Abstract: A thermostat includes an annular flange extending in radial directions and surrounded by a cylindrical large-diameter portion of a housing inner surface, and a frame extending in axial directions from the flange. The thermostat further includes a sealing member that hermetically seals the gap between the flange and the inner surface. The sealing member includes an annular outer peripheral portion sandwiched in the axial directions by the inner surface and a thermostat cover inside the large-diameter portion, and a plurality of protruding portions extending outward in the radial directions from the outer peripheral portion toward the large-diameter portion. The thermostat is disposed inside a housing that defines a portion of a cooling water passage, and opens and closes the cooling water passage according to the temperature of cooling water inside the cooling water passage.

Abstract: In a boat propulsion device, a head portion of an engine includes plug holes, first attachment portions, and a second attachment portion. The plug holes are aligned vertically and parallel or substantially parallel to a crankshaft. The first attachment portions are arranged on the periphery of the plurality of plug holes. The first attachment portions are configured to attach a plurality of ignition coils which are respectively integrated with spark plugs in a coil-on-plug configuration. A second attachment portion is provided separately from the first attachment portions. The second attachment portion is configured to attach an ignition coil connected to the spark plugs in a double ended ignition coil configuration via cables.

Abstract: A vessel propulsion apparatus includes a water pump that is driven by an engine, and supplies water from an water inlet to the engine via a cooling water supply passage. The vessel propulsion apparatus includes an auxiliary cooling passage branching from the cooling water supply passage to extend to an oil pan. A water pressure control valve disposed at a branch position from the cooling water supply passage to the auxiliary cooling passage limits the flow rate of water flowing to the auxiliary cooling passage when a water pressure inside the cooling water supply passage is less than a set pressure. The water pressure control valve is configured to allow a portion of the water inside the cooling water supply passage to flow to the auxiliary cooling passage when the water pressure inside the cooling water supply passage is the set pressure or more to maintain the water pressure to be less than the set pressure while supplying water to the oil pan via the auxiliary cooling passage.

Abstract: An outboard motor includes an engine including a crankshaft that is rotatable about a rotation axis extending in an up-down direction, and a crank chamber that houses the crankshaft. The outboard motor includes an oil pan disposed under the engine to retain lubricating oil to be supplied to at least the crank chamber. The outboard motor includes an oil recovery passage and a first blowby gas passage separate from the oil recovery passage. The oil recovery passage extends downward from the crank chamber to the oil pan and is configured to lead lubricating oil inside the crank chamber to the inside of the oil pan. The first blowby gas passage extends downward from the crank chamber to the oil pan and is configured to lead a blowby gas inside the crank chamber to the inside of the oil pan.

Abstract: An outboard motor includes an engine including a cylinder body and a crank case, an engine holder configured to come into contact with both the cylinder body and the crank case along a second bonding surface, a power transmission shaft passing through a hole between the engine holder and both the cylinder body and the crank case, and a first sealing member between a portion of the power transmission shaft above the second bonding surface and above both the cylinder body and the crank case to separate an oil region above the first sealing member from an external water entering region below the first sealing member.

Abstract: An outboard motor includes an engine including a cylinder body and a crank case, an engine holder configured to come into contact with both the cylinder body and the crank case along a second bonding surface, a power transmission shaft passing through a hole between the engine holder and both the cylinder body and the crank case, and a first sealing member between a portion of the power transmission shaft above the second bonding surface and above both the cylinder body and the crank case to separate an oil region above the first sealing member from an external water entering region below the first sealing member.

Abstract: An outboard motor includes an engine including a crankshaft that is rotatable about a rotation axis extending in an up-down direction, and a crank chamber that houses the crankshaft. The outboard motor includes an oil pan including an oil retaining portion, a cooling water passage disposed along an outer wall surface of the oil retaining portion, an oil recovery passage extending downward from the crank chamber to lead lubricating oil inside the crank chamber to the inside of the oil retaining portion, and a guide member. The guide member includes a shielding portion disposed inside the oil recovery passage so as to be located over an opening of the oil retaining portion, and a guide hole disposed inside the oil recovery passage so as to be located over an inner wall surface of the oil retaining portion.

Abstract: In a boat propulsion device, a head portion of an engine includes plug holes, first attachment portions, and a second attachment portion. The plug holes are aligned vertically and parallel or substantially parallel to a crankshaft. The first attachment portions are arranged on the periphery of the plurality of plug holes. The first attachment portions are configured to attach a plurality of ignition coils which are respectively integrated with spark plugs in a coil-on-plug configuration. A second attachment portion is provided separately from the first attachment portions. The second attachment portion is configured to attach an ignition coil connected to the spark plugs in a double ended ignition coil configuration via cables.

Abstract: An outboard motor includes an engine including a crankshaft that is rotatable about a rotation axis extending in an up-down direction, and a crank chamber that houses the crankshaft. The outboard motor includes an oil pan disposed under the engine to retain lubricating oil to be supplied to at least the crank chamber. The outboard motor includes an oil recovery passage and a first blowby gas passage separate from the oil recovery passage. The oil recovery passage extends downward from the crank chamber to the oil pan and is configured to lead lubricating oil inside the crank chamber to the inside of the oil pan. The first blowby gas passage extends downward from the crank chamber to the oil pan and is configured to lead a blowby gas inside the crank chamber to the inside of the oil pan.

Abstract: A vessel propulsion apparatus includes a water pump that is driven by an engine, and supplies water from an water inlet to the engine via a cooling water supply passage. The vessel propulsion apparatus includes an auxiliary cooling passage branching from the cooling water supply passage to extend to an oil pan. A water pressure control valve disposed at a branch position from the cooling water supply passage to the auxiliary cooling passage limits the flow rate of water flowing to the auxiliary cooling passage when a water pressure inside the cooling water supply passage is less than a set pressure. The water pressure control valve is configured to allow a portion of the water inside the cooling water supply passage to flow to the auxiliary cooling passage when the water pressure inside the cooling water supply passage is the set pressure or more to maintain the water pressure to be less than the set pressure while supplying water to the oil pan via the auxiliary cooling passage.

Abstract: An outboard motor includes an engine including a crankshaft that is rotatable about a rotation axis extending in an up-down direction, and a crank chamber that houses the crankshaft. The outboard motor includes an oil pan including an oil retaining portion, a cooling water passage disposed along an outer wall surface of the oil retaining portion, an oil recovery passage extending downward from the crank chamber to lead lubricating oil inside the crank chamber to the inside of the oil retaining portion, and a guide member. The guide member includes a shielding portion disposed inside the oil recovery passage so as to be located over an opening of the oil retaining portion, and a guide hole disposed inside the oil recovery passage so as to be located over an inner wall surface of the oil retaining portion.

Abstract: A thermostat includes an annular flange extending in radial directions and surrounded by a cylindrical large-diameter portion of a housing inner surface, and a frame extending in axial directions from the flange. The thermostat further includes a sealing member that hermetically seals the gap between the flange and the inner surface. The sealing member includes an annular outer peripheral portion sandwiched in the axial directions by the inner surface and a thermostat cover inside the large-diameter portion, and a plurality of protruding portions extending outward in the radial directions from the outer peripheral portion toward the large-diameter portion. The thermostat is disposed inside a housing that defines a portion of a cooling water passage, and opens and closes the cooling water passage according to the temperature of cooling water inside the cooling water passage.