Lapstrake vs. plank design for 17' Whitehall Rowing Skiff

Discussion in 'Boat Design' started by SailorDon, Mar 11, 2017.

  1. SailorDon
    Joined: Apr 2013
    Posts: 137
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    Location: Livingston, TX

    SailorDon Senior Member

    With respect to the 17' Whitehall Rowing Skiff design, both planked and lapstrake designs are common.
    Question:
    Is lapstrake or planked construction better for rowing performance of these designs?

    Typical planked 17' Whitehall (Glen-L design I think):
    [​IMG]

    Typical lapstrake 18' Whitehall (Heritage 18):
    [​IMG]

    Assuming that each vessel is designed and built to the best performance design of its "class" (lapstrake vs. planked), which type will perform best with respect to recreational rowing?

    Or is there no advantage to lapstrake vs. planked construction, or vice-versa.

    In the examples above, there are differences in design
    1. Fixed seat vs. sliding seat.
    2. Wood hull vs. carbon fiber hull.
    3. Rigger vs. gunwale mount oarlocks.
    4. 300 pounds vs. 90 pounds.
    5. Lapstrake vs. planked.

    My primary interest is in the performance of the lapstrake vs. planked.
     
  2. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Performance is directly related to weight, assuming both boats are the same shape. If the boat is a carvel build, which was common in traditional Whitehall's, it tends to be the heaviest build type, so rowing effort is increased. If it's a traditional lapstrake, it's lighter, if it's a modern glued lapstrake it's lighter still (by a significant amount). If it's a strip planked build, it can be relatively light weight, but usually not as light as a glued lapstrake, unless high modulus sheathings and dainty scantlings were employed in the design. So, in a nutshell, the glued lap will be the lightest, followed by a strip plank designed with more loading in the sheathings than typically seen, next the traditional lap and more conventional strip plank and last the carvel.

    As far as the laps creating resistance, well this is subject to some (considerable) debate, but in the speed ranges you can row one of these, absolutely no discernable difference. Lapstrakes sound much better underway BTW.

    When it comes to "differences in design" well this changes everything and you're not comparing apples to apples. A carbon composite build compaired to a carvel build is like comparing a Camaro to a Volvo sedan. Both are cars, both have wheels and engines of similar HP, but there's clearly a huge performance difference. If performance is the primary goal, you'll want the lightest boat with the best go fast stuff (riggers, sliders, etc.). Of course, this literally comes at a cost. The same is true of comparing different shapes, some will be more efficient underway than others.
     
  3. SailorDon
    Joined: Apr 2013
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    Location: Livingston, TX

    SailorDon Senior Member

    I agree about lalpstrakes sounding better underway. I would add that wooden lapstrakes sound better underway than composite rowing skiffs. I make this judgement based on over 3,000 miles of rowing my Selway-Fisher Mandarin 17
    Thames Rowing Skiff
    [​IMG]
    and 451 miles of rowing my carbon fiber Heritage 18.
    The Heritage 18 is much quieter going through the water than the Mandarin 17.
    Both have lapstrake hulls.
    Both weigh 90 to 95 pounds (empty).
    It is not a fair comparison since the Thames Rowing Skiff design does not have as fine a bow entry as the typical Whitehall designs like my Heritage 18
    You can check a short video I posted to YouTube from a rowing exercise session.


    I have not had the opportunity to row a carvel built Whitehall, so I don't have a milestone against which to judge the performance of my lapstrake Whitehall.
     

  4. rower mike
    Joined: Oct 2016
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    Location: BC Canada

    rower mike Junior Member

    still getting snow up this way

    Hi ROWer Don :p ;)

    good to see you got out on the water again, its been the rowing machine for me...

    thought we'd be finally done with the snow up this way as we'd been hitting approx. 50 degrees during the days... but we just got another 2-3 inches on Thursday afternoon & nite....

    Big old Okanagan lake has been open all winter long though .... but rowing longer distances in below or near freezing weather isn't necessarily the smartest or most enjoyable thing to be doing up this way.

    re: the sound of lapstrake...
    was out fixed seat rowing with my daughter years and years ago when she was in grade 1-2, .... told her it was the Lake laughing and giggling because we were tickling it... She was in the bow and liked that though and gave me this big bearhug from behind. thanks for reminding me of that...
     
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