Downflooding points which occur less than 30 degree of heel

Discussion in 'Stability' started by e.m.milad, Jun 14, 2015.

  1. e.m.milad
    Joined: Jun 2015
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    e.m.milad Junior Member

    Dear My friends
    I am working with stability calculations of a tug with LOA=30.5 and I encountered a special feature. the engine room ventilators are in places which the downflooding angle occur at 28 degree of heel. so I do not know how to apply stability criteria in IS code 2008 to this ship. any help will be highly appreciated.
    -area between 0-30
    -area between 30- 40 or angle of downflooding (which ever is less)
    - area between 30-40 or the angle of downflooding (which ever is less)
     
  2. TANSL
    Joined: Sep 2011
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    TANSL Senior Member

    In my opinion, without knowing the boat, the only thing you can do is increase the height of the downflooding points or reduce their distance from the center line. That is the normal solution for these cases.
     
  3. e.m.milad
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    e.m.milad Junior Member

    Thank you my friend for your answer.
    the boat is known and the down-flooding point exists on the ship.
    I searched a lot but I could not find any resolution or other documents related to the allowable margin for down-flooding point.
    For example in Lloyd s Rules, I found that 40 degree is the minimum angle of down flooding point (clearly because of IS code) but for the lower margin I could not find any regulation or related documents. (for example the angle of heel related to a down-flooding point should not be less than 20 degree or something like this ... )
     
  4. TANSL
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    TANSL Senior Member

    There is no statutory minimum value for the angle of flooding. It must be the angle that allows (whatever its value) that all stability criteria applicable to the ship are met.
    Do not look for you the stability criteria in the Lloyd's but in the IMO "Code of intact stability."
    The tugs also pulling laterally or towing can not put the deck underwater.
     
  5. e.m.milad
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    e.m.milad Junior Member

    Dear Sir,
    Thank you so much for your kind answer, I appreciate it,
    I agree with you.
    but With the down-flooding point less than 30 degree what is your opinion about applying following requirements.
    - Area between 0-30 >0.055
    - Area between 0- 40 or (tet)f >0.09
    - Area between 30-40 or (tet)f >0.03

    while [(tet)f = angle of down-flooding ] is less than 30 degree, it is nonsense to calculate area between 30-(tet)f
     
  6. TANSL
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    TANSL Senior Member

    Dear friend, not my opinion but the result of applying the criteria of stability: the boat does not fulfill them and therefore you must change the ship. Do not be scared by this, it is relatively normal and, therefore, compliance with the criteria is checked. You have to change the location of openings. The solution to change the criteria does not exist.
     
  7. NavalSArtichoke
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    NavalSArtichoke Senior Member

    If you cannot increase the angle of downflooding by raising the height of the vent opening, then you can see if the vessel is capable of operating at a lower draft, such that the angle of downflooding is increased beyond 30 degrees.

    If decreasing the operating draft does not work, then you are stuck with a vessel which cannot comply with the IMO IS Code, I'm afraid.
     
  8. e.m.milad
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    e.m.milad Junior Member

    Dear Friends
    Thank you very much for your replies.
    it is really appreciated.
    I think because the DFP is near 30 (near 28 degree) there will be no problem with increasing the DFP angle of heel by increasing the height of the point.
     
  9. philSweet
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    philSweet Senior Member

    Question from the peanut gallery. If the engine room ventilators were piped inside the hull such that the interior piping provided additional down flooding security, does that qualify under the rules? Or is siphoning and slosh assumed and only exterior locations considered?
     

  10. TANSL
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    TANSL Senior Member

    If there is a bend, at a sufficient height that avoids flooding, the conduit may be valid within. But the vents must have the minimum number of internal interference for good air circulation.
     
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