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Old 03-06-2014, 10:45 AM   #21
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Well, what the heck...I may as well tie in the head and macerator discharge. With a well-timed dump and a rev of the engine, I could spray those pesky jet-skis crossing my wake on the ICW.
This is exactly how the Vinette holding tank is plumbed.
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Old 03-06-2014, 11:26 AM   #22
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ABYC P-1 1.5.7 A separate exhaust system and terminus shall be provided for each engine and generator installation

P-1 also requires that back pressure shall be in accordance with manufacturer specification. Unless you have the ability to measure this on a joint system for both engine and generator you have another problem and will void your warranties.

Adding an a/c discharge to the mix endangers both genny and propullsion engine and is also prohibited by P-1
Don't know what to tell you. There are hundreds of boats that have it that way. There is a 100'+ yatch that visits Sunset Marina every summer. The marina doen't have big enough shore power for them, so they just run their generator all the time. Everything comes out this one pipe in the transom. Then again, maybe they have a generator that requires an 18' exhaust pipe.

Regarding water intrusion, both my generator and my engine have water lifts and the loops look to be 24"+ above the exhaust which exits above the water line. My generator has an exhaust water separator. The water is separated out and goes over board through a seacock in the bottom of the hull (to eliminate the splashing noise I've been told) and only the gas exits through the exhaust pipe.

While I've not done it yet, I will need to measure back plessure on the exhaust system for warranty purposes when we install the new motor.
While I haven't talked to the dealer (manufacturers representative regarding verification of all criteria for warranty), I imagine measuring back pressure on this system is not a big deal as they have to do it on all installations that have a water lift. Who knows, maybe they just put a gauge on the drain plug on the lift.


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Old 03-06-2014, 11:30 AM   #23
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Mr. Poker. "...is also prohibited by P-1". ABYC standards are NOT laws! They are what the boating industry in North America have agreed are probably good ideas to be applied to new builds.
AYBC P-1 1.7.2 states "An indicator shall be provided that is effective at all helm positions to indicate loss of exhaust system cooling water supply. This indicator shall be independent of the engine block temperature indicator(s)."
How many used boats have a loss of coolant water indicator? How many "giant red flags" has this raised on any of YOUR surveys?
I think the point has been made that shared exhausts are common while not, as Mr. RickB pointed out, necessarily a good idea.
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Old 03-06-2014, 11:54 AM   #24
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I don't recall saying anything about law.

My boats have always had raw water flow detector alarms at the helm.
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Old 03-06-2014, 12:15 PM   #25
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Greetings,

prohibited

Use Prohibited in a sentence
pro·hib·it

[proh-hib-it] Show IPA
verb (used with object) 1. to forbid (an action, activity, etc.) by authority or law: Smoking is prohibited here.

2. to forbid the action of (a person).

3. to prevent; hinder.

Didn't mean to yell. Just the way it copied. Good for you that you have a raw water flow detector. My question was how many vessels that you have surveyed failed the survey by not having one? I know several members have such a warning device but I suspect I'm pretty safe in saying that they are in the minority.
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Old 03-06-2014, 12:18 PM   #26
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Think that's pretty much how I explained it being done in post #7. You can see all the pipes if you look in the exhaust, but they all exit the transom in one large exhaust pipe. At least the ones I've seen combined do it that way.

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Perhaps we are confusing semantics but saying the same thing!
I have had the opportunity to look at literally hundreds of these boats in and out (for hurricanes) of the water here in eastern NC and in FL. I may have some photos on another computer, will look next time I have a chance.
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Old 03-06-2014, 12:25 PM   #27
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Greetings,

prohibited

Use Prohibited in a sentence
pro·hib·it

[proh-hib-it] Show IPA
verb (used with object) 1. to forbid (an action, activity, etc.) by authority or law: Smoking is prohibited here.

2. to forbid the action of (a person).

3. to prevent; hinder.

Didn't mean to yell. Just the way it copied. Good for you that you have a raw water flow detector. My question was how many vessels that you have surveyed failed the survey by not having one? I know several members have such a warning device but I suspect I'm pretty safe in saying that they are in the minority.
In context "prohibited" ... if you wish to meet ABYC Standards.
Surveyors do not pass or fail boats, they simply point out issues.
I always recommend (in my reports) raw water flow alarms where there is no engine temperature gauge (common on sailboats) or plastic mufflers.

PS. Sharing exhaust for any purpose is illegal in Canada (TP1332E) and European RCD,
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Old 03-06-2014, 12:27 PM   #28
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Ted: I don't think I've got that 24" above the water line for the lifts.....more like 16-18", limited by the veranda sole. Still, that's a lot more than I had for the genset when it was mounted under the galley, which needed an anti-siphon that went through the galley sole and looped under the fridge. For all practical purposes, the joint exhaust should work, and I envisioned the genset exhaust tubed into the top of the main exhaust, just as you described.

I've gone this far and to great expense for this swap. I'll do the two separate exhausts as recommended, but since both the main and the genset exhaust exit on the port side, it only makes sense to exit them easily to the port transom. Many boat owners complain about genset exhaust exits on one side or another, especially when they are rafting. I really dislike the idea of two separate exhausts on one side of the stern, but....
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Old 03-06-2014, 12:40 PM   #29
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Another plus with separate exhaust is you can look over the transom and see that both are pumping water as they should. Combined, the genny water flow could be reduced and it would be hard to tell.

When I installed the genny in my personal boat, I sent the exhaust out the port side a few inches above WL. When running hull speed, the exhaust is buried. In hindsight, I'd rather have run it straight out back to the transom.

On a few boats around here with genny and water lift in ER, and a long straight FG tube out to the transom, the long tube seems to get rid of the annoying whoosh-whoosh. The water flow seems to have a chance to even out in the pipe and just spill out the exit (mostly). Provided the tube is large enought, like 2" for 5-6kW.
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Old 03-06-2014, 12:51 PM   #30
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Mr. bp. RE: your PS....TP 13332E 9.1.2.7 does indeed state "No additional discharges other than cooling water shall share the exhaust gas passage." but does not mention sharing exhaust inputs to the same cooling passage that I could find.
TP 13332E as far as I can see is a LAW as are USCG requirements unlike AYBC which are recommendations. Not meaning to pick on you at all but the general consensus seems to be that AYBC is the law. I fully understand the need for guidelines and the guidelines DO provide direction and uniformity.
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Old 03-06-2014, 12:53 PM   #31
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Ted: I don't think I've got that 24" above the water line for the lifts.....more like 16-18", limited by the veranda sole. Still, that's a lot more than I had for the genset when it was mounted under the galley, which needed an anti-siphon that went through the galley sole and looped under the fridge. For all practical purposes, the joint exhaust should work, and I envisioned the genset exhaust tubed into the top of the main exhaust, just as you described.

I've gone this far and to great expense for this swap. I'll do the two separate exhausts as recommended, but since both the main and the genset exhaust exit on the port side, it only makes sense to exit them easily to the port transom. Many boat owners complain about genset exhaust exits on one side or another, especially when they are rafting. I really dislike the idea of two separate exhausts on one side of the stern, but....
The reason ABYC "recommends" (is that better ) that genny exhaust not exit at the transom is due to the potential for CO poisoning for people on the swim platform. This standard was adapted after a USCG press release and a NIOSH investigation of generator related fatalities in house boats.
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Old 03-06-2014, 01:10 PM   #32
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Agree with that. If you have (or plan to install) a swim platform, genny exhaust is better at hullside.

Also, CO risk is WAY higher with gasoline gennies. Diesel does create CO, but much less. I don't think I've heard of any CO poisoning cases with diesels.
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Old 03-06-2014, 01:13 PM   #33
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The problem with CO and diesels is that CO is cumulative and does not disperse from the blood for up to two weeks. Kids sitting on a swim platform over a long weekend can build up a significant amount of CO in their blood.
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Old 03-06-2014, 01:45 PM   #34
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The problem with CO and diesels is that CO is cumulative and does not disperse from the blood for up to two weeks.
Where did that come from, an ABYC class?

How about a 4 to 5 hour half life in fresh air, far less if treated with pure oxygen. The reduction is exponential.

Carboxyhemoglobin half-life in carbon monoxide-poisone... [Chest. 2000] - PubMed - NCBI
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Old 03-06-2014, 01:52 PM   #35
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Well, what the heck...I may as well tie in the head and macerator discharge.

It's already been tried.

thezld.com - Brochure

One of the steamboats I used to work on had a dedicated injector on the boiler front for just that purpose ... we called it the sh*t shooter.
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Old 03-06-2014, 02:01 PM   #36
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Where did that come from, an ABYC class?

How about a 4 to 5 hour half life in fresh air, far less if treated with pure oxygen. The reduction is exponential.

Carboxyhemoglobin half-life in carbon monoxide-poisone... [Chest. 2000] - PubMed - NCBI
Don't know any boats that carry pure oxygen and the half life is irrelevant without oxygen once it's in your blood.
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Old 03-06-2014, 02:09 PM   #37
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Yesterday at the wildlife museum I volunteer at, I noticed a tank of C02 with a hose leading to a clear plastic box. That's a testimony to the gas's effectiveness.
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Old 03-06-2014, 02:16 PM   #38
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Greetings,
Mr. m. And your point is? I think you've lost part of your post.
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Old 03-06-2014, 02:19 PM   #39
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I think Mark means CO not CO2
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Old 03-06-2014, 02:19 PM   #40
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RT, the point is C02 is an effective killer. I'd presume the reader can add 2 plus 2. Sorry for the goof. Confused C0 with C02. Both deadly gases.
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