Marine propulsion systems having exhaust gas relief outlet

1. 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

a conduit that conveys exhaust gas from the exhaust gas relief outlet to a discharge outlet located above the water on the marine vessel when the outboard motor is operated at idle speed so as to discharge exhaust gas to atmosphere when the outboard motor is operated at idle speed;

wherein the conduit is sloped along the entire length so that water does not stagnate therein; and

wherein the conduit extends through the marine vessel at a location that is higher than the exhaust gas relief outlet and higher than the discharge outlet.

2. The system according to claim 1 , wherein the marine vessel comprises a hull and wherein the discharge outlet is on the hull.

3. The system according to claim 2 , wherein the conduit extends through one of a port and starboard side of the hull.

4. The system according to claim 2 , comprising a muffler receiving exhaust gas relief from the conduit.

5. The system according to claim 4 , wherein the muffler is located on the hull.

6. The system according to claim 1 , wherein the outboard motor is at least partially enclosed by a portion of the marine vessel.

7. The system according to claim 6 , wherein the portion of the marine vessel is an engine housing that surrounds all sides of the outboard motor that are above the water.

8. The system according to claim 1 , wherein the conduit comprises a flexible hose.