Exhaust hose questions

[CharlieO.]

What is this part that is between the exhaust hose and transom exit? I thought it was a check valve it appears to have some sort of baffles inside on the outer perimeter.



Is it common to have this sort of splice in the exhaust hose? It looks like a four inch exhaust hose was used as a sleeve to couple the 3 1/2 inch exhaust hose together. Everything thing was double clamped .

I am planning on replacing the exhaust hose so just want to be sure I do it correctly.

Best place to source exhaust hose? Any tips on install and preferred hose?

 

[O C Diver]

It's most likely a muffler.

Ted

 

[psneeld]

Fat part looks like a muffler.

While done, splicing hose to hose is not as preferred as using fiberglass connectors (reducers if warranted) with stainless reinforcing rings.

 

[CharlieO.]

I don’t know why it being a muffler didn’t cross my mind, maybe because it’s rubber. I always thought the muffler was on the engine room end of the hose where the engine exhaust goes into the top of a stainless steel cylinder then the exhaust hose goes from the top of there to the exit.

 

[mvweebles]

Looks like you have a fairly straight run. Fiberglass tubing would be preferable to hose if you have space to slide it in. You can use short sections of old hose as couplers.

https://www.fisheriessupply.com/centek-vernatube-fiberglass-wet-exhaust-tubing/1100502-10

I'd remove the muffler and see how it goes without it. Also, if your engine is below waterline, I'd confirm this is a muffler and not a check valve which would be an inadequate way to address possible back flooding of the engine.

Peter

 

[CharlieO.]

Looks like you have a fairly straight run. Fiberglass tubing would be preferable to hose if you have space to slide it in. You can use short sections of old hose as couplers.

https://www.fisheriessupply.com/centek-vernatube-fiberglass-wet-exhaust-tubing/1100502-10

I'd remove the muffler and see how it goes without it. Also, if your engine is below waterline, I'd confirm this is a muffler and not a check valve which would be an inadequate way to address possible back flooding of the engine.

Peter

It is a mostly straight run except the 90 degree turn in the engine room.
Why do you suggest going without out the muffler, pretty sure it’s not a check valve as I can look see through it from the end. The ‘muffler’ is not easy to get to so it will be a one and done. Removal of rudder post and water tank to get to where to muffler is attached to the transom. We are very happy with the decibel level inside and out while underway. I do plan on replacing the thru transom fitting also so will give that muffler a good inspection once completely removed.

I only want to get this deep into the lazerette once, so want to be sure I do it correctly.

 

[rslifkin]

It is a mostly straight run except the 90 degree turn in the engine room.
Why do you suggest going without out the muffler, pretty sure it’s not a check valve as I can look see through it from the end. The ‘muffler’ is not easy to get to so it will be a one and done. Removal of rudder post and water tank to get to where to muffler is attached to the transom. We are very happy with the decibel level inside and out while underway. I do plan on replacing the thru transom fitting also so will give that muffler a good inspection once completely removed.

I only want to get this deep into the lazerette once, so want to be sure I do it correctly.

If you want a permanent solution, consider installing fiberglass tubing for that whole run. You could even glass that right through the transom to eliminate the hose joint in there for less future maintenance.

Mufflers can go anywhere in the run, so you could still have one back there with tubing, just a question of where in the run it fits best.

 

[RT Firefly]

Greetings,
Mr. CO. Yep. Muffler. Had two on our 1950 Chris Craft. Twin Hercules gas engines but copper tubing for the long runs. Even said "Quiet-tone" or similar. I concur with replacing all with FG tubing. I think one can even get 3" to 4" transitions (LOTS of profiles and shapes).

 

[mvweebles]

Why do you suggest going without out the muffler, pretty sure it’s not a check valve as I can look see through it from the end. .......

I only want to get this deep into the lazerette once, so want to be sure I do it correctly.

Because it sounds like you already have a traditional lift muffler in the engine room, albeit stainless steel which is not a good material given the hot, caustic nature of salt water exhaust.

Exhaust problems are probably the #1 cause of premature engine death in our class of boats. My suggestion would be to carefully examine the entire system from engine to outlet. Don't assume that because it's worked for years that it was properly designed and installed.

I don't blame you for only wanting to do it once. It's expensive and, as you mention, often tedious.

Peter

 

[rslifkin]

Interestingly, despite having huge 2 stage water lift mufflers, I've considered adding a small muffler in line to my exhausts further back (as depicted here).

At a certain RPM range there's a bit of an echoing drone from the exhausts (which are otherwise very quiet) that could likely be reduced by an extra muffler to break up the 12 foot run of tubing. The only part I haven't figured out is why the drone seems to be worse from the starboard side than the port, yet there's nothing different between the systems (and they sound identical at other speeds).

 

[mvweebles]

Interestingly, despite having huge 2 stage water lift mufflers, I've considered adding a small muffler in line to my exhausts further back (as depicted here).

At a certain RPM range there's a bit of an echoing drone from the exhausts (which are otherwise very quiet) that could likely be reduced by an extra muffler to break up the 12 foot run of tubing. The only part I haven't figured out is why the drone seems to be worse from the starboard side than the port, yet there's nothing different between the systems (and they sound identical at other speeds).

Mufflers might help given you have larger, higher RPM gassers, especially with twins prone to a harmonic drone. Guessing CharlieO's 34-ft CHB has a single Ford Lehman 120, perhaps a Perkins 6.354, either of which are typically run around 1800 RPMs, maybe 2200 RPMs tops. I'd be curious what other folks do - there are a lot of similarly conigured boats out there.

CharlieO - leaving aside muffler question, why are you servicing your exhaust hose? Is the rest of the system in good condition? The mixing elbow? And the Stainless Steel lift muffler?

Peter

 

[PM]

If you already have a water lift muffler what you are showing is probably a back flow preventer. I would not bypass it.

pete

 

[rslifkin]

Mufflers might help given you have larger, higher RPM gassers, especially with twins prone to a harmonic drone. Guessing CharlieO's 34-ft CHB has a single Ford Lehman 120, perhaps a Perkins 6.354, either of which are typically run around 1800 RPMs, maybe 2200 RPMs tops. I'd be curious what other folks do - there are a lot of similarly conigured boats out there.

CharlieO - leaving aside muffler question, why are you servicing your exhaust hose? Is the rest of the system in good condition? The mixing elbow? And the Stainless Steel lift muffler?

Peter

Oddly, the drone on mine is right in the slow cruise region. It's most noticeable from about 1200 - 1500 RPM, so even lower RPM than many of the diesels here cruise at. As best I can determine, at that RPM there's enough of just the right frequency to resonate in the big, long exhaust pipes between the mufflers and the transom outlets (about 12 feet of 5" fiberglass tubing).



Thinking about that resonance, for all of its downsides, the long run of rubber hose that CharlieO has currently might actually be quieter, as the rubber will be less likely to resonate than fiberglass.

 

[CharlieO.]

Mufflers might help given you have larger, higher RPM gassers, especially with twins prone to a harmonic drone. Guessing CharlieO's 34-ft CHB has a single Ford Lehman 120, perhaps a Perkins 6.354, either of which are typically run around 1800 RPMs, maybe 2200 RPMs tops. I'd be curious what other folks do - there are a lot of similarly conigured boats out there.

CharlieO - leaving aside muffler question, why are you servicing your exhaust hose? Is the rest of the system in good condition? The mixing elbow? And the Stainless Steel lift muffler?

Peter

Peter you are correct I have the Lehman 120, usually cruise 1700 rpm.
Reason for the exhaust hose assessment is swim platform bracket replacement. Project creep. To get to to the swim platform hardware I needed to remove to the water tanks, to remove the water tanks I had to remove my rudder so I could pull the rudder shaft out. While I am in there the only thing else is the exhaust and it runs outboard of the port water tank, this is the only time I will have this kind of access. Hard piping from the transom to at least thru the aft bulkhead seems appealing though. My only concern with that is that would put my muffler under the port bunk.

 

[rslifkin]

Peter you are correct I have the Lehman 120, usually cruise 1700 rpm.
Reason for the exhaust hose assessment is swim platform bracket replacement. Project creep. To get to to the swim platform hardware I needed to remove to the water tanks, to remove the water tanks I had to remove my rudder so I could pull the rudder shaft out. While I am in there the only thing else is the exhaust and it runs outboard of the port water tank, this is the only time I will have this kind of access. Hard piping from the transom to at least thru the aft bulkhead seems appealing though. My only concern with that is that would put my muffler under the port bunk.

You could likely keep the muffler in a similar location. Just splice it into the hard pipe run (either with hose couplers or glass the pipe to the muffler connections).

 

[CharlieO.]

You could likely keep the muffler in a similar location. Just splice it into the hard pipe run (either with hose couplers or glass the pipe to the muffler connections).

The muffler takes up the whole run in the Lazarette from the transom to just thru the bulkhead under the port bunk. The muffler is made of some sort of hard rubber. The appeal of hard piping from the transom is eliminating any clamps or connections somewhere inaccessible.

 

[Jeff F]

I have a similar in line muffler like yours in addition to a water lift unit. I thought my boat may not have had a water lift originally, but not sure. In any case it's very quiet on the outside.

If the inside of your exhaust hose looks ok I'd be tempted to put it back together and find a different project. My limited understanding is that the hose typically deteriorates from the inside.

 

[alormaria]

Congratulations! You've found the one thing different between our boats.


Mine does not have that muffler-like thingy in the exhaust hose. Never did. Just straight exhaust hose out the back.


If you decide to replace the hose with a straight fiberglass tube let me know. I'd pay good money to see how you are going to get it in that boat!



I used a short 6" fiberglass tube to join the two 12' hoses when I replaced mine.

 

[CharlieO.]

Congratulations! You've found the one thing different between our boats.


Mine does not have that muffler-like thingy in the exhaust hose. Never did. Just straight exhaust hose out the back.


If you decide to replace the hose with a straight fiberglass tube let me know. I'd pay good money to see how you are going to get it in that boat!



I used a short 6" fiberglass tube to join the two 12' hoses when I replaced mine.

If I were to go the fiberglass tube route I would go through the transom. I am thinking of just using a three foot section of fiberglass pipe from hose to muffler to replace that current hose joint. The hose itself checks out good, may or may not replace it.

Like Jeff said, might be better off reallocating effort on other things.

I will be rebedding\fastening the through transom exhaust fitting and putting the good clamps on muffler end in the lazerette. I have much more intimate knowledge of my exhaust hose system now, and check that off my wish I knew more list. I do have silicone hose from the exhaust elbow to the water lift.

 

[RT Firefly]

Greetings,
When I removed the engine to replace the fuel tanks, last fall, in our 23' Penn Yan Avenger (1979 vintage), the exhaust hoses looked fine from the outside BUT the first inside layer had de-laminated to the point where you could barely see end to end in a 4' section. There was still an opening and it did not seem to affect the operation of the motor (Mercruiser 210?HP) but both 3'' and 4'' were well past their useful life IMO. I suspect age and time took their toll.
Hope to get an extra .7HP! Vroom.

 

[CharlieO.]

RT, I will definitely do a more thorough inspection but upon initial man handling from both ends I haven't seen cause for alarm yet. I do feel more confident now knowing I can replace the hose with access from the aft cabin and engine room.

 

[kapnd]

The reducing splice is in no way kosher. IF the reduction is acceptable??, it should be done with a concentric reducer to preserve the flow line in the bottom of the pipe.
I’d use fiberglass tubing wherever possible, only using rubber to make connections and soak up misalignments. That run should always drain towards the transom. Rubber sections inevitably develop sag, trapping water.

 

[CharlieO.]

The reducing splice is in no way kosher. IF the reduction is acceptable??, it should be done with a concentric reducer to preserve the flow line in the bottom of the pipe.
I’d use fiberglass tubing wherever possible, only using rubber to make connections and soak up misalignments. That run should always drain towards the transom. Rubber sections inevitably develop sag, trapping water.

It wasn't actually a reducer the two 3 1/2" hose were coupled together with a piece of 4" hose sleeved over the top and clamped. I'm considering adding fiberglass tubing from the splice in the hose to the muffler.

 

[kapnd]

It wasn't actually a reducer the two 3 1/2" hose were coupled together with a piece of 4" hose sleeved over the top and clamped. I'm considering adding fiberglass tubing from the splice in the hose to the muffler.

A break in the line should be coupled with a sleeve of fiberglass pipe on the inside of the pipe, so that the rubber can be securely clamped over a rigid ferrule.
Your surveyor missed an important boo boo that your insurance company would surely not like.

 

[Comodave]

If it were me doing the work, all the effort to assess the condition of the hose would be a waste of time. I would just replace it unless you could ensure it was less than 10 years old. Most hoses have a life expectancy of 10 years. I would bet that the hose is way older than it life expectancy.

 

[Each finger a marlinspike]

When you put it back together make sure you are double hose-clamping all exhaust connections, it's a USCG requirement and not done on the previous installation in your photos. Check all your other exhaust connections in case they did them improperly also.

 

[lwarden]

Looks like a Salisbury muffler, not very common these days. As others have stated, the splice to it is not Kosher. I would probably put a Vernatone FG muffler in it's place with longer runs of FG tubing as possible. I played around with these on my last boat and they really quieted down the boat significantly.

 

[Nick F]

> . . . it should be done with a concentric reducer to preserve the flow line in the bottom of the pipe.. . .

This is a nice detail, but I think you meant to say ECCENTRIC. (as in right hand image)

 

[Comodave]

I was doing some work in the engine room of our last boat and had the starboard engine out of the engine room. I just happened to glance at one of the exhaust hose clamps and it was just hanging on the hose nowhere near tight. The PO had used some Ace Hardware type of clamps and it had rusted through. So I replaced all of the clamps on both exhausts.

 

[C lectric]

Mufflers work by slowing the gas travel in the large part and then speed it again in the smaller part. Same volumn is still travelling. That speed change affects the sound waves causing reflections backwards at the muffler outlet port and direct interference to the faster incoming waves as they exit from the engine side.

Often they also have baffles and partial bulkheads to force the sound waves to change direction which also breaks up sound pulses from the engine.

In your case with a water lift it may not be needed but talk to a marine exhaust guy.

No, I don't know all the technical terms.

I sort of half wonder if the P.O. added that "muffler" to help quiet the noise from an inadequately, to them, muffled engine.

Just a guess.