Watercraft propulsion system

Details Watercraft propulsion system Watercraft propulsion system

1998-10-30

2001-07-03

Morano, S. Joseph (Department: 3617)

Marine propulsion

Jet drive

C440S084000, C123S192200

Reexamination Certificate

active

06254442

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to a personal watercraft and more particularly to an improved propulsion system and balancing arrangement for such watercraft.
Personal watercraft represent a very rapidly growing segment of the total watercraft market. Although personal watercraft have a wide variety of features and configurations, they have in common the fact that they are designed primarily to have a hull that is quite small and which accommodates a rider and no more than a few additional passengers. Frequently, but not always, the rider and passenger sit on a straddle type seat and in tandem fashion. With this type of watercraft, the riders' area is generally positioned at the rear of the watercraft.
This type of watercraft is also commonly propelled by a so-called “water jet propulsion unit” that is generally mounted in the hull under surface at the rear of the watercraft and generally underline the rearward portion of the riders' area.
This type of construction, particularly in a small watercraft, provides a significant rearward weight bias. Therefore, it is desirable and has been the practice to mount the engine for the propulsion device in a generally forward position and so that it lies at least in part beneath the forward portion of the riders' area. Thus, the center of balance of the watercraft can be optimized and can accommodate varying numbers of riders without the balance being significantly upset.
This gives rise, however, to a problem in connection with the transmission of vibrations and noise to the rider and his passengers. This is particularly true when the engine has only a few cylinders and the space limitations or other factors may not permit full engine balancing by the engine crankshaft alone.
It is, therefore, a principle object of this invention to provide an improved propulsion system for a watercraft of the personal type which will have a compact nature and which will maintain good balance and elimination or reduction of the transmission of noise and vibrations to the riders.
It is a further object of this invention to provide an improved and compact, low vibration propulsion system for a personal watercraft.
SUMMARY OF THE INVENTION
The feature of this invention is adapted to be embodied in a personal watercraft and propulsion system therefor. The personal watercraft is comprised of a hull that defines a rider's area at the rear thereof for accommodating a rider and a minimum number of passengers. A jet propulsion system is supported in the hull at the rear end thereof and at least in substantial part beneath the riders' area. An internal combustion engine is supported within the hull at a position disposed forwardly of the jet propulsion unit and at a position that is at least in part below the forward portion of the riders' area. The engine has a plurality of cylinders and a crankshaft driven by pistons that reciprocate in the cylinders and which is defined an engine body. The engine drives the jet propulsion unit through a transmission system. A balance shaft is driven from the engine crankshaft and contained within the engine body for reducing the transmission of noise and vibrations to the riders


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