Round bilge or chine ?

Discussion in 'Sailboats' started by Oscarpp, Jul 13, 2020.

  1. Oscarpp
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    Oscarpp Junior Member

    How about a round bilge with a full length chine ?? Looks good for stability and interior habitability, doesn't it ? Wetted surface similar to a round bilge. A boat i am interested in is designed this way.
    Thanks, Oscar
     
  2. BlueBell
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    BlueBell Ahhhhh...

    What boat is that?

    Oh, and welcome to the Forum.
     
  3. upchurchmr
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    upchurchmr Senior Member

    We need a picture or at least the boat/ manufacturer.
    Your description could mean different things to different people.
    Some of us don't have a very good imagination - or at least it does not match others. :rolleyes:
     
  4. Oscarpp
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    Oscarpp Junior Member

    Yes a picture is better than a long story ! It seems many recent boats are designed this way, hence my question.
    As an example, below is the hull picture of a 53' german boat designed by FinoteConq (sister ship reviewed/video by YachtingWorld), a source of inspiration for my project.
    Pasteboard - Uploaded Image https://pasteboard.co/JhA7YGv.jpg
     
  5. upchurchmr
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    upchurchmr Senior Member

    A picture is great - if it shows the feature.
    I don't see anything but a round bilged hull.
    Another?
     
  6. Oscarpp
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    Oscarpp Junior Member

  7. Oscarpp
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    Oscarpp Junior Member

    I am trying to further understand the advantages of designing a monohull with a chine vs. a mere round bilge.
    Not considering the multiple hard chines designs, but rather a single chine aft till midships or even a full length chine with a round bilge underneath.
    Given the larger number of production boats designed that way nowadays, there must be more to it
    than only fashion or appearance ?? Thanks
     
  8. TANSL
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    TANSL Senior Member

    In general it will depend on what you want to do with your boat.
    If you want a planing hull, the bottom in the back half of the hull needs to be as flat as possible (though not horizontal), which forces you to use chines.
     
  9. Oscarpp
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    Oscarpp Junior Member

    Yes, however believe most of the production /cruising boats designed that way will rarely go planing ...?
     
  10. TANSL
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    TANSL Senior Member

    The shapes of a boat are defined according to how the boat must work, to obtain the hull that best meets the SOR of the boat and, to some extent, the material to be used and the human and mechanical resources available to the builder. Therefore the answer to the question "round bilge or chine?" depends on many variables that you should define beforehand.
     
  11. Rumars
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    Rumars Senior Member

    There are 3 drivers behind what you see now with this chine, performance, space and fashion. The fashion originated with the racing boats and it is a big driver, people want their boat to look modern and fast. The racing boats that originally developed it were box ruled downwind machines like the minis, and they used it to have the widest planing bottom and still fit the rule. As it happens such a form also allows maximum interior space for a given lenght, much more then the previous generation with flared sides and pinched sterns.
    The upside of this form is great downwind capabilities (planing is a function of SA/D ratio), and good form stability. The downside is that upwind this boats need to go at a big angle of heel, and that can be uncomfortable (and scary).
     
  12. Mr Efficiency
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    Mr Efficiency Senior Member

    I didn't see anything but round bilges in the OP's links, but perhaps my eyes deceive me.....
     
  13. Oscarpp
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    Oscarpp Junior Member

    These chines are not like hard chines but still visible with some actual curvature break. I agree with the drivers mentioned by Rumars notably space and fashion but trying to further understand performance... on relatively heavy/non racing boats.
    Especially given the fact this is now used in the design of so many different boats (see the 2 links i posted earlier a light "cruiser-racer" and an heavy expedition yacht) including a lot of standard family cruising / production boats !
    See for instance European Yacht of the Year 2019: Best family cruisers - Yachting World https://www.yachtingworld.com/boat-test/european-yacht-year-2019-best-family-cruisers-120534 what is said about the winning Beneteau Ocenis 46 : "The key to the design is in the full-length chine, which creates a narrow wetted surface area, yet at the same time increases the amount of internal volume"
     
  14. Mr Efficiency
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    Mr Efficiency Senior Member

    Without a close-up picture, maybe one of the boat on a sling, I'm not sure what the chine that isn't a chine, looks like.
     

  15. Rumars
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    Rumars Senior Member

    He is talking about the intersection of the bottom skin area to the vertical topsides. The intersection is above the waterline and continues forward at an angle past midships where the topside gets more flare and blends into the hull bottom. If they where true chined boats they would be single chined shallow V bottoms with vertical topsides, but in practice most are U shaped, a rounded bottom connected to a straight topside. I suppose the correct term is firm bilged.
     
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