Rotary engine jet boat

Abstract

A boat includes a hull, an inboard rotary engine, and a jet propulsion unit connected to the engine via a direct drive connection. The hull may be a stepped hull with one or more aft steps. A large, low, substantially flat aft fishing/swim deck is disposed above the engine and an exhaust system of the engine. The exhaust system may vent into the step of the stepped hull and include a check valve that discourages water from backflowing into the engine.

1 . A boat comprising:
 a hull less than 30 feet long;   an aft fishing deck extending across at least 80% of the width of the hull, the deck extending above a bottom of the hull by less than 27 inches;   an inboard engine supported by the hull, the engine having a drive shaft;   an engine exhaust passageway extending from the engine to an exterior exhaust port; and   a propulsion unit supported by the hull and operatively connected to the drive shaft to propel the boat when driven by the drive shaft,   wherein the engine and exhaust passageway are each disposed entirely lower than the aft deck,   wherein the exhaust passageway has a water ingress height defined as a height of water within the exhaust passageway at which water would backflow into the engine, and   wherein the water ingress height is less than 27 inches above a bottom of the hull.   
     
     
         2 . (canceled) 
     
     
         3 . (canceled) 
     
     
         4 . The boat of  claim 1 , wherein:
 the boat has a waterline defined when the boat is fully fueled and ready for operation, but is unmanned;   the exhaust passageway has a water ingress height defined as a height of water above the waterline within the exhaust passageway at which water would backflow into the engine; and   the water ingress height is less than 11 inches above the waterline.   
     
     
         5 . The boat of  claim 1 , wherein:
 the boat has a waterline defined when the boat is fully fueled and ready for operation, but is unmanned; and   the aft deck extends above the waterline by less than 15 inches.   
     
     
         6 . (canceled) 
     
     
         7 . The boat of  claim 1 , wherein the aft deck is vertically separated from a bottom of the hull by less than 26 inches at any longitudinal point along the aft deck as viewed from the side. 
     
     
         8 . The boat of  claim 1 , wherein lateral sides of the hull extend vertically higher than the deck by less than 10 inches at any longitudinal position of the aft deck as viewed from the side. 
     
     
         9 . The boat of  claim 1 , wherein the engine exhaust passageway falls entirely within a downwardly projected outer perimeter of the aft deck. 
     
     
         10 . The boat of  claim 1 , wherein the engine falls entirely within a downwardly projected outer perimeter of the aft deck. 
     
     
         11 . The boat of  claim 1 , wherein the aft deck comprises a flush-mount engine compartment lid that forms part of the aft deck when closed and provides access to the engine when open. 
     
     
         12 . The boat of  claim 1 , wherein the boat is a bass boat. 
     
     
         13 . The boat of  claim 1 , wherein the boat is a runabout. 
     
     
         14 . The boat of  claim 1 , wherein an area of the aft deck is at least 10 square feet. 
     
     
         15 . The boat of  claim 14 , wherein a height of the aft deck does not deviate by more than 2 inches over the course of a foot in any direction. 
     
     
         16 . The boat of  claim 1 , wherein the boat comprises a cockpit having a steering wheel and separate throttle controller. 
     
     
         17 . The boat of  claim 1 , wherein the boat comprises side-by-side seats. 
     
     
         18 . The boat of  claim 1 , wherein the aft deck extends the whole way to a transom of the boat. 
     
     
         19 . The boat of  claim 18 , wherein the aft deck is higher than the transom. 
     
     
         20 . A boat comprising:
 a hull having a length of between 12 and 30 feet;   an aft fishing deck that is at least 4 feet wide and 2.5 feet long and has an area of at least 10 square feet;   an inboard engine supported by the hull, the engine having a drive shaft;   an engine exhaust passageway extending from the engine to an exterior exhaust port; and   a propulsion unit supported by the hull and operatively connected to the drive shaft to propel the boat when driven by the drive shaft,   wherein the aft deck extends above a bottom of the hull by less than 27 inches,   wherein the exhaust passageway is disposed entirely lower than the aft deck,   wherein the exhaust passageway has a water ingress height defined as a height of water within the exhaust passageway at which water would backflow into the engine, and   wherein the water ingress height is less than 27 inches above the bottom of the hull.   
     
     
         21 . The boat of  claim 20 , wherein the boat has a waterline defined when the boat is fully fueled and ready for operation, but is unmanned, and
 wherein the aft deck extends above the waterline by less than 15 inches.   
     
     
         22 . The boat of  claim 20 , wherein lateral sides of the hull extend vertically higher than the aft deck by less than 10 inches at any longitudinal position of the aft deck as viewed from the side. 
     
     
         23 . The boat of  claim 20 , wherein the engine is disposed entirely lower than the aft deck. 
     
     
         24 . A boat comprising:
 a hull;   an inboard engine supported by the hull, the engine having a drive shaft;   a propulsion unit supported by the hull and operatively connected to the drive shaft to propel the boat when driven by the drive shaft;   an exhaust port extending through the hull and opening into an ambient environment; and   an exhaust passageway fluidly connecting an exhaust outlet of the engine to the exhaust port,   wherein the boat is longer than 14 feet,   wherein the exhaust passageway has a water ingress height defined as a height of water within the exhaust passageway at which water would backflow into the engine, and   wherein the water ingress height is less than 26 inches above a bottom of the hull.   
     
     
         25 . The boat of  claim 24 , further comprising an aft fishing deck, wherein the entire aft fishing deck is disposed higher than the exhaust passageway. 
     
     
         26 . The boat of  claim 24 , wherein the water ingress height is less than 25 inches above the bottom of the hull. 
     
     
         27 . The boat of  claim 24 , wherein the boat has a waterline defined when the boat is fully fueled and ready for operation, but is unmanned,
 wherein the water ingress height is less than 11 inches above the waterline.   
     
     
         28 . The boat of  claim 24 , wherein the boat comprises side-by-side seats. 
     
     
         29 . The boat of  claim 24 , wherein the exhaust port is disposed below the waterline. 
     
     
         30 . The boat of  claim 24 , further comprising a check valve in the exhaust passageway, the check valve being oriented so as to discourage water from entering the engine via the exhaust port. 
     
     
         31 . The boat of  claim 24 , further comprising a floating valve seal in a portion of the exhaust passageway that extends at least partially vertically, the floating valve seal being moveable between an upward sealing position and a lower unsealed position, the floating valve seal being configured to move into the upward sealing position in response to a water level in the portion of the exhaust passageway rising, the floating valve seal discouraging water from entering the engine via the exhaust port when the floating valve seal is in the upward sealing position. 
     
     
         32 . The boat of  claim 14 , wherein no two points spaced a foot apart from each other on the aft deck deviate in height from each other by more than 2 inches. 
     
     
         33 . The boat of  claim 30 , wherein the check valve has a closed position that prevents fluid in the ambient environment from entering the engine via the exhaust outlet. 
     
     
         34 . The boat of  claim 31 , wherein, when the floating valve seal is in its upward sealing position, the floating valve seal closes all fluid paths from the ambient environment to the engine via the exhaust outlet.