Venatone inline muffler install

I will be installing inline mufflers on our 6BT5.9M Cummins next month. Looks like a really straight forward install. I am posting to get insights from the group and questions on things I have overlooked. The boat currently doesnt have mufflers. The attached drawing is not to scale but has critical measurement. Mufflers are Venatone MKII Round 1400006.

Support

We just installed two. They will need to be supported. Either in saddles or hung. Are you planning to use Venitone tubing as well? We installed these in an old Chris with six inch copper tubing. How would you like to buy that today. Double clamp everything right.
I witnessed one of these blow up like a bomb. Mechanic installing rebuilt gas engines managed to damn near blow himself out of the boat. The spigots on the mufflers had just been repaired with glass and resin. I'm not sure if the fumes from the resin or the fact the mechanic was having trouble getting the engines to start and possibly flooded the muffler with gas caused ignition. But let me tell the shrapnel went everywhere. Everyone escaped unscathed including the boat. The muffler was in small pieces.

Scary
I wont be using Vernatone tubing. I still have to figure out the supports. I was considering using the 1" bulkhead as a saddle but I think it would just add vibration and noise to the aft cabin. I will probably use straps. That sounded like someone got very lucky when that thing exploded.
How is the noise reduction with these mufflers?
Thanks

Risers

I'm assuming that the risers and lift to exhaust tubing will remain as before. Now is a good time to inspect your exhaust risers. Those turbos really don't like water.

They have a nice sound.

These were behind 8v71s naturals so no turbo rush. Use hangers with rubber padding if possible. Isolate vibration from bulk heads or anything that can abrade the mufflers.

Not much vibration from the muffler itself. I don't think you will have problem hanging them. Best is to glass in a saddle to the hull/stringers, and put a layer of rubber sheet between saddle and muffler. A 6" vernatone should work well with a 6BT (figuring you have 210hp?).

I LOVE the sound of 6B motor with straight exhaust. For about five minutes. Kinda like a Harley.

Don't forget to figure the weight of the water the mufflers will contain. Nylon webbing, like seatbelt size, makes a good, sound/vibration absorbing, hanger when securely attached with cleats above.

Ski in NC,
Harley's sound like an old farm tractor w bad manifold gaskets.

I think vibration should be isolated. The exhaust hangers on cars are flexible for that reason and the gas engines are smoother.

manyboats said:

Ski in NC,
Harley's sound like an old farm tractor w bad manifold gaskets.

I think vibration should be isolated. The exhaust hangers on cars are flexible for that reason and the gas engines are smoother.

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Re: Harley's.. That's where the "five minutes" bit comes in. After five minutes, it is annoying.

With flexible hose between engine and muffler, a firm mounting to hull will not cause a vibe problem in the hull. Nothing significant. Hanging it can cause the overhead to become a diaphragm, which is worse for sound transmission.

Just installed a Vernatone MKII Dual Stage Round Muffler behind a single 6BT5.9. It replaced a rubber Salisbury muffler that had hardened with age. Supported the muffler and all exhaust plumbing with rubber hose.

Recorded a reduction in sound of 3-7 dBa in the main cabin and aft deck. This was a significant improvement, although it increased exhaust resistance, but still well within engine tolerance.

Muffler project update

Well it was supposed to be easy!.............. I installed the port Vernatone MKII with only minor difficulty. The starboard turned into a nightmare. When I cut the exhaust hose I found the starboard hose has significant delaminating issues. It will all have to be replaced. It turned into a bigger job that I could handle at this time. I punted to the boatyard to replace. It will involve interference removal to get to the straps that hold the hose against the hull outboard of cabinetry. Nothing easy about htis one.

With my single engine in my sundeck boat, I was considering installing a Vernalift muffler by Centek as I wouldn't have the room for a longer "inline" Vernatone style muffler.

Dave, If there was delamination of the hose, there was probably a loss of cooling water/high heat at some point and all hose on that side should be suspect.

Port side OK?

Jay N said:

Dave, If there was delamination of the hose, there was probably a loss of cooling water/high heat at some point and all hose on that side should be suspect.

Port side OK?

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The port side looked good and didnt have any signs of delamination. The starboard side had bubbles inside the hose, no signs on the outside of the hose. I will be replacing the entire length on the starboard side exhaust. I changed all hose on both engines this winter and didnt see any issues. The starboard side may have seen a heating event while the previous owner had the boat, no way to tell. The boat is a 1989 and the hoses are probably 25 years old.