Comprehending the air cavity for engine air cooling as it's very confusing help...

[LeifThor]

In regards to the last photo: shouldn't the check valve face the other way?

Hard to explain, but it works beautifully going the way it does. It's not a check valve, and going the way it does, the water shoots in and hits a slight angled slope, which turns it into a perfect spray to meet the hot air. The two earlier designs required the water to go through almost pin holes which I didn't like at all. So the 3rd design has the best spray and biggest through hole, and stainless.

 

[LeifThor]

I can't picture the precise situation you are describing but maybe a aluminum heat shield 1/8" thick with an air gap(1/4") applied to the underside of the settee and close up the gaps with some hi temp gasket tape ?

Yeah Dave I may have to go that route. I'm also considering adding some vents at the top of the engine compartment so at least the heat will have somewhere to go.

 

[Loren Beach]

I can't picture the precise situation you are describing but maybe a aluminum heat shield 1/8" thick with an air gap(1/4") applied to the underside of the settee and close up the gaps with some hi temp gasket tape ?

We have always run the exhaust blower for about 5 minutes after shutting down the engine; especially on a hot day.

 

[Dave G.]

Heat rises so I'm thinking the gaps will experience much more heat due to all of the engine heat concentrating in those areas trying to rise and escape ? Maybe ?

 

[steven]

I idle until temperature drops way down. Takes about 3 - 5 min. Meanwhile I furl the sail and such.

When running, my engine compartment levels off at around 95deg F, without the blower.
But it is under the stair and has lots of room there with plenty of natural air flow - and it is open to the starb lazarette.

Put in a new exhaust leg from engine to water lift muffler last spring (old one blew a hole in the middle of a narrow channel making for some challenging sailing). Built with black pipe (McMaster-Carr) ) and special parts and coaching from Moyer.

 

[LeifThor]

I can't picture the precise situation you are describing but maybe a aluminum heat shield 1/8" thick with an air gap(1/4") applied to the underside of the settee and close up the gaps with some hi temp gasket tape ?

Thanks Dave I think that's going to be part of the solution too. I don't know the name of it, but there's a fire proof material that's usually put behind stoves on RVs that also might be a contender.

 

[LeifThor]

Heat rises so I'm thinking the gaps will experience much more heat due to all of the engine heat concentrating in those areas trying to rise and escape ? Maybe ?

Sounds right Dave. It's funny, it being a closed contained space, I have to speculate and design without any way of observing directly...Tape my iphone in the engine compartment, and do video with light with an incense stick at the end of the air in hose?

 

[LeifThor]

We have always run the exhaust blower for about 5 minutes after shutting down the engine; especially on a hot day.

We've always done that too Loren, except we run ours for 10 (takes at least that long for the engine to cool down). But if our blower is not moving any air around the engine, then all it's doing is the basic job of removing gasoline fumes from the bilge area so the engine area doesn't explode, and sucking up air from any number of places other than where we'd like it to take the air from.

 

[LeifThor]

In regards to the last photo: shouldn't the check valve face the other way?

Wow, somehow it made me response to Kenneth a Kenneth response lol

I responded to this. It's not a check valve Kenneth, and even though the arrow is going the other way, it works perfectly because the raw water shoots in to the air and hits a slightly angled surface and then sprays perfectly across the hose interior as the hot air moves through perfectly cooling it evenly. When I found the stainless part I flipped because it was exactly what I was looking for and ready to get something like it machined but found the fitting instead.

 

[LeifThor]

I think I came up with a solution, all opinions appreciated.

I can't remove the blower taking air from the low point, for that blower does what it's supposed to do removing gasoline fumes and any dangerous gases that settle in the bilge.

And then there's the other hose, which is simply a 4 inch hose from the top side of the engine area exiting on the port stern cowling, an ambient air hose that someone thought somehow would magically suck air from outside in to the engine area, and the blower would then suck out and which has completely failed at it's job.

So the solution which will both suck the air from the bilge, and suck the air from the top of the engine compartment, only needed during the cooling off period after the engine has been turned off, and the water is no longer cooling the engine is, three options I can think of...

a: Add a second blower on the ambient air line to suck the air out of the top of the engine compartment, and only turn it on during the cooling off period after the engine has run.
b: Re-route the ambient air line into the blower line, dividing sucking power, but the most idiot proof.
c: Re-route the ambient hose to the blower, and add a Y valve, so I can choose which hose I want to pull the air from.

 

[Second Star]

If you don't see the intake part of the vent system pulling in any air, why not install another vent fan for the port side that draws as directly as possible from the settee area. Use a separate switch to run it for as long as necessary post shut down.

 

[Loren Beach]

I just remembered the ever-helpful Mr Occam, and he suggests checking/replacing the (relatively inexpensive) blower exhaust hose.... which if old may be broken in many places.
FWIW we have have replaced that old vinyl hose a couple times in the last 25 years.
Found a link, in a quick search:https://www.amazon.com/Bilge-Blower...ywords=boat+blower+hose&qid=1670695050&sr=8-3

 

[LeifThor]

I just remembered the ever-helpful Mr Occam, and he suggests checking/replacing the (relatively inexpensive) blower exhaust hose.... which if old may be broken in many places.
FWIW we have have replaced that old vinyl hose a couple times in the last 25 years.
Found a link, in a quick search:https://www.amazon.com/Bilge-Blower...ywords=boat+blower+hose&qid=1670695050&sr=8-3

I agree completely with replacing the hoses as they’re pretty old, moldy, and holy

 

[goldenstate]

My sense of the general rule is to give a boat engine 10 minutes to warm up when turning on and 10 minutes to cool down before turning off. That does lower the block temp in my experience.

 

[LeifThor]

My sense of the general rule is to give a boat engine 10 minutes to warm up when turning on and 10 minutes to cool down before turning off. That does lower the block temp in my experience.

Having just learned that, couldn’t agree more

 

[LeifThor]

If you don't see the intake part of the vent system pulling in any air, why not install another vent fan for the port side that draws as directly as possible from the settee area. Use a separate switch to run it for as long as necessary post shut down.

I mentioned three options to a solution which your thought was option A, and I’m on the fence between option A or B which is re-routing the ambient hose to the blower so the suck comes from both hoses whenever the blower is running.

 

[Kenneth K]

The cowl vents on the stern, where the corrugated air hoses exit, are not just there to vent exhaust fumes & heat. The are part of the passive ventilation for the entire boat (along with the dorade vent near the bow) which keeps air moving throughout the boat to reduce odors, dampness, and mold.

If changing the system, I'd probably opt for adding new ventilation over re-routing the existing lines.

 

[Dave G.]

a: Add a second blower on the ambient air line to suck the air out of the top of the engine compartment, and only turn it on during the cooling off period after the engine has run.
b: Re-route the ambient air line into the blower line, dividing sucking power, but the most idiot proof.
c: Re-route the ambient hose to the blower, and add a Y valve, so I can choose which hose I want to pull the air from.

If you have to go to a "mechanical" solution, I don't think dividing or rerouting the existing blower line(b&c) is a good option from a safety point of view. As that could compromise the removal of the explosive gasoline fumes, IMHO anyway.