connection between the drive shaft and propeller shaft. The drive train may also contain additional elements, e.g., a splined slip joint or an additional universal joint inside the boat.
This universal joint connecting the drive and propeller shafts may be of a conventional design, with a first rearwardly extending u-shaped yoke attached to the drive shaft, and a second forward extending u-shaped yoke attached to the propeller
Morano S. Joseph
Rhodes & Mason PLLC
Vasudeva Ajay
LandOfFree
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