Metal Round Bottom Sail Boat

Discussion in 'Boat Design' started by MarkSail1, Nov 13, 2012.

  1. MarkSail1
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    MarkSail1 Junior Member

    Help me out here, I am looking to build my first metal sailboat, and came across a method known as the Bezier method. Does anyone have experience with this method of construction? Please let me know what you think about the ease of the build, and effectiveness of the construction. I work well with metal, grew up in my Pops shop, and have the knowhow, but lack the experience with this sort of build. If anyone knows something I should, before I pull the trigger, let me know.
     
  2. DCockey
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    DCockey Senior Member

    You can find previous discussions about this method by going to the "Search" tab and searching for "Bezier Method".
     
  3. MarkSail1
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    MarkSail1 Junior Member

    Just saw that, thanks DCocky, Reading it now would like to go a little more in depth, what do you think about it?
     
  4. PAR
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    PAR Yacht Designer/Builder

    The Bezier method site is just utilizing ship building methods, that have been around for decades. Nothing new, except the hype. A skilled fabricator is much more important than a cute remix of an old technique. What design are you considering?

    Welcome to the forum . . .
     
  5. MarkSail1
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    MarkSail1 Junior Member

    Par,
    I like the look of the old wood round bottoms, and was thinking around mid 20s in size day sail some weekend. What attracted me to this method was the (as presented) ease of construction forming the round bottom. I know how to work metals, and using traditional rolling line heating and some bashing does not seem practical in such a hard radius that is multi directional. I don't want to move away from the metal as the hull material, and I want the round bottom look, and sail. What do you think would be a better alternative?
    Thank You
    Mark.
     
  6. PAR
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    PAR Yacht Designer/Builder

    Every build method and hull material choice has good and bad things to consider. What metal are you debating using; steel or aluminum? A 20' steel hull will be a difficult design, as the weight of this material makes it challenging to say the least in this length. A 20' sailboat of typical proportions will be in the one ton range, with canoe body racers being 3/4's and wholesome cruisers being 1.5 ton. I've recently designed a 20' 1" modest cruising sailboat with a displacement of 2,182 pounds and she would be on the heavier side considering her 18' 4" LWL and 6' 6" beam. A steel hull of these dimensions would need the beam adjusted to compensate for the hull shell's material choice. Once a hull gets into the 26' range, than steel starts becoming a much more viable hull shell material choice, as the penalties/benefits aren't as unacceptable.
     
  7. philSweet
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    philSweet Senior Member

  8. MarkSail1
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    MarkSail1 Junior Member

    I am thinking of using aluminum, strength to weight ratio seems to be most practical. I looked at a few designs (there are only few for small metal round bottoms), and it lead me back to the Bezier. I like the idea of the template; rather than working a sheet riddled with relief cuts and weld, but I am not certain whether or not this method has been tried and proven successful. This would be my first boat build, and I don’t want to start a failing project from concept.
     
  9. eyschulman
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    eyschulman Senior Member

    Why not redi used chine construction?
     
  10. michael pierzga
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    michael pierzga Senior Member

    Aluminum is Good choice. Small steel boats have a short lifespan. To keep weight down the steel plate is thin. Grinding down welds and sandblasting make the thin steel even thinner. Add a bit of corosion to thin steel plate and your boat falls apart. Details like integral steel tanks on a small steel boat are a nightmare.

    Always ask the designer of your chosen boat for advice.

    Look to the Netherlands for design. Metal boats are very popular.
     
  11. Wynand N
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    Wynand N Retired Steelboatbuilder

    Firstly, you are probably referring to the radius chine method that (in most cases) uses a constant radius and just altering the tangent lines to create a round bottom effect.
    It is a very fast and easy way to produce such a boat. However, using different radii along the length of the chine such as the claimed "Bezier" method (quite a few other designers uses same technique - old hat) creates some difficulty and in effect the rolled sections become conical to fit from section to section. I had built such a boat and found the constant radius chine much easier and faster to build and hard to tell the difference.

    Secondly, a proper round bilge hull is a different animal all together and you need to be a very skilled boilermaker/metalworker to do a first class job and such a hull can easily take 2.5 times or more longer to produce than a radius chine one.

    In my personal view a properly executed radius chine such as found in Dudley Dix's designs are much better looking than proper round bilge and can even fool boat designers themselves as I was a witness to. :cool:

    Check my webpage blog for more detail on radius chine method.
     
    Last edited: Nov 16, 2012
  12. michael pierzga
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    michael pierzga Senior Member

    Thats why its best to speak with the designer before choosing a design or build method. Time spent with the designer pays off big time
     
  13. Wynand N
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    Wynand N Retired Steelboatbuilder

    True words Michael. What is most important for an amateur - even professional - builder is the fact that the plans should be builder friendly and nothing left to chance.
    This is where Dudley Dix shines; he had built a few of his designs for himself when he was still residing in SA and know pitfalls that may come in a builders way and design his boats in such a way to prevent just that with full set of plans and detailing, and his after sales service is second to none. Perhaps Im biased towards him because we are friends.

    That said, having built to designs of Shannon, Bruce Roberts, Angelo Lavranos, Dix, Al Mason, Moekli amongst others, the best plans came from v/d Stadt (34 & 40 Norman). Beautifully prepared, complete and everything covered:cool:
     
  14. Frosty

    Frosty Previous Member

    I was drinking with a knowledgeable chappy once who got out of his pocket a 10 dollar note, it can be any currency note.

    He folded it at one end and pinched it together with his thumb and finger. He said that is the perfect racing hull.

    Apparantly you can do the same with flat steel , welding together enough flat plate and drilling holes in the top corners and pulling them together with block and tackle. With careful use of heavy hydraulic diggers etc the hull can be formed in a day.
     
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  15. michael pierzga
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    michael pierzga Senior Member

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