Wave Piercing - What vertical profile to split waves

Discussion in 'Hydrodynamics and Aerodynamics' started by BlunderBus, Dec 8, 2014.

  1. BlunderBus
    Joined: Oct 2013
    Posts: 21
    Likes: 1, Points: 0, Legacy Rep: 17
    Location: New Zealand

    BlunderBus Junior Member

    Hi Guys,

    From observation it looks like most designers go with straight lines for the topsides to the widest point, and just cure it a little near the widest point to take to the transom. Some seem to have a bit of progressive curve to them though. Any thoughts on if the curve is an arch or something progressive like a parabola?

    I see in Ben G's blog of Tank Girl he mentions making the bow a little rounded, using a parabolic shape for the first 50mm.
    http://z10.invisionfree.com/12ft_skiffs/index.php?showtopic=504&st=30
    ...
    Has anyone come across any details about how blunt the bow can be, or should not be?

    I came across...
    http://www.ivorbittle.co.uk/Articles/Bulbous bow/The bulbous bow for my site This one again.htm
    ... which discusses the sideways movement of the water as it is parted, how it accelerates. But no specifics.
    More reading to be done. :)
     

  2. JRD
    Joined: May 2010
    Posts: 224
    Likes: 17, Points: 18, Legacy Rep: 192
    Location: New Zealand

    JRD Senior Member

    Given the 12s have almost no rules, if it was thought to be faster one would have appeared by now. Most likely there is no point moving back from a plumb bow when you need to support an overhanging jib and 100s of kg's in rig tension.

    I've never seen any evidence presented that reverse rake (assuming this is what you mean by wave piercing) has any benefit on a planning mono-hull. If you move the stem-head back toward the mast the topsides wedge is getting blunter which you don't want when ploughing through waves at speed.

    Some further reading for you on (slightly) bulbous bows. Given a Jav has plenty of sail power I don't think a little extra volume fwd would hurt you.

    http://www.biekerboats.com/Bieker_Boats/I-14_B6.html
     
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