Design Displacement vs Construction Displacement

Discussion in 'Sailboats' started by SmokeyBear, May 6, 2020.

  1. bajansailor
    Joined: Oct 2007
    Posts: 3,195
    Likes: 1,262, Points: 113, Legacy Rep: 37
    Location: Barbados

    bajansailor Marine Surveyor

    No worries, I think that we are all a bit susceptible to dyslexic moments - I often later find that I have said something very wrong or totally opposite to what I meant (and this is invariably after proof reading it a few times first).
    Although Alan you could have quietly edited your post as an option (few would have noticed) rather than 'fessing up' re your increases and decreases :)
  2. Blueknarr
    Joined: Aug 2017
    Posts: 1,394
    Likes: 377, Points: 83
    Location: Colorado

    Blueknarr Senior Member

    I read your original context as correct.

    The crew is moving aft to minimize the possibility of pitch-poling
  3. casavecchia
    Joined: Jan 2004
    Posts: 104
    Likes: 2, Points: 18, Legacy Rep: 14
    Location: Italy

    casavecchia Senior Member

    A question for Mr. Alan Gilbert.
    About 25 years ago I built a Wianno 15, a S&S design.
    Alan Gilbert was then Chief Engineer at S&S.
    Was it you?
  4. Will Gilmore
    Joined: Aug 2017
    Posts: 838
    Likes: 353, Points: 63
    Location: Littleton, nh

    Will Gilmore Senior Member

    Alan's excellent summation is very clear and there is nothing I could add except to reinforce the idea that distribution of load is terribly important. I own a Mariner 19 CB 2+2, which is MORC certified. Of course, once one starts loading her for anything more than buoy racing, such as weekend camping, that certification as ocean worthy begins to lose meaning. If one pays attention to load distribution, her righting abilities can actually be improved, but, like Alan said, a stiffer boat, like a heavier boat, has more stationary momentum and therefore is harder on the rigging and everything that rigging is connected to. Sudden changes in strength or direction of wind have less give in the boat that is harder to move.

    -Will (Dragonfly)
    Last edited: May 24, 2020
  5. JotM
    Joined: Jan 2009
    Posts: 98
    Likes: 9, Points: 8, Legacy Rep: 34
    Location: Leiden, the Netherlands

    JotM Junior Member

    I'm sorry to have to disappoint you there. Cees van Tongeren still owns the company but he is the only one left. And, being well into his eighties, he is pretty much retired and has steered others with questions (who were referred to Cees on the Dutch forum to other naval architects.

  6. JotM
    Joined: Jan 2009
    Posts: 98
    Likes: 9, Points: 8, Legacy Rep: 34
    Location: Leiden, the Netherlands

    JotM Junior Member

    As far as I know this used to be common practice. But I've noticed a tendency to communicate light craft displacement (mLC as per ISO 8666) when communicating displacement in brochures and sailing magazines these days. Including reputable names like Hallberg Rassy, where one really has to dig into the manual to find figures for other load conditions, or Hanse Yachts (including the Dehler brand) for which I have not been able to find anything but mLC from public sources about any models introduced over the past 2 decades.
    I wouldn't be surprised this change of practice is for commercial reasons, as it tends to inflate figures like the SA/D ratio and reduces the D/L ratio, signalling a more "sporty" boat. Any thoughts?
    bajansailor likes this.
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.