lapstrake in fiberglass

Discussion in 'Boatbuilding' started by richard, Aug 30, 2001.

  1. richard
    Joined: Aug 2001
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    richard New Member

    At the marina I've been seeing a couple of older fiberglass boats which have been molded to look like wooden lapstrake boats. Does this lapstrake construction in fiberglass have any function, or is it just for looks? Would a smooth hull or a lapstrake hull be better?
  2. Scott
    Joined: Jun 2001
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    Scott Junior Member

    Just for looks, to emulate the wood boats that fiberglass replaced. I don't think it's done too much anymore. I am sure a smooth side is easier to manufacturer and maintain, and I can't see that the faux lapstrake adds anything - maybe a tiny bit of stiffness I suppose, but it's mostly done just for looks.
  3. Bob Wickes
    Joined: Jan 2005
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    Bob Wickes New Member

    Lapstrake in fiberglass boats


    I own a KMV With 400 lapstrakes Norwegian utility boat. The lapstrake, combined with the hull farings combine to make this boat unusually dry in a choppy sea. The Norwegians were out to make an indestructible and unsinkable 14.5 footer (5"10" beam and 450 Lbs weight), and I think they succeeded. My only problem is that I haven't taken her out for two years. She just sits in the boathouse up on dry land.

    Bob Wickes
  4. Raggi_Thor
    Joined: Jan 2004
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    Raggi_Thor Nav.arch/Designer/Builder

    The "strakes" also add stiffness to the hull.
  5. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    For a number of years I brushed off the idea that lap hulls were of any real advantage, other then knocking down some spray. I've since found they do seem to ride softer and surprisingly a bit faster, then a round or chined equal.

    The lap in 'glass look never did come off right. They'd get the gains wrong or leave them off entirely and the crispness of the laps were not there, looking like way to many coats of paint or something.

    I noticed the old Chris Craft, Thomson, White and Lyman hulls rode better. Must have been the extra weight of the soaked wood, right. Now that I've had much more experience with lap hulls, I've found they are light, not heavy. The 25' hardtop Lyman I just finished weighs in at 3,600 pounds and it rides like a dream. A chined version would pound the fillings out of your head in a decent chop. The 27' Chris I have has a real nice ride as well.

    I've been able to ride in many lap hulls, several power and sail of differing sizes and accommodations. While sailing I noticed bubbles, lots of them. They are created as the laps move through the water. I don't know if they offer any cushioning, but something does. I've sailed lap and smooth hulled versions of the same design and the lap construction seems to have been just a touch faster. Maybe the bubbles do something to the boundary layer or act as water ball bearings, I don't know.

    In wooden construction the laps form a longitudinal stringer at the meeting of each plank, making a strong structure. In 'glass you'd get a similar effect, sort of a 'glass angle iron at each lap joint.

    In the end it's hard not to like the look of sweet curves, gently sweeping down the flanks of any boat. The laps make a nice sound when ghosting along and you'll find most folks will look over a lapped hull long before the plastic monoliths currently available.

  6. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    It is possible to use a thinner skin. The laps are structural reinforcements.
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