Heat
The blower is only to remove the heat from the engine compartment, it is not intended to cool the engine or remove exhaust. Those taskes are done by the engines exhaust and cooling sytems.When an engine is installed in the cabin and you run the motor for several hours.....(say you were going 50 miles and there was no wind), the cabin could get hot from the heat being put off from the engine. The blower removes the heat. It all depends on the placement of the motor. On my old Cal sail boat, the engine compartment was under the cockpit and did not affect the cabin with the heat, thus no need for a blower. However on my new 1986 Pearson P36-2, the engine is under the sink in a small compartment in the galley (great access) and I bet it warms the cabin after a few hours of continual running.Greg