Waterlift Muffler on High Speed Planing Vessel

Can a Waterlift Muffler be used on a vessel that operates at speeds above 30 Knots with a gasoline engine installed below the LWL?

If not what exhaust system could be used if dry exhaust is not an option. The engine is to be installed below deck in the center of the cockpit of a center console.

The only other option I can think of is to run dry exhaust below deck to the transom or under a gunnel and then put the water injection elbow on top of a dry riser. Neither sounds like a fun design.

 

Yes, the waterlift muffler will "lift" the water above the waterline so it can drain conventionally via gravity.

Steve

 

The simplest way is to have high risers. You can stack them until they are high enough above the waterline.

 

But if it is an open cockpit boat with the engine below deck where do you put the risers?

 

Water lift has to be used but not a water lock on a high performance engine.

It is absolute necessity that the water injected has to be pumped by the engine exhaust gasses up and out yet be high enough so water slop from outside waves can not get back.

Vetus does a good page on their web site although I feel their measurments are absolute minimal.

What you need to look at id a hot high rise . That is having exhaust gasses higher than water line before injection giving you a little more room to work with.

Pumping the water out with exhaust gasses takes power and on a turbo these systems would be critical.

This is a job that needs to very correct in all aspects.

 

I think you are going to have to explain your setup a little better. Size of vessel please, etc. There has to be a way to get the outlet elbow of a waterlift or water / gas injection mixer of a dry riser above the waterline.


Waterlifts are used all the time in sailboat installations where the engine is below waterline and when done correctly is perfectly acceptable and safe.

Steve

 

25ft Center console. Engine below deck in the center of the cockpit. Engine Hatch is flush with the deck, and deck is self bailing by about 1.5" meaning the top of the engine is about even with LWL.

 

You have problems.

Where do you expect to discharge the exhaust? Even dry exhaust has to discharge above the waterline and even underwater (not practical here) exhaust needs a bypass above the waterline.

Maybe you would run the exhaust to a lift against the transom under the deck and bring the outlet up above the deck and then through the transom above the waterline. You would need enclose this for cosmetic purpose to hide the pipe.

What about using the console to get the gases and water above waterline? You could 180 forward into a lift muffler under the console and then up above the waterline inside the console, but you still need a place to discharge above the waterline.

As for your self bailing cockpit, what happens when a couple of 200lb guys stand in a back corner?

Steve

 

I have a self bailing cockpit now. If two 200 pound guys stand in the back corner sometimes a little water will come in. When they leave the corner the water goes back out. If it becomes a nuisance, I plug the scuppers with a tennis ball. Haven't had a problem.

Also this is a rough drawing of I think what you are talking about with exhausting out the transom. Am I close?

 

No that wont do. When you switch off the motor the water will run back to the engine.

Gonzo was the first to talk of risers.

Because your engine exhausts out is below water line you need to get it higher to a point where you can then inject water and have if flow down to the riser which takes it up again and out.

http://www.frenchmarine.com/marine_exhaust_assemblies.aspx

Dry risers

http://www.sbmar.com/articles/exhaust_system_images/

 

The water isn't injected until the end and at that point it is only downhill to the discharge. Uphill back to the top of the riser. Don't see how water would flow uphill.

 

So ----whats the problem?

 

What you sketched will work, you'll need to hard coat or lag that long hot run aft, it's a low back pressure looking set up so that's good.

You sketch does show the water injection on the wrong side of the riser, should be on the down hill side as you mention.

Steve

 

Idn you said it wouldn't work.

Sorry rough sketch, but yeah it is on the wrong side.