[C320-list] ENGINE SPACE VENTING

[Jeff Hare]

Not to be critical of anyone's answers, because it's great to bounce these thoughts around to help refine your logic, but seriously don't over-think this.  

The engine doesn't need cool ambient air to keep it cool, that's what the raw water heat exchanger is all about. Otherwise they would not put it in an insulated box with a couple lengths of dryer hose.  It also doesn't need any duct work to feed it air to run because there are SO many better paths for hull-cooled bilge air to get into the engine that it's simply a non-issue.

If you really believe that the blower reduces the heat in the aft cabin with the stock hoses, awesome, but it really doesn't.  No way you're moving that much heat out through those crinkled half crushed hoses with our anemic blower. LOL!  You'd have to run the blower till the engine block cools down quite a bit to make any real difference or it'll just reheat the air again.  By then someone sharing the mooring field with you would have launched a torpedo at your boat because of all the racket that thing produces.

If you really want to help remove any excess aft cabin heat, I'd suggest that you open the aft cabin access door at the foot of the bed and aft cockpit locker above the fridge compressor and let convection take over.  If you really wanted to use hoses for some reason, you'd need 4" smooth wall hoses that have fewer bends and a more powerful blower to actually get any reasonable airflow.

I'm pretty certain that the blower and the hoses were only installed to satisfy outdated requirements for a bilge blower (which diesels are exempt from now in the US anyway).

Cheers!
#809   stay'n hoseless  :)
-Jeff Hare

-----Original Message-----
From: C320-list <c320-list-bounces at lists.catalina320.com> On Behalf Of John Meyers
Sent: Monday, March 12, 2018 3:23 PM
To: C320-List at catalina320.com
Subject: Re: [C320-list] ENGINE SPACE VENTING

John

If thing for convection to work you may need one of the openings to be connected to a hose with one end lower than the one without a hose. The one with the hose will let cold/fresh air in when the hot air rises to the vent without the hose.

John Meyers (The other John M)

On Mon, Mar 12, 2018 at 10:08 AM, John morrison <sail-ability at sympatico.ca>
wrote:

> I attended a surveying seminar on the weekend, and for those who may 
> not know ( I didn’t) diesel engine spaces do not require forced 
> ventilation in order to pass a survey. You may want to have it for 
> other reasons as has been mentioned in this forum. I intend to remove 
> the vent hoses from the cowls and let the space vent by convection. 
> The cowls are high up in the stern so warm air should exit pretty 
> well, we'll see  how that works. When the hoses are attached the cowl 
> holes are blocked and hot air from the engine, fridge compressor, 
> cannot escape; unless of course the blower is running.
> Regards
> JohnM
> 1999#574