Exhaust water flow

[Rick.johnson]

There is no exposed exhaust pipe
the engine exhaust come out a hole in the aft hull about a foot under the water line i can't tell if it is also discharging water
all i can see is the exhaust gas blubbing up on the back of the boat

 

[Leeward Rail]

I would contact aqualarm manufacturer and ask how it should be installed. They will confirm if it works for your specific application.

Fwiw, if it is reasonably possible and it was my boat, I would be very tempted to move the outlet above the waterline and modify the system to match. Easy to confirm it's working, and won't possibly sink the boat if it fails.

 

[Johnb]

On my boat:

1 I can quite easily using lung power blow from the downstream side of the raw water pump all the way through the mixing elbow. One time when the raw water outlet from the exhaust manifold got clogged the difference after remediation was readily apparent. This is a real easy quick and dirty test of the sea water side of the heat exchanger, exhaust manifold and mixing elbow.

2 When the engine is running the sea water inlet end of the heat exchanger is cool to the touch, essentially at the same temperature as the sea water. The outlet end of the heat exchanger is only slightly warmer. The exhaust manifold is not very hot, I can put my hand on it.

3 If the sea water is not flowing the exhaust sounds very different. Briefly shut it off and see if you can tell. NOTE BRIEFLY.

Any year now I am going to actually measure the temperatures.

 

[jssailem]

I’d simply stick my hand down in the water and you’ll learn what is happening.

 

[dlochner]

I’d simply stick my hand down in the water and you’ll learn what is happening.

If the PO did that his hand would be wet and he would know what the ambient water temperature was. He would also need exceptionally long arms. You obviously have no understanding of the problem as evidenced by your nonsensical suggestions.

 

[jssailem]

The Catalina 36 in the slip across from me exhausts about a foot under water at the stern port quarter. 6 years ago it was new to my sailing buddy. We questioned how strong was the exhaust flow. Stuck my hand down in the water and was rewarded with an instant answer to the temperature and force question. We used this technique to establish a base understanding what good flow looks like on the surface. If it changes in water flow there would be more bubbles or no bubbles.
Then we’d start looking for why.

 

[Ralph Johnstone]

I would contact aqualarm manufacturer and ask how it should be installed. They will confirm if it works for your specific application.

Looks like @Rick.johnson has an identical outlet to mine and it sees no problem ........................ except when one of the crew forgets to open the sea water inlet. See post #9 and #10.

The hydrostatic back pressure doesn't cause any problems.

 

[heritage]

My H27 has the exhaust port under the stern and at the level or slightly below the waterline. I cannot see the exhaust water flow. But I can hear a distinct pulsing sound caused by the water collecting in the exhaust pipe and muffler and ejected out the bottom of the boat. If the raw water were to stop moving in the exhaust pipe, I should only hear a smooth bubbling sound. Knock on wood, I have never heard that sound.

 

[dlochner]

The various visual, auditory, and tactile methods of monitoring exhaust water outflow will work at a dock. The bigger question is how well do they work when underway? Is the skipper going to climb into the water while motoring at 6 knots to see if the water is warm at the exhaust? I think not. Can someone really hear the change in bubbles over the sound of the engine, the wind, and the water rushing by? Will the skipper really be able to see the change in bubbles and water while motoring along at 6 knots? I think not. That's what all these suggestions are nonsensical and basically worthless once the boat leaves the slip.

The OP has basically 3 choices, live with the exhaust as is, move the exhaust outlet above the waterline where it can be visually verified easily, or add sensors to monitor the water flow and exhaust temps.

 

[FastOlson]

The OP has basically 3 choices, live with the exhaust as is, move the exhaust outlet above the waterline where it can be visually verified easily, or add sensors to monitor the water flow and exhaust temps.

Geez Dave, you let us get to 29 replies before revealing the answer...
This is the sort of logical response that takes a lot of the fun out of Internet Advice...!

(Just kidding; someone had to say it!)

 

[dlochner]

Geez Dave, you let us get to 29 replies before revealing the answer...
This is the sort of logical response that takes a lot of the fun out of Internet Advice...!

(Just kidding; someone had to say it!)

Not a problem, I've got big shoulders and thick skin.

 

[Rick.johnson]

Thanks' Guy's I think I will put in it a clear visual water flow meter
an a electrical temp gauge on the exhaust heat exchanger to monitor the temp
better an leave the exhaust outlet where Hunter design it to be

Again Thanks For all the help

 

[Hayden Watson]

If your strainer has a see-through top, you can usually see the water moving in it. Of course, all of these suggestions are one-time checks, and don't tell you if you lose water flow while operating from something like a clog or a broken impeller. The flow meter looks good for that.

Mark

Yes, I can easily see the water moving in my sea strainer. There is always a little air at the very top and can see the current in that surface.

 

[dmax]

I put one of these on, inexpensive, alarm goes off if exhaust temp exceeds 200 degrees: https://defender.com/en_us/aqualarm...2xztEVDsP-XY90IjyoZHXEaAqNDEALw_wcB#615=34137

 

[Rick.johnson]

That is like i would want to put on her
does the band an sensors just fit around the inboard exhaust hose ??

 

[jssailem]

It is a sensor that fits around the metal exhaust pipe after the water injection point but before the hose connection running to the lift muffler. You want to measure the temperature after the water/exhaust is mixed. In the description, the sensor triggers the alarm when the temp exceeds 200ºF.

 

[Rick.johnson]

Ok Great Thanks will get going an keep her running cool

Thank Rick

 

[dmax]

That is like i would want to put on her
does the band an sensors just fit around the inboard exhaust hose ??

Yes - the band goes around the exhaust hose, wherever is convenient - easy to install. I put it near the muffler exit.

 

[Rick.johnson]

Great Thanks Rick

 

[Hayden Watson]

Yes - the band goes around the exhaust hose, wherever is convenient - easy to install. I put it near the muffler exit.

I am assuming that you do not want to connect the band to the rubber exhaust hose because it is a thermal insulator, and it would take a fairly long time to show an increase in temperature. Personally, I would want to mount it to the metal exhaust elbow after the water injection but on mine, that is only 1 5/8" and the specs say 2" minimum on the band.