exhaust noise

[Capt Ratty]

I have a 1968 tc with twin 6 / 53 Detroits. The exhaust noise is very loud, almost to the point that you can't carry on a conversation without shouting. The rpm is at 1200 to 1500. Are other boats this loud or do I need mufflers?
Is it a design flaw? If I need mufflers, where is a good source?
There are no apparent exhaust leaks. The starboard exhaust hose was recently replaced.
Thanks

 

[J's Dream]

Are they naturals? My 892N's are really loud. People tell me they I wake them up and they live 4 houses away! I think they are just that loud.

 

[Boatsb]

Welcome to the "garbage truck club" I have 8v53's and yes they are loud. naturals don't do well with mufflers and to be honest we got used to it.

 

[Brian Degulis]

Naturals will be louder than turbos. Metal or fiberglass exaust lines will be louder than rubber. A lack of water flow will increase noise. The most efective muffler is the lift type a larger version of what's on your generator. My last boat had 671 naturals Centec 6" lift mufflers made it as quite as a church mouse.

Brian

 

[neosin]

My hatt is loud with 8v71s... But i like it, has that oldschool hotrod boat sound... everyone knows it's my hatt... I've had other hatt guys come up and ask if i did something... lol i even have rubber pipes... I think it's the 871s that have that really deep sound... I like it, sometimes it can bother you in the wrong rpms my 1200rpm is really bad, the drone will make it so you can't speak with out yelling, but my 10kts rpm does very well you can talk normally... Maybe play with your rpms and see if you can find something that works well without eating up to much fuel.

Even 50 - 100 rpms can make a major change the way is drones in the lower helm. My flyingbridge doesn't drone on us at all... You hear it but isn't not loud at all up there.

Today with my engine tech we ran the boat with all of my floors up checking rpm, heat, oil leaks after a tuneup. It helped. Temps are 185 and 183 at 1950rpms doing 14kts. 190 on both at 2050 rpms doing 15.3kts, Didn't test wot as i know it will climb to 200 after about 30 mins. Will be doing some fuel flow tests soon i'll post them up later...

oh yea, running at them rpms with no floors, WOW now thats loud, sounded like i was in the middle of a tug with full load on my lower helm. I can't believe how well my floors deaden the sound.

...out

I have a 1968 tc with twin 6 / 53 Detroits. The exhaust noise is very loud, almost to the point that you can't carry on a conversation without shouting. The rpm is at 1200 to 1500. Are other boats this loud or do I need mufflers?
Is it a design flaw? If I need mufflers, where is a good source?
There are no apparent exhaust leaks. The starboard exhaust hose was recently replaced.
Thanks

 

[Dustoff44]

Is there a source or website for Centec ?

 

[Capt Ratty]

Ok, they are naturally loud. How can I tell if the mufflers are shot. A 40 year old boat with probably the original mufflers? What else can be done without the expense and hassle of replacing them? Access is very limited. Did Hatteras forget something when they put together a luxury yacht? Would it be quieter at a higher rpm? Unlikely. Do you have to wear earplugs? I can't emagine cruising all day with that much noise.

 

[Capt Ratty]

neosin
I will try some rpm variations.
Thanks

 

[neosin]

The only real rpm that just kills me is 1200 - 1240 ish for me. Just DRONES like mad... But about 1320 is almost quiet I can cruise for 8 hours without problem. Mine doesn't have mufflers on the engines. Remember this was the 1970s, mine being a 1972, Big blocks and deep engine sound was very "in"... To me it still is as i used to race drag... So really i like it lol.

Play with your rpm, When i'm at cruise rpm, 1950 - 2050 doing 14 - 15kts i get no drone and it lowers down, you get more water noise than anything else really.


...wanted to add, Inside the salon, forget about it... engine nose at 14kts is nuts. However my wife sleeps in the rear cabin at 8-10kts all the time. My buds watch tv in the salon granted it's turned up when I'm at 8-10kts.

neosin
I will try some rpm variations.
Thanks

 

[Brian Degulis]

Is there a source or website for Centec ?

Yes there should be either search centec or vernatone

Brian

 

[Boatsb]

6" vernatones are $400 each. 8" are $650 or so each. The 6"i s not good over about 275 HP.

 

[jim rosenthal]

Two-cycle Detroits ARE loud. It would be worth putting mufflers in; I had a ride recently on a Chris-Craft MY with 6v92TAs. It had factory waterlift mufflers and was very quiet for a boat with DDs. In-line mufflers would be easier to put in, I suspect. Neither will be cheap.

Much of the time spent on the current Blue Note repower project was spent on the exhaust system. This is difficult to install without taking up the aft deck. She had straight pipes before, marginally acceptable with turbos, not acceptable with naturals. She was loud. 4 cycle diesels are inherently quieter than DDs (I don't know why) but with her new exhaust systems she will be much quieter.

 

[Nonchalant1]

Send a PM to "Walter P" on the forum. He has a beautiful 48MY that he put new 4 mufflers in (even though they recommended only 2) and it's so quiet on the bridge that he has to check the tachs to make sure when the engines are running. He can tell you the make and model he put in. He had to disassemble cabinets, etc. to do the work.

Doug

 

[captainhawk]

if you want vernalift or vernatone muffler info search

Centek not centec

company website is www.centekindustries.com and their tech reps are great on the phone.

product list on the internet is much better than what most marine stores or mechanics will tell you. A lot of design variations and sizes coupled with fiberglass tubes and elbows helps with installation. most marine stores stock only a few size combinations.

I put an inline vernalift on a small dive boat with Detroit 453 - shopping now for gen muffler for 45 Hatt.

 

[neosin]

note and update, after putting on the new props that have loaded the engine the noise level has went down quite a bit at 9kts cruise. At 15kts now it's quite a bit better i'd say 30%. It's still loud but it seems to have lowered it having the right load on the engines. FYI, my old props was about an inch in dia short and inch in pitch short, I now have 26x30 with cups. Wouldn't give them up for anything now. That's on 350hp 8v71N's

 

[Pete]

Captainhawk, please comment further on the results you achieved on the DD 453. I am ready to replace the original mufflers on a 48 LRC with 453N's. I have purchased the two Centek Veralift MKII inline dual water lift mufflers, the blue exhaust hose, lengths of fiberglass exhaust tubing, and clamps. All I need now is the motivation to tear into the boat and get it done. Hopefully the results you achieved will kick start me.

I have been on a noise reduction campaign for several years. To date I have replaced the air intakes on the engines with Air Seps, added vinyl/fiberglass/sheet lead sound reduction material to the entire engine room overhead, and installed sound reduction carpet pad in the salon with no hatch cut outs. Engine room access is through the lazarette only. At the current level, normal voice conversation is easy while standing over the engines in the salon. But, I still wake up a lot of folks when I start the engines due to exhaust noise. And if two people go stand in the cockpit while at cruise speed you will not be able to communicate with each other.

I am going on a short cruise this weekend and will be taking some measurements in the cockpit using an audio meter and will do it again when I complete the muffler job. This will provide at least one data point which I will post when available.

Pete

 

[wolfeman]

I have been working on DD for years and have had good luck with lift mufflers making them extremely quiet . The best have been with custom built mufflers. Not only do they seem more quiet but are built to fit into what area is available in your engine room or under he cockpit. Lift mufflers have many advantages such as acting as a surge tube and preventing the air surge through the engine when at the dock. I have started using a service in Stuart Florida near me who has competitive prices and short turnaround time getting the job done. It is called Extreme Marine Power and the owner Bob can be reached at 772-486-7968.