Engine room Air Intake/ Ventilation

Michael, I didn't pick on you with my last post on this thread, knowing how you are about things, but you've backed up your misstep with more of the same. If you positively pressurize the compartment, you will (not if, but will) blow fumes and heat into living spaces, unless great extremes are taken to seal the space, which frankly is silly and not especially economical except in ships. A 25' cabin cruiser isn't going to have hermetically sealed engine spaces, therefore you create a low pressure area inside the compartment so any potential for leakage is eliminated, typically being drawn out a duct, from convention or a blower.

 

Thank you ! thats the most possitive thing i have read for a while and lots to think about !!

 

all good stuff
thanks to all

 

Another detail for ventilation....Make it RAT proof. Very serious damage can be inflicted by rats during winter layup. Design rat proof wire grates for intake and exhaust to protect against these intruders.

 

Or positively pressurize the compartment and let the fumes forced out, choke them to death.