SUBMERGED MARINE EXHAUST SYSTEM

Abstract: An improved marine engine exhaust system for discharging engine exhaust above the water line when at idle or low speeds, and below the surface of the water at high speed in a submerged turbulent region generated by a hydrodynamic fitting (60) fixed to an undersurface of the vessel hull (12) wherein the gas is maintained for a period of time, until the low pressure area following the vessel has passed.

Description: SUBMERGED MARINE EXHAUST SYSTEM BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to marine exhaust systems and more particularly to a marine exhaust system for discharging marine engine exhaust below the surface of the water. 2. Description of the Prior Art Marine exhaust systems found on motorized vessels typically discharge engine exhaust through discharge ports located above the water line towards the rear of the vessel or stern. Marine engine exhaust comprises a mixture of gas and cooling water. Conventional marine exhaust systems, typically known as water lift mufflers include: an internal combustion engine having at least one exhaust manifold for ducting engine exhaust to a muffler wherein exhaust gas sound is attenuated, and an exhaust pipe originating at the muffler and terminating at a discharge opening in the hull, located proximate the stern. Engine exhaust is discharged toward the rear of the vessel and above the water line where, in theory, the gases are dissipated or carried away from the vessel. There are a number of inherent disadvantages present in the conventional prior art marine exhaust systems and methods. Firstly, Engine exhaust must first pass through a muffler so that excessive noise may be attenuated prior to discharge. Since marine exhaust includes a corrosive mixture of gas and water, marine mufflers must be rugged and are known to add substantial cost and weight to vessels. Secondly, when a vessel is at idle, engine exhaust gas tends accumulate around the vessel since the discharge ports are sized for higher exhaust flow rates, and low flow exhaust flow rates, like those experienced at idle or low speed, are not discharged with sufficient velocity to completely clear the area. Thus, engine exhaust discharged through hull openings may accumulate in proximity to the vessel thereby irritating those on boar unless carried away or dissipated by prevailing winds. Thirdl most motorized vessels that incorporate conventional mari exhaust systems suffer from a problem resulting from the l pressure area formed behind a moving vessel, often referred as the "station wagon effect". Typically, a low pressure are caused by the vessel structure moving through the atmospher develops near the stern of a vessel . Engine exhaust discharg near the stern of a moving vessel therefore, is caught in t resulting low pressure area and recirculates into the passeng compartment thereby irritating those on board. Since engi exhaust includes carbon monoxide gas, a high exhaust g concentration circulating within the passenger compartment extremely undesirable. The prior art reveals a number of attempts directed towa overcoming the aforementioned problems. For example, U. Patent No. 5,234,364 issued to Ito, discloses an EXHAUST SYST FOR SMALL PLANING BOAT. Ito teaches an exhaust system having exhaust pipe which terminates in a flush discharge openi formed in a lower surface of the hull for discharging engi exhaust through the body of water in which the watercraft operating. The system incorporates an expansion chamber f silencing engine exhaust, and a low speed exhaust discharge li extending from the highest portion of the exhaust pipe, throu the hull, to an area above the water level so as to provide low speed exhaust discharge for discharging exhaust when t watercraft is operating at idle or low speeds. Dischargin engine exhaust through a flush hull opening below the surface however, causes the exhaust to flow with the fluid boundar layer formed by the water on the moving hull and results in th exhaust surfacing immediately behind the craft where the exhaus is likely to recirculate within the passenger compartmen because of the aforementioned station wagon effect. U.S. Patent No. 5,078,631 issued to Harbert, also disclose a MARINE EXHAUST SYSTEM. Harbert discloses a marine exhaus system for separating the gas from the water of a gas/wate mixture produced by a marine engine and expelling the gas a sufficient distance from the hull of a boat to place it outside of the turbulent boundary layer surrounding the hull and the low pressure area following behind the boat. Harbert, however, relies on an intricate variable exhaust gas discharge outlet that reduces the outlet opening area at low flow rates for projecting exhaust gases a maximum distance from a boat hull, and does not contemplate discharging exhaust gases below the surface of the water. U.S. Patent No. 4,509,927, issued to Ikeda, discloses a BOTTOM EXHAUST HIGH SPEED BOAT having a hull including a grooved bottom. Ikeda teaches an engine exhaust pipe extending into a midportion of the grooved bottom, and a duct fixed to the surface of the hull extending between the opening of the exhaust pipe and the front of the grooved bottom for transporting exhaust gases to the front of the grooved bottom whereby the grooved bottom is filled with exhaust gases thereby decreasing frictional resistance. As has been described, the prior art has not overcome the aforementioned problems with marine engine exhaust. Thus, there still exists a need for a marine engine exhaust system for muffling a marine engine and discharging engine exhaust a sufficient distance from an idling vessel such that exhaust gas does not concentrate in proximity to the passenger compartment, and that discharges exhaust below the surface of the water, beyond the fluid boundary layer formed on the bottom of the hull while cruising, such that the discharged exhaust is further muffled and surfaces behind the low pressure area following the vessel thereby preventing recirculation within the passenger compartment. SUMMARY OF THE INVENTION The present invention contemplates an improved marine engine exhaust system for discharging exhaust, including a mixture of gas and water, above the water line when at idle or low speeds, and below the surface of the water at higher speeds in a turbulent region wherein the exhaust is maintained for period of time, until the low pressure area following the vess has passed, after which the exhaust surfaces and dissipates. The marine exhaust system of the instant invention includ a marine engine having at least one exhaust manifold throu which engine exhaust, including a mixture of gas and cooli water, flows. The exhaust manifold is in fluid communicati with a means for ducting the exhaust from the engine. T engine exhaust is thus ducted from the engine to an accumulati means wherein exhaust sound is attenuated, thereby partial silencing exhaust noise, and the exhaust-borne water is allow to pool . The accumulating means incorporates primary and bypa exhaust outlets . The bypass exhaust outlet comprises a pi penetrating the accumulating means wall at an angle a terminating a predetermined distance from the accumulating mea floor. The bypass outlet is sized to handle all of the engi exhaust at idle and low engine speeds, and is connected by exhaust hose to an exhaust discharge port located in the hu above the water line. The bypass handles all exhaust at id since exhaust discharged below the hull tends to rock an idli vessel. The primary outlet originates at a liquid level l point on the accumulating means and extends downwardly throu the hull bottom terminating in a hydrodynamic exhaust dischar means. The primary outlet is sized to handle the majority exhaust gases at higher speeds when engine exhaust outp exceeds the exhaust capacity of the bypass outlet. The hydrodynamic exhaust discharge means, or fitting, i mounted to hull bottom and includes: a mounting flange fo fixing the hydrodynamic exhaust means to the bottom of the hull a downwardly extending foil means defining an exhaust channel and, a hydroconical exhaust discharge in fluid communicati with said foil means. The hydrodynamic exhaust discharge mean is shaped such that the downwardly extending foil creates les drag, and hence less turbulence in its wake, than t hydroconical exhaust discharge. As a result, when the vesse travels through the water discrete turbulence layers are formed below the hull undersurface by water passing around the hydrodynamic exhaust fitting. Hydrodynamic forces operating on the fitting also cause the formation of an area of low pressure proximate the hydroconical exhaust discharge outlet, that, when combined with an increase in exhaust system pressure resulting from higher engine exhaust output, allow engine exhaust to exit the vessel below the surface of the water through the hydroconical exhaust discharge. Engine exhaust is thus discharged in a turbulent region formed by the hydroconical portions wake, and entrapped, thereby maintaining the exhaust below the surface for a period of time such that when the exhaust finally surfaces the vessel is a sufficient distance from the point of exhaust surfacing as not to induce exhaust gas recirculation within the passenger compartment. Therefore, when the marine engine is started, engine exhaust, including a mixture of exhaust gas and cooling water, is ducted to an accumulating means wherein the water pools. At idle or low speed, engine exhaust entrains water from the accumulator floor, thereby silencing and cooling the engine exhaust, and exits the accumulator through the bypass outlet whereafter the exhaust is discharged out the side of the vessel, at sufficient velocity so as to project the exhaust away from the vessel in a conventional manner. As the engine is throttled up and the vessel begins moving through the water, the exhaust pressure increases and the hydrostatic pressure at the submerged discharge outlet decreases due to hydrodynamic forces. At a point, depending upon the specific hydrodynamic design, but usually about 10 - 15 knots, the pressure at the submerged exhaust outlet decreases, while exhaust system pressure increases, until the exhaust back pressure overcomes hydrostatic forces thereby allowing exhaust to flow out of the submerged exhaust outlet. The discharged exhaust is trapped for a period of time in the resulting turbulent region generated by the shape of the hydrodynamic fitting. The exhaust remains submerged, until the top side low pressure area following behind the vess has passed, thereby preventing exhaust from recirculating with the passenger compartment . In accordance with the instant invention, it is an obje thereof to provide an improved marine engine exhaust system f discharging engine exhaust below the surface of the water. It is a further object of the instant invention to provi a marine engine exhaust system for discharging exhaust below t surface of the water in a buoyancy retarding turbulent region Still another object of the present invention is to provi a marine engine exhaust system that eliminates the need for conventional marine muffler. Yet another object of the present invention is to provi a marine engine exhaust system, having no moving parts, th discharges exhaust above the surface while at idle and l speeds, and discharges the majority of exhaust below the surfa in a turbulent region at high speeds . A further object of the present invention is to provide marine engine exhaust system wherein hydrodynamic forces acti proximate a submerged exhaust outlet function in combinati with exhaust system pressure to allow the discharging of engi exhaust below the surface of the water. In accordance with these and other objects which wil become apparent hereinafter, the instant invention will now described with particular reference to the accompanyin drawings. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 depicts a perspective view of the instan invention mounted in a vessel hull and connected to an engin exhaust manifold. Figure 2A depicts the exhaust accumulator in plan view. Figure 2B depicts the exhaust accumulator in perspectiv view. Figure 2C depicts a side view of the exhaust accumulator Figure 2D depicts a rear view of the exhaust accumulator Figure 3A depicts the submerged hull mounted hydrodynamic exhaust discharge fitting in plan view. Figure 3B depicts the submerged hull mounted hydrodynamic exhaust discharge fitting in perspective view. Figure 3C depicts a side view of the submerged hull mounted hydrodynamic exhaust discharge fitting. Figure 3D depicts a rear view of the submerged hull mounted hydrodynamic exhaust discharge fitting. Figure 4 depicts an exploded view of the submerged hull mounted hydrodynamic exhaust fitting and a partial vessel hull in section. Figure 5A depicts an alternate embodiment of the exhaust accumulator, for use with engines having a single exhaust manifold, in plan view. Figure 5B depicts the alternate embodiment accumulator of Fig. 5A in perspective view. Figure 5C depicts a rear view of the alternate embodiment accumulator of Fig. 5A. Figure 5D depicts a right side view of the alternate embodiment accumulator of Fig. 5A. Figure 6 depicts the instant invention installed on a marine engine having in-line cylinders with a single exhaust manifold. Figure 7A illustrates exhaust flowing out of the submerged hydrodynamic exhaust discharge fitting of the instant invention. Figure 7B illustrates exhaust flowing out of a flush hull bottom opening and recirculating within the passenger compartment. DESCRIPTION OF THE PREFERRED EMBODIMENTS Turning first to Figures 1 - 4, the marine exhaust system of the instant invention includes a marine engine 10, having cylinder banks in a conventional V configuration, mounted in a marine vessel, generally designated 12. Each cylinder bank incorporates an exhaust manifold 20a and 20b, through which engine exhaust, including a mixture of gas and cooling water flows. Each exhaust manifold is in fluid communication with means for ducting the exhaust from the engine, 30a and 30b, v exhaust risers 22a and 22b. Engine exhaust thus flows throu piping 30a and 30b from the engine to an exhaust accumulator 4 In the preferred embodiment, as best depicted in Figure accumulator 40 is formed from an elongated cylinder forming chamber and having a pair of exhaust inlets 42a and 42b, bypass outlet 44 disposed between inlets 42a and 42b, and primary outlet 46. Exhaust accumulator 40 functions attenuate exhaust sound thereby silencing the engine exhaus In addition, accumulator 40 functions to collect cooling wat discharged by engine 10 and carried by exhaust gases. Wat entering accumulator 40 through inlets 42a and 42b thus collec in the accumulator forming a liquid floor. The accumulator bypass exhaust outlet 44 comprises section of pipe penetrating the accumulator 40 wall at an ang and terminating a predetermined distance from the accumulat floor as best depicted in Figure 2C. Exhaust outlet 44 th originates within accumulator 40 at an opening 45 existing on substantially horizontal plane within inches of the liqu floor. Exhaust outlet opening 45 is so configured a positioned relative to the floor of the accumulator facilitate removal of water collected on the accumulator flo by entrainment with flowing exhaust gas. Bypass outlet 44 sized to handle all of the engine exhaust at idle and low engi speeds, and is connected by an exhaust hose 50 to an exhaus discharge port 52 located in the hull above the water li substantially toward the vessel's rear or transom. A primary outlet 46 originates at a liquid level low poi on the accumulator and extends downwardly. An exhaust pipe 4 is connected to outlet 46 and extends downwardly through t bottom of the hull. Primary exhaust outlet 46 is sized t handle the majority of the engine exhaust at higher speeds whe engine exhaust output exceeds the exhaust capacity of bypas outlet 44. A hydrodynamic exhaust means comprising discharge fitting 60, as best seen in Figures 3A-D and Figure 4 is fixed to the bottom of the hull by stainless steel fasteners 61, and is in fluid communication with accumulator 40 via primary outlet 46 and exhaust pipe 48. Hydrodynamic exhaust discharge fitting 60 is mounted to the bottom of the hull and includes : a mounting flange 62 for fixing the hydrodynamic fitting to the bottom of the hull; and, a downwardly extending streamlined foil section 64 terminating in a hydroconical shaped exhaust discharge outlet having a leading surface 66 and an exhaust outlet 68. In the preferred embodiment the hydroconical exhaust discharge is bullet shaped. The hydrodynamic exhaust discharge fitting is structured such that the downwardly extending foil section 64 creates less drag than the bullet shaped discharge structure 68. As a result, when the vessel is moving, turbulent regions are formed below the hull by hydrodynamic fitting 60, and particularly by foil section 64 and bullet discharge 68. Since the bullet shaped exhaust discharge 68 is less streamlined than is foil section 64, the bullet 68 generates greater turbulence in its wake thereby creating a discrete, highly turbulent region, separated from the bottom of the hull by a region of substantially less turbulence that is created by foil section 64. Furthermore, the hydrodynamic forces operating on the fitting effectively lower the hydrostatic pressure at outlet 68, that, when combined with an increase in exhaust system pressure resulting from higher engine output and the limited capacity of bypass outlet 44, allows exhaust gases to exit the vessel below the surface of the water through the hydrodynamic fitting 60 via discharge 68 by overcoming the hydrostatic back pressure. The exhaust is thus discharged in the turbulent region formed by the hydroconical sections wake and entrapped, thereby maintaining the exhaust below the surface for a period of time such that when the exhaust finally surfaces the vessel is a sufficient distance from the point of exhaust surfacing as not to induce exhaust gas recirculation within the passenger compartment. Therefore, when the marine engine of a vessel incorporati the instant invention is started, engine exhaust including mixture of gas and cooling water, is ducted from engi manifolds 20a and 20b to accumulator 40 by exhaust pipes 30a a 30b connected to accumulator exhaust inlets 42a and 42b, where exhaust noise is attenuated and water collects on t accumulator floor. At idle or low engine speeds, engine exhau entrains, or scavenges, water from the accumulator floo thereby further silencing and cooling the engine exhaust, a exits the accumulator 40 via bypass outlet 44 whereafter t exhaust is carried by exhaust hose 50 to a discharge outlet located on the vessel side above the water line. Dischar outlet 52 is sized such that exhaust discharge velocity carri exhaust a sufficient distance from the vessel to preve recirculation within the passenger compartment. Exhaust prevented from exiting primary outlet 46 since the exhaust ba pressure is not sufficient to overcome the hydrostatic pressu existing at hydrodynamic discharge outlet 68. As the engine is throttled up and the vessel moves throu the water with increasing speed, the volume of exhaust generat by the engine increases causing an increase in the overa exhaust system pressure. Furthermore, the pressure at dischar outlet 68 decreases due to hydrodynamic forces. As bes depicted in Figure 7A, at a design point of 10 - 15 knots, t exhaust system pressure rises, and the hydrostatic pressure a the submerged discharge outlet 68 decreases, until the exhaus back pressure overcomes hydrostatic forces thereby allowi majority of exhaust to flow out of the submerged dischar outlet 68 via primary outlet 46, exhaust pipe 48, and fitti 60. The discharged exhaust is trapped, for a period of time, i the resulting submerged turbulent region produced by th hydroconical bullet 68 wake, surfacing only after the lo pressure area following the vessel has passed. In contrast, a best depicted in Figure 7B, exhaust discharged out of a flus hull opening would flow along the hull surfacing closely behin - li ¬ the vessel where it would recirculate in the low pressure area following the vessel . An alternate embodiment for engines with in-line cylinders having a single exhaust manifold is depicted in Figures 5A-5D and Figure 6. In this embodiment a marine power plant 10, such as a diesel engine, having in-line cylinders forming a single cylinder bank, is mounted in a vessel 12. A single exhaust manifold 20 directs engine exhaust, including a mixture of gas and water, to exhaust piping 30 via an exhaust riser 22. This embodiment incorporates an accumulator, generally designated 70, having a single exhaust inlet 72 and bypass and primary exhaust outlets, 74 and 76 respectively. Accumulator 70 has an expanded body portion 78 disposed between exhaust inlet 72 and primary outlet 76, and is connected to inlet 72 and outlet 76 by transition sections 79a and 79b. Bypass outlet 74 includes a tubular exhaust pipe partially inserted in accumulator expanded body portion 78 disposed between transition sections 79a and 79b as best depicted in Figures 5C and 5D. Body portion 78 has an expanded cross- sectional area to compensate for the loss of free area, or obstruction, caused by the insertion of tubular exhaust pipe 74. Bypass exhaust outlet 74 originates at outlet opening 75 located proximate the body portion 78 floor. Bypass exhaust outlet opening 75 is so configured and positioned relative to the body floor to facilitate removal of water collected on the body floor by entrainment with flowing exhaust gas. Bypass outlet 74 is connected by exhaust hose 50 to a hull discharge outlet 52 located above the water line near the transom. Exhaust pipe 80 connects to outlet 76 and extends downwardly through the hull bottom. Primary exhaust outlet 76 is sized to accommodate the majority of exhaust at higher speeds when engine exhaust output exceeds the exhaust capacity of bypass outlet 74. A hydrodynamic exhaust discharge fitting as previously described (not shown in Fig. 6) is fixed to the bottom of the hull by stainless steel fasteners, as best depicted in Figure 4, and is in fluid communication with exhaust pipe 80. Therefore, when the marine engine of a vessel incorporati the alternate embodiment of instant invention is started, engi exhaust including a mixture of exhaust gas and cooling water, ducted from the engine manifold 20 to accumulator 70, v exhaust riser 22 and exhaust piping 30 connected to accumulat exhaust inlet 72, wherein exhaust noise is attenuated and wat collects. At idle or low speeds, engine exhaust entrains, scavenges water from the accumulator floor, thereby furth silencing and cooling the engine exhaust, and exits t accumulator 70 via bypass outlet 72 whereafter the exhaust carried by exhaust hose 50 to a discharge outlet 52 locat above the water line on the vessel side proximate the transo Discharge outlet 52 is sized such that exhaust velocity carri exhaust a sufficient distance from the vessel to preve recirculation within the passenger compartment. Exhaust prevented from exiting primary outlet 76 since the exhaust ba pressure is not sufficient to overcome the hydrostatic pressu existing at the hydrodynamic fitting discharge 68. As the engine is throttled up and the vessel begins movi through the water, the exhaust flow rate increases causing increase in the overall exhaust system pressure. Furthermor the pressure at discharge outlet 68 decreases due hydrodynamic forces acting on the fitting as previous described. As best depicted in Figure 7A, at a design point 10 - 15 knots, the pressure at the submerged discharge outl decreases to a point where the exhaust back pressure overcom hydrostatic forces thereby allowing bulk of exhaust to flow o of the submerged discharge outlet 68. The submerged exhaust trapped for a period of time in the resulting turbulent regi in the bullet outlet 68 wake, surfacing only after the l pressure area following the vessel has passed, as previous described. In contrast, as best depicted in Figure 7B, exhaus discharged out of a flush hull opening would flow along the hul surfacing closely behind the vessel where it would recircula in the low pressure area following the vessel. The instant invention has been shown and described herein in what is considered to be the most practical and preferred embodiment. It is recognized, however, that departures may be made therefrom within the scope of the invention and that obvious modifications will occur to a person skilled in the art.

Claims: CLAIMS What Is Claimed Is: 1. An exhaust system for use with a marine engine mounte in a vessel, said vessel having a hull with an undersurface tha is submerged when said vessel is placed within a body of water said exhaust system comprising: means for ducting engine exhaust including both gas an cooling water; means for accumulating said engine exhaust, said means fo accumulating including an inlet means for receiving said engin exhaust from said ducting means, a primary outlet means fo expelling said engine exhaust through said vessel hull, and bypass means for expelling engine exhaust to the surroundin atmosphere, said bypass means being a low flow rate outlet suc that exhaust gas flowing through said bypass means entrain water pooled in said accumulating means thereby providing baffling means for silencing engine exhaust noise; and said primary outlet means being a high flow rate outlet i communication with said body of water at a submerged location said primary outlet means communicating with a submerge hydrodynamic exhaust outlet means fixed to said hul undersurface; said hydrodynamic exhaust outlet means including downwardly extending streamlined first section having a lo coefficient of drag for minimizing turbulent wake, said firs section terminating in a second section having a highe coefficient of drag for generating a submerged layer o turbulent wake separated from the bottom of the hull by a regio of substantially less turbulence created by said first section, said second section incorporating a submerged exhaust outlet, for discharging exhaust in said submerged turbulent layer suc that said exhaust remains submerged until said vessel ha cleared the vicinity. 2. An exhaust system for use with a marine engine according to claim 1, wherein said means for accumulating engine exhaust comprises and elongated tubular member defining an exhaust chamber and having at least one exhaust inlet, a bypass outlet in communication with the surrounding atmosphere, and a primary outlet in communication with said body of water. 3. An exhaust system for use with a marine engine according to claim 1, wherein said primary outlet means communicates with a hydrodynamic exhaust outlet means for discharging engine exhaust in a submerged turbulent region generated by said hydrodynamic exhaust means . 4. An exhaust system for use with a marine engine according to claim 1, wherein said hydrodynamic exhaust outlet means comprises a hydroconical means in communication with a foil means, said foil means disposed between said hydroconical means and said hull undersurface and in communication with said primary outlet means. 5. An exhaust system for use with a marine engine according to claim 3, wherein said hydrodynamic exhaust outlet means comprises a fitting defining an exhaust passage and having a flange for fixing said fitting to said hull, a bullet-shaped member having an exhaust outlet, and a foil member disposed between said hull and said bullet-shaped outlet. 6. An exhaust system for use with a marine engine mounted in a vessel, said vessel having a hull with an undersurface that is submerged when said vessel is placed in a body of water, said exhaust system comprising: at least one exhaust manifold and a marine exhaust riser for receiving engine exhaust including gas and cooling water, from said engine; exhaust piping in communication with said manifold; an accumulator defining an exhaust accumulating chamber said accumulator having an exhaust inlet in communication wit said exhaust piping, a primary outlet and a bypass outlet; said accumulator bypass outlet sized for low exhaust flo rates and in communication with the surrounding atmosphere; said accumulator primary outlet communicating with submerged hydrodynamic fitting for discharging exhaust in submerged location below said hull; said hydrodynamic fitting fixed to said hull and includin a downwardly extending streamlined first section terminatin with a turbulent wake generating second section defining submerged exhaust outlet for discharging exhaust in a submerge turbulent layer whereby discharged exhaust remains submerge until said vessel has cleared the vicinity. 7. An exhaust system for use with a marine engin according to claim 6, further comprising a hydrodynamic fitting having an exhaust outlet in communication with said primar accumulator outlet, and fixed to said hull such that engin exhaust is discharged in a turbulent region generated by sai hydrodynamic fitting. 8. An exhaust system for use with a marine engine mounte in a vessel, said vessel having a hull with an undersurface tha is submerged when said vessel is placed within a body of water, said exhaust system comprising: a pair of exhaust manifolds each incorporating a marin exhaust riser for receiving exhaust, including gas and coolin water, from said engine; an accumulator having first and second exhaust inlets fo receiving engine exhaust from said manifolds,- a pair of exhaust ducts each fluidly connecting an exhaus manifold to one of said accumulator inlets; said accumulator having a bypass outlet, in communicatio with an ambient discharge port located in said hull, and size to accommodate all low speed engine exhaust; said accumulator having a primary outlet, sized to accommodate engine exhaust produced at high speed, and in communication with a submerged hydrodynamic fitting for discharging exhaust in a submerged location below said hull; said hydrodynamic fitting fixed to said hull undersurface and including a downwardly extending streamlined section having a low coefficient of drag for minimizing turbulent wake terminating in a second section having a high coefficient of drag for generating a submerged layer of turbulent wake, said second hydrodynamic fitting section incorporating a submerged exhaust outlet, for discharging exhaust in said submerged turbulent layer such that said exhaust remains submerged until said vessel has cleared the vicinity. 9. An exhaust system for use with a marine engine mounted in a vessel, said vessel having a hull with an undersurface that is submerged when said vessel is placed within a body of water, said exhaust system comprising: means for ducting engine exhaust including both gas and cooling water; means for accumulating said engine exhaust, said means for accumulating including an inlet means for receiving said engine exhaust from said ducting means, a primary outlet means for expelling said engine exhaust through said vessel hull, and a bypass means for expelling engine exhaust to the surrounding atmosphere, said bypass means being a low flow rate outlet such that exhaust gas flowing through said bypass means entrains water pooled in said accumulating means thereby providing a baffling means for silencing engine exhaust noise; and said primary outlet means being a high flow rate outlet in communication with a hydrodynamic exhaust outlet means comprising a fitting defining an exhaust passage and having a bullet-shaped member with a submerged exhaust outlet, and a foil member disposed between said hull and said bullet-shaped outlet, such that said engine exhaust flowing through said primary outlet means is discharged below said hull.

Inventors: HAMM JOHN REGINALD, KEEHN DOUGLAS ALLEN JR, OUSLEY FRANK BENSON III, POWELL WILLIAM WESLEY, HAMM, JOHN, REGINALD, KEEHN, DOUGLAS, ALLEN, JR., OUSLEY, FRANK, BENSON III, POWELL, WILLIAM, WESLEY
Applicants: RAY IND INC, RAY INDUSTRIES, INC.
Application year: 1996
Main classification: B63B3
IPC codes: B63H21, F01N7