Exhausts

stamfordian

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If you have a wet exhaust can you have it exiting above the waterline ,?? mine does ,and have fitted a silencer,with no watertrap or swan neck,do i really need these ,given that the exhaust manifold is also above waterline also??,i have fitted a flapping outlet fitting,
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If you do not fit a water trap and a syphon you might find that it is ok, but still might invalidate your engines warranty, this is what I found.

The syphon being the most important if your exhaust water inlet is indeed above the WL.

<font color=blue> Julian </font color=blue>

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Hello Tony
Now is the time to get it all done right, fine re outlet above the water line if you dont mind the noise.
I would advise you to have a ( swan neck ) and inject the water into the last downward section of exhaust.
What was up with the engine not running the other week ?

Cheers
Mick

smile you'l be on your boat soon ;-)
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Nothing wrong with an exhaust pipe exit above the waterline -most of them do. I think the swan neck is very important because it is supposed to stop a following sea forcing its way back up the pipe when the engine is not running. Even if the inlet is above the waterline, a following wave can be significantly higher than that!
 
Having fitted a Vetus wet exhaust to a Yanmar 3GM the installation was as follows:

Water injection into exhaust from exhaust elbow on engine (I bought modification kit to 3GM to raise the level of the injection point to give greater degree of safety).

Short section of exhaust hose to give a fall of greater than 30cm to water trap.

From water trap a section of hose no more than 300cm to highest point possible (I guess this length is determined by the volume of the hose -v- the volume of the water trap)

Then from the top of this loop to the final exhaust fitting out of the boat (about 30cm above water line in my case)

This is as per instructions which came with the water trap.

The point of the high loop in the exhaust is to try and prevent water working its way back through the exhaust system by placing some of the system as high above water line as possible.

The syphon break is installed between water injection into exhaust and (in my case) the heat exchanger (as this is a 3GM30F). This syphon break is again as far above water level as possible. This works for me despite the engine being (for the most part) below the water line.

Jeff.
 
Hi Mick
You wouldn,t believe what some plonker had done,he,d picked up a piece of imperial tube instead of metric 10mm,and tightend up.The pipe didn,t leak diesel put let a tiny amount of air in....result the inneviatble intermitent air lock in the pump.....doh!!!/forums/images/icons/smile.gif/forums/images/icons/blush.gif

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