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Rubber hose or fiberglass exhaust tube??

Discussion in 'Technical Discussion' started by Pascal, Nov 22, 2015.

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  1. Pascal

    Pascal Senior Member

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    part of the refit on my 53 hatt includes replacing the 45 year old exhaust hoses running from the ER to the transom... About 20/25' on each side. They also need to go from 6 to 8" diam to accommodate the higer hp engines

    What is best? Fiberglass exhaust tube or rubber exhaust hose? Both will have to be supported, the tube is a little cheaper and coudl be glassed in at the transom eliminating the costly bronze flanges. I have seen both used in applications with long runs aft.
  2. Capt Ralph

    Capt Ralph Senior Member

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    I have worked with both. I really prefer the glass tubes. Tab in a couple of knees to help support the tube in a few places and reduce resonating (vibrating a chord).
    Wrap them with heat and sound foam. Never worry about them again. No clamps buried to worry about also.
    Bring the tubes out past your transom a few inches. Stronger bond on both sides of the transom and in the future you can ad deflectors or external baffles if needed.

    Use a premium double bump silicone hose between your dump can and the muffler.
    Exhaust temp alarm on the dump can also.

    Sleep well.

    Are you using stock dump cans or custom builds?

    Did you think about thru the hull, below the water line exhaust with just an idle relief tube astern (or sides)?
  3. Pascal

    Pascal Senior Member

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    I want to keep it simple just a straight tube aft.

    I was planning to run the tubes out a couple of engines to glass them on both sides, you confirmed it :)
  4. Capt Ralph

    Capt Ralph Senior Member

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    Simple is usually the best route. Your hands are full of enough work.
  5. Marmot

    Marmot Senior Member

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    Don't forget to add a couple of feet at the engine room end to form a surge tube. It will help reduce the chance of water reaching the engine when waves hit the transom.
  6. Capt J

    Capt J Senior Member

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    I too agree with fiberglass tubes. That is a long run with exhaust hose and there's a lot of places in that length of run for rubber hose to sag or chafe. Provided you have a straight shot, I'd go with the fiberglass tube. Might want to talk to d'angelo's to do the turbo to boat exhaust section and see where they recommend tieing into it.
  7. Pascal

    Pascal Senior Member

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    I m going to let the cummins dealer / installer handle the ER connection

    One concern with the fiberglass tube is how it is almost a straight run but not quite so as th hull tapers at th stern. Tube comes in 10' section so I guess it is easy to put a few degrees at the connection.
  8. Bill106

    Bill106 Senior Member

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    Do you have lift mufflers in the ER now Pascal? If you do straight tubes aft would be just fine, if not I'd suggest a liner muffler tube for the first section to reduce noise throughout. Glass together (with high temp resin if possible) the sections and a short piece for the transom penetration connected with hose (if accessible) makes the install much easier with transom curve). I also like to isolate hard tubing (and mufflers) from the hull to reduce noise rather than glassing them in. A simple ring of the same diameter exhaust hose where they pass through bulkheads.

    Attached Files:

  9. Pascal

    Pascal Senior Member

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    No lift mufflers in the ER but inline mufflers near the stern which may not be needed for the cummins according to cummins guy. I like the flexible hose at the stern to relieve stress.
  10. Bill106

    Bill106 Senior Member

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    The Cummins guy doesn't think you'll need mufflers??? :rolleyes: Granted they will be quieter than the 53's but still... I can't wait till our rep stops in next time and I ask him that question. If you're switching from 6" to 8" diameter the old in line mufflers won't work anyway but I wouldn't consider not using some type of muffler and the close to the engines you can get it the better. If you can't get it close, wrapping the tubing (like Hatteras often does) with sound absorbing insulation would definitely be a good idea.
  11. Capt Ralph

    Capt Ralph Senior Member

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    I understand the transom has a curve. Just bore new hole straight back.
    Bill106 has a pretty pic. If the tube is supported, I do not understand the need for hose and clamps.
    You think your ole Hatt hull flexes and would twist the tubes at a different rate?
  12. Bill106

    Bill106 Senior Member

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    That's actually two separate pieces rcrapps, the transom tube is glassed in and the "tube" is a linear muffler. This is the same thing on the 64' "Still Kickin" from that other thread. (I hope I resized it correctly Carl!)

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  13. Capt Ralph

    Capt Ralph Senior Member

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    Ah, That is a muffler. Got ya now.

    Still thinking, can you do away with the hose and clamps? The linear muffler looks glassed in or near permanently installed. Glass it all in and reduce an inspection/maintenance item, those clamps and hoses.
  14. Bill106

    Bill106 Senior Member

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    I guess the sections could be glassed together but the muffler is isolated with rubber and those are trim rings covering them. In the fishing game unwanted radiated sound is considered a no-no so everything that can be done to isolate noisy components is attempted.
  15. Capt Ralph

    Capt Ralph Senior Member

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    I'm sorry Pascal for taking up your post. We both may learn something.

    Old school thoughts I was raised with; some boats raised fish with their sounds. The target was not a bad tone or excessive resonating ring. Of course, nothing scientific or verified. But the old tubs did not have those fancy thoughts of your stealth fisher. Of course old tubs had old engines. Who knows now days what really turns a fish on / off. They did raise fish. **** well, there were more fish also...

    Meanwhile, in keeping Pascal happy, would solid glassed in tubes, no hosed and clamps be quieter or make more noise for humans.
    I did recommend in post #2 a wrap on the tubes as I have done before for some of my (so far) happy customers.
  16. Bill106

    Bill106 Senior Member

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    Ha! The best fish raising boat I built had 12V71TI's hard mounted with the exhaust solid as well, no torsion couplings on the shafts either. It was noisy but there's something about the sound of those two strokes humming along that brought them in!

    If I was doing solid tubes on a budget, I'd glass and wrap them and run with it. I would try to muffle the noise with some kind of muffler as far forward as possible but that would be plenty.
  17. Capt J

    Capt J Senior Member

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    Back in the day the fishiest boat I know of was Bone Shaker, an old Whiticar that had 6-71 NA's in it. It was slow, like 13 knots at cruise, but that boat would win just about every tournament it entered in. It helped that it had a great Captain as well, VJ Bell at the time. But they repowered the boat with modern power 5-10 years ago and it suddenly didn't catch nearly as much fish.

    I'd want solid glass tubes through the boat with rubber to mount them at both the transom and exhaust riser to allow some movement for the transom or motor.
  18. bigbill

    bigbill New Member

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    pascal, on my 58yf the tube is glassed in to the transom, it is only about 8 inches inside the transom then a short piece of hose then glass tube, the second length of tube is connected with a short piece of hose. from the factory the glass tubes are within one inch of the other but the hose piece is 18 inches long at the connection. be sure to use the ss crush sleeve from centek inside of the glass so it doesn't crush at the clamp area
  19. Scallywag

    Scallywag Member

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    Hey Pascal, for reference on the muffler/no muffler issue... If you remember, Panacea has the exhaust elbows dump right into the un-baffled 15 foot splash rails (aluminum of course). No muffler on Cummins the 6CTAs. Ride isn't whisper quiet, but quiet enough and practical.

    Added photo for reference.

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  20. Pascal

    Pascal Senior Member

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    Thanks bill, so hatteras switched to fiberglass on the 58s... Good info

    Brian, I forgot you have C series on Panacea! Should have remember considering how much time we spent down there :) I recall the boat being pretty quiet. I have to say I will miss the rumble of DD V8 but that's about all I ll miss about those beasts. The 8V71s are too loud but I ve run a neighbor's 58 hatt and at cruise the exhaust of the 8V92s is loud from the FB