Converting a dry exhaust to wet.

The diagram by Apex1 shows the vaccum break which is very important. It keeps water from siphoning back into the engine. Sometimes it is not installed and nothing happens for a long time until the boat gets heeled over or loaded in a different way.

 

How do I change a wet exhaust on a jet boat with 350 v8 motor?

 

What exactly is your goal? Changing is easy........open your wallet and get it done.

 

That is a long way to go to the boat yes?

 

Hi Nikostos, you have a fine looking boat there.
You want to cool the exhaust down because of safety and noise concerns right?
However you have an air cooled engine that is noisy by definition.
I think your project is far too complicated for little gain.

A water cooled engine needs raw water to cool the coolant that cools the engine. This raw water needs to get piped out somwhere and so the cooling for the exhaust is a sort of fringe benefit. Some people use the exhaust to heat a water tank fortheir shower...sorry not suggesting you do that.

Others with a water cooled engine know of the downside of strains and rubber impellers imploding and so get rid of the whole thing and go kel cooled and dry stack.

You have an air cooled (no pump what a blessing) and a dry stack. No raw water pump, no danger of sinking and other niceties.

Why change it?

Noise? Build a proper muffler.

This is my idea. Keep exhaust exactly where it is. Have one pipe for the exhaust. If your original is 1.5" go 2". Your muffler can be built this way. Internal pipe 2" diameter straight trough say one meter long. External pipe 3.5" diameter, about 80cm long. The internal pipe will have a series of 3mm holes all along and all around.
Before you weld the external pipe on, you must wind insulating fabric tape, string or similar to cover all the 3mm holes. We used to use asbestos but obviously you don't want to handle that stuff so find suitable alternative. You also will need two reductions from 3.5 to 2". Weld the first reduction from external pipe to internal leaving some 100mm to join to the exhaust pipe. Stuff the space between the internal and external pipe with fibreglass. Weld the second reduction to join both pipes, leaving again 100mm.
Build a little metal flap so that when the engine shuts down it falls shut and stops the rain from coming in
Noise problem solved.
Burning issue. Add a shield around your muffler. You can buy them from wood fire stoves suppliers.
This way you keep simplicity and safety and don't have to get into adding pumps and exhausts and drilling holes in your boat.

 

Good advice Marco!

No not yours, that was a bit late and did not hit the nail, the others on page back!


Sasha

 

Remember the Vetus dimensions are minimum!! and not ideal.

Wet exhausts are a real pain to get right and many boats do not have the right Diameter.

Vetus warns you of this and you can phone them.

Once you mix water with the exhaust you need a 4 x increase in Dia than would normally be required.

You got a dry and you want to go wet!!!!!!!!!!!!