Exhaust Angle and Noise Reflection 2

[JimMorrison]

Hello All, I have been involved in replacing the exhaust system for the Diesel Generator in a small size craft to reduce the exhaust noise and stop the local residents complaining! As part of the modification we increased the nominal bore of the pipework and fitted a reactive absorptive silencer.
We are now looking at the exhaust outlet and this is where I am seeking advice. The outlet penetrates the hull at the waterline and is facing the water at roughly 45 degrees from horizontal. I have been told that this may cause the exhaust gasses to be reflected and projected away from the craft at exit volume, not good for the locals!

Does anyone have any experience of this or know of any literature that deals with this issue? Any help would be much appreciated

Thanks,

Jim

 

[pawelmaz]

You can see web side of Vetus company. They offer also complete exhaust system form motorboats. On electronic catalog you can see a sollution of proper line or even order parts what you need for.

http://www.vetus.nl

Regards

Pawel

Ps. Their component is permitted by most marine registers

 

[MikeHalloran]

If the silencer is working, it shouldn't be an issue, though it may 'burp' as the boat rolls at anchor.

I've learned enough about designing silencers to keep me out of that particular business, but I've bought a bunch of them, and I've developed a rule of thumb:

A 'hospital grade', i.e. very quiet, dry silencer, for a Diesel, will be about as big as the engine itself. I don't mean the piston displacement, I mean the total envelope volume of the engine. Smaller silencers can be had, and will make more noise.

A 'wet' silencer with roughly the same performance will occupy about half the volume, and be a bit cheaper and a bit lighter.

All silencers work best if you consult the manufacturer, and take their advice.



Mike Halloran
Pembroke Pines, FL, USA

 

[pauljohn]

Try looking at the 'Gensep' from Centek or some similar product. They reduce the sound of generators a huge amount by seperating the exhaust gas and cooling water flow. We use them frequently.