AU605138B2

AU605138B2 - A propeller guard

Info

Publication number: AU605138B2
Application number: AU69877/87A
Authority: AU
Inventors: Dennis Eugene Eller
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-03-10
Filing date: 1987-03-10
Publication date: 1991-01-10
Anticipated expiration: 2007-03-10
Also published as: GB8705629D0; CA1267572A; GB2187695A; GB2187695B; AU6987787A; US4680017A

Description

l;(llU 1 605138 FORM

COMMONWEALTH

OF AUSTRALIA Patents Act 1952 COMPLETE SPECIFICATION (Original) FOR OFFICE USE: Class 6 67 7 Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: 0 oO 0 00 0 0 0 o o o o o o00 o o 0 o a 4 0 04 0O 0 0 00 0 00

CICC

c e t; t Priority: This document contains the amendments made under Section 49 and is correct for printing.

Related Art: Name of Applicant: Address of Applicant: DENNIS EUGENE ELLER 814 North Wooster, Algona, Iowa 50511

USA

DENNIS EUGENE ELLER Actual Inventor(s): Address for Service: DAVIES COLLISON, Patent Attorneys, 1 Little Collins Street, MELBOURNE VIC 3000 Complete Specification for the invention entitled:

A

"Issae.s i APROPELLER GUARD r MOvm rm The following statement is a full description of this invention, including the best method of performing it known to me 1 I, i. 00 0 000 00 0 00 0 cc 0 0 0 00 .o o o 0000 a o a 0 ao 0 0 0 o o 0 0 0 BACKGROUND OF THE INVENTION The propeller of a motorboat typically dwells at an elevation below the bottom of the boat. Accordingly, it is not unusual for the propeller to become damaged by contact with objects on the bottom of the body of water when the boat is operated in shallow water. Such damage to the propeller decreases the performance of the boat. Repairing or replacing the propeller is costly. Accoringly, it is desirable to protect the propeller from such damage.

Furthermore, water skiers and other swimmers have been accidentally injured by boat propellers which are unprotected. Therefore, it is desirable to provide a propeller guard as a personal safety feature.

Also, it is understood that a boat moves forward in response to the water forced rearwardly by the propeller. This movement is in accordance with the basic physics principle that for every action there is an equal and opposite reaction.

However, in the operation of motorboats, some of the water which is acted upon by the propeller is forced radially outwardly rather than linearly rearwardly. The force of the radially dissipating water does not contribute to the forward motion of the boat and is therefore wasted. Accordingly, it is desirable to eliminate such radial dissipation of water and direct all water acted upon by the propeller in a linearly rearward direction.

Therefore, a primary objective of the present invention is the provision of a motorboat propeller guard which protects the propeller from damage and which improves the performance of the motorboat.

I

-2- Another objective of the present invention is the provision of a performance guard which can be quickly and easily attached to the propeller unit.

These and other objectives will become apparent from the following description of the present invention.

SUMMARY OF THE INVENTION According to the present invention there is provided a propeller guard for a motorboat including a motor, a propeller operatively connected to said motor, a lower housing with opposite leading and trailing edges and terminating in a vertically disposed skeg, said propeller R being mounted on said lower housing adjacent said 0 00 trailing edge and above said skeg, and a pair of horizontally disposed cavitation plates having forward 00o and rearward ends extending laterally from said lower o o housing and above said propeller, said propeller guard o b comprising: a rigid U-shaped sleeve having a forward end and opposite rearwardly extending legs and an elongated U-shaped channel formed therein, said channel having a closed 0 forward end and open rearward ends adapted to extend at o0 o least to the rearward ends of said cavitation plates, the rearward ends of said channel being spaced whereby said S 25 sleeve is adapted to slide over said cavitation plates with said rearwardly extending legs extending on each side of said lower housing, said channel adapted to receive said cavitation plates until said forward end of said sleeve engages said leading edge of said lower housing to thereby prevent rearward movement of said guard; d means for closing said open rearward ends of said channel; anA a propeller shield having open inlet and outlet ends, being attached to said sleeve and adapted to encircle said propeller and thereby protect said propeller from contact with foreign objects.

-3- 1,gJnspe. 00 1 ky69877.cla,16 C If i I- C 3a In one aspect, the invention includes a frame member extending downwardly from the forward end of said sleeve and adapted to engage said leading edge of said lower housing substantially along the length thereof, and a plurality of longitudinally disposed ribs extending between said frame member and said shield adapted to further protect said propeller from contact with foreign objects.

In another aspect of the invention, the means for closing 10 said open rearward ends of said channel includes a latch pivotal about a horizontal axis connected to said sleeve and fastening means releasably extending through said latch and said sleeve to secure said latch to said S' sleeve.

Preferably a cylindrical propeller shield extends downwardly from the sleeve and encircles the propeller so as to protect the propeller from contact with foreign objects. A plurality of concentrically positioned arcuately shaped rings form a gridwork which is releasably mounted over the open outlet end of the shield to further protect the propeller from contact with foreign objects. A channel-shaped frame member extends between the forward end of i 901009.gjnspe.OO1,ky69877.cla.17 1 the sleeve and the lowermost portion of the open inlet end of the shield. This frame member engages the leading edge of the lower housing substantially along its length.

A plurality of horizontally disposed ribs extend between the frame member and the shield to further protect the propeller from contact with foreign objects.

ma'y be The guard4i mounted on the motorboat by first removing or pivoting the rear gridwork out of its normal outlet covering position. Then, the entire guard is slid rearwardly into place with the cavitation plates a0 being received within the channel of the sleeve until 0 0 a o "o the forward frame member engages the leading edge of 0 0o0 0 09 oo the lower housing. Thus, the guard is supported by the Oo00 0o0 cavitation plates. A latch is then closed and secured at 0 00 0 0a tooso 15 the rearward end of the sleeve legs so as to prevent forward movement of the guard with respect to the 04 0 propeller unit.

O 00 0 0 9 o° o When the guard is in position, the longitudinal axis 0o of the shield is co-extensive with the axis of rotation of the propeller. Also, the open inlet end of the shield 0 is coplanar with the forward edge of the propeller and the open rearward end of the shield extends rearwardly beyond the rearward end of the propeller. Accordingly, Sthe open inlet end of the shield allows an unrestricted flow of water to the propeller. The water is acted upon by the propeller and is ejected linearly rearwardly -4-

-NT

1 from the open outlet end of the shield without radial dissipation of the acted upon water, so as to propel the boat forwardly with increased acceleration and velocity.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a perspective view of an outboard motor having the guard of the present invention mounted thereon.

Figure 2 is a sectional plan view taken along lines 2-2 of Figure 1.

o0 Figure 3 is a partial side view of the guard of the o' present invention in position on a propeller unit.

0 00 °0 Figure 4 is a partial rearward view of the guard in 0 00 o 0 15 position on a propeller unit.

Figure 5 is a sectional view taken along lines SO of Figure 2.

0 00 S00 Figure 6 is a sectional view taken along lines 6-6 *o 6o of Figure 3.

o 0 DETAILED DESCRIPTION OF THE DRAWINGS 0 The performance guard of the present invention is generally designated in the drawings by the reference numeral 10. Guard 10 is adapted for use on motorboats having either an outboard motor 12, as shown in Figure 1, or an inboard-outboard motor (not shown). A propeller r 1 14 is operatively connected to motor.12 by conventional drive means (not shown). A lower housing 16 encloses the drive means and includes a leading edge 18 and a trailing edge 20. The lower housing terminates in a skeg 22. A pair of horizontally disposed cavitation plates 24 prevent air from being sucked downwardly by the rotation of the propeller.

An exhaust pipe 26 is provided for venting of motor 12.

The above description of the outboard motor is conventional and does not constitute a part of the present invention.

Guard 10 of the present invention basically includes a oo mounting sleeve 28 and a cylindrical shield 30. Mounting 0- 009 S\eee g b:s 28 is generally U-shaped and includes a pair of rear- S1P 0 3L o wardly extending legs 32. A U-shaped channel is formed within 0 00 o o sleeve 28. Channel 34 has a closed forward end 36 and open o 15 rearward ends 38.

Sleeve 28 is adapted to slide rearwardly around lower 0° housing 16 such that one leg 32 is on either side thereof S"e and such that cavitation plates 24 are received within channel So 34. The forward end of the cavitation plates engages the closed forward end of channel 34, so as to prevent further rearward movement of sleeve 28. A latch 40 is pivotally connected to the rearward end of each leg 32 by hinge pin 42, and is locked to an extension 44 of leg 32 by nut and bolt assembly 46 or the like. Thus, latches 40 close the open rearward ends 38 of channel 34 so as to substantially prevent forward movement of sleeve 28 with respect to motor 12.

-6- S-f 0 0 0 000 0 0 0 00 0 00 00 0 00 0 00 00 4 0 00 00 4 O 0 Shield 30 is secured to sleeve 28 by welding or the like.

Shield 30 has an open inlet end 48 and an open outlet end When sleeve 28 is in position on cavitation plates 24, the longitudinal axis of shield 30 is co-extensive with the axis of rotation of propeller 14. Also, when guard 10 is in place, the plane defined by inlet end 48 is coplanar with the plane defined by the forward edge of the propeller blades. The plane defined by outlet end 50 is positioned rearwardly of the plane defined by the rearward edge of the propeller blades.

This positioning of shield 30 with respect to propeller 14 enhances the performance of the motorboat. More particularly, the open inlet end 48 of shield 30 allows an unrestricted feed of water to the propeller. The water which is acted upon by the propeller is ejected linearly rearwardly from the open outlet end of the shield without any radial dissipation of the water, as would result in the absence of shield 30. Thus, a greater quantity of water is forced rearwardly such that the boat reacts by moving forwardly with greater acceleration and velocity. The wasted force of radially dissipating water which is normally present in the absence of shield 30 is therefore converted to a useful propelling force by shield Guard 10 also includes a forward frame member 52 which has an upper end 54 which is secured to the forward portion of sleeve 28 and a lower end 56 which is secured to the lower portion of the inlet end of shield 30. Frame member 52 is channel-shaped so as to extend around leading edge 18 of -7- CC t

C

1 lower housing 16, and engages the leading edge along its substantial length. Thus, frame member 52 provides structural support for guard 10 and protects leading edge 18 and skeg 22 from damage caused by contact with foreign objects.

A plurality of horizontally disposed ribs 58 extend between frame member 52 and shield 30 on either side of lower housing 16 so as to further protect propeller 14 from contact with foreign objects. Ribs 58 are shown to be substantially flat straps, however, other construction is possible, such 00 0a as round bars.

o 0o The open outlet end 50 of shield 30 is normally closed Io by a gridwork 60, as best shown in Figure 4. Gridwork 60 is o pivotally secured to shield 30 by a hinge 52 and a 4 0* plurality of removable pins 64. Accordingly, by removing the appropriate pin 64, gridwork 60 can be pivoted out of 06 SI its normal position over outlet end 50 of shield 30 so 0 0 that guard 10 can be quickly and easily mounted and 0 04 o 0 removed from motor 12.

Preferably, gridwork 60 is comprised of a plurality of concentrically positioned circular or arcuately shaped 0d4d.a rings 66. Other gridwork patterns are also feasible, such as criss-crossed bars. Gridwork 60 further prevents propeller 14' from contacting foreign objects, particularly when the propeller is operated in the reverse direction to move the boat rearwardly. Also, gridwork 60 protects skiers and other swimmers from being accidentally hit by the propeller.

-8j 1 From the foregoing, it is seen that at least all of the stated objectives are accomplished by the performance guard of the present invention.

Claims

4. 4 ~-~HAI; NT 1 l 3 1.gJrspe.OO1ky69877.cla,1O r i a -r II__ 11 further protect said propeller from contact with foreign objects. 2. A guard according to claim 1 wherein said ribs are flat straps each having a primary surface disposed in a horizontal plane. 3. A guard according to claim 1 wherein said frame member is channel-shaped in cross section so as to be adapted to extend around the leading edge of said lower housing. 4. A guard according to claim 1 wherein said means for i closing said 'earward ends of said channel includes a O 15 latch pivotal about a horizontal axis connected to said sleeve and fastening means releasably extending through said latch and said sleeve to secure said latch to said o4Soo sleeve.
5. A guard according to claim 1 further comprising a gridwork releasably mounted over said outlet end of said l 4 °shield adapted to further protect said propeller from So, contact with foreign objects. o 25 6. A guard according to claim 5 Wherein said gridwork includes a plurality of concentrically positioned arcuately shaped rings.
7. A guard according to claim 5 further including hinge means for pivotally connecting said gridwork to said shield, said hinge positioned at the bottom of said shield and gridwork for pivoting said gridwork from a closed upstanding vertical position, rearwardly and downwardly.
8. A guard according to claim 1 wherein said shield is substantially cylindrical, and said shield adapted to be '900131,gjnspe.001,ky69877.cla,11 %.c^A r 4 r 12 i o 0 o t0* 04c 444 44 C 4 CC' CC secured in position arQund said propeller such that the longitudinal axis of said shield is coextensive with the axis of rotation of said propeller, and such that the inlet end of said shield is coplanar with the forward end of said propeller and the outlet end of said shield extending rearwardly beyond the rearward end of said propeller, wherein the open inlet end of said shield allows an unrestricted flow of water to said propeller, and whereby the water acted upon by said propeller is ejected linearly rearwardly from the open outlet end of said shield without radial dissipation so as to move the motorboat forwardly with increased acceleration and velocity. 15 9. A guard according to claim 1 wherein said m..ans for closing said open rearward ends of said channel are further defined by each of said rearwardly extending legs including a latch hinged about a horizontal axis and adapted to leave an open space between said legs for said 20 lower housing and cavitation plate to pass. A propeller guard for a motorboat including a motor, a propeller operatively connected to said motor, a lower housing with opposite leading and trailing edges and terminating in a vertically disposed skeg, said propeller being mounted on said lower housing adjacent said trailing edge and above said skeg, and a pair of horizontally disposed cavitation plates having forward and rearward ends extending laterally from said lower housing and above said propeller, said propeller guard comprising: a rigid U-shaped sleeve having a forward end and opposite rearwardly extending legs and an elongated U-shaped channel formed therein, said channel having a closed forward end and open rearward ends adapted to extend at least to the rearward ends of said cavitation plates, the rearward ends of said channel being spaced whereby said I S 90131. gJ nspe. 001 ,ky69877 .cla. 12 I L- i C r CC C fC t 4 13 sleeve is adapted to slide over said cavitation plates with said rearwardly extending legs extending on each side of said lower housing, said channel adapted to receive said cavitation plates until said forward end of said sleeve engages said leading edge of said lower housing to thereby prevent rearward movement of said guard; means for closing said open rearward ends of said channel, said means including a latch pivotal about a 10 horizontal axis connected to said sleeve and fastening means releasably extending through said latch and said sleeve to secure said latch to said sleeve, a propeller shield having open inlet and outlet ends being attached to said sleeve, said shield adapted to encircle said propeller, thereby protecting said propeller from contact with foreign objects.
11. A guard according to claim 10 wherein said latch pivotal about a horizontal axis leaves an open space between said legs for said lower housing and cavitation plate to pass.
12. A propeller guard for a motor boat including a motor, a propeller operatively connected to said motor, a lower housing with opposite leading and trailing edges and terminating in a vertically disposed skeg, said propeller being mounted on said lower housing adjacent said trailing edge and above said skeg, and a pair of horizontally disposed cavitation plates having forward and rearward ends extending laterally from said lower housing and above said propeller, said propeller guard comprising: a rigid U-shaped sleeve having a forward end and opposite rearwardly extending legs and an elongated U-shaped channel formed therein, said channel having a closed forward end and open rearward ends adapted to extend at least to the rearward ends of said cavitation plates, the C C C~D COO CC C C C C 0 01009gjnspe.0O1.ky69877.cla,13 rl 14 rearward ends of said channel being spaced whereby said sleeve is adapted to slide over said cavitation plates with said rearwardly extending legs extending on each side of said lower housing, said channel adapted to receive said cavitation plates until said forward end of said sleeve engages said leading edge of said lower housing to thereby prevent rearward movement of said guard; means for closing said open rearward ends of said channel; a propeller shield having open inlet and outlet ends and being attached to said sleeve, said shield adapted to encircle said propeller and thereby protect said propeller from contact with foreign objects, and a gridwork releasably mounted over said outlet end of said shield to further protect said propeller from contact with foreign objects, a hinge means for pivotally connecting said gridwork to said shield, said hinge 0 positioned at the bottom of said shield and gridwork for pivoting said gridwork from a closed upstanding vertical position, rearwardly and downwardly. QI'(O a 0
13. A motorboat including a motor, a propeller o @mGn operatively connected to said motor, a lower housing with 0 25 opposite leading and trailing edges and terminating in a vertically disposed skeg, said propeller being mounted on said lower housing adjacent said trailing edge and above said skeg, a pair of horizontally disposed cavitation plates having forward and rearward ends extending laterally from said lower housing and above said propeller, and a propeller guard according to any one of the preceding claims.
14. A propeller guard substantially as hereinbefore 7P 901009,gjnspe.001,ky69877.cla,14 C .I _r 1 -L -r 15 described with reference to the accompanying drawings. DATED this 9th day of October 1990 DENNIS EUGENE ELLER By His Patent Attorneys DAVIES COLLISON C C C C CC 0 CO 00 0 0000 0 a 0 0 0 000-00 0 a IT~v '-1 -tT O~l
901009. gjnspe .001. ky69877.cia,