Added drag of external chine logs

Discussion in 'Hydrodynamics and Aerodynamics' started by waterbear, Dec 14, 2019.

  1. waterbear
    Joined: Mar 2016
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    waterbear Junior Member

  2. bajansailor
    Joined: Oct 2007
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    bajansailor Marine Surveyor

    I am just wondering why you would want to have chine logs (either inner or external) on a simple 12' skiff ?
    The consensus of the previous thread you referred to seems to suggest that there is not going to be much difference.
    And surely it would be much easier to build the skiff using the simple 'stitch and glue' method rather than having chine logs as well?
  3. waterbear
    Joined: Mar 2016
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    waterbear Junior Member

    One good reason is to get a fair curve on the chine. On Hannu's skiff the bottom panel is not lofted, but traced from the 1/4" sides which will be wobbly without the chine log.

    The other reason is one can build a boat without glass/epoxy, which has benefits.

  4. messabout
    Joined: Jan 2006
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    messabout Senior Member

    Interior chine logs are the tried and true method that was used reliably by our ancestors......before Epoxy. Stitch and glue method is not necessarily easier than internal chine logs...unless you have a lot of flare and need to make a rolling bevel on the logs. The infamous Bolger boats often had plumb sides which avoided the need for tricky beveling. That was not his reason for using plumb sides. One of his designs: Black Skimmer, had external chine logs. I poo- pooed that practice until I sailed one of the Black Skimmers for a few days. I think that he did the external logs because the boat used twin Lee boards and the external logs made a place for the board to rest when on the lee side.

    The purist in me would not allow any such awful appendages such as external logs. On the other hand, such eddy making, violations of proper boat building principles, did not seem to make much if any difference in the way the boat behaved. For a really small boat, like a 12 footer, weight matters. Even small amounts of weight that the chine logs involve are of at least some interest. A one by one and one half inch strip of fir that is 12 feet long will weigh something close to four pounds, and other stringers will also add up to a disappointing lot of weight. That of course depends on the intended function of the boat. If it is to be a lively sailor then make it lightweight. If it is only a harbor bound boat for tending mooring buoys, or some such function, then never mind the weight. The glued fillets of the S&G method does save a few pounds.
    bajansailor likes this.
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