Planing 10m Motor Yacht

Discussion in 'Boat Design' started by Simon_PL, Nov 3, 2019.

  1. SailDesign
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    SailDesign Old Phart! Stay upwind..

    I have taken them into consideration, but never to the extent of having them affect the static condition overmuch. Congrats if you still do. I take into account the likely speed and use, and tune deadrise (and therefore volume) to suit. But I never really look at the expected movement of effective CG vs drive vector.
     
  2. TANSL
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    TANSL Senior Member

    Dear and respected friend (allow me that familiarity), the CoG cannot move, appreciably, during the operation of the boat.
    I have had to change the shape of the hull or the position of the weights as a result of the study of the boat in planning condition. If that has never happened to you, all I can say is that you have been very lucky.
     
  3. SailDesign
    Joined: Jan 2003
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    SailDesign Old Phart! Stay upwind..

    Hence my use of the term "Effective CG" to mean the combination of actual CG and the centre of lift. If you have never had to calculate the effective centre of lift/gravity in this fashion, then YOU have been very lucky...
     
  4. TANSL
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    TANSL Senior Member

    I understand, and I like, your sarcasm due to my mistake. I think we both talk about the same.
     
  5. SailDesign
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    SailDesign Old Phart! Stay upwind..

    Probably very true - go in peace. :)
     
  6. Yellowjacket
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    Yellowjacket Senior Member

    Just because it's stylish, doesn't make it a good boat. If you're using it as a tender of big yacht to go back and forth from an anchorage to a dock in calm waters like the Med, well then that's fine. But in the real world what the OP posted and the Wally that you showed are going to be very wet boats. They're going to take a ton of spray over the bow in any kind of waves, and as I noted if you stop quickly you're going to take the following wave right over the platform and it'll wash right through the boat. So yea, go for it, but just be aware of what you're going to get with something like that. Serious boats for use in other than calm waters don't look like that for good reasons.

    And CAD programs like to make flat surfaces and sharp corners. Things like the roof panel and the sides are flat and flat surfaces have no inherent stiffness, where curved surfaces are inherently stiff. While flat surfaces are easier to make, to get them to be sufficiently stiff will require a lot of stiffening members to make them work.
     
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  7. SailDesign
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    SailDesign Old Phart! Stay upwind..

    All (mostly) true. But the fact remains this is an incredibly popular/fashionable hullform. Personally, I hate modern houses, but it uis what people want, and anyt new designer who doesn't play with the form is shooting themsleves in the foot. PLay with things, see what they do, try things out. Then when your first customer in a year walks through your door you can rightly say "Yes, I've played with that idea - but I have thoughts on improvement."

    Don't slam the guy because he was inspired one of the most successful company's styling.
     
  8. kerosene
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    kerosene Senior Member

    And you are not at all arguing about semantics?
     
  9. TANSL
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    TANSL Senior Member

    @kerosene, I'm afraid I don't understand why you speak now in semantics, unless you just want to bother. What I wanted to express is that when the ship is in motion, other forces can intervene that make the weight of the volume of water displaced by the hull less than the total weight of the ship. If that has something to do with semantics, then OK, I'm "arguing about semantics".
     
    Last edited: Nov 13, 2019 at 3:36 PM

  10. SailDesign
    Joined: Jan 2003
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    SailDesign Old Phart! Stay upwind..

    We may have been, but all is well now. Don't rock the boat....
     
    TANSL likes this.
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