CA2044350A1 - Device used in jet-propelled gliding boats for preventing floating obstacles from being drawn in - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
The present invention relates to a device used in jet-propelled gliding boats for preventing floating obstacles from being drawn in, wherein a scope gate for preventing entry of garbage, seaweed, fishing fines and other floating obstacles is attached to a water intake port formed in the bottom surface of a boat body, and the water drawn from the water intake port is accelerated by an impeller housed in a water intake duct and spouted rearwardly of the boat body, the device being characterized in that the scope gate is in lattice form composed of a pelf of attacking seats associated with the bottom surface of the boat body and a single longitudinal partition wall extending along the travel center fine of the boat body or a pair of longitudinal partition walls extending parallel with the travel center fine of the boat body, interconnecting the attacking seats, substantially the latter half or halves of the longitudinal partition wall or walls project downward by a fixed amount beyond the bottom surface of the boat body, while a transverse partition wall is disposed in the intermediate portion or portions of the projecting latter half or halves to assume an inclined state sloping rearwardly upward at a fixed angle, whereby a larger space for water intake is defined between the transverse partition wall and the front attaching seat and a smaller space for water intake is defined between the transverse partition wall and the rear attaching seat.

Description

;~044350 SPECIFICATION

DEVICE USED IN JET-PROPELLED GLIDING BOATS FOR
PREYENTING FLOATING OBSTACLES FROM BElNG DRAWN IN

BACKGROUND OF THE INVENTION
Small-sized gliding boats of the jet-propelled type arranged for a slngle person to rlde In a standlng posture or some persons to ride ln a seated posture have lncorporated thereln a jet-propelling devlce (or water ~et pump) adapted to be drlven for rotatlon by an engine mounted on the boat.
Such ~et propelllng device is deslgned to draw water through a water lntake port formed in the bottom surface of the bost body, acceleratlng said water by an Impeller Installed In a water Intake duct (or pump case) to spout It rearwardly of the boat body, the reactlon force serving as the propelllng force for the boat body. Thus, the jet propelllng devlce has the danger of drawing not only water but also garbage, seaweed, fishlng llnes and other var~ous floatlng obstacles. To~prevent such obstacles from belng drawn In, as found In Japanese Patent PublIcatlon No.
~8356/1986, and Japanese Utallty Model Publlcatlon Nos.
28640/1980 and 317~9/1979, a lattice called scope gate or grate is attached to the bottom surface of the boat body to cover sald water Intake Port.

Z044~50 .

To prevent floating obstacles from being drawn in, the number of partitlon bars could be Increased to partltion the interior of the lattlce more finely; It may be sald that the more flnely it ls partltloned, the greater the effect attained. In that case, however, the amount of water that can be drswn in through the water intake port would also decrease, and the water flow would be bubbled or agltated.
Such phenomenon becomes particularly noticeable when the boat body Is turning. The reason is that durlng the turning of the boat body, the natural flow of water from the water intake port toward a water intake duct Is held back or dashes hard agalnst the partition bars. As a result, a cavitation phenomenon takes place In the water Intake duct (pump case), corrodlng the Impeller or causing the loss of propelllng energy.
Further, the more finely the Interlor of the lattlce of the scope gate is partltloned, the greater the welght of the scope gate It~elf. Furthermore, flner partltionlng makes it less easy to visually inspect the lnterior of the water Intake duct from the water Intake port. More particularly, If a floating obstacle enters the water intake duct and twlnes Itself around the impeller or the lmpeller shaft, the operatlon for removal thereof cannot be performed easily and efflclently.
If the scope gate Is made of an opaque metalllc materlal, thl~ drawback Is partlcularly notlceable. And before the aforesaid visual lnspection can be made, the boat body must be turned over to direct Its bottom surface upward; thls operation requires heavY labor.

SUMMARY OF T~IE IN~ENTION
The present Inventlon has been accompllshed to solve these problems, and an ob~ect thereof is to provide an arrangement whereln to partltlon the water intake port formed in the bottom surface of the boat body, the scope gate for preventlng floating obstacles from being drawn In Is made in lattice form, comprising a pair of attaching seats by which it is attached to the boat bodY and a palr of longitudinal partition walls extending parallel with the travel center line of the boat body to bridge the space between said seats, the latter halves of said longitudlnal partition walls extending downward by a fixed amount beyond the bottom surface of the boat body, a transverse partition wall disposed in said extending portions in an Inclined state sloping rearwardly upward at a fixed angle, the lower surface of sald transverse partition wall extending downward beyond the lower surface of the boat body, thereby arresting floating obstacles to prevent them from entering the water intake port In the boat body.
Another ob~ect is to provide an arrangement wherein the transverse partition wall bridges the space between longitudlnal partltion walls in such a manner as to deflne a 20~4350 larger space between It and the front attachlng seat and a smaller space between it and the rear attachlng ~eat and is disposed In an Incllned state sloplng rearwardly upward at a fixed angle, whereby water is drawn In wlth no resistance through the water intake port such that the flow llnes of water taken from the front larger space lnto the water intake port is dense and the flow rate is hlgh whlle the flow lines of water taken from the rear smaller space into the water intake port is sparse and the flow rate is low, and the pressure in the smaller space Is negative relative to that in the larger space, with the result that floating obstacles once arrested by the lower surface of the transverse partltlon wall are hardly drawn from the smaller space located therebehind into the water Intake port and Instead they are moved rearwardly of the boat body by the actlon of water flowing along the bottom surface of the boat body.
That is, the lattice of the scope gate Is not of flnely partitloned constructlon, 60 that water Is smoothly guided from the water lntake port In the boat body Into the water Intake duct wlthout being excessively held back or being caused to bubble or belng agltated, thus elImlnatlng the posslblllty of cavltatlon taking place In the water Intake duct, whlle allowlng vlsual inspectlon of the Interlor of the water Intake duct easily from outside and preventing garbage, seaweed, flshlng llnes and other varl 0U8 floatlne Z04~350 obstacles frnm being drawn ln together wlth water.
Such object can be attalned by providlng an arrangement whereln the longitudinal partitlon wal 18 of the 6cope gate extendlng along the travel center line of the boat body are reduced In number to unlty, substantlally the latter half of such single longitudlnal partition wall extending downward by a flxed amount beyond the bottom surface of the boat body, the extending latter half being blfurcated and sloping rearwardly upward at a fixed angle to provlde a transverse partltion wall, the front ends of the branches belng contlnuou6 with the rear attachlng seat, with the result that a palr of larger water intake spaces are defIned between the transver6e partltlon wall and the front attachlng seat and a smaller water Intake space Is deflned between the transverse partltion wall and the rear attaching seat.
The smaller water Intake space Is poslttoned rearwardlY
of the lower surface of the transverse partltlon wall where floatlng obstacles are once arrested, and the same as the above may be sald about the Interrelatlonshlp between the flow llnes and flow rate of water drawn therefrom into the water Intake port and those of water drawn frnm the larger spaces Into the water Intake port; thus, floatlng obstacles once arrested are posltlvely pushed away rearwardly of the boat body along the bottom surface of the boat bndy by the water energy. Accordlng to such arrangement, the normal water drawing action at the water Intake port of the boat body can be made further smooth and the scope gate ltself can be further simpllfled.
Another obJect of the lnventlon is to Provlde an arrangement wherein the transverse partition wall is V- or U-shaped as seen in a bottom vlew such that it graduallY
extends forward as its center located on the travel center line of the boat body is approached, whereby floating obstacles once arrested by the lower surface of said transverse partition wall are efflciently pushed away rearwardly in two diverging directions so that they are prevented from entering the water intake port.
A further obJect of the invention is tn provide an arrangement wherein the scope gate Is made by inJection molding of a transparent or translucent engineering plastic material so that thls lnJection moldlng, coupled wlth the employment of a construction in whlch the Interior of the lattice is not flnely partitioned, allows the Interlor thereof tn be seen easily from outside, while even if floating obstacles should twine themselves around the impeller or the propeller shaft in the water intake duct, they can be efficiently removed, the scope gate being light in weight and adapted for mass production.
- Other ob~ects as well as the arrangement of the Invention wlll become apparent from the following detailed description of preferred embodiments.

204~3so BRIEF DESC~IPTION OF THE DRAWINGS
Fig. 1 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 portlon of the boat body Fig. 3 is a sectional view taken along the line 3-3 in Fig. 2;
Flgs. 4 and 6 are a perspectlve view and a bottom vlew of a scope gate;
Fig. 6 Is an enlarged sectlonal vlew taken along the llne 6-6 in Fig. 6;
Flg. 7 Is an enlarged sectlonal vlew taken along the llne 7-7 In Flg. 5;
Flg. 8 18 a perspectlve vlew of a spacer;
Flgs. 9 and 10 are a perspective vlew and a bottom vlew ~howing a first modlfled embodiment of a scope gate;
Flg. 11 Is an enlarged sectlonal vlew taken along the llne 11-11 In Flg. 10;
Flgs. 12 and 13 are a perspectlve view and a bottom view showlng a second modlfied embodlment of a scope gate;
Ftg. 14 18 a sectlonal vlew taken alnng the line 14-14 In Flg. 13; and - Flg. 15 Is an enlarged sectlonal vlew taken along the llne 16-16 ln Flg. 13.
.

~044350 DETAILED DESCRIPTION OF THE PRE~ERRED EM~ODIMENTS
The concrete arrangement of the Inventlon wlll now be descrlbed in detall wlth reference to the drawlngs. In Fig.
1 schematlcally showlng a ~et-prnpelled small-slzed glldlng boat in its entlrety, the character A generally denotes a boat bodY made of fIber-reinforced plastlc (FRP), sald boat body belng of hollow sealed constructlon Including a front reglon deflned as an englne room 10 and a rear reglon with ~ts 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 wlll be provided wlth a seat for a driver. The numeral 12 denotes an englne contained in the engine room 10 for drlvlng a jet-propelllng devlce (water ~et pump) B through a propeller shaft 13 to impart a propelling force to the boat body A.
The propeller shaft 13 extends along the travel center llne O-O of the boat body A to a posltlon below the floor deck 11 and Is connected at Its front end to the crank shaft (not shown) of the englne 12 through a clutch 14.
Integrally rotatably connected to the-rear end of the propeller shaft 13 are an Impeller 16 and gulde vane~ l6.
The numera1 17 denotes a water Intake duct servlng as a pump ca~e for recelvlng the Impeller lfi and,gulde vanes 16, sald water Intake duct belng dlsposed below the floor deck 11, wlth Its front slde provldlng a water Intake port 18 whlch opens in the mlddle of the bottom surface of the boat body A.
~ hen the lmpeller shaft 13 is drlven for rotatlon, Its Impeller 15 draws water through the water intake port 18.
In the water Intake duct 17, the water drawn ls accelerated and forced rearward by the Impeller 16 and Its flow Is regulated by the guide vanes 16, thereupon it is spouted out through a steering nozzle 19 whlch opens ln the stern of the boat body A; the reaction to the spouting force advances the boat body A.
The steerlng nozzle 19 ls manually controlled from the floor deck 11 to change Its direction, whereby the boat body A can be ~teered. In additlon, the numeral 20 denotes a pump case cover attached to the middle reglon of the bottom ~urface of the boat body A.
Since there Is a danger of garbage, seaweed, fishlng lines and other various floating obstacles being drawn in together wlth water through the water intake port 18, a scope gate C for preventing entry thereof 18 attached to the mlddle reglon 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 Inventlon, the scope gate G is made of a llght alloy or tranæparent or translucent polYcarbonate resin, polyacetal resin or other thermoplastic englneering plastlc materlal preferably havlng hlgh bendlng elastlcitY
Into the fnrm of an elongated lattlce.
In ~Ig~. 4 through 7 showlng a baslc embodlment of a _g_ Zl~4~;~5~) scope gate G, the numerals 21 and 22 denote a palr of attaching seats having a wldth w2 smaller than the width wl of sald water intake port 18. The front attachlng seat 21 has a palr of bolt receiving holes 23 on opposlte sldes, whlle the rear attachlng seat 22 ls centrally formed with a bolt receiving hole 24 whlch preferably ls elongated in the longltudlnal dlrectlon. The number and dlsposltlon of bolt receiving holes 23 and 24 may be freely changed in connection with the boat body A.
The attaching seats 21 and 22 are applied at their flat surfaces to the bottom surface of the boat body A and then, as shown in Figs. 2 and 3, fixed thereto by a plurality of stud bolts 26 and 26 so that the scope gate G can be removed or exchanged.
The open edges of the attaching seats 21 and 22 of the scope gate G opposed to the interior of the lattice are .
formed as slope surfaces rearwardly ascending at glven angles ~ and ~ wlth respect to the horlzontal surface.
Thus, water can be smoothly drawn from the water lntake port 18 of the boat A into the water Intake duct wlthout disturbing water.
The numeral 27 denotes a pair of flow regulating longltudlnal walls spanning the space between the attaching seat 21 and 22 and extending parallel with the travel center line 0-0 of the boat body A to partitlon the water Intake port 18 of the boat body A wlth the lateral surfaces thereof being approxlmately orthogonal to the attaching surfaces of said seats 21 and 22.
In this sense, the walls have been referred to as the "longltudinal partltlon walls". By maklng the entire scope gate G by iniection molding of the aforesald plastic material havlng hlgh bending elastlcity, the longitudinal partition walls 27 can be transversely.deformed as if they were plate springs durlng the turning of the boat body Q.
Thus, during the turnlng of the boat body Q, the longltudlnal partition walls 27 of the scope gate C are sub~ected to the water pressure acting thereon and are thereby elastlcally deformed transversely to and fro, thus allowlng water to flow without being held back or disturbed;
thus, water Is smoothly drawn in through the water intake port 18. For this reason, the cavltation In the water Intake duct 17 i~ effective!y suppres~ed.
Further, the cross-sectlons of the longltudlnal partitlon walls 27 are preferably ln the form of a bas1c trlangle or trapezold wlth Its thlckne6s gradually decreaslng upward, as suggested In Flg. 7. That Is, the surfaces of the longitudlnal partltlon walls 27 are formed a~ slope surfaces wlth the thlckness gradually decreaslng upward.
- Wlth the arrangement thus made, even If the boat body Q
Is tllted durlng turnlng, the longltudinal partltlon walls(2 o the scope gate C Integral therewlth are also tllted such 204435~) that the wall surfaces are orthogonal to the water surface, w1th the result that the holding back and disturbance of water are effectively suppressed, and substantiallY the same of thc boat bodr A
amount of water as during stralght travel/ls smoothly drawn from the water Intake port 18 into the water Intake duct 17.
When the longitudinal partltlon walls 27 are seen laterally of the boat body A, as Is clear from Flgs. 4 and 6. thelr upper surfaces are f1at, whereas thelr lower surfaces are V-shaped gradually downwardly pro~ectlng as the approxlmately intermedlate reglons a are reached.
That ls, the lower surfaces of the approxlmately front halves of the longltudlnal partltlon walls 27 are forwardly upward slope surfaces connected flush to the lower surface of the froht attachtng seat 21, whlle the lower surfaces of the remalnlng rear hslves are rearwardly upward slope ~urfaces connected flush to the lower surface of the rear attaching seat 22; thus, each Intermedlate reglon a where the slope surfaces cross each other projects downward by the greatest amount. The character r suggests the crosslng angle between the forwardly and rearwardly upward slope surfaces.
Thus, In the case where the scope gate G Itself Is Integrally made of sald plastlc materlal, the Intermedlate r¢glons a remotest from the palr of attachlng seats 21 and 22 can be phys~cally reinforced to be free from dama~e thereto. ~urther, the front halves of the longltudlnal . - ............. .. . ..

partltion walls 27 have their lower surfaces deslgned to define forwardly upward slope surfaces therefore, the boat body A can be given lift by water acting on said surfaces.
At any rate, as is clear from Fig. 3, the scope gate C
of the present invention is adapted to be fixed at sald attaching seats 21 and 22 to the bottom surface of the boat body 9 such that the rear portions of the longitudinal partitlon walls 27 proJect by a flxed amount h downward beyond the lower surfsce of the boat body A.
In that case, a spacer 28 shown In Fig. 8 ls preferably interposed between the rear attaching seat 22 and the bottom surface of the boat body A so as to adjust said amount of pro~ectlon h.
That is, the spacer 28 Is shaped to correctly fit on the rear attachlng seat 22 of the scope gate G; thus, it is applled to the rear attachlng seat 22 for attachment to the bottom surface of the boat body A by sald stud bolt 26 through a communlcation hole 29 alIgned wlth a bolt recelvlng hole 24, thereby increaslng the amount of proJectlon h. It Is posslble to decrease the amount of proJectlon h by removlng the spacer 28.
The numeral 30 denotes a transverse partltlon wall transversely extendlng between the Intermedlate portlons of the longltudlnal partltlon walls 27, thereby dlvldlng the Interlor of the lattlce of the scope gate G Into a front, larger water Intake space Sl and a rear, smaller water X0~4350 intake space S2. That Is, the larger space Sl IB located between the front attaching seat 21 and the transverse partition wall 30, while the smaller space S2 Is located between the transverse partitlon wall 30 and the rear attachlng seat 22.
In thls case, s~nce the rear halves of the longltudlnal partltlon walls 27 project downward by a f i xed amount h beyond the bottom surface of the boat body A, the lower surface b of the transverse partltlon wall 30 is connected flush to the lower surfaces of the longltudlnal partltlon walls 27; thus, as is clear from Flg. 3, it also proJects downward beyond the bottom surface of the boat body A.
- The surface of the transverse partitlon wall 30 is formed as a rearwardly upward slope surface crosslng the horizontal surface at a fixed angle ~ to be substantially parallel wlth the edges of the openlngs In the attachlng seats 21 and 22, so that water is smoothly gulded from the water Intake port 18 of the boat body A Into the water intake duct 17.
In the case of the bas~c embodiment shown In Figs. 4 through 7, when the transverse partltlon wall 30 is seen from the bottom surface of the boat body A, the scope gate G Is curved In v- or U-shape gradually extendlng forward a~
- the center c posltloned on the travel center llne 0-0 Is approached. Partly because the lower surface b of the transverse partltlon wall 30 proJects downward beyond the bottom surface of the boat body A as descrlbed above, floating obstacle6, whlle betng arrested, are moved In two dlverglng dlrectlons laterally of the boat body A thus, their accldental entry lnto the water lntake port 18 Is effectlvely prevented.
So long as the surface of the transverse partition wall 30 is an lncllned surface sloplng rearwardly upward at a fixed angle ~ wlth lts lower surface b pro~ecting downward beyond the bottom surface of the boat body A to be exposed, use may be made of a scope gate G shown in Flgs. 9 through 11, whlch is a first modified embodiment, having a transver6e partition wall 30a which is straight as seen In a bottom view and whlch is orthogonal to its longltudinal partition walls 27a.

In addition, the rest of the arrangement In the first .shov~n in Fi~. 9 throu~h ll modified embodlment/is substantlaliy the same as the embodlment shown In Flgs. 4 through 7; thus, the correspondlng parts are denoted by llke reference numerals wlth the letter "a" added thereto, and a detailed descrlptlon thereof 16 omltted.
Flg~. 12 through l~ 6how a second modlfled embodiment of a scope gate a accordlng to the present Inventlon, wherein a ~Ingle longltudlnal partltlon wall 27b ls posltloned on the travel center llne 0-0 of the boat body A and extends between the attachlng seats 21b and 22b, and the rear end of sald longltudlnal partltlon wall 27b 16 blfurcated to 2()4435~) provide a transverse partition wall 30b, the front end~ of the resulting branches being connected to the oppnslte sldes of the rear attachlng seat 22b, whereby a smaller space S2 f or water intake is deflned between the transverse partitlon wall 30b and the rear attachlng seat 22b.
According to this second modlfled embodiment, the larger space Sl for water intake de$1ned between the front attaching seat 21b and the transverse partltlon wall 30b Is bisected by the slngle longltudlnal partltlon wall 27b.
However, regardless of this blsectlon, It stlll opens wlder than the smaller space S2.

In addltlon, the rest of the arrangement in the ShOWII in Firs. 12 throu~h 15 second modlfled embodiment/ls substantlally the same as the embodiment shown In Flgs. 4 through 7; thus, the correspondlng parts are denoted by like reference numerals wlth the letter "b" added thereto, and a detalled descrlptlon thereof Is omitted.
The functlons nf the scope gate C wlll now be descrlbed on the basls of the baslc embodlment shown ln Flgs. 4 through 7. The scope gate G Is fixed to the bottom surface of the boat bodY A to partltlon the water Intake port 18 of the boat body such that substantlally the latter halves of the palr of longltudlnal partltlon walls 27 prnJect downward by a flxed amount h beyond the bottom surface of the boat body A; therefore, a sidesllp preventlng effect (so-called edglng effect) can be attalned durlng the turnlng of the Z04435(~

boat body A. Further, if the boat body runs on shallows or on drlftlng wood, Its bottom surface wlll not hit the same and hence damage thereto Is avolded.
Partlcularly, In the Intermedlate portlons of the latter halves of the longitudinal partition walls 27 pro~ectlng downward beyond the bottom surface of the boat body A, the transverse partltlon wall 30 Is disposed to assume an Inclined state sloplng rearwardlY upward at a flxed angle 9, whereby the smaller space S2 for water lntake Is defined between the transverse partltion wall 30 and the rear attaching seat 22; therefore, wlthout having to flnely partltion the scope gate G ltself, it can be physlcally reinforced by the transverse partitlon wall 30 and the entry nf garbage, seaweed and other varlous floating obstacles through the water lntake port 18 is prevented.
That is, durlng the use of the boat body A, water flows along the bottom surface of the boat body A In two dlrectlons: a dlrection x toward the water intake port 18 and a rearward dlrection y. Partlcularly, as the rear end edge of the water Intake port 18 is approached, the water force in the dlrection y increases, 80 that floating obstacles tend to be gathered at said rear end edge.
In that case, in the present Inventlon the latter halves of the longitudlnal partltlon walls 27 pro~ect downward by a fixed amount h and the lower surface b of the transverse partJtlon wall 30 dlsposed In the Intermedlate portlons of 44;~51~

said longltudlnal partltlon walls also projects downward beyond the bottom surface of the boat body A. As a result, floatlng obstacles once arrested thereat are pushed away rearwardly of the boat body A by water flowlng In the dlrectlon y wlthout enterlng the water Intake port 18.
Further, the transverse partition wall 30 disposed in an Inclined state sloplng rearwardly upward at the flxed angle divides the interior of the lattlce of the scope gate C
into the front larger space S1 for water intake and the rear smaller space S2 for water intake therefore, whereas the flow llnes of water moving in the direction x from the front larger space S1 are dense and the flow rate is high, so that the water is drawn Into the water intake port 18 without any reslstance, the flow llne of water moving In the dotted-line dlrectlon x from the rear smaller space S2 are sparse and the flow rate is low and the pressure is negative relative to that In the larger space S1, wlth the result that floatlng obstacles once arrested by the lower surface b of the transverse partition wall 30 are hardly drawn from the smaller space S2 located therebehlnd into the water Intake port 18 and Instead they are rellsbly moved rearwardly of the boat body A by the actlon of water flowing in the directlon Y.
Such functlon can also be attalned In exactly the same manner by the first and second modlfied embodiments descrlbed above. Particularly, as Is clear from the basic ~044350 embodiment shown in Figs. 4 through 7 and the second modified embodiment shown in Figs. 12 through 15, if the transverse partltion wall 30 or 30b are ~- or U-shaPed as seen from the bottom 6urface of the boat bodY A gradually extending forward toward the center c located on the travel center line O-O of the boat body A and are curved in transversely bifurcated skirt form, then sald floating obstacles wlll be pu~hed away along such curved 6urface in two diverglng directions obliquely rearwardly of the boat body A, so that the entry of said floating obstacles through the water intake port 18 can be prevented.
At any rate, the interior of the scope gate G of the present Inventlon does not have to be flnely partitioned and hence the sufflclent amount of water to be drawn In can be obta~ned also durlng the turnlng of the boat body A without dlsturblng the water flow, and yet the entry of floating obstacles can be rellably prevented. Furthermore, the requlred arrangement Is very 61mple. The technlcal slgnlf1cance and value of the inventlon lle In these polnts.
Thus, the Inventlon provldes a devlce used In ~et-propelled glIdlng boats for preventlng floatlng ob6tacles from belng drawn In, whereln a scope gate G for preventlng entry of floatlng obstacles Is attached to a water Intake port 18 formed In the bottom 6urface of the boat body, and the water drawn from the water Intake pnrt 18 1~ accelerated by an Impeller 1~ houoed In a water Intake duct 17 and ~04ar35~) spouted rearwardly of the boat body A, sald devlce being characterized In that as shnwn In the baslc embodlment of Flgs. 4 through 7 and the first modlfied embodlment of Flgs.
9 through 11, sald scope gate G Is In lattlce form composed of a palr of attachlng seats 21, 21a or 22, 22a associated wlth the bottom surface of the boat body A and a pair of 27 and 27a longltudinal partitlon walls/extending parallel wlth the travel center llne 0-0 of the boat body A to interconnect said attachlng seats, substantlally the latter halves of sald longitudlnal partltlon walls 27 and 27a pro~ect downward by a fixed amount h beyond the bottom surface of the boat body A, while a transverse partltion wall 30 or 30a is dlsposed in the Intermedlate portlons of the pro~ectlng latter halves to assume an InclIned state sloping rearwardly upward at a fixed angle ~, whereby a larger space Sl for water intake Is deflned between the transverse partitlon wall 30 or 30a and the front attachlng seat 21 or 21a and a smaller space S2 for water Intake Is defIned between the transverse partltion wall 30 or 30a and the rear attachlng seat 22 or 22a.
Therefore, as descrlbed wlth reference to Flg. 3, garbage, seaweed and other floatlng obstacles can be rellably prevented from enterlng through the water Intake port 18 of the boat body A; thus, the intended ob~ect can be attained wlthout dl~turblng the flow of water to be drawn in.
Such functlon and effect can also be attalned In exactlY

the same manner by the arrangement descrlbed in Clalm 2 corresponding to the second modlfled embodlment shown In Figs. 12 through 16. If the arrangement of Clalm 2 Is employed, slnce the s1ngle longitudlnal partltlon wall 27b extending along the travel center line 0-0 of the boat body Q is sufflcient, the normal water drawlng action can be further enhanced while preventing the entry of floatlng obstacles; besldes thls, the required arrangement is simple, a fact which is advantageous for mass productlon.
Further, if the basic embodiment shown in Figs. 4 through 7 and the arrangement described In Clalm 3 correspondlng to the second modified embodiment shown in Flgs. 12 through 16 are employed, slnce the transverse partltion wall 30 or 30b Is V- or U-shaped as 6een in a bottom vlew gradually ProJectlng forward toward the center c located on the travel center llne O-O of the boat body Q and 1~ curved In transversely bifurcated sklrt form, floatlng obstacles can be pushed away more efflciently along the curved surface oblIquely rearwardly of the boat body A;
thu6, thelr entrY through the water Intake port 18 can be prevented, whlle normal water can be gulded Into the water Intake port 18 wlthout any reslstance.
In each of the embodlments descrlbed above If the enttre scope gate G IB Integrally made by InJectlon moldlng of a tran6parent or translucent thermoplastlc englneerlng plastlc materlal, as descrlbed In Clalm 4, then thls arraneement, ~0443S0 coupled wlth the constructlon ln wh~ch the interlor of the cope gate G is not finely partltloned, allows easily visual inspectlon of the interior of the water Intake duct~-om the water intake port 18. If floating obstacles should enter the water intake duct ~nd twlne themselves around the lmpeller or the propeller shaft, they can be easlly and efficiently removed. Further, the scope gate is suitable for mass productlon and ls light in welght.

Claims (4)

1. A device used in jet-propelled gliding boats for preventing floating obstacles from being drawn in, wherein a scope gate for preventing entry of floating obstacles is attached to a water intake port formed in the bottom surface of the boat body, and the water drawn from the water intake port is accelerated by an impeller housed in a water intake duct and spouted rearwardly of the boat body, said device being characterized in that said scope gate is in lattice form composed of a pair of attaching seats associated with the bottom surface of the boat body and a pair of longitudinal partition walls extending parallel with the travel center line of the boat body to interconnect said attaching seats, substantially the latter halves of said longitudinal partition walls project downward by a fixed amount beyond the bottom surface of the boat body, while a transverse partition wall is disposed in the intermediate portions of the projecting latter halves to assume an inclined state sloping rearwardly upward at a fixed angle, whereby a larger space for water intake is defined between the transverse partition wall and the front attaching seat and a smaller space for water intake is defined between the transverse partition wall and the rear attaching seat.

2. A device used in jet-propelled gliding boats for preventing floating obstacles from being drawn in, wherein a scope gate for preventing entry of floating obstacles is attached to a water intake port formed in the bottom surface of the boat body, and the water drawn from the water intake port is accelerated by an impeller housed in a water intake duct and spouted rearwardly of the boat body, said device being characterized in that said scope gate is composed of a pair of attaching seats associated with the bottom surface of the boat body and a single longitudinal partition wall extending along the travel center line of the boat body to interconnect said attaching seats, substantially the latter half of said longitudinal partition wall projects downward by a fixed amount beyond the bottom surface of the boat body, a transverse partition wall is disposed in the intermediate portion of the projecting latter half and is in transversely bifurcated skirt form assuming an inclined state sloping rearwardly upward, the front ends of the resulting skirt-like branches being connected to the rear attacking seat, whereby a larger space for water intake is defined between the transverse partition wall and the front attaching seat and a smaller space for water intake is defined between the transverse partition wall and the rear attaching seat.

3, A device used in jet-propelled gliding boats for preventing floating obstacles from being drawn in as set forth in Claim 1 or 2, wherein the transverse partition wall is V- or U-shaped gradually projecting forward as the center located on the travel center line of the boat body is approached.

4. A device used in jet-propelled gliding boats for preventing floating obstacles from being drawn in as set forth in Claim 1 or 2, wherein the scope gate is integrally made by injection molding of a transparent or translucent thermoplastic engineering plastic material;