Mooring Arrangement

Discussion in 'Boat Design' started by rdlopez, Jun 19, 2014.

  1. rdlopez
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    rdlopez New Member

    Hi Guy's,

    What is the Criteria to designate a capacity for mooring lines and bollard?
    Also what is the expected wind speed to be consider?


    Rolan
     
  2. gonzo
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    gonzo Senior Member

    It depends on conditions. However, mooring usually are set in protected waters. Depending on the bottom, 10-15% of the vessel's displacement is adequate.
     
  3. TANSL
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    TANSL Senior Member

    Depends, among other factors, on the displacement of the boat and the area exposed to wind. To my knowledge, does not depend on the bottom of the boat. Classification Societies offer formulas to determine the need for anchoring and mooring equipment. The attachment is a copy of what it calls the Special Service Craft of Lloyd's Register.
    As for the layout, the designer must make a study to define the most convenient way to do these maneuvers, the approach to the dock, etc.. It is good to ask for input and collaboration, in this sense, an experienced skipper.
     

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  4. gonzo
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    gonzo Senior Member

    A clay bottom can use a lighter mooring weight than in a hard shell one. The reason is that in clay the weight will sink in and that will give it more holding power.
     
  5. TANSL
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    TANSL Senior Member

    OK, Gonzo, in some of the things you say you have more reason than a saint. But overall, you're wrong. Never in my life have I heard that mooring and anchoring equipmente of a ship should be designed in accordance with the seabed. In general, it would be stupid to do so. That would condemn the boat to anchor only in certain places. Many boats have no means to know how is the bottom on which they want to anchor. Also, keep in mind that, when a ship needs to anchor, it can not choose the bottom to do so. Also keep in mind that much of the effect of retention do not realize the anchor, but the chain, which sometimes is more important than the anchor.
     
  6. DCockey
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    DCockey Senior Member

    What do you mean by "mooring":

    1) Tied to the shore?

    2) Tied to a permanently set anchor or array of anchors?
     
  7. rxcomposite
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    rxcomposite Senior Member

    Aren't we getting confused here?

    Mooring refers to securing fast to a permanent structure on shore such ay piers, quays, ect, or even a permanent anchor dropped into the seabed or waterway.

    Anchoring is by dropping a heavy object (such as anchor, or even stones) to the the seabed and held secure by its weight or grip to a clay, sand, or rock bottom.

    So which one are we discussing?

    PS David beat me in posting
     
  8. gonzo
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    gonzo Senior Member

    Mooring is a permanent arrangement. Therefore, taking into consideration the bottom type is not only logical but the usual method. Mooring weights (when iron) are adequate at about 10% displacement in protected waters with little or no currents.
    TANSL: the OP did not ask about anchoring.
     
  9. rxcomposite
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    rxcomposite Senior Member

    Rolan- You mean this one (attached)

    Not much written on PNA except for minimum rope size but search SONAME on Facebook since you are from PI. I think somebody has posted bollard design in there. I assume you mean ships bollard design, not shore bollard.

    If you are looking for anchoring, you need to calculate first your equipment number (EN). There is also an excellent spreadsheet posted over there.
     

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  10. waikikin
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    waikikin Senior Member

  11. TANSL
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    TANSL Senior Member

    Gonzo,I know exactly what the OP was asking for.
    If he had talked about anchoring perhaps could have recommended a type of anchor or another, according to the seabed at he wanted to anchor. I repeat again that it seems silly to define the anchoring in function of only one type of seabed.
    The OP asked about mooring and for that, it is even more ridiculous considering the seabed. Consider the total weight of the boat and the wind area. To talk about a % of displacement makes no sense.
     
    Last edited: Jun 22, 2014
  12. Grey Ghost
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    Grey Ghost Senior Member

    I don't know. The question could be asking different things. I guess? he is asking about ships where permanent moorings don't give? In a storm I dragged a marina "mooring" 100' with 3/4" line and the line didn't break.
     
  13. Poida
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    Poida Senior Member

    Boats are generally not moored in very deep water.
    Rather than re-invent the wheel, grab a mask and snorkel and see what the other boats are moored too.
    Of similar size of course.
    Or ask other boaties what they are using.

    Poida
     
  14. rxcomposite
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    rxcomposite Senior Member


  15. waikikin
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    waikikin Senior Member

    I just edited another link to that post, a Navy reference, there's heaps to consider especially in regards to crew safety around mooring, where I work the interface of vessel to wharf is a high risk zone & also working areas around bitts etc.
    A place I used to work(& sometimes still) has had fatality in the past & some serious injuries.

    Jeff.
     
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