Keel edge

Discussion in 'Sailboats' started by Phosphor, Sep 6, 2005.

  1. Phosphor
    Joined: Mar 2004
    Posts: 31
    Likes: 1, Points: 0, Legacy Rep: 11
    Location: Mass.

    Phosphor Junior Member

    Hello.
    My dad and I sail a 24' Bristol, made back in '69. It has a very snub-nosed bow, and that shape is carried down into the keel.
    Also, it doesn't point very well into the wind, leaving an arc of around 105 degrees that we must tack through sailing close-hauled. I think the two are related but I am not sure...

    One solution I was thinking of, is what if we reshaped the leading edge of the keel and the bow a little so that it bit more into the water? I'm thinking of moving more towards the shape of a J 24's fin keel edge, but I won't be able to get it as fine. Would this help our pointing situation?

    Any advice would be much appreciated. Thanks! :)
     
  2. Skippy
    Joined: Nov 2004
    Posts: 568
    Likes: 1, Points: 0, Legacy Rep: 12
    Location: cornfields

    Skippy Senior Member

    The blunt bow is a reasonable suspect for poor pointing, but the keel is probably not, except for the overall long, shallow dimensions. The keel should have a smooth airfoil shape, whereas a finer V shape is good near the surface. Adding to the bow will increase weather helm, which may be okay depending on how much there is already, and will increase the waterline and make the bow finer overall, all of which helps to bring the speed up. One problem the longer bow might create is broaching issues running downwind in a healthy breeze. Then your weather helm will be a liability if the boat yaws and the bow starts digging in.
     
  3. Phosphor
    Joined: Mar 2004
    Posts: 31
    Likes: 1, Points: 0, Legacy Rep: 11
    Location: Mass.

    Phosphor Junior Member

    I completely forgot to think about weather helm. Oops. The weather helm is definitely not weak, but a tad on the strong side. How fine of a point should I go? Is it possible to meat a nice medium?
     
  4. Skippy
    Joined: Nov 2004
    Posts: 568
    Likes: 1, Points: 0, Legacy Rep: 12
    Location: cornfields

    Skippy Senior Member

    You'll want to consult with a professional NA for precise numbers. Bristols seem to be very well designed cruisers, so rather than "fixing" it, you might also want to consider trading to another design that better suits your needs. A lot of cruisers have heavily cut-away bows for downwind stability, as opposed to racing designs with plumb bows and square forefoots (forefeet?) for pointing at the expense of rough-weather safety.
     
  5. Phosphor
    Joined: Mar 2004
    Posts: 31
    Likes: 1, Points: 0, Legacy Rep: 11
    Location: Mass.

    Phosphor Junior Member

    Sounds good. I was just trying to get a primary feel for it. I'm not planning on taking any action until I consult someone for it. Ya know? Don't want to screw up a boat or a boat's safety just for performance. Thanks again. :)
     

  6. jehardiman
    Joined: Aug 2004
    Posts: 3,776
    Likes: 1,169, Points: 113, Legacy Rep: 2040
    Location: Port Orchard, Washington, USA

    jehardiman Senior Member

    As another point, a tacking angle of 105 degrees across the true wind for the shallow full keel that she has is not all that bad. Have you moved the jib sheeting angle in yet and have got a really, really flat main? Both will do more for tacking angle than than expensive keel work.
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.