UNDER WATER EXHAUST FOR GENNY

N

NAWTICAL1

Member
exMember
Joined
Sep 15, 2006
RO Number
23427
Messages
140
I recall a thead on the old site about someone (Rommer?) configuring a method for the gen set to discharge its exhaust under water.

If anyone has any info concerning cautions (ingesting water ) benefits (less exhaust noise) and instructions, it would be appreciated.
 
if you go to Centex's website, they offer a water/air seperator for generators. it takes the exhaust mix from the lift silencer and separates the water and air. the water can go over the side at the waterline or below it, no splashing. the air comes out above the waterline. it gets rid of almost all the noise from the air side and all of the water noise. i installed one 3 years ago and was very happy with it.

good luck.
 
exhaust1.jpg


exhaust2.jpg
 
rommer: you need a siphon break it that
 
There is, a small hole drilled in the plastic fitting. Can't see it in the picture.
 
I made the same modification and drilled a hole in the elbow to provide a vacuum break. I have had no problems so far, but the vibration under the platform is still annoying. I am going to extend the exhaust out from under the platform entirely this weekend. I will update with results.
 
How far under water did you go Gary? I have no such vibration that I'm aware of.
 
Pressure fit, however there is a stainless steel clamp holding the entire assembly in place to the swim platform support so it doesn't move.

The rubber piece is available at your local Home Depot/Lowes and is a wet vac adaptor for going from a large hose to smaller hose. RIDGID Universal Power Tool Adaptor Model VT1407

VT1407.gif


Cut at the first step to the left from the square part. Use a dremmel type tool to reduce or taper the edge to help it fit in and the press in. The largest diameter fits perfectly around a 2" PVC fitting.

Total cost about $20

Cut the noise which is amplified by the large swim platform WAY down!
 
BTW - the end of the PVC tube goes roughly 6" below the surface and is out of the water when the boat is on plane.
 
Thanks Rommer, Vic,

I was wondering how much noise reduction would occur and if I had to worry about water ingestion.

All that is needed is a small vent hole? No flapper valve?

I have a side exhaust discharge, so some modifications will be needed.

If anyone has applied this to a side discharge, please post.
 
Would be really hard to do permanently with a side mount since the thing would be subject to lots of water pressure when under way. Made one for a friend with a side mount using thin line to tie the device off to a cleat. He would reach over and push it in when anchored. If it popped off the string would keep it from sinking. Not a perfect solution but it worked for him.
 
Thanks for the response. I was thinking about a removable version.
 
nautical;

my boat had a side discharge originally. i kept that for the air discharge and installed a separate water discharge at the transom under the swim platform at the water line. i then installed a 90' elbow so there is no water noise and no additional backpressure other than the air/water seperator. there is a built in air gap in the separator and there is virtually no exhaust noise now from a Kohler 8EOZ genset. the only noise is that which escapes the sound enclosure and the slight vibration the unit makes when running. leaving the air discharge at the side of the boat is probably wise in eliminating some of the station wagon effect on the exhaust gases while at anchor.
 
Vic,

This sounds like a job I may be able to do myself. It also sounds like it may eliminate some of the risk involved with water ingestion that is common with the typical wet exhaust. Correct?

I slept on the boat for the first time with the gen set running. That exhaust noise kept me awake most of the night. The strange thing is, I have a sound shield on this boat and could not actually hear the gen set engine, just the exhaust. My previous boat did not have a sound shield. I think I slept better hearing the constant hum of the engine rather than the hi lo sound of the exhaust.
 
nawtical;
You can do this yourself. The only risk of water ingestion that I am aware of is if you overcrank the generator and it fails to start. Eventually you will fill the pot and the water will not lift out to the exhaust and will flow back into the manifold. This issue is the same on any installation where the overboard exhaust line is above the manifold. The siphon issue goes away with the separator. If you sleep on the hook you will appreciate the difference it makes and so will the other people in the anchorage.
 
Vic33004,

what is the link o Centex's website? I can't seem to find it via google searches.

Thanks.
 
So I did mine this winter.
Gas Genny.
Same setup.
I got like 5 of the adapters on ebay for $15.
Easy to install.
It is definately queiter.
Still noisy bc u here a bubble noise.
Now it sounds like one motor is running bc I have underwater exhaust for my motors.
But pretty happy with the result.
I think I may still look to route it off the side.
Any noise under swim platform is going to echo a little, but it definately made it quieter.
 
You must log in or register to reply here.
Back
Top