Air intake penetration of sufficient size to keep air velocities at a low level (ie: below 6metres per second, optimum 3.5 - 4.5 metres/sec). This aids in limiting external noise and potential water induction.

Air supply duct sized suitably to suit volume being supplied without creating substantial restrictions (ie: give the air an easy path to follow).

Engine room fan located between the air in penetration and the engine room so as to pressurize air into the engine room.

Within the engine room, the air supply must be distributed and directed so as to create a good passage accross operating equipment and ambient space prior to exiting the engine room.

Air out duct may follow the exhaust system in the case of a dry stack style exhaust or alternatively may simply exit the engine room space at a location best suited to assit in complete circulation of the engine room.

Air out penetration may be located anywhere on the vessel, however it is essential to consider potential engine room noise and heat, and also to prevent expelled engine room air from being drawn into the engine room supply air. (ie: you don't want the air out of the engine room being drawn back in).