Rising Exhaust outlet ??

[Ersin]

As years go by, my boat H340 became heavier and so exhaust outlet comes closer and closer to sea level,now almost 5-6 cm.
The book of Yanmar says ıt sould be at least 10 cm higher from the sea level.
On the other hand,the sound of exhaust also changed to sound as it some dry exhaust.
Now I want to rise it about 5-6 cm higher.
Anybody has any experience/info about that kind of problem?
İf I can do it,does it make any harm to system?

Or anybody has any other suggestions?
Thanks

 

[kloudie1]

Kinda normal but ya may want to study your system carefully.. here is an article :
http://www.westmarine.com/webapp/wc...10001&page=Exhaust-System-Basics#.UUNI6tZNa84
Ya have to be careful that the water in any vertical risers has a place to go when the engine shuts off. The size of the lift muffler is a bit critical ..
EDIT: the water in the hoses is generally pushed along by the exhaust gas, but when you stop the engine .. all the water in any riser will go to the low point.. That should be the lift muffler.. and it should have enough capacity so that the water does not get anywhere close to the engine exhaust out..

 

[Paul F]

The important part of the exhaust is a high gooseneck in the exhaust hose as high as you can get it in the boat before the hose is directed to the thru-hull outlet. You can add a flapper at the outlet to prevent sea-water from entering.
http://www.yanmarhelp.com/i_exhaust.htm

 

[Ralph Johnstone]

The Last Thing I Would Worry About ................

Anybody has any experience/info about that kind of problem?

................. is the closeness of the exhaust outlet to the water line, as long as you have a big,high internal loop as previously mentioned here.

In fact, our 1999 Hunter 310 was designed with the exhaust outlet about 5-6 cm. BELOW the water line. Makes for very quiet running in the cockpit. The attached photo is a shot looking up at the exhaust outlet on the underside of the hull. Water would have to rise more than one meter in the exhaust hose to go over the top of the internal loop. If that were to happen, flooding the engine would be the least of my worries .