chine height at bow and at transom

Discussion in 'Boat Design' started by Hunterr, Jul 15, 2015.

  1. Hunterr
    Joined: Jun 2015
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    Hunterr Junior Member

    When making Chine height at bow or transom higher, What is pros and cons?
    Is the chine relating to only rolling period?
    Now i intend to make chine height at bow higher in order for boat to have fine visual.
     
  2. Rurudyne
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    Rurudyne Senior Member

    Two things: First, I just listened to How to Talk Minnesotan so even though I'm a Texan there are similarities so I hope none of that seeps in, though it probably will.

    Secondly, this is something I've wondered about myself. I mainly have approached it with relation to slamming, which may be odd given that I'm not looking to go fast. As I've tried to get a v-berth situated as far forward as I can in my DelftShip model it does seem apparent that that lovely high chine cuts in on your space a bit; however, it seems to me that not slamming and v-berths are a good combination, especially if the slamming happens while at anchor in the ICW because you've slipped away from where you thought you were and there's some weather about that could be better. Now others have praised the far forward head as was the fashion with those lovely Lake Union boats and with these, which will actually be used underway, I can see a good argument to having a high chine line even if it means you're reaching behind you for the toilet paper unless, of course, you are okay with your problems coming back to visit you. Naturally if you only plan on going slow in a lake you can choose without fear of making a wrong choice. I'd like to say I'd thought deeper about the subject but if I acted like I had I'd be just fooling myself. Whatever.
     
  3. Grant Nelson
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    Grant Nelson Senior Member

    Keep your chine a pecent or two of beam below the watterline aft. Forward your main concern is keeping a sharp enough 'V' to avoid pounding. I. Believe its around 50 degrees in section view where the keel comes out of the water. You can go dwn to 40 in protected waters and up to 60 in open seas. As Rurudyne indicates this means also the higher your chine at the bow the less beam you will have for accomidations. I assume you are talking about a plannong speedboat.
     
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  4. Mr Efficiency
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    Mr Efficiency Senior Member

    Chine of what ?
     
  5. PAR
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    PAR Yacht Designer/Builder

    The best advice for this poster maybe just rude, simply put, open your textbooks and keep studying. In a nutshell there are so many variables, that questions like these all but impossible to answer and the sign of someone, very early in their studies. Keep studying and we will not tell anyone you asked, a few years from now when you realize the answers and that you asked this, a few years prior.
     
  6. Jamie Kennedy
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    Jamie Kennedy Senior Member

    I think Grant Nelson answered it well but it is difficult to discuss the chine in the absence of context. The chine is primarily a consequence of what you are trying to achieve in terms of overall hull shape and volume, for both hydrostatic and planing and handling characteristics. The distribution of weight is also significant. Putting a bridle and saddle on a pig does not a race horse make.
     
  7. Hunterr
    Joined: Jun 2015
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    Hunterr Junior Member

    recommanding book plz.
     
  8. SaltOntheBrain
    Joined: Feb 2007
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    SaltOntheBrain Senior Member

    Start with Dave Gerr's "The Nature of Boats".
     
  9. PAR
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    PAR Yacht Designer/Builder

    The Nature of boats, will not provide the subtle design answers he's been looking for. He needs a full blown course or an apprenticeship.
     
  10. kerosene
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    kerosene Senior Member

    But nature of boats is a good 1st book nevertheless.
     
  11. gonzo
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    gonzo Senior Member

    The profile has to be considered in relation with the beam and entry angle. A very narrow hull will handle waves well with a relatively flat bottom.
     

  12. Eric Sponberg
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    Eric Sponberg Senior Member

    Hunterr,
    Interestingly, no one that I know of in the modern world of boat design has ever written or discussed any guidelines as to how to make a chine line and at what heights the chine should be from bow to stern. I have always advocated that this is an excellent field of study for someone doing a master's or doctor's thesis in college.

    That said, if you are working on a powerboat design, then the chine at the stern should be just slightly under water, as Grant said, and then a mix what looks good and what the requirements would be for the deadrise of the bottom surface in the forward half of the boat, also as Grant alluded to. The sweep of the chine line is done pretty much by eye as anything else, kind of by a gut feeling for what you think is going to work. There are very few guidelines to follow.

    In the last two decades or so, some designers, myself included, have added chines and lifting strakes to sailboat hulls. Actually, chines go back much further--centuries--when boats were made of planks and the some of the butt joints between planks were chines. But the modern era of the last few decades the designers have been putting chines and strakes in rounded hullforms simply to benefit from the hydrodynamics that chines and strakes provide. Witness the last few runnings of the Volvo Round the World Races--almost all chined hull forms. For these boats, the styles vary--some will have the chines partially submerged at amidships or aft, some will not be submerged at all anywhere along their lengths when in the upright position. Again, there are no hard and fast guidelines--you draw what you think looks right, try to justify your choices one way or another, and move on. That is one of the nice things about boat and yacht design--you can let your imagination go with the flow, so to speak, and come up with intriguing vessels.

    Good luck,

    Eric
     
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