NZ189140A

NZ189140A - Engine exhaust through boat hull

Info

Publication number: NZ189140A
Application number: NZ18914079A
Authority: NZ
Inventors: M R Henwood
Original assignee: M R Henwood
Priority date: 1978-12-11
Filing date: 1979-12-18
Publication date: 1984-03-30

Description

<div class="application article clearfix" id="description"> 189140 t. NEW ZEALAND PATENTS ACT, 1953 No.: 189140 Date: 11 December 1978 1 COMPLETE SPECIFICATION "IMPROVEMENTS IN OR RELATING TO EXHAUST SYSTEMS AND/OR BOAT HULLS" I fW®, MARK ROBIN HENWOOD, a British Subject and New Zealand Citizen of 634 Great North Road, Grey Lynn, Auckland, New Zealand hereby declare the invention for which I /~->p^pray that a patent may be granted to mejy&y and the method by which it is to be performed, to be particularly described in and by the following statement: - - 1 - 18914^ This invention relates to an exhaust system and/or a boat hull. It is an object of the present invention to provide an exhaust system and/or a boat hull which will at least provide the public with a useful choice. Accordingly the invention consists in a boat having a hull and an engine exhaust system, said boat including: a member connected to a bottom surface of and extending beneath said hull intermediate of the length thereof, part of said bottom surface and said member defining a chamber below the water line of the boat, said member having a bottom surface, the rear portion of said member defining a rearwardly facing step between said bottom surface of said member and the part of the bottom surface of said hull extending rearwardly of said member, and said chamber having a rearwardly facing mouth opening outwardly; and at least one engine exhaust pipe extending from said engine exhaust system through said boat hull into said chamber, for passing engine exhaust gases from said system into said chamber and for discharging said gases rearwardly through said mouth and along said bottom surface of the part of said hull extending rearwardly of said member. To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting. One preferred form of the invention will now be described with reference to the accompanying drawings in which; Fig. 1 is a transverse, cross sectional view of part of a boat hull and exhaust system according to the invention; and N.Z. PATENT C ■ -K - 2 - 2 9 NOV 1983 189140 Fig. 2 is a longitudinal cross-section on A-A in Figure 1 of part of a boat hull and exhaust system according to the invention. In the invention a boat hull is provided which has a member 1 forming the bottom thereof and members 2 forming the side surface of the boat although other constructions are envisaged. If desired, a downturned part 3 may be provided at the outer extremity of the undersurface 1. Thus an outer rib is provided along the side edge of the undersurface 1. In the construction described a keel 4 is provided but it will be apparent that the invention may be used for other configurations. One or more and preferably a plurality of apertures 5 are provided in the member 1 below the general water line of the boat in normal use. These apertures are fed by outlet exhaust pipes 6 which preferably extend from one or more, preferably two, common headers 7. Such exhaust pipes are preferably provided in equal numbers on each side of the centre line of the boat. There may be any suitable number of apertures 5, for example six apertures 5, spaced equally each side of the keel 4. In the preferred form of the invention a chamber is formed below the member 1 and preferably a chamber 8 is provided each side of the keel 4 or centre line of the boat, the chamber 8 having a mouth 9 which is rearward facing in use. The undersurface 1 of the boat also preferably has a - 3 - 189140 wedge 10 provided therein so that the undersurface 11 of the wedge and the undersurface 12 of the chamber 7 lie in substantially the same plane. That is to say, a rearward facing step is provided in the lower surface of the hull by the mouth 9 of the chamber 8. A vent pipe 13 preferably extends from the header chamber 7 to a point exterior of the boat hull preferably above the water line. The vent pipe 13 is desirably provided with a valve 14 operable from the control panel of the boat. An inlet 15 to the header chamber 7 is also provided which leads from the motor (shown pecked and diagrammatically at 17) which is to be used to drive the boat. The use of the invention is as follows. In use, the exhaust gases from the powering motor 17 pass to the header 7 and then pass downwardly through the exhaust pipes 6 into the chamber 8 there to be dispelled beneath the boat. During the period that the boat is moving water flow rearwardly along the underside of the boat will cause a venturi effect to occur at the mouth 9, thus sucking or drawing the exhaust gases down the pipes 6 to chamber 8. The dimensions of the pipes 6, chamber 8 and other parts will depend upon the volume of the output gases and also how deep in the water the exhaust ports are to be positioned. The aperture size of the outlet pipes and outlets 5 will need to be larger where the outlets are deeper and also where the 189140 throughput of gases is larger. The chambers 8 desirably extend over a substantial width of the below water line length of the boat and it is also envisaged that the aperture size of, for example, the pipes 6 or the outlets 5 could be made variable, for example, by providing flaps 18 (shown in the left hand outlet 5 in Figure 1) which can be used to partly cover the aperture 4 and which may be controlled from any control panel of the boat. During the initial start-up of the boat before it is moving the exhaust gases will be passed through the pipe 13, the valve 14 being opened for this purpose, to the exterior of the boat but as the venturi effect begins to occur at the mouth of 9 of chamber 8 more gases will pass through the outlet ports 6 and some air may be drawn inwardly through the pipe 9 to the header chamber 7. Such inward drawing of air may be prevented by closing valve 14. This will also aid the directing of gases to pipes 6 and can also be used where there is risk of water entering header 7 through pipe 13. Thus it can be seen that an exhaust system and/or a boat hull are provided which at least in the preferred form of the invention have the following advantages: ].. The exhaust system reduces the back pressure felt by the motor. This is desirable as control of back pressure can be critical with motors commonly in use today. 2.x As a substantial proportion of the exhaust gases are dispelled beneath the boat the aesthetic appeal of the boat is 189140 enhanced as there is no substantial blackening or darkening around the exhaust ports of the boat. 3. The presence of an air layer below a substantial part of the hull of a boat has some effect in reducing friction between the boat hull and the water through which it is passing. </div>

Claims

<div class="application article clearfix printTableText" id="claims"> WHAT I CLAIM IS; 1891*0;1. A boat having a hull and an engine exhaust system, said boat including:;a member connected to a bottom surface of and extending beneath said hull intermediate of the length thereof, part of said bottom surface and said member defining a chamber below the water line of the boat, said member having a bottom surface, the rear portion of said member defining a rearwardly facing step between said bottom surface of said member and the part of the bottom surface of said hull extending rearwardly of said member, and said chamber having a rearwardly facing mouth opening outwardly; and at least one engine exhaust pipe extending from said engine exhaust system through said boat hull into said chamber, for passing engine exhaust gases from said system into said chamber and for discharging said gases rearwardly through said mouth and along said bottom surface of the part of said hull extending rearwardly of said member.;2. A boat as claimed in claim 1 wherein a wedge-shaped element is connected to the bottom of said hull at a position forwardly of said member, said element having a bottom surface extending in substantially the same plane as said bottom surface of said member and tapering forwardly to the bottom surface of said hull.;3. A boat as claimed in either claim 1 or claim 2 wherein said step and said mouth are dimensioned to achieve, upon movement of said boat through the water, a venturi effect tending to draw said gases outwardly from said exhaust pipe and said chamber.;4. A boat as claimed in any one of the preceding claims wherein a pair of separate said chambers are provided, one each of said;N.Z. PATENT OFFICE;2 9 NOV 1983;- 7 -;OEIVED;1 C91 -';0;chambers being positioned on each side of the longitudinal centre line of said boat hull.;5. A boat as claimed in claim 4 wherein said at least one exhaust pipe comprises a plurality of exhaust pipes extending into each said chamber.;6. A boat as claimed in claim 5 further comprising at least one header connecting said engine exhaust system to said plurality of exhaust pipes.;7. A boat as claimed in claim 6 further comprising a vent extending from said header through said boat hull at a level above said water line.;8. A boat as claimed in claim 7 further comprising control valve means in said vent for opening and closing said vent.;9. A boat substantially as herein described with reference to the accompanying drawings.;DATED THlSo2&/^ DAY OF AJooesnber (9*3 A. J. PARK 8c SON PER f. Q AGENTS FOR THE APPLICANT tt.£. PATENT OmC£ 29N0V1983 </div>