J/30 Class Association Forums J/30 Forum The Boat, Sails and Equipment Help! Lost my stern ventilator cowl covers

The answer is the engine can somewhat breathe without them, but if you do a long engine run, the engine compartment gets very warm. With the cowl vents you put fresh air into the air filter rather than hot air, thus the engine runs better. Also, any fumes generated end up in the boat if the engine compartment is not vented. This could be a safety issue. I noticed the boat smelled better after installing the ventilation cowl to replace the blank plugs that were in the deck. I also replaced the brittle, cracked ventilation hose with the same size flexible aluminum dryer duct.