Marine propulsion systems, intake air systems for marine propulsion systems, and marine propulsion systems having exhaust gas relief outlet

A marine propulsion system for propelling a marine vessel in water, the system comprising:

• an outboard motor coupled to a marine vessel, the outboard motor comprising an exhaust gas relief outlet and a primary exhaust gas outlet that is located lower than the exhaust gas relief outlet on the outboard motor and that discharges exhaust gas to the water;
• and
• an exhaust conduit conveying exhaust gas from the exhaust gas relief outlet to a discharge outlet located on the marine vessel;
• wherein the exhaust conduit is sloped along its length so that water does not stagnate therein;
• wherein the outboard motor has a first inlet that receives intake air for combustion;
• a second inlet located on the hull of marine vessel;
• and
• an intake conduit conveying the intake air from the second inlet on the marine vessel to the first inlet on the outboard motor.