Engine Compartment Blower for Diesel ?

[muchmsw]

Hi all;

I have a question about whether or not a diesel powered boat (Beneteau 352) requires positive ventilation of the engine compartment to be safe, or to conform with any Coast Guard or other regulations.

Currently, the engine blower comes once the ignition is turned on, and stays on until the engine is killed and the key switched off.

Is this correct? I've been on several charter boats with diesel engines, and previously owned a boat with an Atomic 4, and I don't remember ever having a blower constantly on for the engine compartment.

We'd like to add a switch for the blower, to clear the compartment of fumes, etc. as a safety precaution before starting (might be overkill?) and run it occasionally to clear out engine smells after running the engine.

Any thoughts, oh wise ones?

Steve

[DeepFrz]

A diesel powered boat does not "require" any positive ventilation but a blower will help keep the temperature of the engine compartment down.

[Iolite]

Our Jeanneau 40 has a thermostat on the blower it only comes on when the boat is operated in hot weather. also will cycle on and off as needed.

[never monday]

A blower is not required by regulation on a diesel boat.
Running a blower is a good idea for ventilation. This also provides cool air for the engine to breathe.

[lorenzo b]

To check if the engine is getting enough air run it with the compartment closed and then open the hatch and listen wether the engine runs differently.Blowing air in will help the engine, blowing out will cool the engine after it shuts down. Blowing out when the engine is running will fight the engine's natural draw of air through the vent, blowing in to cool the engine when off may force some hot air into the rest of the boat.

[David M]

I would only add a forced draft ventilation if the compartment is running too hot. But then if it is running too hot it may be better to add some passive ventilation. Some diesel manufacturers will only warrant a diesel if the engine compartment temperature stays X amount of degrees below the outside ambient temperature.

[FSMike]

Each of our engine rooms has a dorade piped to the forward end of the compartment for fresh air intake, and a vent with exhaust fan mounted in the aft end of the compartment. The fans are always on when the engines are running, and we typically run them for a few minutes after shutting down the engines.
Can't think of a reason to not use them when the engines are running.

[capt_douglas]

I connected a timer to my engine room blower on the Endeavor 37. It would come on when the key was turned on, and was programmed to stop 15 minutes after the key was turned off. I felt that the added air flow would cool the engine down better, prevent heat migration from the less than stellar engine room insulation, and remove any "vapors".

I also had a bypass switch that I could use to turn the blower on when working in the engine compartment.

[DeepFrz]

capt_douglas, did you make the circuitry for the timer yourself or was it off the shelf? If you designed it yourself would you mind posting the schematic? Thanks.

[coopec43]

A two liter diesel engine uses 9 cubic meters of air per minute. If that amount of air cannot flow into the engine "room" per minute the engine will "starve"and lose power.

[nhschneider]

We installed a Jabsco 35515-0010 blower back in ‘97 and we turn it on whenever the engine or genset is running - it probably has over 10,000 hours on it. It does draw almost 5 amps but we feel it’s worth it.

Fair winds and calm seas.