Large reverse chine

Discussion in 'Boat Design' started by romeomikehotel, Mar 5, 2019.

  1. romeomikehotel
    Joined: Feb 2019
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    Location: Ft Lauderdale

    romeomikehotel Junior Member

    What is the consensus on these? I’ve heard no more than a 5* angle and around 3 inches but who knows if that’s true. My last boat had chines about 5.5-6 inches wide and it did pretty good with. 22.5* deadrise.

    What would be the outcome of much larger chines (10 inches for example)? Would a boat turn better or worse? Would it slam more on plane in rough water? How would this change as the reverse angle increases?

    My unprofessional guess is that it would get on plane faster but slam more. I’ve read of people talking about “tripping” over the chine in a hard fast turn but that only makes sense if the chine angle was significant, otherwise the angle of the keel as the boat leans would be much more perpendicular to the water that the chine would ever be.

    Here’s one of the forum members with from what I can gather, an 11” reverse chine at the transom... looks like there’s a whole company making boats with government contracts using this design.

    1A7B726F-D287-4629-95C8-9B50250CFCB7.jpeg DDBBD164-54D3-4C1F-A4E8-32B41E693556.jpeg FBBED5FB-6DC3-499D-A182-4F13B1FFEDC7.jpeg

    Here’s an example of a pretty steep (I think) reverse chime, though not extremely wide as above.
    Last edited: Mar 5, 2019
  2. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    If you are adding more beam to a boat, yes, more lift, if not adding more overall width, but there is substantial deadrise inboard of it, yes, more lift, if there is minimal deadrise, and not adding beam, minimal effect. Boat will turn flatter, plane more easily, hold plane at lower speed, ride may suffer, boat will be stiffer in both axes underway. If the boat is likely to leave the water where this flat is, expect a firmer ride. Additionally, running down seas could mean more "bog". If the boat has a warped plane bottom, all effects will be further amplified. There really isn't any "magic", the ultimate wide reverse chine is the gull-wing shape, and it does plane easily and carry good loads, but the ride is not much good in most cases, and explains why they are not more common.
    romeomikehotel likes this.
  3. DCockey
    Joined: Oct 2009
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    Location: Midcoast Maine

    DCockey Senior Member

    I don't see a reverse chine in the lines which were added to the first post.

    I remember reading somewhere that too large a reverse angle on the chine flats can lead to the spray striking the water too close to the boat and bounce back and be blown into the boat. I thought it was Donald L. Blount's book but can't find it there.
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