Patent Publication Number: US-6699087-B1

Title: High-volume, no-drag sea chest with purge capability

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     None. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to the field of marine sea chests, specifically to a sea chest configured for flush-mounting within the hull of a marine vessel having inboard engines to provide a large volume of sea water substantially without drag or cavitation for cooling the engines. The inlet through the bottom surface of the present invention sea chest has a critical keyhole shape that causes eddys to form at its outside edges when the marine hull into which it is mounted moves in a forwardly direction and further causes seawater to flow into the sea chest at the center of each leading edge. The present invention sea chest also has an orifice through its top surface from which a quick burst of air or water can be sent to clean debris clogs and eliminate the need for manual cleaning. Such debris removal can be performed on a voluntary basis, or as an automated response to a predetermined amount of change in monitored data, such as temperature readings. Size is not a limiting factor and the present invention sea chest can be made to any size appropriate to the vessel to which it is installed, as long as the shape of the keyhole inlet is preserved. Also, it can be mounted almost anywhere below the water line of a marine hull, but typically would be in a location near the inboard engines. Although not limited thereto, use of the present invention is generally contemplated for large and high-speed marine vessels. However the present invention sea chest can also provide benefit to other marine vessels, including those having a length dimension as small as twenty feet. 
     2. Description of the Related Art 
     One use for sea chests in the hulls of large marine vessels is to collect the seawater needed for engine cooling. Current sea chests typically have one large opening through a bottom surface for drawing in water and one or more inlet openings through an opposing top surface leading to seawater pumps. The effectiveness of a sea chest depends upon a combination of its size and the volume of seawater that can flow into it and made available to the seawater pumps for engine cooling. To keep the vegetation, garbage, and other debris often found in seawater from entering the sea chest and clogging the inlet openings of the seawater pumps, a screen or grill is generally employed )over the large opening of the sea chest. Divers are required periodically for manual cleaning of such screens and grills. In addition to the cleaning expense, many prior art sea chests seawater have scoops to collect seawater that produce a considerable drag. In contrast, the present invention provides a more efficient sea chest inlet configuration through its bottom surface that enhances seawater flow into the inlet openings leading to the seawater pumps. The present invention does not require a screen or grill covering, since it has a purge opening through its top surface that allows for a quick burst of air or water to unblock any type of debris that might be temporarily clogging it. It also has a flush mounting within the marine hull that prevents drag. Further, since no divers are required for periodic cleaning, operating costs for a marine vessel using the present invention are reduced. There is no sea chest known with a keyhole-shaped inlet opening through its bottom surface and all of the advantages of the present invention. 
     BRIEF SUMMARY OF THE INVENTION—OBJECTIVES AND ADVANTAGES 
     The primary object of this invention is to provide a sea chest that is configured and positioned to induce a large volume of seawater through the opening in its bottom surface. A further object of this invention is to provide a sea chest that draws sufficient volumes of seawater to eliminate cavitation. It is also an object of this invention to provide a sea chest that prevents drag. A further object of this invention is to provide a sea chest that is easily and cost-effectively maintained. It is also an object of this invention to provide a sea chest that can be mounted almost anywhere in a ship&#39;s hull, although preferably near to the engines. A further object of this invention is to provide a sea chest with durable construction for long-term use. It is also an objective to provide a means of cooling marine engines in the event of water pump failure during a performance run. 
     As described herein, properly manufactured, and installed flush with the hull of a boat or large ship, the present invention sea chest provides a large volume of seawater for the cooling of marine engines with little or no drag. The flush mounting and resulting elimination of drag reduces fuel consumption. In addition, the small size and simple design of the present invention, as compared to prior art sea chests, allows it to be mounted almost anywhere in a marine hull, although typically it would be positioned near to the engine location. The large volume of seawater flowing through the present invention sea chest is provided by the unique keyhole shape of the single inlet opening through its bottom surface, which causes the laminar flow across a forwardly moving marine hull to form eddys at the outside edges of the keyhole opening and seawater to flow into the sea chest at the center of its leading edge. The eddys that are formed on the two angular sides of the keyhole-shaped inlet redirect the inertional energy to flow upward into the sea chest, inducing the main flow of seawater to follow. The eddys are formed by the rounded edges on the bottom side of the narrow portion of the keyhole-shaped opening. The efficiency of the sea chest can be increased by use of inwardly sloping edges adjacent to the narrow portion of keyhole-shaped inlet. The rear portion of the keyhole-shaped opening, with its larger and wider dimensions, is also preferably angled on its rear topside surface to enhance upward flow and maximize efficiency of the present invention sea chest. Thus, due to the velocity of the hull as it moves in a forwardly direction, the keyhole-shaped opening prevents water from bypassing it and as long as a bypass valve is added at the pump, the present invention sea chest will continue to provide seawater for engine cooling purposes even in the event of water pump failure during an endurance run. Due to the large amount of seawater induced to flow into the keyhole-shaped inlet, cavitation is eliminated as the seawater moves through the top surface of the sea chest and upward into the inlet side of the seawater pumps, preventing steam bubbles that are low in temperature and pressure from forming. The operating cost of a marine vessel using the present invention sea chest is also reduced since it is easily and cost-effectively maintained. Instead of requiring usage of a screen or grill, and divers to periodically clean vegetation, garbage, and/or other debris there from, a quick purging burst of air or water can be forced from the orifice through the top surface of the present invention sea chest to dislodge anything clogging it. The air and water bursts can be manually performed or automatically activated in response to a predetermined amount of change in monitored data. Also, the most preferred embodiment of the present invention sea chest is attached to a collar on the inside of the hull with a large number of closely spaced-apart oversized bolts, to keep it securely attached to the hull. The use of oversized bolts, and a large number of them, increases sea chest longevity. Recessed perimeter openings through the bottom surface of the sea chest are configured and dimensioned for flush mounting of the bolts. 
     While the description herein provides preferred embodiments of the present invention, it should not be used to limit its scope. For example, variations of the present invention, while not shown and described herein, can also be considered within the scope of the present invention, such as variations in the perimeter and depth dimensions of the sea chest; the thickness of the collar used on the inside of the marine hull for sea chest attachment; the number, size, and type of bolts used to attach the collar and sea chest in their usable positions against the marine hull; the type of sealant used between the collar, sea chest, and hull; the size of the purge orifice through the top surface of the sea chest; and the length and width dimensions of the single keyhole opening through the bottom surface of the sea chest although such dimensions must remain in proportion when elongated to substantially preserve the keyhole configuration for maximum efficiency during use. Thus, the scope of the present invention should be determined by the appended claims and their legal equivalents, rather than being limited to the examples given. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     FIG. 1 is a bottom view, as installed, of the most preferred embodiment of the present invention sea chest having a single keyhole-shaped inlet opening through its substantially rectangular bottom surface, two spaced-apart inlet openings through its top surface and being positioned above the wider end of the keyhole opening with each such top surface inlet opening leading to the inlet side of seawater pumps, a purge/cleaning orifice also through its top surface and located centrally above the keyhole opening, a plurality of bolts around the sea chest perimeter, and the sea chest being mounted flush within an opening in a marine hull, with the shaded areas around the keyhole-shaped opening indicating inwardly sloping edges. 
     FIG. 2 is a bottom view of the most preferred embodiment of the present invention collar used on the inside of a marine hull to securely hold the sea chest in its usable flush-mounted position within the hull, with the collar having a large and substantially rectangular central opening, as well as a plurality of smaller spaced-apart openings through its perimeter each configured for the insertion therethrough of a bolt. 
     FIG. 3 is a bottom view of a second preferred embodiment of the present invention sea chest having two inlet openings through its top surface that are larger than those shown in FIG.  1 . 
     FIG. 4 is a perspective view of the top surface of the most preferred embodiment of the present invention sea chest being secured through a collar with bolts, nuts, and washers, with one of the inlet openings being visible and shown extending beyond the top surface of the sea chest, and the purge/cleaning orifice being shown adjacent to the inlet opening. 
     FIG. 5 is a sectional top view of the most preferred embodiment of the present invention sea chest positioned within a marine hull, with the purge/cleaning orifice and one inlet opening through the top surface of the sea chest being visible, and also with arrows showing eddy formation and seawater flow toward the inlet openings leading to the inlet side of seawater pumps. 
     FIG. 6 is a sectional side view of the most preferred embodiment of the present invention sea chest attached to a marine hull near to its keel, with the purge/cleaning orifice and both inlet openings visible through the top surface of the sea chest, and also with arrows showing eddy formation and seawater flow toward the inlet openings of the seawater pumps. 
     FIG. 7 is a bottom view as installed of the most preferred embodiment of the present invention sea chest having a single keyhole-shaped opening through its bottom surface, two inlet openings through the top surface of the sea chest and located above the wide end of the keyhole opening with such inlet openings leading to the inlet side of seawater pumps, a purge/cleaning orifice also located through the top surface of the sea chest and positioned centrally above the keyhole opening, arrows showing eddy formation and seawater flow toward the inlet openings leading to the inlet side of seawater pumps, and a plurality of recessed openings around the sea chest perimeter configured for recessed attachment of bolts, with the shaded area around the keyhole-shaped opening indicating inwardly sloping edges. 
     FIG. 8 is a bottom view of the most preferred embodiment of the present invention sea chest similar to that in FIG. 7, with the addition of broken lines showing hidden surfaces and features, and the shaded areas around the keyhole-shaped opening indicating inwardly sloping edges. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIGS. 1-8 illustrate the most preferred embodiments of the present sea chest invention, to specifically include first preferred embodiment  2  and second preferred embodiment  46 , all of which provide a large volume of seawater flow  32  for cooling of the inboard engines of a marine vessel (not shown in its entirety) substantially without drag or cavitation. The flush mounting of the bottom surface  4  of the present sea chest invention within a recessed opening  16  in a marine hull  30 , and resulting elimination of drag, reduces fuel consumption. The operating cost of a marine vessel using the present sea chest invention is also reduced since it is easily and cost-effectively maintained via its purge/cleaning orifice  12 . Size is not a limiting factor for the present sea chest invention and although it is generally contemplated for use on large and high-speed marine vessels, the potential for small size and its simple design allow it to be mounted almost anywhere on a marine hull  30  near the engine location (not shown), even on marine vessels having a length dimension as small as twenty feet. The large volume of seawater flow  32  is provided by the unique shape of its single large keyhole opening  6 , which causes the laminar flow across a forwardly moving marine hull  30  to form eddys  34  at the outside edges of keyhole opening  6  and the seawater flow  32  to pass through the bottom surface  4  of the present sea chest invention at the center  44  of leading edges  42  in its keyhole opening  6 . Leading edges  42  preferably have an inwardly sloping configuration to increase sea chest efficiency. Due to the large volume of seawater flow  32 , cavitation is eliminated as the seawater moves upward into the inlet side of the seawater pumps, preventing low pressure and temperature steam bubbles from forming. Instead of requiring the usage of a screen or grill, and divers to periodically clean vegetation, garbage, and/or other debris there from, a quick purging burst of air or water can be forced through purge/cleaning orifice  12  located centrally through the top surface  8  of the present sea chest invention. The burst travels through the interior of the present sea chest invention to dislodge debris clogs (nor shown) therein, as well as those blocking seawater entry through keyhole opening  6  to eliminate the need for manual cleaning. Such debris removal can be performed on a voluntary basis, or as an automated response to a predetermined amount of change in monitored data, such as temperature readings. Also, the present sea chest invention is attached at its perimeter to a collar  18  positioned on the inside of the marine hull  30  with a large number of oversized bolts  14 , to keep it securely fixed within hull  30 . Use of bolts  14  that are oversized, and a large number thereof in a closely spaced-apart configuration, increases the longevity of the present sea chest invention. 
     FIGS. 1 and 3 respectively show a first preferred embodiment  2  and a second preferred embodiment  46  of the present sea chest invention having one large keyhole-shaped opening  6  through its bottom surface  4 . One difference between the two illustrations is that the inlet openings  10  through the present invention&#39;s top surface  8  in the second preferred embodiment  46  shown in FIG. 3 are larger than those shown in FIG.  1 . Also, marine hull  30  is missing from FIG. 3, as is the shaded inward sloping configuration of the leading edges  42  adjacent to the narrow end of keyhole-shaped opening  6  and the angled rear topside surface  48  adjacent to the wider end of keyhole-shaped opening  6 . With its sloping configurations of leading edges  42  and rear topside surface  48  shown in FIG. 1, first preferred embodiment  2  has a greater operating efficiency than the second preferred embodiment  46  having no sloping edges, as shown in FIG.  3 . Inlet openings  10  are shown in their respective illustrations located above the trailing wider end of a keyhole-shaped opening  6 . It is the configuration and dimension of the keyhole-shaped opening  6  relative to bottom surface  4  that is critical to the present invention and causes the formation of the eddys  34  at the outside/leading edges. (shown in FIGS. 7 and 8 by the number  42 ) of keyhole-shaped opening  6 , which are responsible for inducing a high-volume of seawater flow (such as that indicated by the number  32  in FIG. 5) into all embodiments of the present invention, including first preferred embodiment  2  and second preferred embodiment  46 , at the center portion of leading edges  42  and through the interior cavity toward inlet openings  10 , the center portion of leading edges  42  being shown in FIGS. 7 and 8 by the number  44 . When the marine hull  30  into which the present invention sea chest is installed is moving in a forwardly direction, the eddys  34  that are formed on the two angular sides of the keyhole-shaped inlet redirect the inertional energy to flow upward into the sea chest, inducing the main flow of sea water  32  to follow. The eddys  34  are formed by the rounded edges on the bottom side of the narrow portion of keyhole-shaped opening  6 . The efficiency of the present sea chest invention is increased by use of inwardly sloping leading edges  42  adjacent to the narrow portion of keyhole-shaped opening  6 . The rear portion of keyhole-shaped opening  6 , with its larger and wider dimensions, also preferably has an angled rear topside surface  48  configured to further enhance upward flow and increase efficiency of the present invention sea chest over use of inwardly sloping leading edges  42  alone. Thus, due to the velocity of marine hull  30  as it moves in a forwardly direction, keyhole-shaped opening  6  prevents seawater  32  from bypassing it and as long as a bypass valve (not shown) is added at the pump, the present invention sea chest will continue to provide seawater  32  for engine cooling purposes even in the event of water pump failure during an endurance run. The present sea chest invention is shown in FIGS. 1 and 3 to have a rectangular perimeter configuration. However, its perimeter configuration is not limited thereto, even though a rectangular configuration may be preferred for ease and efficiency of installation. The present sea chest invention can be mounted anywhere on marine hull  30  under the water line, however, to minimize the amount of conduit (not shown) needed for transport of the collected seawater to the seawater pumps, it is contemplated that one or more present invention sea chests be flush-mounted to hull  30  near to the marine engines needing the cooling benefit of the collected seawater. The size of the first preferred embodiments  2  used is also not critical, as long as each is proportioned to the size of the marine hull  30  to which it is attached, the amount of seawater required for marine engine cooling, and the number of other present sea chest inventions also providing seawater for marine engine cooling. Also, as the size of the present invention sea chest changes, the keyhole-shaped opening always substantially remains in the configuration shown in FIGS. 1,  3 ,  7 , and  8 . FIG. 1 shows each inlet opening  10  in first referred embodiment  2  located at a spaced-apart distance from the other above the wide end of keyhole-shaped opening  6  and positioned to lead to the inlet side of seawater pumps (not shown). It is considered within the scope of the present invention for larger present sea chest inventions  2  to have more than two inlet openings  10 , as long as each is visible through the wider end of keyhole-shaped opening  6  and they are collectively able to take in the amount of seawater needed for engine cooling without cavitation. Also, as long as the positioning relative to keyhole-shaped opening  6  and the aforesaid functional requirements for engine cooling are met, the size, number, and configuration of inlet openings  10  are not limited to that shown in FIG.  1  and FIG.  3 . Inlet openings  10 , should be visible through the wider end of keyhole-shaped opening  6  to achieve high volume water flow therethrough. In addition, FIGS. 1 and 3 show first preferred embodiment  2  and second preferred embodiment  46  each having a purge/cleaning orifice  12  located through its top surface  8  and positioned centrally above keyhole-shaped opening  6 . Purge/cleaning orifice  12  is configured to allow for a sufficiently strong blast of air or water to be sent therethrough for unblocking vegetation, other marine life, and debris that accumulates in and around the present sea chest invention and its keyhole-shaped opening  6 . Although not shown, the blast of air or water can be manually activated, repeated as often as needed, and made of varying durations. In the alternative, blasts of air or water can be automatically activated in response to a predetermined amount of change in monitored data, such as but not limited to temperature readings. The positioning of inlet openings  10  relative to keyhole-shaped opening  6 , as well as the shape of keyhole opening  6 , the substantially centered positioning of keyhole-shaped opening  6  through bottom surface  4  when installed, and the substantially centered positioning of purge/cleaning orifice  12  relative to keyhole-shaped opening  6  are critical to the effective operation of the present sea chest invention to provide a high volume of cooling water flow without cavitation, and all should be formed and positioned substantially as shown in FIG.  1 . Consequently, little variation in component positioning for second preferred embodiment  46  shown in FIG. 3, to preserve a high level of operational efficiency. FIGS. 1 and 3 further show many spaced-apart bolts  14  around the perimeter of bottom surface  4 , with FIG. 1 showing bottom surface  4  mounted flush within a recessed opening  16  in a marine hull  30 . The recessed openings within which each bolt  14  is shown are not marked in FIGS. 1 and 3, however in FIGS. 7 and 8 they are clearly shown and identified by the number  40 . Although the rectangular configuration shown in FIGS. 1 and 3 for bottom surface  4  is not critical, and it theoretically could have any shape, it is critical that the shape and dimension of bottom surface  4  and that of the recessed opening  16  through hull  30  closely correspond to one another. When a large number of bolts  14  are used, and in addition when bolts  14  are oversized, they increase the longevity of the present sea chest invention. Although not shown, it is contemplated for a sealant to be used between bottom surface  4  and hull  30  to prevent seawater flow  34  from being diverted from keyhole-shaped opening  6  and instead entering marine hull  30 . All components of the present sea chest invention, to include bottom surface  4 , top surface  8 , bolts  14 , and any nuts  26  or washers  28  needed to secure bolts  14 , should be made from durable and corrosion-resistant materials such as but not limited to stainless steel. Carbon fiber is another material contemplated for bottom surface  4 , top surface  8 , and collar  18 . 
     FIG. 2 shows the most preferred embodiment of the present invention collar  18  used on the inside of a marine hull  30  to securely hold all preferred embodiments of the present invention sea chest, including first preferred embodiment  2  and second preferred embodiment  46 , in their usable positions. FIG. 2 shows collar  18  having a plurality of spaced-apart fastener openings  22  through its perimeter, with each fastener opening  22  configured for the insertion therethrough of one bolt  14 . Although the collar  18  shown in FIG. 2 is not drawn in exact proportion to the first preferred embodiment  2  shown in FIG.  1  and the second preferred embodiment  46  shown in FIG. 3, it is contemplated for fastener openings  22  to be aligned with the positioning of the bolts  14  shown in FIGS. 1 and 3, and for the central collar opening  20  to be slightly larger than the perimeter dimension of corresponding bottom surface  4  of the first preferred embodiment  2 , the second embodiment  46 , or other embodiment used (not shown). Thus, in any embodiment of the present sea chest invention where bottom surface  4  has a different number of recessed openings  40  from that shown in FIGS. 7 and 8, the collar  18  used to secure it to marine hull  30  would have a corresponding number of identically spaced apart fastener openings  22  through its perimeter. The thickness dimension of collar  18  should be sufficient for it to have the needed strength to securely attach the embodiment of the present sea chest invention used to marine hull  30  within recessed opening  16 . Collar  18  should also be made from durable and corrosion-resistant materials, such as but not limited to stainless steel, carbon fiber, or bronze, and be connected to bottom surface  4  of the present sea chest invention with fasteners, such as but not limited to bolts  14 , nuts  26 , and washers  28 , that are also made from durable and corrosion-resistant materials. 
     FIG. 4 shows the first preferred embodiment  2  of the present sea chest invention attached to a collar  18  with bolts  14 , nuts  26 , and washers  28 , as well as one inlet opening  10  having a shut-off valve handle  24  and a purge/cleaning orifice  12  through top surface  8 . The configuration of the portions of inlet opening  10  and purge/cleaning orifice  12  extending beyond top surface  8  is not critical and according to the intended application may differ from that shown in FIG.  4 . The perimeter dimension of top surface  8  is shown in FIG. 4 to be slightly smaller than the central opening (marked by the number  20  in FIG. 2) through collar  18 . It is contemplated for the scope of the present sea chest invention to include sturdy fastening means other than bolts  14  to be used for connecting bottom surface  4  and collar  18  to marine hull  30 . Further, when bolts  14 , nuts  26 , and washers  28  are used for such connection, the number of each used may vary from that shown in FIG.  4 . In addition, it is preferred for bolts  14 , and any nuts  26  or washers  28  needed to secure bolts  14 , to be made from durable and corrosion-resistant materials, such as but not limited to stainless steel, and for bolts  14  to be numerous and oversized so as to increase the longevity of the present sea chest invention. 
     FIGS. 5 and 6 show the first preferred embodiment  2  of the present sea chest invention positioned within a recessed opening  16  in a marine hull  30 , with purge/cleaning orifice  12  and arrows showing eddy formation  34  and seawater flow  32  moving toward inlet openings  10  that lead to the inlet side of seawater pumps (not shown). In addition, FIG. 6 shows mounting of first preferred embodiment  2  with a washer  28 , nut  26 , and bolt  14  near to keel  38 . In comparing FIGS. 5 and 6 to FIGS. 7 and 8, eddy formation  34  is shown via arrows to be at the outside/leading edge of the keyhole-shaped opening  6  through bottom surface  4  (in FIGS. 7 and 8 the inwardly sloped outside/leading edges of keyhole-shaped opening  6  are marked with the number  42 ), which are responsible for the high-volume of seawater flow (such as that indicated by the number  32  in FIG. 5) being drawn into the present sea chest invention at the center portion of leading edges  42  and through its interior cavity, (the center portion of leading edges  42  being shown in FIGS. 7 and 8 by the number  44 ). As can be seen in FIGS. 5-8, seawater flow  32  bypasses purge/cleaning orifice  12  and is directed primarily through inlet openings  10 . The high volume flow of seawater through the present sea chest invention during forward movement of marine hull  30  is a direct result of the configuration of the inwardly sloping outside/leading edges of keyhole-shaped opening  6 . In FIGS. 5 and 6, the bottom surface  4  of the present sea chest invention is shown to laterally extend beyond the perimeter dimension of top surface  8 . It is the extension of bottom surface  4  that is used in combination with collar  18  to provide a secure connection of the present sea chest invention within the recessed portion of the opening  16  in marine hull  30 . Such extension also provides a surface for the application of sealant (not shown). Although two inlet openings  10  are shown in FIG. 6, only one inlet opening  10  is shown in FIG. 5, with the second inlet opening  10  being hidden from view behind the visible inlet opening  10 . 
     FIGS. 7 and 8 show first preferred embodiment  2  of the present sea chest invention having its critical keyhole-shaped opening  6  through bottom surface  4 , with FIG. 7 devoid of broken lines, other than those forming the ends of the arrows showing eddy formation  34  that show travel of seawater to inlet openings  10 , thus more clearly showing the relation of eddy formation  34  and seawater flow  32  relative to keyhole-shaped opening  6 . FIGS. 7 and 8 also show two inlet openings  10  positioned above the wider end of keyhole opening  6 , each visible through keyhole-shaped opening  6 , and each leading to the inlet side of seawater pumps (not shown). In addition, FIGS. 7 and 8 show a purge/cleaning orifice  12  located centrally above keyhole-shaped opening  6 , arrows showing eddy formation  34  and seawater flow  32  toward the inlet openings  10  leading to the inlet side of seawater pumps, and a plurality of recessed openings  40  around the perimeter of bottom surface  4  that are each configured for recessed attachment of a bolt  14 , or other fastener (not shown). It is contemplated for openings  40  to be sufficiently recessed for the flush mounting of fasteners such as bolts  14  to eliminate drag and thereby boost marine engine fuel efficiency. FIG. 8 further has broken lines showing top surface  8  and angled rear topside surface  48 . Shaded areas around the keyhole-shaped opening indicate the preferably used inwardly sloping edges associated with leading edge  42  and angled rear topside surface  48 . 
     To use the present invention sea chest, including first preferred embodiment  2  and second preferred embodiment  46 , one would first make an opening within a marine hull  30  that is slightly larger than top surface  8 , with a recessed portion adjacent thereto having a depth corresponding to the thickness of bottom surface  4 , as well as a perimeter dimension corresponding to the amount that bottom surface  4  extends beyond top surface  8 , so that bottom surface  4  can be mounted flush with marine hull  30  to eliminate drag. The present sea chest invention can be any size that is appropriate to the marine hull  30  into which it is to be secured and mounted almost anywhere below its water line, however, typically the present sea chest invention would be placed in a location near to the marine engines (not shown) for which it is to provide seawater flow  32 . Openings  40  through the perimeter of bottom surface  4  also have a recessed configuration so that the top of the fasteners inserted therethrough, such as bolts  14 , will be mounted flush with bottom surface  4 . Bolts  14 , or other fasteners used through recessed openings  40 , are preferably oversized, closely spaced apart, plentiful in number, and made from corrosion-resistant material, to promote longevity of the present invention sea chest. Prior to securing bottom surface  4  within the recessed opening  16  of hull  30 , although not shown, marine quality adhesive or other sealant is typically used between bottom surface  4  and the recessed portion of opening  16 , as well as between collar  18  and hull  30 , to make certain that all seawater  32  passing beyond hull  30  is directed into the present sea chest invention and through inlet openings  10 . As installation occurs, the present sea chest invention must be oriented with the narrower end of its keyhole-shaped opening  6  in the direction of forward travel of the marine vessel within which it is mounted to be effective, and manually held in position against hull  30  within recessed opening  16 . Collar  18  is then placed on the inside of hull  30  with its fastener openings  22  each aligned with one of the recessed openings  40  through bottom surface  4 . Although not shown, holes corresponding in position to fastener openings  22  in collar  18  can be predrilled through hull  30  for faster installation. Thereafter, bolts  14  or other fasteners are each inserted through a different one of the recessed openings  40 , a preformed/predrilled hole in the recessed portion of opening  16 , subsequently extended through the corresponding one of the fastener openings  22  in collar  18 , and secured with one or more nuts  26  and/or washers  28 . When the marine vessel (not shown) within which the present sea chest invention is mounted requires seawater flow  32  for cooling its engines, shut-off valves such as that controlled by the shut-off valve handle  24  in FIG.  4  and which communicate with inlet openings  10 , can be opened to permit seawater flow  32  therethrough. Although not shown, manual and automated opening of the shut off valves is contemplated. During forwardly movement of marine hull  30 , the configuration of keyhole-shaped opening  6  creates eddys  34  at its inwardly sloping outside/leading edges  42  and a large volume of seawater flow  32  to enter the bottom surface  4  of the present sea chest invention at the center  44  of outside/leading edges  42 . Due to such large volume of seawater flow  32 , cavitation is eliminated. Should vegetation, marine life, garbage, and/or other debris accumulate in or around the present sea chest invention or keyhole-shaped opening  6 , and block the flow of seawater  32  therethrough, a quick burst of air or water can be forced through purge/cleaning orifice  12  located centrally through the top surface  8  of the present sea chest invention, and thereafter through the interior of the present sea chest invention to dislodge debris clogs (not shown) and eliminate the need for manual cleaning or use of a screen or grate. Such debris removal can be performed on a voluntary basis, or as an automated response to a predetermined amount of change in monitored data, such as but not limited to temperature readings (not shown). Use of the present sea chest invention is generally contemplated for large and high-speed marine vessels, however it can also provide benefit to other marine vessels, including those having a length dimension as small as twenty feet.