Mounting My Genset

[Excalibur]

I have a 4kw genset that I am going to mount in my carvel planked Chris Craft SeaSkiff. The maker's repair manual shows a suggested mounting where the water cooled exhaust passes through the transom, just like the main power. The maker wants a 2" exhaust. Should I run the exhaust through the transom on my old wooden boat, or out through the side? Are there any extra things I need to worry about if I take it out the transom? The gensets a Kohler 4EZ.

[rbgarr]

Re transom mounted exhaust: If you have a swim platform and spend time swimming off it, don't run the generator to run your stereo, blender, etc while at anchor. People have drowned and died from CO poisoning that way. The exhaust at anchor in a breeze may also be sucked back in to the boat via the station wagon effect if you have a cabin, etc.

Re side exhaust: if you moor dockside and use the generator there don't moor so the exhaust gets trapped between hull and dock.

In either case be sure the generator is mounted fore and aft like the engines, so water doesn't back up into the cylinders if trapped in the exhaust during a hard heel or big waves/wash from the side.

[Gary E]

In over 45 yrs of owning power boats, I have never seen or even heard of a side exhaust, run it out the transom just like the manual says and make sure there is a good fall from the manifold so water will not enter the engine.

[rbgarr]

From ABYC Standards, Section P-1 (and I know some don't regard them as useful)

1.5.2 ... (the exhaust from a gasoline generator) shall be installed in one of the following locations:

1.5.2.1 in the proximity of the intersection of the hull side and transom on the side of the boat, or

1.5.2.2 in the bottom of the boat,or

1.5.2.3 in the transom positioned as far outboard of the centerline as practicable, or

1.5.2.4 above the highest occupied deck and its weather enclosure/cover

As mentioned, Kohler's recommendations should be followed if possible. Check with them if you have a question.

[sdowney717]

what about under water exhaust?
extend a tube 3 inches under and cut the pipe at a 45 degree angle.
you would need a small hole to prevent a reverse siphon action.
I have wondered about doing something like this myself.

I added underwater exhaust extensions to my main engines, they were made by Submarine Research Inc, in 1960
Given to me by the marina taken off an old wooden hulk they were breaking up. They are made of a hard rubber, screw into the transom covering the exhaust outlett and run down into the water with the exit cut at 45 degrees and oval in shape. patent number 3162171
http://www.freepatentsonline.com/4002136.html
http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=%2Fnetahtml%2FPTO%2Fsrchnum.htm&r=1&f=G&l=50&s1=4002136.PN.&OS=PN/4002136&RS=PN/4002136
you will need quicktime plugin to view the one I have number 3162171. What amazed me was something made in 1964, I could find detailed instructions on how it worked, how to install it, picture diagrams etc...

I just read an article that underwater exhaust reduces CO by about 40%. New boats are built with an underwater exhaust and a valve arrangement with a side exhaust. at idle it exhausts out the side and after 1500 rpm, the exhaust exits underwater.

[Excalibur]

I was on a charter boat earlier this year and his genset exhaust was run through the side just forward of the transom, and that's what prompted the question. I'll run it through the transom next to the port main exhaust. I have no swim platform and use a boarding ladder over the side for water access, so that should work well. The manual is pretty explicit as to the fall required, it's 1/2" per foot. Chris craft kindly put in extra framing on the centerline aft of the fuel tanks just in case I wanted a genset, so mounting should be a piece of cake. Thanks all!