Exhaust anti-siphon hose

MMLOGAN

Member III
Vented Loop

Mark,

On my Yanmar it is a true vented loop. Mine is mounted next to the trash bin, just below the opening to the Starboard lazzarette. Yours appears to be mounted to the top of the engine compartment which would seem to be the correct place.
 
ant siphon

I have a 1983 Mark 3, 35"...Sketcher.
Found out the original hose was not strong enough. Coming back from a two week cruise, (motoring) bilges were overflowing and water coming on the sole.

With much panic, found the anti siphon had burst near the exhaust end. Replaced with gas line hose.


Hilco on Sketcher
 

MMLOGAN

Member III
Did not mean to confuse!!!

Mark,

My vented loop looks to be the same as the one in your link with the exception that it is metal rather than plastic.
My overflow hose leads back down to the engine bilge area. Not sure if that is proper. PO did that work...
 

Shelman

Member III
Blogs Author
I just rebuilt my entire exhaust system including the anti siphon hose, through hull, and vented loop/pipe. I used a true tee fitting with a reducer instead of the soldered in pipe bit. http://www.ericsonyachts.org/infoexchange/entry.php?258-Exhaust-Rebuild-E-26
there is no valve in the anti siphon loop system, just a hose to drain the loop and introduce air into the loop to prevent siphon. It must exit transom above heeled waterline in order to function.

There is also some good info from sbmar website : http://www.sbmar.com/articles/designing_a_marine_exhaust_system/

you need a vented loop to prevent siphon flooding of the exhaust and subsequently your engine valves unless your wet injection spillover point is quite allot higher than your exhaust spillover point down stream from the lift muffler.
 
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mkollerjr

Member III
Blogs Author
I just rebuilt my entire exhaust system including the anti siphon hose, through hull, and vented loop/pipe. I used a true tee fitting with a reducer instead of the soldered in pipe bit. http://www.ericsonyachts.org/infoexchange/entry.php?258-Exhaust-Rebuild-E-26
there is no valve in the anti siphon loop system, just a hose to drain the loop and introduce air into the loop to prevent siphon. It must exit transom above heeled waterline in order to function.

There is also some good info from sbmar website : http://www.sbmar.com/articles/designing_a_marine_exhaust_system/

you need a vented loop to prevent siphon flooding of the exhaust and subsequently your engine valves unless your wet injection spillover point is quite allot higher than your exhaust spillover point down stream from the lift muffler.

Thanks. Do you have a link or photo, or more description on the tee fitting you used?

Mark
 

Shelman

Member III
Blogs Author
It is exactly like the one mainsail built, shown in the link. I will snap a picture and post it here.
 

Shelman

Member III
Blogs Author
siphon break ericson 26 sailboat.jpgericson sailboat transom through hulls.jpg First picture is my new siphon break with raw water bypass bolted to the underside of the counter next to the sink. The second picture is my transom with the new through hull for the bypass discharge directly above the exhaust outlet.
Let me know if I can post any other helpful pictures. :)
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
Nice!

View attachment 16102View attachment 16103 First picture is my new siphon break with raw water bypass bolted to the underside of the counter next to the sink. The second picture is my transom with the new through hull for the bypass discharge directly above the exhaust outlet.
Let me know if I can post any other helpful pictures. :)
The transom arrangement of the syphon break outlet over your exhaust is now exactly like the stock scheme on our Olson 34. I might also want to copy your syphon break fitting combo, if ours ever needs replacement -- it looks very well thought out!


Loren
 

mkollerjr

Member III
Blogs Author
Thanks for the photos. Looks like you put something together with bronze fittings. I will look to do something similar. The marine sail photo kind of confused me, because it looks like he did it all in brass, which I thought you weren't supposed to use in salt water.

Matk
 

Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
Thanks for the photos. Looks like you put something together with bronze fittings. I will look to do something similar. The marine sail photo kind of confused me, because it looks like he did it all in brass, which I thought you weren't supposed to use in salt water.

Matk
Come over to the Stainless Steel fitting side... :)
Feel the power of the (shiny) Force!)

:rolleyes:

Loren
 

mkollerjr

Member III
Blogs Author
Hmm, putting together all these bronze fittings to get this to work is getting expensive and also adding a lot of joints to the system. I'm thinking of just installing a 5/8" Marelon vented loop instead. They have an option of replacing the threaded vent cap with a 1/4" nipple for the hose to the fitting at the transom. Seems a lot simpler. Am I missing something?

mark
 

Shelman

Member III
Blogs Author
Stainless is cheeper too! I always feel torn betwene the bronze and the stainless. Stainless can develope pitting I know but bronze can de-zink so I think it's a wash. I prefer bronze because its softer and it always seems that I need to make a cut or file a sharp edge and it's a breeze with the bronze.
 

Keith Parcells

Sustaining Member
Hmm, putting together all these bronze fittings to get this to work is getting expensive and also adding a lot of joints to the system. I'm thinking of just installing a 5/8" Marelon vented loop instead. They have an option of replacing the threaded vent cap with a 1/4" nipple for the hose to the fitting at the transom. Seems a lot simpler. Am I missing something?

mark
I would definitely use the Marelon vented loop. No corrosion or galvanic issues possible with Marelon.
 

Shelman

Member III
Blogs Author
Yup the marelon will work just fine for that. It just wasn't as compact and conforming for where I wanted to put it.
Almost anything is better than the little soldered/brazed on bit that I took out. It's days we're numbered... The one at the transom was similar and had already failed.
 

Curtis

Junior Member
bronze elbow thru-hull replacement

Hi Everyone,

I was replacing the old, crazed exhaust hose on our E-38 when the iron pipe extending from the bronze exhaust exit elbow sheared off (the bronze elbow is attached to the thru-hull at the underside of the transom and has the funny little nipple soldered to it).

The bronze elbow is a goner - too corroded to reuse.

I'm looking for ideas for a replacement. I'd like to get a sea-valve on that thru-hull so we can close it in following seas (just need to remember to open it before starting engine!). I'm a total newbie on this stuff, so forgive me if the solution is obvious!!

I'll try to post some pictures when I get to the boat later today.
 

footrope

Contributing Partner
Blogs Author
Hi Everyone,

I was replacing the old, crazed exhaust hose on our E-38 when the iron pipe extending from the bronze exhaust exit elbow sheared off (the bronze elbow is attached to the thru-hull at the underside of the transom and has the funny little nipple soldered to it).

The bronze elbow is a goner - too corroded to reuse.

I'm looking for ideas for a replacement. I'd like to get a sea-valve on that thru-hull so we can close it in following seas (just need to remember to open it before starting engine!). I'm a total newbie on this stuff, so forgive me if the solution is obvious!!

I'll try to post some pictures when I get to the boat later today.
I attached a picture of the exhaust valve and elbow installed in my E38. The shutoff valve is a full-flow type and happens to be 2" in diameter. When my exhaust system repair/installation was done in 2004 I was a newbie and I had it done by a shop and they did a good job. It was expensive. The exhaust size was increased from 1.25" to 2" diameter and that meant new everything from the exhaust flange back to the thru-hull. You may not want to go that far if you have the smaller diameter.

I've never felt we needed to close it in a following sea in our little piece of inland paradise here in the Northwest. So, basically, I never close it. The exhaust hose has a big bend that comes above the waterline in the lazarette as yours probably does. But, if I were to go offshore the valve is there. The little hose is a siphon break or vent from a tee in the raw water outlet hose that goes to the exhaust elbow fitting. That tee is raised up above the waterline too above the engine.

NewExhaustShutoffValveThruhullJuly2004-small.jpg
 

Kenneth K

Sustaining Member
Blogs Author
I've been following this post with interest because, as Jerry said earlier, the E32-3 has the same setup (none of which I understood until reading this post).

I agree with Cory's thought that,

“I am still a little confused though why they "vented" the antisiphon line to a fitting that is sometimes below the waterline when the boats in motion. But at rest it would obviously do its job….”

Most of these systems are new to me but it seems like this anti-siphon loop would have to be viewed in two different ways, depending on whether the engine is running or not running.

With the engine running: (it seems…..)

- (1) there is no need for the anti-siphon function of the loop. The engine is putting out enough exhaust gas pressure to force both air and water up a 1.5” (or greater) exhaust pipe. The danger of water “entering” the exhaust pipe (let alone, progressing further, via siphoning, into the engine) with the engine running should be a non-issue.

- (2) the danger of exhaust fumes entering the anti-siphon line at the tee (and thus, venting at the line's exit point) seems remote. A steady stream of water should be flowing through the raw water line (that the anti-siphon line tees into), on it’s way to the mixing elbow. If a steady stream of water is not running through the line, you have bigger problems and a pending overheat, and you won’t have the exhaust fumes for long….

- (3) the possibility of water entering the anti-siphon line at the “tee” seems pretty likely. This would occur if there is corrosion or blockage past where the raw water line hits the injection elbow. A flow restriction at the injection elbow might force water into the anti-siphon loop. This possibility may be one of the reasons why Ericson plumbed the anti-siphon vent back to the exhaust pipe at the thru-hull: it may have to vent air, water, or both.

With the engine stopped: (it seems…..)

- (4) now there IS a need for an exhaust-line anti-siphon loop (if your engine is below the waterline). The head-scratcher here is that with the engine stopped, say when sailed and heeling, it's possible that both the exhaust line and the anti-siphon vent (which share a thru-hull) are submerged……and you have no anti-siphon protection in precisely the situation when you need it.

- (5) obviously, there is no danger of exhaust entering, or engine raw-water leaving, the anti-siphon loop with the engine not running.

So………..If the above are true, then ideally, the anti-siphon loop should be vented to the atmosphere in a location that is

A) above the waterline when sailing (#4 above), and
B) suitable for the drainage of both air and water (#3 above)

This gives me the thought that high up on the transom might be the ideal place for an anti-siphon vent. On my boat, the fuel tank vent is on the port-side upper transom.

Maybe the starboard side would be the ideal place to vent the exhaust anti-siphon loop.
 

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Loren Beach

O34 - Portland, OR
Senior Moderator
Blogs Author
Once you start gathering information, it might maybe perhaps be possible to over-think this. i.e. there really is not a problem :rolleyes:

OTOH, if the original water-lift muffler is ever replaced, the capacity Does Indeed have to be sufficient for the water that it has to hold when the engine is shut off.

On our boat both the highest loop for the exhaust and the small-diameter syphon vent hose are routed high up under the lip of the cockpit seat hatch, on the inside face of the fiberglass where it's closest as possible to the center of the boat. When the engine is shut off, both hoses drain down and out the transom from that high point. Any sea water on the forward side would indeed drain back into the muffler, but it appears that the muffler was correctly sized for this.
We have spent most of a day running down wind in big seas, and while occasional sea water sloshed up thru the drains (!) :)
there was never an evidence of it getting to the muffler and engine.

My "swag" is that Ericson designed this part of the system very well, and that routing that involved tee-ing the syphon drain into the inside of the transom exhaust fitting was done to reduce thru-hulls for appearance's sake. Just a guess, however.

The syphon exit is just above the exhaust in the photo is this thread - different than the "Ericson's" of that period, with their inside T fitting on the exhaust fitting.
http://www.ericsonyachts.org/infoexchange/showthread.php?7890-Transom-Thru-Hull-Replacement
Reply #5.

Loren
 
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