Diesel Generator exhaust

I have a 3 cylinder Yanmar 12 KW diesel Genenerator to install. The vessell is a steel hulled sailing barge. I assumed I would do a typical wet exhaust. An acquaintance is suggesting a dry exhaust. I guess the issue is the possibility of water intrusion into the genset. I could get exhaust straight up but I have the water exhaust muffler. Any opinions out there. I have notioced that shrimpers and other work boats seem to prefer the dry exhaust.

 

"Wet exhaust systems have decided advantages over dry exhaust systems. They are quieter, cleaner and cooler; and do not pose a fire or burn hazard (eliminating the need for insulation beyond the water injection point). Today, most pleasure boats with inboard engines (for power, auxiliary, generator) have wet exhaust systems." http://www.tridentmarine.com/stage/wetexhaust.htm[

"The following factors are of great importance:
Exhaust gas temperatures can reach very high levels. A diesel engine can easily produce an exhaust gas temperature of 600° C or more. The speed with which sound can be transmitted through air is dependent on the temperature of the air. This applies to exhaust gases as well. The higher the exhaust temperature, the higher the speed of sound through the gas.
The sound level, i.e. the relative volume of sound as experienced by the human ear, is in turn dependent on the speed of sound. As the speed of sound transmission reduces, so the sound level will reduce proportionally.
In the past, many boats used a “dry” exhaust system, in which the exhaust gases were transported to outside the hull without any form of cooling. The resultant hot exhaust pipe had to be thoroughly insulated, but even so, it produced a tremendous amount of noise. However, reduction of exhaust gas temperature to about 40° or 50°C can be achieved by injecting the engine cooling water into the exhaust line. This is how a “wet” exhaust system works. In addition, the typical diesel exhaust smell is also considerably reduced. A further major advantage of reducing the temperature, is the fact that all exhaust components downstream from the engine outlet can be made from rubber or synthetic materials. This permits greater design sophistication and weight reduction and ensures freedom from corrosion."
http://www.frenchmarine.com/Content.aspx?Content=9

 

Thanks. I have a water muffler left over from the previous generator. The exhaust takes a high bend the drops to discharge thru the hull. Hopefully this is enough to stop any water infiltration. The genset is fresh water cooled. I was going to use a heat exchanger ann a raw water loop and eject the used raw water into the engine exhaust. I was told to use an electric pump off the generator in lieu of a belt and an engine mounted raw water pump. I was told it would be more reliable and I could place the pump closer to the water inlet into the boat. Any thoughts?

 

I've never had an electric motor driven raw water pump, but the idea sounds good. I've never had a problem with suction head or a broken belt (keping fingers crossed tightly ), but the freedom to locate the pump where it is more convenient to reach for maintenance would count for a lot with me. Disassembling and reassembling a pump by feel is not a skill I really wanted to acquire!

Scroll to near the bottom of this page for some ideas on wet exhaust installation. They are promoting their own products, but the install info might be helpful: http://www.silencermarine.com/inglese/silenziatori.htm

 

I used to work in the design department for a company building the high speed patrol boats for the Taiwan coustguard. For smal engines like generators we used to let the exhaust out about 20cm abow sealevel and veld on a 90 degre albow pointing into the water.

Fully sumerged exhaust outlets have a greater risk off leting water inn if your veld cracks. For larger engines we used half sumerged outlets.