What is this in our 61's exhaust?

[Tawney1]

Could it be internal baffles/whatever from the muffler that have disintegrated?

I have no idea what's actually inside the mufflers. Surely there's no FG packing like auto mufflers use.

Added:

I enhanced the pic and brought up the brightness a ton on my computer to see the actual opening into the muffler itself and I don't see any of this stuff. I don't understand how if it came from the muffler originally, it could have adhered to the top of the pipe as well as the bottom.

Is it possible that some Cr@p washed INTO the pipe from the water while the boat was sitting for a prolonged period or that a "friend" dumped this stuff in there while it was on the hard?

Mike, many thanks. However, this is NOT any sort of foreign material which has somehow become deposited into the exhaust tubes. This is OEM stuff that is now coming-out of the openings in the tube where the stuff was originally installed.

I have also made some phone calls, and no one seems to be able to tell me, without speculation, what this is and whether this is a natural progression of deterioration of older (our boat is a 1985 -- third from the last 61' MY to be made by Hatteras) exhaust tube or something bad....

[SKYCHENEY]

My boat is a 1985 as well. I have smooth fiberglass pipes from the transom to the muffler, no riffling. It looks to me like that stuff is fiberglass or fiberglass over some sort of mesh material. I would assume that the outside of the pipe is still in good shape (take a look from inside to make sure). If the overall integrity of the pipe is okay, then I don't think I'd worry too much about that stuff on the inside. Just keep an eye on it and make sure it doesn't restrict the flow.

Other option: Call Hatteras

[MikeP]

Ah ,yes, in looking more carefully at the brightened version, I see what you are talking about-it appears there is some packing around the pipes themselves and this "stuff" is extruding through slits or vents or whatever in the pipe aft of the muffle itself.

I suppose in this case it could be regular old FG packing around the pipe as is used in road mufflers. It would probably reduce sound level a bit and looks very much like some of the old "glasspack" mufflers from the 60's - a row of vents in the pipe with FG packed on the outside. But this seems crazy on a boat where large amounts of water would be rushing through.

Seems downright bizarre! Wonder if this is standard construction? Must be, how else did it get there?

[Thomas W Peavy]

Could this be some type of silencer design? If you were to make a silencer for a firearm the anulus of the silencer would have steel wool or some type of fabric to absorb the sound of excaping gases.

[Tawney1]

Okay guys, here are photos of the starboard exhaust pipe. This side is not as deteriorated or pronounced as the port pipe. You can see how the original packing appeared in some of the slits.

I have called Hatteras, but no response yet....

[captddis]

With the better picture I can see the muffler. Most of the Hatt mufflers had those strips, I believe it is for silencing. The 61 I take care of looks the same inside and my 46 has them as well. As long as they are intact, I would not worry. I have replaced some Hatt mufflers were the baffles came loose.

[Genesis]

That's pretty bizarre - my boat didn't have those..... at least I don't think it did!

If its not blocking anything and the outside is ok (no leaks) I wouldn't be too worried.... but do keep an eye on it.

[MikeP]

So are these exhaust pipes a double wall pipe with FG (or whatever) sandwiched in the middle? Seems a strange application for such a thing though I can see that it would help reduce noise but it's obvious that at some point the thing will fail and the FG will do exactly what it's doing.

Then again, it's hard to complain that it ONLY lasted 20+ years!

[neosin]

geez looks like some cat went up there and you cranked it up and blew the poor sob out... That's what i would of guessed if you didn't say anything..

[Tawney1]

geez looks like some cat went up there and you cranked it up and blew the poor sob out... That's what i would of guessed if you didn't say anything..

LOL. It does look like that...; but

I have the official word from Hatteras!

They don't know -- but they know who does.

They have referred me to the exhaust manufacturer, which is Marine Exhaust Systems.

Thanks for all the input! I will post the response/information I get from MES.

Paul