rowing boat reverse bow

Discussion in 'Boat Design' started by bob clair, Mar 25, 2018.

  1. bob clair
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    bob clair Junior Member

    hi does anyone have any pics or info on reverse bows or tear drop shaped sections in the bows of rowing boats/kayaks etc
     
  2. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Welcome to the forum.

    I'll assume you mean a bulbous bow on a human powered craft? This hydrodynamic approuch is specifically intended to work (well) at a specific speed. Under or over this set speed, the bow treatment is a determent and not an advantage, so you'll be pulling a significant amount of water along with you, from stroke to stroke. Simply put if you've designed something that can continuously maintain a specific speed, this is an option. Human power suggests this isn't the case, so maybe looking elsewhere might be a better option. Now, some racing human powered hull forms may employ a wave piercing bow, which can help a small amount, but again it's all about the speed you can continuously sustain, that'll make this feature (or any other) viable.
     
  3. bob clair
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    bob clair Junior Member

    Thanks.its not so much bulbous bows but reverse bows and a hull section thats wider below the waterline than above like the ac cats . Theres lots of kayaks and rowing boats moving that way and i remember seeing some boats at the boat show in 2013 like that and there was even a boat at henley in c2006 but i cant find any pics
     
  4. gonzo
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    gonzo Senior Member

    Most of those designs are based on marketing and not engineering. Why do you think would be an advantage for your intended use?
     
  5. PAR
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    PAR Yacht Designer/Builder

    Agreed, you'll find every new feature show up in the following years offerings at the boat shows, even if they offer very little to the design's abilities. These bows, as a rule have a narrow range of operational attributes, they can offer. If your design can operate within these speed ranges, then yes, it may be a good idea, but given the usual Froude numbers these operate within, not so much.
     
  6. bob clair
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    bob clair Junior Member

    Its for a study project so really interested in the history from galleys to 1908 dreadnoughts to 2009 ac yachts
     
  7. gonzo
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    gonzo Senior Member

    The galleys had rams, which were for sinking enemy ships, not for any speed or handling advantage.
     
  8. Angélique
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    Angélique aka Angel (only by name)

    Hi Bob,

    Below a reverse bow Feadship Predator (built in 2008), and a reverse bow tender in the same style, and further below some canoes with a reverse type of bow . . .

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]
     
    Last edited: Mar 27, 2018
  9. Angélique
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    Location: Belgium ⇄ The Netherlands

    Angélique aka Angel (only by name)

    These (as shown in post #8, except for the first pic), are usually called Canadian Canoe . . .
     
  10. Angélique
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    Angélique aka Angel (only by name)

    Just remembered yet another reverse bow canadian canoe . . :)

    Thread: Cardboard Boat Regatta ---> Post #39

    [​IMG]

    Gonzo in a beautiful DIY built cardboard Canadian Canoe with only duct tape at the seams and no further waterproofing, taking some rapids . . :cool:
     
    Last edited: Mar 27, 2018
  11. Dolfiman
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    Dolfiman Senior Member

    For your investigation on reverse bow, you can have a look on these recent design :
    Bourbon boats with Xbow :
    BOURBON construit de nouveaux navires à étrave inversée https://www.meretmarine.com/fr/content/bourbon-construit-de-nouveaux-navires-etrave-inversee

    DCNS Navy boat design :
    DCNS propose des navires à étrave inversée https://www.meretmarine.com/fr/content/dcns-propose-des-navires-etrave-inversee
    (Note that here there is also a question of much radar reflection)

    Wave piercing for multihulls issue :
    A Look at Wave-piercing Bows on Multihulls https://www.sailmagazine.com/multihulls/a-look-at-wave-piercing-bows-on-multihulls

    And last but not least, the Incat wave piercing catamaran ferry, initiated by Phil Hercus in early 80's, that really launched a new approach on such bow, that now proliferate on other type of boats :
    INCAT - Building the World's Fastest, Efficient, Environmentally Clean, High Speed Ships. https://www.incat.com.au/
     
    Doug Lord likes this.
  12. Mani Kandasa
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    Mani Kandasa Junior Member

    The DDG-1000, drop dead gorgeous evolution of the dreadnaughts, on sea trails at Ft Lauderdale


    IMG_7551.JPG IMG_7552.JPG

    The DASH-trimaran concept ...

    5594a.PNG
     
  13. bob clair
    Joined: Mar 2018
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    bob clair Junior Member

    THAnks everyone. Keep em coming
     

  14. bob clair
    Joined: Mar 2018
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    Location: uk

    bob clair Junior Member

    Thanks. I realised it wasnt to try and win the olympics but is amazing how they created those curves
     
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