Port and starboard funnels

Discussion in 'Stability' started by e.m.milad, Jul 12, 2015.

  1. e.m.milad
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    e.m.milad Junior Member

    Good day every body
    I want to ask from experienced members about funnels which are positioned side of the boat. can they be watertight? or not? is it possible?
     
  2. TANSL
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    TANSL Senior Member

    It depends on the height from the waterline to which they are situated, like any boat structure. Treatment need not be different from any other deckhouse.
     
  3. e.m.milad
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    e.m.milad Junior Member

    I think I could not make this clear, I meant a penetration in hull which acts as engine outlet (exhaust). in some cases a flap is uses in the end of the pipe to ensure there will be no ingress of water into the exhaust.
    This point should be considered down flooding point? I do not know :confused:
     
  4. TANSL
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    TANSL Senior Member

    Exhaust openings of the engine must always be open. (The wet exhaust are another matter). A shutoff valve is placed to avoid, in case of fire, the more oxygen in the area. That point will be considered as a possible point of flooding. If there is a problem, you can increase the distance from the water, decrease the distance to the centerline, or both.
    A different issue is the engine casings. They should be sealed to keep out, for example, rainwater. Moreover, without having access openings that allow flooding of the engine room, they must be watertight and openings with regulatory coaming height.
    Any opening, through which flooding below the main deck can occur, should be considered as a possible point of flooding.
     
    Last edited: Jul 13, 2015
  5. PAR
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    PAR Yacht Designer/Builder

    It depends on the size and use of the boat. Most pleasure boats do not have any valves or seals in the exhaust system. Occasionally some will install a flap, to prevent a following sea or wave from entering the exhaust pipe, but these are only necessary on boats with certain configurations. A properly installed system will have a loop, to prevent a follow sea from climbing up the exhaust. Some boats don't have the room to rig up a loop in the exhaust, so they'll employ a flap.
     
  6. TANSL
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    TANSL Senior Member

    PAR, although I have completed my answer talking about the exhaust ducts, e.m.milad has asked about funnels. The boats to which you're referring, may not have funnels.
    In some cases, exhaust with only one clap are prohibited and, of course, they would be considered as possible flooding points and probably not meet the standards.
     
  7. gonzo
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    gonzo Senior Member

    e.m.: are you referring to a North Sea setup?
     
  8. e.m.milad
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    e.m.milad Junior Member

    Thank you TANSL, PAR . I think using flap may prevent ingress of water through. it means a progressive flooding will not happen. I mean there may some water which pass through, but it is not progressive and as long as a point has not progressive flooding it is not down flooding point.
    dear GONZO, no it is not about a north sea setup, I mean not as serious as that!
     
  9. PAR
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    PAR Yacht Designer/Builder

    Maybe you need to post a photo or sketch of the setup you're talking about. I'm assuming this is a the typical pleasure boat exhaust, which doesn't need a flap or valve, except in special situations, where a loop can't be provided. TANSL is referring (I'm assuming) to larger vessels and in these cases, you really don't need a valve if designed properly, though (again) there are several situations where you might need something. A more descriptive post about your concerns, with some images would clarify the situation, so more application specific replies can be offered.
     
  10. TANSL
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    TANSL Senior Member

    My limitations with the English language are known to all of you and the nuances of a language are difficult to control but to me a vessel of, let's say, less than 14 m in length (put you the size that you like) does not have "funnels". If I'm wrong, I would greatly appreciate any explanation.
     
  11. PAR
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    PAR Yacht Designer/Builder

    To me at least, a funnel is a dry exhaust stack, which by it's nature wouldn't need any valves or flaps. An exhaust pipe on the other hand could be any type of exhaust system. Again, I do think clarification is in order so we know what the OP is looking for, the system type, configuration, etc. He mentioned funnels on the side of the boat, which would be an odd pleasure boat configuration, though possible. I assumed, possibly incorrectly, that by "funnel" he simply means pleasure boat exhaust pipe outlet. This is why I'm asking for some clarity on the application.
     
  12. e.m.milad
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    e.m.milad Junior Member

    https://www.imageupload.co.uk/image/Zyjc
    this is an example
    what I said, is exhaust outlet of engine, which is simply shown here
    it is a wet exhaust but I am talking about dry exhaust with same configuration
     
  13. TANSL
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    TANSL Senior Member

    Thank you for your explanation, PAR. In view of the imgane published by e.m.milad, it looks like you were right. However, although I am not an authority on the subject, I think that talk of "funnel" in this case is not entirely correct.
    Back to the original question. Being a dry exhaust, it would be that it was surrounded by what I call a "funnel", if only to avoid burns people. In that case, the consideration on its sealing and as possible flooding point, should be entirely different.
     
  14. PAR
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    PAR Yacht Designer/Builder

    A dry exhaust doesn't need a flap or valve, assuming a reasonable exhaust routing. If you can't get enough height in the routing, you might consider some flaps and possibly a valve, but this would be pretty odd on a dry exhaust.

    A dry exhaust of the "same configuration" would simply loop well above the LWL, then back down to it's through hull, near the LWL. The only reason to do this would be to cool the exhaust outlet, on a dry system. A stack would be less prone to several issues.

    I'm not sure what the "funnel" TANSL is referring to, possibly what I'd call a stack cage, heat shield or other protective cover, to prevent accidental burns. Typically these wouldn't be anywhere near the LWL. What make, model and year boat are you discussing? This would focus the discussion a bit and allow us to refine replies.
     

  15. TANSL
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    TANSL Senior Member

    Undoubtedly, we can be talking about for centuries, without being able to give the right answer, if e.m.milad does not tell us exactly what he wants to do. The words I use, well or badly used, have no sense without knowing the configuration of the boat and its exhaust ducs.
    As always, to get an adequate response, you must first ask the right question.
     
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