Any point in scow bow without canting keel?

Discussion in 'Sailboats' started by pironiero, Oct 27, 2020.

  1. pironiero
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    pironiero Junior Member

    Is there Any point in scow bow without canting keel? I can be wrong but for its best performance you need to be as vertical to water as possible, amirite? so in other words its not quite effective to make scow bow on a boat without catning keel OR a very long one
     
  2. Will Gilmore
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    Will Gilmore Senior Member

    That is true, but every sailing design has its optimum angle of heel and other angles that it sails on with less efficiency. The smaller racing scows rely on a shifting crew. There are also sail plans that make upright sailing easier by tilting the sail to spill heavy air instead of heeling the boat for the same purpose.
    [​IMG]

    -Will (Dragonfly)
     
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  3. Olav
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    Olav naval architect

    pironiero,

    have a look at some of the latest production designs in the Classe Mini 6.50 (i.e. Vector, Maxi, to some extent also Wevo*). Due to the production classe rules of the Classe Mini they are not allowed to have movable appendages, so no canting keels. Also the draught is quite moderate with a maximum of 1.60 m (in contrast to the 2 m of a prototype Mini).

    Of course these boats suffer in light conditions. Scows have quite a large wetted surface area when upright, so in very light air it should well pay off to heel the boat to leeward with a canting keel - otherwise you are doomed, especially if there is still some old swell. However, they tend to show a good overall performance, but in case of the Mini they are optimised for downwind sailing and this is where scows do excel.

    *(yet to be homologated as "bateau du série")
     
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  4. tlouth7
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    tlouth7 Senior Member

    The entire point of a scow hullshape is to achieve high righting moment and a balanced submerged shape when heeled.

    Sailing scows flat is often very slow because of the large wetted area and associated drag. Canting keels may be used to deliberately heel the boat in light airs to reduce this.

    The upshot is that scows can make sense in fixed keel classes where there is a limit on LOA.
     
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  5. sharpii2
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    sharpii2 Senior Member

    The scow bow, or perhaps more accurately, the pram bow, is a really good down wind shape. It tends to climb up the backs of waves, rather than trying to plow through them.

    A long, sharp bow can be a terrible thing when going down wind in rough seas. It can have a very bad habit of burying itself, or skewing uncontrollably to port or starboard while sailing fast.

    Working sailboats, with a few exceptions, had shorter, more blunt bows. The exceptions often were boats that had to be rowed long distances, and ones that had to sail upwind a lot.

    Part of the reason Joshua Slocum's Spray was able to sail on a 24 hour basis without self stearing, besides her long keel, was probably her blunt bow.
     
  6. CT249
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    CT249 Senior Member

    Back in the days of scow Moths, one of their weaknesses was actually the fact that they buried downwind in chop far more than conventionally-bowed boats. The scows had lower freeboard (because otherwise they would suffer from excessive weight and windage) and when that fat bow went under chop you were in big trouble.
     
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  7. sharpii2
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    sharpii2 Senior Member

    I can certainly identify with that.

    The first boat that I ever owned was a sailing scow I built myself.

    It's plan for was a perfect rectangle.

    On its first successful sail, it stuffed a wave. The boarding sea lifted a 20 lb navy anchor and set it gently on my lap.

    During another outing, the Lee corner of the bow dug in, and the weight of the water that came on board quickly capsized the boat.

    A scow bow, or perhaps more accurately, a pram bow, does not only have a transom high enough to provide ample buoyancy, but has a curved transom/bottom joint, to keep the Lee corner from digging in.

    Also, a pram bow would be half as wide as the boat or less.

    San Francisco Bay Pelican sailboats had a similar bow, and IFIRC, never had a problem with stuffing a bow.
     
  8. Doug Halsey
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    Doug Halsey Senior Member

    Yes, it's important not to lump all scows together as if they were the same.

    Here are three very different designs - all of them scows (Y-Flyer, Southeaster, OptimistPram):
    Y-Flyer_Scow.jpg Southeaster_Scow.jpg OptimistPram_Scow.jpg
     
  9. CT249
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    CT249 Senior Member

    As far as I've been able to find out, from a LOT of historical digging (see for example Pt 1.14:”A radical departure”: the scow https://sailcraftblog.wordpress.com/2016/10/08/scows-21-sept/) the scow and pram are, at least in racing terms, quite different beasts. When the scow really arrived in racing in the 1890s, their line of development was from the flat Raters. Clinton Crane and George Duggan made the line of development pretty clear, as does the ILYA history.

    The pram appears to follow a different line of development. While terminology and etymology aren't written in stone and the term has been used in different ways, as far as sailboat development goes they appear to be generally considered quite different; for example in Commonwealth nations we called scow Moths scows, but Mirrors, Cadets etc were called prams, as was the Optimist. I can't actually find anything on Google that calls an Opti a scow, even on the ILYA sites.

    So as far as I can find out, an Opti style boat with its higher and narrower bow would be called a pram, and the scow Moth with its low freeboard and wide bow was definitely a scow. Certainly, they seem to sail very differently downwind in chop.
     
  10. waikikin
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    waikikin Senior Member


    & then there was the "snub nosed bow transom" as well.
    J.
     
  11. Doug Halsey
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    Doug Halsey Senior Member

    I'm not an authority on the etymology, but I've always thought of hulls as being of two general types: those with pointed bows (skiffs?) and the others (scows). Under that assumption, of course I would consider prams to be a type of scow. As you imply, there could be regional (or other) differences in usage though.

    For what it's worth, here's an example of a flat-nosed barge 1n 1929 referred to as a scow:
    1929-10-15_The_Miami_News_MiamiFlood.jpg
     
    Last edited: Nov 6, 2020
  12. messabout
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    messabout Senior Member

    For whatever it is worth, Inland Lakes Scows are designed such that the are at their best when in heeled attitude. Herreshoff figured that out a long time ago and was criticized for producing a boat that could easily defeat conventional ballasted boats. His scows were barred from gentleman's competition thereafter.

    A canting keel might be of some advantage only if controlled so as to adjust the scow to its most efficient heel angle.
     
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  13. jehardiman
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    jehardiman Senior Member

    I concur...
    A better question is "Why have a canting keel with a scow hull form?"....
     

  14. CT249
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    CT249 Senior Member

    Actually, it wasn't Herreshoff who created the first racing scow. I'm not sure he ever did any "true" scow; although Reliance was sometimes referred to as such, Herreshoff's letters in Mystic Seaport state that he refused Iselin's request to design a huge scow and produced Reliance instead.

    There's references to scow-type boats racing in the 1850s around rivers in the NY area, and the Clapham design "Bouncer" types were known as "scows" when they arrived in 1890. Larry Huntington applied the same basic design in 1894 with Question, which did well in the Seawanhaka Cup trials, and that then inspired Clinton Crane etc to develop their flat, full-ended "Raters" or "15 footers" for the Seawanhaka Cup. 1.13: The Seawanhaka Cup (Draft) https://sailcraftblog.wordpress.com/2016/09/21/1-13-the-seawanhaka-cup-draft/

    George Duggan, designer of the Canadian boats that took and held the Seawanhaka Cup for years, stated clearly that his early designs like Glencairn 1 used the scow concept of sailing the boat on an angle of heel to reduce wetted surface area, a long-water symmetrical immersed shape, and increasing stability by moving the centre of buoyancy to leeward.

    The ILYA scows came along after the first Scow-type "Raters". But both Duggan and the ILYA historians specifically referred to the existence of "pointed bow scows" and of "square nose scows". Some 1920s authors from the ILYA areadid refer to square nose boats as "true scows", but in the same piece stated that "the matter of bow shape has nothing to do with the generic type, either the pointed-bow or scow-shaped type of hull developed under the rules being true scows". The "typical scow" was described as having "a very flat floor, a form bilge, and sections that are generally parallel throughout.
     
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