3.1.1 Generator Set Compartment Ventilation
This section does not cover the design of the ventilation system as it
pertains to ventilation of fumes from the engine compartment. The
requirements for ventilation of fumes varies considerably from one boat
design to the next, as well as from country to country, and therefore, the
boat manufacturer is responsible for ensuring their application is in com-
pliance with the appropriate industry regulations and standards.
According to boating standards and legislation the engine compartment
ventilation system has multiple tasks. Included the following:
• To supply the engine with combustion air.
• To maintain a low temperature in the engine compartment.
Fresh air should enter the engine compartment as low as possible and the
heated air should be discharged from the highest point.
If a separate air duct (or similar) is used to provide engine compartment
ventilation, or additional ventilation, care must be taken to prevent sea-
water and spray from entering it.
WARNING Ventilating air is required to clear the bilges, as well as the compartment in which the
engine is located, of potentially toxic and ammable vapours.
3.1.2 Intake air requirement
The generator set normally draw air from the engine room.
Engine compartments with natural draft ventilation must have vent openings of sucient size and location to accom-
plish the tasks previously outlined, see table below for absolute minimum required area ventilation opening.
An ample supply of air within the temperature limits of the generator set and carry away heat from the generator set in
the engine room is thus assured.
A ‘sealed’ engine compartment must have a good ventilation to maintain reasonable engine room temperatures. High
temperature of intake air reduces engine performance and increases engine coolant temperatures. Air temperatures
above 40 degrees C (104 degrees F) reduce the engine power by 1% for each 5.5 degree C (10 degree F) of rise. To mini-
mise these eects the engine room temperature must not be more than 15 degrees C (30 degrees F) above the outside
ambient air temperature.
Apply a combination of ventilators, blowers and air intake ducting to met the temperature limit.
In cases where it is impossible to met the above mentioned temperature limit with using natural ventilation connections
are available, both for air inlet and air exhaust of the sound box. With these connections the generator set can be directly
connected to air ducts.
Air inlets should be louvred to protect the engine room where appropriate the generator set from water spray. Even bet-
ter is a cowl ventilator with dorade box located as high as possible.
The air inlet ducts should run to the bottom of the engine room to clear fumes from the bilges and to circulate fresh air..
Air outlets should be at the top of the engine room to remove the hottest air.
An engine room blower (optional) should be used as an extraction ventilator to remove air from the engine room. Such
air intake should be positioned as low as possible.
GENSET
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