Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
20~43~9
SPECIFICATION
WATER DRA'~ING AND GUIDING DEVICE
FOl~ Jl~`'r~ OPl~,I,I,~I~ GL,IDIIlG ~OATS
BACKGROUND OF THE INVENTION
Small-sized gliding boats of the jet-propelled type
arranged for a single person to ride in a standing posture
or some persons to ride in a seated posture have
incorporated therein a jet-propelllng device (or water jet
pump) adapted to be driven for rotation by an engine mounted
on the boat.
Such jet propelling device is designed to draw water
through a water intake port formed in the bottom surface of
the boat body, accelerating said water by~an impeller
installed in a water intake duct (or pump case) to spout it
rearwardly of the boat body, the reaction force serving as
the propelling force for the boat body. Thus, the jet
propelllng device has the danger of drawing not only water
but also garbage, seaweed, fishing lines and other various
floating obstacles. Therefore, to prevent entry of suc~l
obstacles, a special lattice called scope gate or grate is
attached to the bottom surface of the boat body to cover
said water intake port.
The scope gate which has heretofore been most popular,
as shown in Figs. 12 and 13, is in the form of an elongated
rectangle comprising a pair of front and rear attaching
. . .
;~044349
seats 1 and 2 and a pair of side bars 3 and 4, said lattice
having one or more partition bars 5 projecting parallel wlth
said side bars 3 and 4. At any rate, the whole structure is
usually made by casting of aluminum alloy or other light
metal. The side bars 3 and 4 and partition bar 5 are shown
circular in cross section in these figures, but bars having
vertically elongated elliptical and rectangular cross
sections are also known.
Such scope gate is removably or exchangeably attached to
the bottom surface of the boat body to cover the water
intake port while projecting somewhat downward. In the
attached state, the side bars 3 and 4 and partitlon bar 5
extend parallel wlth the travel center line of the boat
body, so that, coupled with the high rigidity of the metal
product, they add to the straight-travel stability during
glldlng of the boat body.
Since it is attached to the bottom surface of the boat
body in such a manner as to project somewhat downward, even
if the boat body runs on shallows or on drifting wood, the
bottom surface will not hit the same; thus, the scope gate
serves to prevent the boat body from being damaged.
Furthermore, during the turning of the boat body, it
provides the boat body with a sldeslip preventing effect
(so-called edging effect) with sald side bars 3 and 4 and
partltion bar 5 servlng as fins, and lt also increases the
rate of flow of water into said water Intake port.
2044349
Further, another advantage Is that the larger the number
of partition bars, the greater the effect of preventing
entry of obstacles.
However, such advantages will not necessarily manifest
themselves during the turnlng of the boat body. The reason
is that the scope gate is made of metal.
More particularly, first, if the conventional scope gate
projects too much downward from the bottom surface of the
boat body, the sideslip preventing effect of the side bars 3
and 4 and partltion bar 5 on the boat body will be
excessively high owing to the high rigidity of the metal
product, resulting in a high resistance to the turning of
the boat body to make it dlfficult to attain smooth steering
of the boat body. For beglnners, such conventional scope
gate even has the danger of rolllng the boat body sldeways.
On the contrary, if It does not at all projcct downward
from the bottom surface of the boat body, the aforesaid
advantages cannot be obtalned. ~ich exPerlence is requlred
in determining the moderate amount of pro~ectlon. It seems
that a scope gate equlPPed wlth a projection adjusting
mechanlsm has not been commerclally avallable.
Secondly, even If the rate of flow of water into the
water Intake port can be Increased by attaching the scope
gate to the bottom surface of the boat body In such a manner
as to project downward therefrom, the high rigldlty of the
metal product causes the side bars 3 and 4 and partitlon bar
~U44349
5 to excessively hold back the natural flow of water movlng
from the water intake port to the water intake duct, or the
water dashes against them and is thereby agitated, bubbling
and disturbed.
As a resultl cavitation takes place ln the water intake
duct (or pump case), corroding the lmpeller or causing
energy loss. It is clear that the larger the number of said
partition bars 5, the more noticeable are such problems.
Thirdly, since the conventional scope gate is a metal
product, it forms an obstacle to visual inspection of the
interlor of the water intake duct through the water intake
port of the boat body. For example, if a floating obstacle
enters the water intake duct and twines itself around the
impeller, impeller shaft or the like, the twining state
cannot be visually inspected unless the boat body is turned
upside down to bring its bottom surface into view, and this
operation of turning upside down requlres hard labor. And
the larger the number of partition bars 5, the more
remarkable is such problem.
Fourthly, essentlally such scope gate is used by being
removably or exchangeably attached to the bottom surface of
the boat body in accordance with the user's taste, steering
skill and experlence. And the attaching bolts tend to
loosen owing to vibrations or chocks produced in the boat
body during the gliding of the boat body. Not infrequently,
It is only after the user has landed that he finds that the
--4--
X04A349
scope gate is missing.
Therefore in practice a sllicone type blnder ls
applled to the scope gate attaching bolts despite the fact
that the scope gate is intended to be removably attached to
the boat body. If the scope gate should be missing since
the conventional scope gate is a metal product it sinks
into depths never to be found thus polluting the sea and
lakes.
SUMMARY OF THE INVENTION
The present invention has been proposed to solve these
problems.
First an object of the inventlon is to provide an
arrangement wherein the scope gate is made of polYcarbonate
resin or other engineerlng plastic materlal having hlgh
bending rigidity said scope gate being in the form of an
elongated rectangle having a pair of attaching seats and a
palr of flow regulating vertlcal walls said flow regulating
vertical walls being adapted to be laterally flexed like
plate springs durlng the turning of the boat body;
therefore even if it ls attached to the boat body to
project downward from the bottom surface of the boat body
lt does not glve the boat body an excesslvely high sldeslip
preventing effect so that even a beginner can steer the
boat body for turnlng safely and smoothly while assurlng
smooth reliable water drawing action without holdlng back
-5-
Z044349
the natural flow of water moving from the water lntake port
to the water lntake duct or without undesirably agitating
water or decreasing the flow rate of water, thereby
preventlng cavitation from taking place in the water intake
duct.
Particularly, if the cross-sections of the flow
regulating vertical walls capable of deforming like plate
springs are shaped symmetrical and in the form of a basic
triangle or trapezoid with its thickness gradually
decreasing upward, it follows that if the boat body is
tilted during turning, since the upwardly tapered surfaces
of the flow regulating vertical walls are flexed into
substantially parallel relation to the water surface, the
ob~ect of smoothlng the flow of water moving from the water
intake port to the water intake duct can be rationallY
attained.
Secondly, an object of the invention is to provide an
arrangement wherein a partition flow regulating vertical
wall is installed parallel with and between said flow
regulating vertical walls, said partition flow regulating
vertical wall having a substantially isosceles triangular
cross-section wlth lts thickness gradually decreaslng
upward, whereby the scope gate ls internally partitioned to
make it difficult for floatlng obstacles to enter and the
water drawlng action during the turning of the boat body is
smoothed.
z044:~49
Thirdly, an ob3ect of the invention is to provide an
arrangement wherein t~)e lower surface reglons of the flow
regulating vertical walls are substantially V-shaped as seen
laterally of the boat body with their lower edges pro3ecting
graduallY downward starting with the opposite sides toward
the middle, whereby, despite the fact that the scope gate
itself is a plastic product allowing the flow regulating
vertical walls to flex, the intermediate regions of the
flow regulating vertical walls farthest from the pair of
opposed seats are physically structurally reinforced to
increase the durability of the scope gate.
Fourthly, an object of the invention is to provide an
arrangement wherein the scope gate is made of transparent or
translucent plastic material so that it can be seen through;
thus, the interior of the water intake duct can be reliably
vlsually inspected from the water intake port wlthout having
to turn the boat body upside down to bring its bottom surface
Into vlew.
This ob3ect can also be attained even If sald partition
flow regulatlng vertlcal wall is added, so long as it is
also transparent or translucent.
Fifthly, an ob3ect of the invention is to provide an
arrangement wherein the scope gate, whlch Is a molding of
plastic material, is colored with a coloring agent,
particularly with a fluorescent material, so that if an
accident should happen in the offing to make the boat body
Z044349
incapable of traveling, the coloration facilitates search
for the boat body. Further, slnce the scope gate is a
plastic prod~ct, lt floats on water, a fact which also
facilitates search if it should be missing.
Slxthly, an object of the invention is to provlde an
arrangement wherein the open edges of the pair of attaching
seats opposed to the interior of the lattice of the scope
gate are formed as slope surfaces rearwardly ascending at
given angles, whereby water is introduced lnto the water
intake port with much less resistance during travel of the
boat body.
Other objects as well as the arrangement of the
invention will become apparent from the following detailed
description of preferred embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. l is a schematic side view of a jet-propelled
gliding boat with the present invention applied thereto;
Fig. 2 is an enlarged bottom view showing the rear
portion of the boat body;
Fig. 3 is a sectional view taken along the line 3-3 ln
Fig. 2;
Fig. 4 is a perspective view of a scope gate;
Fig. 5 is a sectional view taken along the line 5-5 in
. ~ig. 4;
Fig. 6 is an enlarged sectional view taken along the
Z~44349
line 6-G in Fig. 4;
Figs. 7 and 8 are front sectional views showing two
modifications corresponding to Fig. 6;
Fig. 9 is a front sectional view for explainlng flexure
produced in the scope gate during the turning of the boat
body:
Fig. 10 is a perspective view showing a modification of
a scope gate corresponding to Fig. 4;
~_ Fig. 11 is an enlarged sectional view taken along the
line 11-11 in fig. 10;
Fig. 12 is a perspectlve view showing a conventlonal
scope gate; and
Fig. 13 is an enlarged sectional view taken along the
line 13-13 in Fig. 12.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The concrete arrangement of the invention will now be
descrlbed in detail with reference to the drawings. In Fig.
1 schematically showlng a 3et-propelled small-sized gliding
boat in its entirety, the character A generally denotes a
boat body made of fiber-reinforced plastic (FRP), said boat
body being of hollow sealed construction including a front
region defined as an engine room 10 and a rear region with
its upper surface defined as a floor deck 11 for a driver to
ride in a standing posture. In some cases, the middle area
of the floor deck 11 will be provided with a seat for a
_g_
2044349
driver. The numeral 12 denotes an engine contained ln the
engine room 10 for drlving a jet-propelling device (water
jet pump) B through a propeller shaft 13 to impart a
propelling force to the boat body 9.
The propeller shaft 13 extends along the travel center
line of the boat body A to a position below the floor deck
11 and is connected at lts front end to the crank shaft (not
shown) of the engine 12 through a clutch 14. Integrally
rotatably connected to the rear end of the ~peller shaft 13
are an impeller 15 and guide vanes 16. The numeral 17
denotes a water intake duct serving as a pump case for
receiving the impeller 15 and guide vanes 16, said water
intake duct being disposed below the floor deck 11, with its
front side providing a water intake port 18 which opens in
the middle of the bottom surface of the boat body A.
When the impeller shaft 13 is driven for rotation, its
impeller 15 draws water through the water intake port 18.
ln the water intake duct 17, the water drawn is accelerated
and forced rearward by the impeller 15 and its flow is
regulated by the guide vanes 16, thereupon It is spouted out
through a steering nozzle 19 which opens in the stern of the
boat body 9; the reaction to the spouting force advances the
boat body A.
The steerlng nozzle 19 is manually controlled from the
floor deck 11 to change its direction, whereby the boat body
A can be steered. In addition, the numeral 20 denotes a
--10--
Z(~44349
pump case cover attached to the middle region of the bottom
surface of the boat body A.
Slnce there Is a danger of garbage, seaweed, flshing
lines and other various floating obstacles belng drawn in
together with water through the water intake port 18, a
scope gate C for preventing entry thereof is attached to the
middle region of the bottom surface of the boat body A to
cover the water intake port 18, as shown in Figs. 2 and 3.
In the present invention, the scope gate C is made by
in~ection molding of a polycarbonate resin ~preferably, one
marketed under the trade name of Taflon, from Idemitu
Petroleum Chemistry Co., Ltd.) having high bending rigidity
(desirably, about 23,000 kg/cm2 or above), polyacetal resin
or other thermoplastic engineering plastic material into the
form of an elongated rectangle, as shown In Figs. 4 through
6, the entire molding being transparent.
In Figs. 4 through 6 showing the scope gate C, the
numerals 21 and 22 denote a pair of attaching seats having a
width w smaller than the width s of said water intake port
18. The front attaching seat 21 has a pair of bolt
receivin~ holes 23 on opposite sides, while the rear
attaching seat 22 is centrally formed with a bolt receiving
hole 24 which desirably is elongated in the longitudinal
direction. The number and dispositlon of bolt recelving
holes 23, 24 may be freely changed In connection with the
boat body A.
2044349
The attachlng seats 21 and 22 are applied at thelr flat
surfaces to the bottom surface of the boat body A and then
fixed thereto by stud bolts 25 and 26 so that the scope gate
C can be removed or exchanged.
The open edges of the attachlng seats 21 and 22 of the
scope gate C opposed to the Interior of the lattlce are
formed as slope surfaces 21a and 22a rearwardly ascendlng at
given angles ~ and p with respect to the horizontal surface.
Thus, water can be smoothly drawn from the water lntake
~- bodv
port 18 of the boat/A lnto the water intake duct wlthout
disturbing water.
The numerals 27 and 28 denote a palr of flow regulatlng
vertical walls spannlng the space between the attachlng seat
21 and 22 and extending across the water intake port 18 of
the boat body A with the lateral surfaces thereof being
approximately orthogonal to the attaching surfaces of sald
seats.
Thus, coupled wlth the fact that the scope gate C itself
is made of sald plastic materlal, thls arrangement ensures
that durlng the turnlng of the boat body A, the urglng force
of water ls supported by the uprlght surfaces of the flow
regulating vertlcal walls 27 and 28, whlch then flex to and
fro as shown ln chain lines in ~ig. 9 as if they were plate
sprlngs. This flexure of the flow regulating vertlcal walls
27 and 28 al IOW6 water to flow wlthout excesslvely holding
back or dlsturblng the same; thus, water is smoothly drawn
- 2044349
in through the water intake port 18 of the boat body A.
~o(l Y
In addltion, when the boat/~ s travelIng stralght wlth
the uprlght lateral surfaces receiving no pressure of
water laterally of the boat body A, the flow regulatlng
vertlcal walls 27 and 28 are, of course, restored to the
original state.
Further, the cross-sections of the flow regulatlng
vertical walls 27 and 28 are shaped symmetrical and In the
form of a basic triangle or trapezoid with its thickness
as sllown in Fig. 6.
gradually decreasing upward, /That is, the lateral surfaces
of the flow regulatlng vertical walls 27 and 28 are slope
surfaces 27a, 27b and 28a, 28b with the thickness gradually
decreasing upward at angles of r and ~.
As a result, water can be extremely smoothly drawn into
the water inLake port 18 as It Is gulded to the travel
center line of the boat body A. Further, even if the boat
body A Is tilted durlng turnlng, the flow regulating
vertlcal walls of the scope gate C integral therewlth are
also tilted sUch that their upright lateral surfaces are
orthogonal to the water surface as suggested In Fle. 9.
Therefore, holdlng back and disturbance of water are
suppressed, and substantlally the same amount of water as
durlng 8 tralght travel Is smoothly drawn from the water
Intake port 18 Into the water Intake duct 17.
For this reason, the cross-sectlons of the flow
reeulatlng vertlcal walls 27 and 28 should, most
-13-
204~349
effectlvely, be In the shape of an isosceles trapezoid shown
in Fig. 6, or a modification thereof such as an ellipse, an
oval or a waterdrop, as shown in Flg. 7. However, so long
as the symmetrical cross-sections of the flow regulating
vertical walls 27 and 28 are malntained, the cross-sections
may be in the form of a non-isosceles trapezold, as shown
in Fig. 8, or a right triangle.
When the flow regulating vertical walls 27 and 28 are
seen laterally of the boat body A, as is clear from Figs. 3
through 5, their upper surfaces are horizontal, whereas
their lower surfaces are V-shaped gradually downwardly
projectlng as the approximately intermediate region Is
reached.
That is, the lower surfaces of the approximately front
halves of the flow regulatlng vertical walls 27 and 28 are
forwardly upward slope surface 27c and 28c connected flush
to the lower surface of the front attaching seat 21, while
the lower surfaces of the remaining rear halves are
rearwardly upward slope surface 27d and 28d connected flush
to the lower surface of the rear attaching seat 22; thus,
the approxlmately middle region where the slope surfaces
27c, 28c, 27d, 28d cross each other projects downward by the
greatest amount. The character A denotes the crossing angle
between the forwardly and rearwardly upward slope surfaces
27c, 28c, 27d, 28d.
Thus, the scope gate C itself Is integrally made of said
X(~4349
plastic material to enable the flow regulating vertlc~l
walls 27 and 28 to flex durlng turning movement, whlle the
intermediate region between the flow regulatlng vertical
walls 27 and 28 remotest from the attaching seats 21 and 22
can be strengthened to be free from the danger of belng
physically broken. Further, the front halves of the flow
regulating vertical walls 27 and 28 have their lower
surfaces designed to define forwardly slope surfaces 27c and
28c; therefore, the boat body 9 can be given lift by water
acting on said surfaces during travel of the boat body A.
Figs. lO and ll show a modification of a scope gate
corresponding to Figs. 4 through 6, and the relation to
Figs. 4 through 6 is indicated by multlplylng the numbers by
lO. In this modification, a partition flow regulating
vertical wall 290 is interposed between the flow regulating
vertical walls 270 and 280 in parallel relation to the
latter, thereby enhanclng the effect of preventing entrY of
floating obstacles. The cross-sectional shape of the
partition flow regulating vertical wall 290 is determined in
positional relation to the flow regulating vertical walls
270 and 280; thus, it is an isosceles trapezoid or an
a~ own in Fi1r. 11
Isosceles triangle,/or it is a modification of said figure,
such as an ellipse or a waterdrop shape. In addition, the
partltlon flow regulating vertlcal wall 290 may be Increased
In number to two or more so long as they extend parallel
with the flow regulatlng vertical walls 270 and 280.
.
-15-
2044349
At any rate, in attaching the scope gate C to the bottom
surface of the boat body A, lt Is effective, as is suggested
in Fig. 3, to position it such that the rear halves of the
flow regulating vertical walls 27 and 28 proiect downward
beyond the bottom surface of the boat body A by a glven
amount h-
Thereby, floatlng obstacles tendine to adhere to the
rear end of the water intake port 18 formed in the bottom
surface of the boat body A are qulckly guided rearward bY
the rear halves of the flow regulating vertical walls 27 and
28 projecting downward beyond the bottom surface of the boat
body A. Further, when the boat body A is turning, the rear
halves of the flow regulatlng vertical walls 27 and 28
exhlblt the effect of preventing sidesllp of the boat body
A. However, in that case, slnce the flow regulating
vertlcal walls 27 and 28 themselves wlll flex to and fro, as
descrlbed above, there Is no danger of the sideslip
preventing effect being too high.
It has been stated that the scope gate C is molded of
tranæparent or translucent plastlc material, In addition to
this transparency, It Is desirable to apply a suitable
fluorescent coloring agent. Then, even If an accldent whlch
makes lt Impossible for the boat body A to glide should
happen, the boat body can be easily searched for with the
color as a gulde.
As descrlbed above, the scope gate C of the present
-16-
~OA4349
Invention is integrally molded of transparent or translucent
engineering plastlc material into the form of an elongated
lattice, and a pair of longitudinally extending flow
regulating vertical walls 27 and 28 are adapted to flex to
and fro during the turning of the boat body A. Thus, water
can be drawn very smoothly without the danger of excesslvely
holding back or disturbing the flow of water moving from the
water intake port 18 to the water intake duct 17 or the
danger of decreasing the flow rate of water. Nor is the
danger of causing cavitation in the water intake duct 17.
Further, since the scope gate C can be seen through, the
interior of the water intake duct 17 can be inspected by
simply glancing at the water intake port 18 without having
to turn the boat body A over to bring its bottom surface
into view. Such effect will not be lost even if the
partition flow regulating vertical wall 290 is interposed to
partition the lattice, and the efficiency of inspection and
maintenance is high.
Partlcularly, lf the cross-sections of the flow
regulating vertical walls 27 and 28 are made symmetrlcal and
In the form of a baslc triangle or trapezold with its
thickness gradually decreas}ng upward, then water can be
cxtremely smoothly drawn into the water lntake port 18 along
the travel center line during straight travel of the boat
body A. Further, if the boat body A ls tilted durlng Its
turnlng, the upwardly converging slope surfaces 27a, 27b and
20~i4349
28a, 28b of the flow regulating vertlcal walls 27 and 28 are
caused to be orthogonal to the water surface. This, coupled
with said flexure, causes the same amount of water as during
straight travel to flow into the water intake port 18 while
more smoothly regulating the flow without the danger of the
flow regulating vertical walls 27 and 28 holding back or
disturbing water.
If the bottom surfaces of the flow regulating vertical
walls 27 and 28 are V-shaped, as seen laterally of the boat
body A, gradually downwardly pro~ecting as the approximately
lntermediate regions are reached, then the approxlmately
intermediate regions of the flow regulating vertical walls
27 and 28 remotest from the palr of attaching seats 21 and
22 can be physically reinforced to be free from damage
thereto whlle maklng the scope gate C itself in the form of
a plastlc article to allow the flow regulating vertical
walls 27 and 28 to flex; thus, the durability is enhanced.
Further, if a partltlon flow regulatlng vertical wall
290 is Interposed between the flow regulating vertlcal walls
270 and 280 in parallel relation to the latter and its
cross-section is in the form of an lsosceles triangle or an
Isosceles trapezoid with Its thlckness gradually decreasing
upward, then slnce the interlor of the lattice of the scope
gate C is partltioned by the partltlon flow regulatlng
vertical wall 290, the entry of floatlng obstacles into the
water Intake port 18 can be prevented more reliably whlle
-18-
20443~9
said flexure is being exhibited during the turning of the
boat bodY 9-
lf the open edges of the attaching seats 21 and 22 ofthe scope gate C opposed to the interior of the lattice are
formed as slope surfaces 21a and 22a rearwardly ascending at
given angles a and ~, then water can be introduced more
smoothly into the water intake port 18 by the rearwardly
ascending slope surfaces 21a and 22a of the attaching seats
21 and 22.
Further, if the entire scope gate C ls calored
preferably with a fluorescent colorlng agent, the boat body
9 can be given an external appearance which is harmonious
with the boat body C. Thus, if an accident which makes
gliding impossible or an accident of coming off of the scope
gate C should happen in the offing, the search thereof is
facilitated.
--19--
