(Scow bow) - vs - (Wave piercing bow)

Discussion in 'Boat Design' started by Gunnar Sommerlund, Jul 10, 2017.

  1. Gunnar Sommerlund
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    Gunnar Sommerlund Junior Member

    Hello, this is my first time on this forum "i have been lurking around". <- (Bear with me)

    I haven't been able to find information regarding "differences" between scow and piercing bow types.
    I know that a sharp bow has a minimal wet surface, while scow i focused more about planning capabilities and is popular in lake sailing (in America).

    The reason i,m asking is because i have decided to spend next couple of years designing a sailboat in range of 25' to 30' foot. for sailing inshore waters of Denmark, and participating in local races now and then.

    The Scow seems to be gaining popularity (in mini transat) and i cant stop wondering why there arent more of them around.

    I have uploaded an example of arkemas mini transat and figaro 3 . I Absolutely love their designs.

    They are both made for open ocean right?


    gros_plan_aile_arkema1.jpg figaro3.jpg
     
  2. Doug Lord
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    Doug Lord Flight Ready

    The scow shape for Mini's began with David Raisons boat a few years ago and has proven to be very fast. The newest versions like Arkema and SeAir have taken another major leap in technology utilizing lifting foils to completely fly the boat. And two years ago Hugh Welbourn and Quant boats introduced the worlds first foiling keelboat scow the Quant 23.Very exciting times!

    The Quant 23 takes off in a 5 knot breeze and foils upwind in 7-8knots of wind. It uses a unique foil system that doesn't require constant adjustment and that drastically increases the righting moment of the boat. According to those that have sailed it ,it is very easy to learn to fly:

    Q23_kite.jpg

    SeAir Mini with Welbourn foil system:

    Mini sea air with welbourn foils.jpg
     
  3. Gunnar Sommerlund
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    Gunnar Sommerlund Junior Member

    Thank you for your feedback. alltho i wasnt looking for a foiling design. I have seen some of your posts on trimarans and multihulls in general. could you shed some light on advantages and disadvantages on scow vs narrow hulls?
     
  4. Doug Lord
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    Doug Lord Flight Ready

    Gunnar, I haven't sailed a Mini but while I think the new scows are amazing I think they are not pretty in the traditional sense. I guess it depends on what you want to do. I would consider using foil assist if not full flying. Good Luck!
     
  5. gonzo
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    gonzo Senior Member

    The Mini Transat has developed boats specialized in downwind sailing. If that is what you are considering, the blunt bow and shape conducive to surfing is great. For an all around boat, it is not the best.
     
  6. SamSam
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    SamSam Senior Member

  7. Gunnar Sommerlund
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    Gunnar Sommerlund Junior Member

    That is good to know. Becouse i,m looking for a design that preforms well inshore. Coastal cruising no more then 20 miles from shore.
     
  8. SamSam
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    SamSam Senior Member

  9. gonzo
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    gonzo Senior Member

  10. Gunnar Sommerlund
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    Gunnar Sommerlund Junior Member

    Thank you guys for the links. I will lurk arround and post what crazy ideas i come up with =)
     
  11. CT249
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    CT249 Senior Member

    One issue is that one of the big benefits of the scow is that they increase righting moment, but often at the expense of extra wetted surface and wave drag as I understand it. The extra righting moment is more of a plus if you have a big rig, and the extra drag is less of a problem if you have a big rig and a significant problem if you have a small one. So you tend to see scow bows on boats with big rigs. In some ways, something like a 25 foot scow is often simply a 28 foot boat with the bow chopped off; in fact in some small boat classes where there was a length restriction and big rigs, designers just used to design a longer boat and then effectively chop the bow off at the desired length. So you had 14 foot "snub bow" boats that were effectively 16 footers with the front cut off.

    It may just underline how designing a boat to a set overall length is actually quite artificial in some ways. A 22' scow would often become a better boat for minimal extra cost if you added with 3' of pointy nose onto it. Which leaves one to wonder where the advantage is, if one is not limited by LOA.
     
  12. Doug Lord
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    Doug Lord Flight Ready

    Scows, like the inland lake scows in the US and even the Mini scows are designed to sail at an angle of heel that reduces wetted surface and changes how the bow interacts with waves.
    You can see how much the wetted surface is reduced with the right angle of heel in the pictures below:

    Scow angle of heel.jpg

    Scows Upwind-.jpg

    Scow-spin reach.jpg
     
  13. PAR
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    PAR Yacht Designer/Builder

    The advantage of a scow hull form is the heeled waterline symmetricity, compaired to a more conventional canoe body. A a scow heels and as Doug points out, the typical canoe body's WL's tend to become very asymmetric with a strong rounding moment, yet the scow's WL's are less so and move dramatically to leeward, increasing the couple, but also decreasing resistance.

    Comparing a fine bow canoe body, particularly if fat butted for downwind efforts, to a scow just isn't a fair comparison. They're using different principles and hydrodynamic tricks to get their performance envelop. For inshore cruising and occasional racing, the more common triangular canoe body would be the reasonable choice. The scow is a fairly specialized hull form and you'll get dinged pretty hard, if you show up at the local 'round the buoys event, with a scow against a bunch of canoe sloops. Lastly, the scow hull form isn't the best choice for a cruiser, IMO, just no internal volume, which is high on the priority list in a cruiser.
     
    Last edited: Jul 15, 2017
  14. Doug Lord
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    Doug Lord Flight Ready

    Paul, when you compare a "Mini" scow hull with another 21-22 footer the Mini has a ton of internal volume but the 28' E scow sure doesn't-like you said.

    Mini 888 with uptip foils 8-8-15.jpg
     

  15. Gunnar Sommerlund
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    Gunnar Sommerlund Junior Member

    That was very educational. thank you.
     
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