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Description  |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
This disclosure relates in general to an improved maneuvering system for
small boats, and more particularly to a bow thruster for small boats which
greatly facilitates operations done at slow speeds such as docking in
congested area.
2. Discussion of the Prior Art
The increased congestion present in many docking areas for small boats has
created a problem for the boat operators. Small boats are usually
maneuvered by the propulsion system located in the rear of the boat.
Either a steerable outboard engine or rudder pivoted to one direction or
the other with a consequent movement of the bow of the boat to the
opposite side. In small, cramped spaces maneuvering the boat is difficult
at best even for many skilled operators, and many accidents such as
ramming another vessel or the dock occur. The problem of maneuverability
exists because the bow of the boat responds only to the engine or rudder
in the rear. The present invention provides an auxiliary maneuvering
system which enables the operator to steer the bow of the boat as well as
the stern, making the boat much more maneuverable. In the past, apparatus
for steering the bow of a small boat that the applicant has been have had
many limitations. Such steering devices include those requiring the
cutting of large holes through the bow of the boat to install a large
propeller in a tube transverse to the bow of the vessel. Such units have
difficult hull installation and require substantial hull repair after
installation. Further, the large transverse tunnel with the propeller
enclosed creates a water trap which in turn increases the flow drag on the
boat hull, making the vessel more difficult to propel through the water.
The speed of the boat, therefore, is lowered and fuel consumption
increased. The present invention uses only small diameter inlet and outlet
fittings through the hull and therefore avoids many of the above-mentioned
problems.
A preliminary search of the prior art was performed by applicant and the
following patents were found to be of possible interest:
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U.S. Pat. No. ISSUE DATE INVENTOR
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917,201 4/6/09 Vollmer
961,306 6/14/10 Mayell
1,240,932 9/25/17 Brown et al
3,078,661 2/26/63 Spence
4,056,973 11/1/77 Dashew et al
4,214,544 7/29/80 Dashew et al
4,265,192 5/5/81 Dunn
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In the patents discovered by the search, the first three, namely Vollmer,
Mayall, and Brown et al, have various propelling and steering apparatus
which discharge water below the water line of the boat which is not what
applicant does, and in fact, would not work for his application. Spence
shows nozzles which discharge to the rear of the boat unlike applicant's
apparatus although they do discharge above the water line. The two Dashew
et al patents and the Dunn patent show discharge of water above the water
line in the bow of the boat as does applicant. The present invention,
however, differs significantly from these inventions which require control
valves and a relatively complicated arrangement of conduits to perform.
Applicant's invention does not require control valves, and does not
require a bypass conduit such as Dunn requires while the water pump is
operating, but before maneuvering is to occur. Applicant's system is
controlled simply by an activation switch which can turn the water pump on
in a normal or reversed mode or turn the pump off. The direction of bow
thrust is controlled by this switch. The present invention has the
advantage of being simple, easier to install and less expensive than the
system of Dunn or Dashew et al.
It should be noted that a further possible reference is Dornak (U.S. Pat.
No. 3,933,113). Dornak's apparatus functions in a different manner than
applicant's apparatus. The rotation of Dornak's apparatus is rotation of
his nozzle 23, not his pump. The nozzle 23 could be rotated to a different
discharge position. The present invention does not rotate any nozzle or
the direction of nozzle discharge. If Dornak's pump 32 were reversed, the
flow of water would be from the nozzle 23 to an exit in the bottom of the
hull producing no directional change as the present invention can by a
reversal of pump rotational direction. In other words, reversing Dornak's
pump would make his entire system inoperable. Further, it would not be
obvious given Dornak how to reverse his pump and produce directional
change successfully as does the present invention due to the difference in
function and structure of his apparatus vis-a-vis the present invention.
Further, the present invention claims at least two rotors in addition to
the above arguments which distinguish the present invention from Dornak.
Further comments can be made regarding Dashew et al (U.S. Pat. No.
4,056,073) which was cited in the parent case. Firstly, valve 44 is a
directional control valve used by Dashew et al. applicant's desire from a
functional and economic standpoint was to use a simple apparatus to
achieve maneuvering in tight spaces without using a valve as does Dashew
et al. The present invention has no directional valves, nor would desire
any valves due to complexity and economic considerations. The two rotors
of the pump of the present invention in a unique way, given the prior art,
perform the directional changes required, taking the place of a valve 44
as shown in Dashew et al. The use of the pump with its rotors as in the
present invention would not be obvious given Dashew et al who shows only a
valve to change direction. The valve may obtain a result of maneuvering
the boat, but is different structurally vis-a-vis the present application.
This structural difference is a key difference and in this difference lies
the heart of the present invention. Further, Dashew et al does not go as
far as to render the present invention obvious. The valve 44 is too much
different than the use of two rotors in a pump to achieve directional
control. The present invention can eliminate the use of directional
valving with its apparatus. This factor should show that this invention
differs enough from Dashew et al as to render it patentable over Dashew et
al.
SUMMARY OF THE INVENTION
The present invention provides apparatus for maneuvering a boat in tight
spaces by allowing the pilot the capability of moving the bow of the boat
by means independent of the boat's engine. Thrusting the bow to either
side in a controlled manner is accomplished by the following apparatus. A
bow starboard side nozzle located in the hull of the boat above the water
line is provided, as is a corresponding bow port side nozzle also located
above the water line. An inlet port is located in the boat hull below the
water line and provides an inlet for water drawn by a positive
displacement bi-directional water pump. The water pump is connected
between the inlet port and the starboard side and port side outlet
nozzles. The water pump has an inner and outer rotor as described in
detail subsequently. Rotation of these rotors in one direction produces
water flow from the inlet port through the starboard side outlet nozzle
allowing the bow to be thrust to the port side, while rotation of the
rotors in the other direction produces a water flow from the inlet port
through the port side nozzle allowing the bow to be thrust to the
starboard side. The port and starboard nozzle exit from the boat hull
above the water line and impinge on the surrounding water. This force
caused by the impinging stream of water allows the maneuvering of the boat
to occur. The water pump is powered by an electric motor connected thereto
which is capable of running in a normal or reversed mode. The modes of the
electric motor determine the direction of rotor rotation of the water pump
and thus the direction of the bow thrust. An activating switch is provided
for the electric motor which can activate the electric motor in a normal
or reversed mode. The maneuvering of the boat hull can be controlled
ultimately by the pilot's use of the activation switch.
It is therefore an object of the present invention to provide an apparatus
for maneuvering a boat in small, tight spaces such as near a dock which is
relatively simple and easy to use.
Another object of the present invention is to provide apparatus for
maneuvering a boat in small, tight spaces which is easy to install on
already existing boats.
A further object of the present invention is to provide a bow thruster for
a boat which is relatively inexpensive and substantially increases the
ability of the boat's maneuverability in small, tight spaces.
Yet another object of the present invention is to provide apparatus for
maneuvering a boat in small spaces which doesn't require a large aperture
in the boat's hull.
Still another object of the present invention is to provide apparatus for
maneuvering a boat in small spaces which doesn't require the additional
complication of directional control valves.
These and other objects and advantages of the present invention will become
more apparent from the following detailed description when taken in
conjunction with the attached drawings.
BRIEF DESCRIPTION OF THE FIGURES
FIG. 1 is a diagrammatic vertical longitudinal section through a small boat
equipped with the bow thruster of the present invention.
FIG. 2 is a diagrammatic top plan view in section taken along line 2--2 of
FIG. 1.
FIG. 3 is a diagrammatic vertical sectional view of a positive displacement
bi-directional water pump used in the present invention.
FIG. 4 is a diagrammatic vertical partial sectional view of the pump of
FIG. 3 taken along line 4--4 of FIG. 3.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIGS. 1 and 2, the bow thruster of the present invention can
be described in detail. FIG. 1 shows a bow thruster of the present
invention generally designated as 10 within a small boat 12 in a preferred
embodiment. The hull 14 of the boat 12 is submerged in a body of water 15
having a water line 16. Within hull 14 is located the bow thruster 10. Bow
thruster 10 comprises a through the hull suction inlet 18 located below
the water line 16 and directly communicating with the body of water 15.
Inlet 18 is connected through suction line 20 to the positive displacement
bi-directional pump generally designated as 22 and described in further
detail in FIGS. 3 and 4. Pump 22 is directly connected to a reversing
electric motor 24 which can drive pump 22 in a clockwise or
counterclockwise direction depending on the choice of the boat operator.
The motor 24 can be suitably mounted to a base 27 located in hull 14. As
shown in FIG. 1, the pump 22 and motor 24 can be mounted in the aft
(rearward) end of the boat 12. A reversing switch 26 is connected through
a two conductor wire 28 to electric motor 24. The reversing switch 26
would preferably be located in a convenient location on the instrument
panel (not shown) of the boat 12. Connected to the pump 22 is a port side
pressure line 30 which terminates in a port side high pressure nozzle 32.
Also connected to the pump 22 is a starboard side high pressure line 34
opposite the port side pressure line 30 terminating in the fore of the
boat 12 in a starboard side high pressure nozzle 36. Both port and
starboard nozzles 32 and 36 are located outside of the hull 14 above the
water line 16 and are generally directed outwardly and downwardly toward
the water 15.
Referring to FIGS. 3 and 4, the positive displacement bi-directional pump
22 can be described in further detail. The advantage of the pump 22 with
respect to prior art systems is that the use of pump 22 eliminates the
need for directional control valves and any by-pass lines that are
required after a conventional pump is started but before the system is
called upon to maneuver the boat. Installation is simplified and more
economically feasible for the small boat owner. Pump 22 has a pump body 38
which contains an outer rotor 40 and an inner rotor 42. The axis of
rotation of the inner rotor 40 is slightly offset from the axis of
rotation of rotor 42, typically about 1/8th inch for the present
application. The inner rotor 42 has a series of protrusions 44a through f.
The outer rotor has a series of indentations 46a through g. A plenum 48 is
defined by the space between the inner rotor 42 and outer rotor 40. The
plenum 48 communicates with inlet 18 through conduits 50 and 52. Conduit
50 has a check valve 54 located directly upstream of the inlet 18 and
similarly conduit 52 has a check valve 56 located upstream of inlet 18.
The conduits 50 and 52 directly communicate with the plenum 48 formed by
the inner rotor 42 and outer rotor 40. The pump 22 also has a pair of
outlet ports 58 and 60 which contain check valves 62 and 64 respectively.
The outlet ports 58 and 60 connect directly to the port and starboard high
pressure lines 30 and 34 (FIG. 2). A drive shaft 66 (FIG. 4) from the
electric motor 24 is keyed by key 68 to the inner rotor 42. The inner
rotor 42 will then rotate in the direction that drive shaft 66 of electric
motor 24 is rotating as determined by the operator through the use of
switch 26. Switch 26 can either be in an off position, in a position
resulting in clockwise rotation of drive shaft 66 of electric motor 24, or
in a position resulting in counter-clockwise rotation of driveshaft 66 of
electric motor 24. As inner rotor 42 begins to rotate the protrusions 44a
through f, and especially 44c and 44d as shown in FIG. 3 partially mesh
with the indentations 46a through g and especially 46c and 46d to move
outer rotor 40 in the same direction as inner rotor 42 forcing an amount
of water from inlet port 18 into plenum 48 and through outlet port 58 or
60 (depending on the direction of rotation of rotors 40 and 42).
Referring to FIGS. 3 and 4, the operation of pump 22 can be described. In
general the pump 22 depending upon the direction of rotation of rotors 40
and 42, will direct water from inlet 18 to either the port or starboard
high pressure lines 30 or 34 and ultimately through either the port or
starboard high pressure discharge nozzles 32 or 36. Water flow is allowed
through only one of lines 30 or 34 and stopped through the other depending
on the direction of rotation of rotors 40 and 42. For example, if drive
shaft 66, outer rotor 40, and inner rotor 42 are rotating clockwise, water
is drawn through inlet 18 past check valve 54, through conduit 50, into
plenum 48, past check valve 64, and through outlet port 60 to either the
port or starboard high pressure nozzle 32 or 36. Water flow into conduit
52 is prevented by check valve 56, and water flow from outlet port 58 is
prevented by check valve 62. If the rotors 40 and 42 of pump 22 are
rotating counterclockwise, the opposite flow occurs. Water flows from
inlet 18, past check valve 56, through conduit 52, into plenum 48, past
check valve 62 and through outlet port 58. Check valves 54 and 64 prevent
water flow from inlet 18, through conduit 50 and outlet port 60. The
direction of rotation of rotors 40 and 42 can be determined by reversing
the driveshaft 66 of electric motor 24 and controlled by the operator from
reversing switch 26. Reversing switch 26 can, therefore, determine whether
the water flow from inlet 18 will be directed to the port high pressure
nozzle 32 or starboard high pressure nozzle 36 which in turn determines
the direction in which the boat 12 will be maneuvered. This maneuvering
can be accomplished with a relatively simple scheme requiring no
directional control valves.
Given the above discussion, operation of the system can be described. The
operator will choose which direction the bow of the boat 12 will be thrust
to, and cause a discharge through the opposite high pressure discharge
nozzle 32 or 36 by using switch 26. For example, if the bow of boat 12 is
desired to be directed to the port side, the operator will use switch 26
to cause a flow of water from inlet 18, through pump 22 to the starboard
high pressure line 34 and out starboard side high pressure nozzle 36. The
water will discharge from nozzle 36 and impinge upon the body of water 15
controllably maneuvering the bow of the boat 12 toward the port side. Of
course, to maneuver the bow of boat 12 to the starboard side, the
discharge of water would be directed to occur out of port side nozzle 32
by switching the switch 26 to the appropriate position. Pump 22 will be
caused by motor 24 to rotate the rotors 40 and 42 in the opposite
direction as the first example and cause a movement of the bow toward the
starboard side.
The invention has been disclosed using the above described embodiment of
pump 22. It should be noted that pump 22 as described is a preferred
embodiment, but other pumps known in the art as rotary gear pumps could be
substituted for pump 22 with suitable results.
The invention may be embodied in other forms without departing from the
spirit or essential characteristics thereof. The present embodiments are
therefore to be considered in all respects as illustrative and not
restrictive, the scope of the invention being indicated by the appended
claims rather than the foregoing description, and all changes which come
within the meaning and range of equivalency of claims are therefore
intended to be embraced therein.
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