3880/3860/4080/4060/3780 Generator Exhaust Mod

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Re: 3880/3860/4080/4060/3780 Generator Exhaust Mod

Postby kellyg » Thu May 14, 2009 2:24 pm

Jim,

I did the modification 2 years ago without adverse effects, but under the advice of the Westerbeke tech I did not submerge the PVC pipe. I have read here most people do place it underwater, but I will play it on the safe side! I use my genset mostly overnight, so the noise is not that much of an issue to me while in the cabin. To do this safely, I have added 3 additional carbon monoxide sensors.

**You will notice that the thru hull used on the 2001 3780 is not the same as in subsequent years, so the 'rubber' adapter does not fit snugly in place.

Image
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Re: 3880/3860/4080/4060/3780 Generator Exhaust Mod

Postby Southern Cross » Thu May 14, 2009 2:56 pm

Some people seem to be worried about adding back pressure to the exhaust system by placing the pipe under water. If 1.42 psi is a limit for the 7.3 as Chris_in_Texas stated earlier then I would not worry about a few inches of depth. For those of you that Scuba dive, you may remember that you increase atmospheric pressure onefold for every 33 feet of depth. This works out to 0.4336 psi per foot of water depth. Divide this by 12 inches per foot and you get 0.036 psi per inch of depth. This clearly shows that submerging the exhaust of the genny say six inches or so would only increase back pressure by 0.2 psi. This should be minimal impact on operation of the genny... go 3 inches if really worried about it for a 0.1 psi increase.

Here is a good web site to calculate pressure at any depth (of salt water) using any unit of pressure. Note that the web site uses atmospheric pressure for zero depth so be sure to subtract 14.6959 psi from any depth if you want to use standard air pressure as a zero baseline.

http://www.gazza.co.nz/waterpressure.html


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Re: 3880/3860/4080/4060/3780 Generator Exhaust Mod

Postby Jim_In_Calif » Thu May 14, 2009 6:57 pm

Thanks for the input Gary and Martin. Gary did you think of a way to snug up the adapter? This site is so great for answers.
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Re: 3880/3860/4080/4060/3780 Generator Exhaust Mod

Postby kellyg » Thu May 14, 2009 9:45 pm

I am heading down to the boat tomorrow to work on it. I will post my results.
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Re: 3880/3860/4080/4060/3780 Generator Exhaust Mod

Postby boatlover14 » Sun Jul 11, 2010 8:43 pm

I did the modification to my 7.3 Kohler on my 2006 3880 and put a release hole at the elbow. I noticed how water now exits the hole on the vented loop leading form the kohler hoses in the bilge. My aft bilge now comes on every few minutes when I run the generator.
I added a second hole half way down the pvc, and the water still comes out of the vented loop. Any recommendations?
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Re: 3880/3860/4080/4060/3780 Generator Exhaust Mod

Postby rommer » Sun Jul 11, 2010 10:17 pm

I'd say the vented loop is defective.

It's supposed to be a siphon break and should not allow water thru.
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Re: 3880/3860/4080/4060/3780 Generator Exhaust Mod

Postby boatlover14 » Mon Jul 12, 2010 7:33 pm

Should the vented loop have a thin clear hose attached to the middle of the loop
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Re: 3880/3860/4080/4060/3780 Generator Exhaust Mod

Postby boatlover14 » Sat Jul 31, 2010 8:30 am

I replaced the vented loop and there is a constant flow of water into the bilge throug ha clear hose off the vented loop. The modification only is submerged a few inches and I have 2 release holes for pressure. Any other suggestions since I hate to see water constantly flow into the bilge through the clear hose off the vent. Should there be a hose off the vent?
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Re: 3880/3860/4080/4060/3780 Generator Exhaust Mod

Postby rommer » Sat Jul 31, 2010 8:57 am

Is the loop ABOVE the water line?

Vented loops must ALWAYS be above the water line in all cases.

http://www.myboatsgear.com/featured_pro ... 0loops.asp

Granted the picture is for a waste line but the principle is the same for genny lines. BTW - the clear plastic line is to vent ODOR to another location. Sounds like someone added the vented loop improperly as Regal doesn't install them at the factory for this model boat.
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jabsco vented loop.jpg
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Re: 3880/3860/4080/4060/3780 Generator Exhaust Mod

Postby boatlover14 » Sun Aug 01, 2010 6:13 am

I will try that today. It is above waterline but horizontal.

Do you know anything about the sliding door? A mechanic knocked it offtrack and I wanted to know where to loosen rollers and re engage locking mechanism. They forced it without holding down handle. The starboard side is almost not sitting on the metal frame at all
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Re: 3880/3860/4080/4060/3780 Generator Exhaust Mod

Postby osukat » Mon Mar 21, 2011 7:23 pm

I was curious if anyone else had installed this since the last post. I have a 2006 3860 with the gas generator and just have a couple of questions with the installation.
1. I have all the parts and will be up to the boat this weekend to install but since I haven't looked at the exhaust system for a while I'm not sure what type of noise sepression/muffler system is on the gas genny now. I believe it is the Kohler 7.3 model. Just want to make sure I am not creating a siphoning situation.

2. With the PVC extending below the water line, is there any issues with it while underway? Does it drag or is it out of the water at that point?
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Re: 3880/3860/4080/4060/3780 Generator Exhaust Mod

Postby rommer » Tue Mar 22, 2011 1:11 pm

The PVC pipe is out of the water when on plane so no drag.
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2003 Regal 3880 (Traded in and sold)
2003 Regal 2860 (Sold)
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Re: 3880/3860/4080/4060/3780 Generator Exhaust Mod

Postby Above The Drink » Mon Jul 11, 2011 9:29 pm

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Re: 3880/3860/4080/4060/3780 Generator Exhaust Mod

Postby rommer » Tue Jul 12, 2011 3:24 pm

Gotta love how well it works eh?!
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Re: 3880/3860/4080/4060/3780 Generator Exhaust Mod

Postby WM4060 » Sun Jul 14, 2013 8:35 pm

I did this mod yesterday. It works great! Thanks so much for the tip.


rommer wrote:This mod dramatically quiets the generator exhaust noise.

Image

Image

The exhaust extension is a pressure fit, however there is a stainless steel clamp holding the entire assembly in place to the swim platform support so it doesn't move.

The rubber piece is available at your local Home Depot/Lowes and is a wet vac adaptor for going from a large hose to smaller hose. RIDGID Universal Power Tool Adaptor Model VT1407

Image
(Available at http://www.ridgidparts.com/accessories/VT1407.phtml)

Cut at the first step to the right from the square part. Use a dremmel type tool to reduce or taper the edge to help it fit in and the press in. The largest diameter fits perfectly around a 2" PVC fitting.

Total cost about $20

Cuts the noise which is amplified by the large swim platform WAY down!
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Re: 3880/3860/4080/4060/3780 Generator Exhaust Mod

Postby timp4411 » Sat Aug 31, 2013 4:34 pm

What's the PVC pipe size needed.... a 2"... correct ?

I assume it open on the end that goes underwater with no additonal adapters correct ?

And no problems with it falling out ? Even with all the vibration ?

How deep did most of you have the exhaust extensio going underwater? Is it 6", 4", 3"... just want to know what most of you have done.

This is one of the best Mods I've seen.... I can't wait to try once we get the 3860.

Thanks !
Last edited by timp4411 on Fri Sep 20, 2013 12:40 pm, edited 1 time in total.
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Re: 3880/3860/4080/4060/3780 Generator Exhaust Mod

Postby phatj33pyj » Mon Sep 02, 2013 6:18 am

Anyone done this mod on a 2760?

We were rafted up all weekend and I had the generator running. The echo between the boats was annoying since mine is a port discharge. I was hoping this mod might help.

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2001 Regal 2760
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Re: 3880/3860/4080/4060/3780 Generator Exhaust Mod

Postby Comfortably Numb NC » Mon Sep 02, 2013 7:01 pm

I tried this mod a couple weeks ago on my starboard side exhaust and did not achieve any noticeable reduction in sound. Last weekend I replaced the original 1998 water-lift muffler with a Vetus NLP3 water-lock muffler and the exhaust noise was greatly reduced. It also lowered the tone of the exhaust note. At 100' the splash of the water from the exhaust is louder than the exhaust.
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Re: 3880/3860/4080/4060/3780 Generator Exhaust Mod

Postby timp4411 » Fri Sep 20, 2013 12:44 pm

Rommer,

Thank you for sharing this great idea, I do have acoupe of questions....



Is the elbow a 45 degree ?

Can you tell me the length of the pipe from the elbow ?

Someone said there exhaust end is 5"-6" under water... is that about how deep your goes ?

I want to cut it and assemble it all before I go to the boat, so the info will allow me to do that.

And I see the SS clamp holding things togeather right at the exhaust openign from the boat, but you said: "The exhaust extension is a pressure fit, however there is a stainless steel clamp holding the entire assembly in place to the swim platform support so it doesn't move.". So is there also another clamp I cant' see in the picture holding the extension pipe to the swim platform support tube ?

Thanks
Last edited by timp4411 on Mon Sep 23, 2013 9:00 am, edited 1 time in total.
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Re: 3880/3860/4080/4060/3780 Generator Exhaust Mod

Postby rommer » Fri Sep 20, 2013 7:24 pm

timp4411 wrote:Rommer,

Thank you for sharing this great idea, I do have acoupe of questions....



Is the elbow a 45 degree ?


Sorry, don't remember. Looks like it might be smaller than a 45 from the pics. Get a 45 and a 30. They are about a buck and a half each.


Can you tell me the length of the pipe from the elbow ?


Again, it's been years since I did the mod. IIRC it was roughly 12-16" but maybe someone else can chime in that has done the mod more recently.


Someone said there exhaust end is 5"-6" under water... is that abotu how deep your goes ?


Yes

I want to cut it and assemble it all before I go to the boat, so the info will allow me to do that.

And I see the SS clamp holding things togeather right at the exhaust openign from the boat, but you said: "The exhaust extension is a pressure fit, however there is a stainless steel clamp holding the entire assembly in place to the swim platform support so it doesn't move.". So is there also another clamp I cant' see in the picture holding the extension pipe to the swim platform support tube ?


Yes, there is a ss clamp below the water line that holds things together.
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2004 Silverton 48/50C
2003 Regal 3880 (Traded in and sold)
2003 Regal 2860 (Sold)
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