Gen set mounting

[SIBERNUT]

I'm installing a small diesel gen set. Exhaust will be above waterline in any case, but. Is higher better if room allows? (SMALL, STABILITY NOT A FACTOR)
Any other things I should consider? Plenty of access room.
TKS ALL!

 

[utclmjmper]

I personally would want it as low as possible considering oil changes and so forth..>>>Dan

 

[SIBERNUT]

Why low? Dont want water back up into exh. Would you put a drip pan under it?

 

[Keysdisease]

Consider secondary isolation, that is a second set of isolators in addition to the OEM mounts. Most Gen manufacturers account for this and provide mount points that are equidistant from the C/G.
The gen mfg may tell you "you don't need that" but there's a reason its standard on larger yachts, and the performance is much more noticeable on a small genset in a smaller boat.
Also consider a gen/sep in the exhaust. Not only will it make the exhaust much quieter. but if installed properly it will make back flooding near impossible.

Do both these things, and instead of saying "I feel the generator running" you will say "I think I feel the generator running

https://centekmarine.com/product/category/generator-exhaust/

 

[SIBERNUT]

Reply to gen

Tks! It's a Westerbeke with rubber mounts, are you saying I should do add'l ones? If I can figure it out, here's a pic of the muffler(?) I will use but on a different gen.

 

[mvweebles]

Good article from Northern Lights highlighting install considerations. Note three variations on Page 3 (exhaust manifold >1-foot above load/heel waterline; between 0-ft and 1-ft above waterline; and below waterline).

https://www.northern-lights.com/media/PDFs/misc_pdfs/dont_drown_me.pdf

Peter

 

[Comodave]

First make sure the platform is completely solid, no flex. Maybe add a 3/4” layer of plywood and glue and screw it down so you don’t get any oil canning noise from the platform. Then I add a vibration absorbing layer under the corners of the genset. Check with Soundown as to what they would recommend based on the genset weight. You can put in a too stiff absorption layer and it won’t do much if anything. The absorption layer needs to be loaded enough to work. I also have put a PSA pad on the bottom of the genset to absorb more noise. Soundown can give you specific recommendations but since you are starting from scratch you might as well do it as best as can be. You will enjoy the benefits every time you run the genset.

 

[twistedtree]

Good article from Northern Lights highlighting install considerations. Note three variations on Page 3 (exhaust manifold >1-foot above load/heel waterline; between 0-ft and 1-ft above waterline; and below waterline).

https://www.northern-lights.com/media/PDFs/misc_pdfs/dont_drown_me.pdf

Peter

Pay careful attention to this, and if there is anything you are unsure of, find someone to consult with. Exhaust installations are very boat-specific, and it's surprisingly easy to mess them up and very quickly ruin an engine. Even boat builders who do this all the time STILL screw it up with surprising regularity, moistly because they don't really understand the principals of what needs to be accomplished.

 

[mvweebles]

Pay careful attention to this, and if there is anything you are unsure of, find someone to consult with. Exhaust installations are very boat-specific, and it's surprisingly easy to mess them up and very quickly ruin an engine. Even boat builders who do this all the time STILL screw it up with surprising regularity, moistly because they don't really understand the principals of what needs to be accomplished.

Amen. Surprisingly, I'd reckon that almost every builder has had generator exhaust install issues somewhere along their lifecycle. Manifold may be above waterline at half-load but below waterline at full-load. It's a surprisingly common problem.

Peter

 

[SteveK]

I'm installing a small diesel gen set. Exhaust will be above waterline in any case, but. Is higher better if room allows? (SMALL, STABILITY NOT A FACTOR)
Any other things I should consider? Plenty of access room.
TKS ALL!

Above at anchorage, would it be quieter below waterline. Underway with following seas, an abrupt stop, can still enter without flapper.

 

[C lectric]

Go to www.sbmar.com and do some reading about exhaust systems from an expert.
Tony Athens does lot of exhaust systems for all kinds of engines but there are a few common requirements to ensure a good , non flooding of the engine installation.

Twisted Tree makes a very good point that it is all to easy to do a screw up installation that costs the life of ANY engine.

 

[fgarriso]

Consider secondary isolation, that is a second set of isolators in addition to the OEM mounts. Most Gen manufacturers account for this and provide mount points that are equidistant from the C/G.
The gen mfg may tell you "you don't need that" but there's a reason its standard on larger yachts, and the performance is much more noticeable on a small genset in a smaller boat.
Also consider a gen/sep in the exhaust. Not only will it make the exhaust much quieter. but if installed properly it will make back flooding near impossible.

Do both these things, and instead of saying "I feel the generator running" you will say "I think I feel the generator running.

 

[SIBERNUT]

First thing I have to do is ID that muffler and go from there.

 

[Bob328]

I installed a new nextgen 5.5kw genset on my Marine Trader 34dc last summer. The main concern per the engineers is that you have a gentle slope from the water lift exhaust to the thru hull exhaust fitting without any looping or sagging. Works great in all seas I also was told to make sure the mount was at least 3/4 inch fiber glassed plywood. i doubled mine to make 1 1/2 platform. It has no vibration and very low noise while running.

 

[Keysdisease]

Secondary Isolation is exactly that, in addition to the mounts on the unit now. Two sets of mounts are better than one, as COMODAVE says. Just like the picture I posted, there are mounts inside the cabinet as well as the ones circled.

A gen sep is a gas/water separator that works with a lift muffler. The lift muffler (most basic and common gen muffler) "lifts" the gas and water up as much as 4ft to the gen sep where the water and gas are separated. The water discharges through a dedicated thru hull and the gas exits (typically) at the boot somewhere. Any water coming up the gas exhaust at the boot gets separated at the gen sep and is just diverted to the water discharge. Very difficult to backflood an generator if a gen sep is installed correctly. Much quieter too.

These treatments need to be done with knowledgeable direction, won't work or might be worse if done incorrectly

Tks! It's a Westerbeke with rubber mounts, are you saying I should do add'l ones? If I can figure it out, here's a pic of the muffler(?) I will use but on a different gen.

 

[SIBERNUT]

TKS for the pointers! I am using a Hydro Hush muffler and will follow their diagram. Mounts will be as supplied by Wbeke on top of 2" channel spanning 26" apart stringers and above water line.

 

[twistedtree]

I just took a look at Westerbeke's engine and generator installation manual. It has sections on exhaust layout and raw water intake layout to protect against water intrusion. It's quite good - I'd even say better than NorthernLights' because it's more explanatory. I'd suggest reading it a number of times to be sure you understand WHY each guideline is the way it is. Then follow it all carefully.