bertram31.com

I’m looking for opinions on fiberglass exhaust systems versus a rubber hose system. I’m installing a six inch exhaust system with new custom made stainless risers. I’m leaning towards an all fiberglass exhaust (straight tube out the back with no muffler). I would glass the tube solid to the boat and install one rubber hose isolation fitting to transition from the riser to the fiberglass exhaust.

Good idea or bad?

Thanks for everyone's input.

Vince

Vince,

I have been told (which means I really don't know for sure) that the all rubber exhaust systems are quieter?? Maybe some of the other guys could confirm, or deny this? It makes sense that the rubber would absorb some of the sound and the hard glass may resonate sound.

I would also like some feed back on this one because I have an exhaust system to build and the glassed in pipe sounds like a good idea to me. I need as much engine noise control as I can feasibly achieve.

While we are on the subject, would it help to wrap the exterior of a glass pipe exhaust with a Soundown type product?

the guys that are doing my instsall are gonna use a short piece of fiberglass tuge and then hose,the tube won't be no more that around 3'-4' long then hose.they said it will be alot quiter with the hose.i am using the blue silicone hose on my exhaust,.my engines are in and hooking up today,, wiring - shafts - exhaust.

phil

Gentlemen,

My name is Steve Moyer and I manage the Ft lauderdale branch of Soundown. Captain Patrick was kind enough to let me join you guys for this type discussion.

There are pro's and con's to each option. Given the type of vessel we are talking about the difference in noise above decks would probably be the same.

With the fiberglass tubing option I would connect to the engine end with a "hump" hose connector to reduce vibration. Straight exhaust hose is pretty stiff, even the silicone, and it will still transmit some vibration. Also, wherever the tubing is supported it should be isolated with a vibration isolation pad to help reduce transmission of vibration even further. Lastly, you may want to consider another "soft' connection at the transom to further reduce vibration where the exhaust penetrates the transom.

Soundown does make an exhaust wrap for wet exhaust, however with no muffler and the fact that fiberglass tubing is inherently stiff from it's shape airborne noise is not going to be the a problem that can be addressed with insulation, however structure borne noise can.

Hope you find this helpful,

Steve Moyer
Soundown Ft Lauderdale

Steve - thanks for the info and welcome aboard. On another subject, I installed 1" lead core Soundown in the engine boxes of my B31 about 12 years ago (Cummins 6BTAs) and it works great. However the mylar edge tape is shot and I need to replace the tape and maybe get some new mechanical fasteners where a few have broken off. Can I buy from you?

Vic Roy
VLR@RKKDLAW.COM
800 260 9908

Hello Captain Vic,

Thanks for the welcome aboard.

By all means you are welcome to call or e-mail and we can supply you direct with whatever you need. We do have distributors in some parts of the country where it might be easier/less expensive to buy through them than direct, but right now we have no distribution in the great State of Louisiana.

Thanks,
Steve Moyer
Soundown Ft. Lauderdale
smoyer@soundown.com
954-761-9188

Thanks Steve,

I realize all boats are different, but does the exhaust wrap provide a "noticeable" difference in most applications?

Based on these inputs, it appears that the best solution for noise control would be rubber hose with a sound barrier wrap.

Hi Scot,

In most cases a really quiet boat is the result of attention to ALL the noise sources and is a result of the cumulative effect of treating them all.

To answer your question, on a B31 exhaust wrap would probably not provide a "noticeable" difference. Attention to other noise sources would be time and money better spent.

That said, if the engine boxes, underside of the deck, forward and after bulkheads, air trunks, cable, wire and hose paths were all treated and mufflers installed, then exhaust wrap would probably result in a "noticeable" difference.

As many of you have experienced, you treat one noise source and suddenly you notice noise coming from somewhere else. Well, of course that noise was always there, you just couldn't hear it over the noise you just reduced. This would be the case of exhaust wrap on a B31, just pretty far down the chain of noise sources.

Hope this answers your question Scot,

Thanks,

Steve Moyer
Soundown Ft. Lauderdale

Thanks Steve,

The big picture approach with attention to detail is definately the way to go for noise control. Sounds like exhaust wrap is more icing on the cake than basic needs.

Sending you a PM.