Old Design needs Updating Help

Discussion in 'Boat Design' started by RumnCoke, Aug 31, 2013.

  1. RumnCoke
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    RumnCoke Junior Member

    Hello Skippers, Designers, and Builders,
    I want to just cut to the chase directly. I am a lifelong RC Sailboat Racer and Builder.
    I have a few hull design profiles I wish to put into sailing software. I have 15 cross section stations for each hull. All the math has been checked.
    This boat class is a development class with few limitations on materials used, and overall displacement. My hulls were designed for a displacement of 7.5 pounds many years ago, but todays boats are averaging a static displacement between 5.2 and 5.8 pounds.
    I want the designs reduced for a suitable displacement so they will sail on their lines correctly. I want them tested for drag and perhaps tweaked if necessary. I am confident I have the answers to most of the questions that will be asked by a naval architect/boat designer to get the job done.
    The final digital version will have to be in a format that will lend itself to CNC production for a plug.
    I have the resources lined up for female molds at that point.
    I am reaching out here to anyone that may have a direct interest or someone that can direct me to possible source.

    Thank You,
    RumnCoke :)
     
    Last edited: Aug 31, 2013
  2. abAndad
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    abAndad Energetic Naval Architect

    Hi RumnCoke,
    I'm so sorry to say this:D, but really I didn't find out what is your problem?:confused::rolleyes::confused::?:
     
  3. RumnCoke
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    RumnCoke Junior Member

    @abAndad,
    No need to be sorry about it. I am 3d modeling software challenged and need my designs, that are on paper, converted to digital form in some kind of boat design software and then the hull massaged down from a displacement weight of the current 7.5 pounds to something around 6 pounds. Within the boat design software there are programs that allow for flow analysis while healed or not. If my hulls have any major drag points that may be reworked for some better flow, then I would want to have that done as well. I am fairly certain that the hulls a pretty clean as far as drag vs sailing performance, but with a displacement reduction I am not so certain what consequences might pop-up.
    Please make no mistake. I am not looking for charity, but a business deal with payment for services rendered. No pun intended.
     
  4. SamSam
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    SamSam Senior Member

    If you use the same lines, how can you have "the designs reduced for a suitable displacement so they will sail on their lines correctly"? Although you would have less total weight, wouldn't you still have around 7.5 pounds displacement? I mean if you kept the boat the same size and reduced the weight by 20%, the lines wouldn't work anymore, would they?
     
  5. RumnCoke
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    RumnCoke Junior Member

    Sorry if I wasn't clear. Let me put it this way. The hulls were designed with an overall static operating weight of 7.5 pounds. The hull will displace 7.5 lbs and sit on its lines. Today, I can build a hull of this size that weighs only 4 ounces. With all materials, rigging, 4 lbs of ballast, and electronics, I can build the boat to weigh in at 5lbs 6 ounces. Lightness being a key factor here as my sail area is limited to 600sq inches. I am allowed a 2" roach on the mainsail and a 1.5" roach on the headsail. Most successful sail plans for my boats use a 60% main and a 40% jib sail area ratio and profiles seem most efficient at approximately a 5 to 1 ratio. Lighter boats are faster most times. Since these are models, a designer need not be concerned with any structural problems. The hulls will be completely self-supporting shells made from infusion laminated Spread Tow Carbon Fiber with layers of Carbon and Kevlar scrim added as needed for final hull stiffness.

    The lines will have to be reduced yes to achieve a reduced displacement. However since there are multiple flow lines to interact with the surface area the original performance characteristics and appearance may still be recognized.
    What I mean is, for instance, that the Length of the boat may not be adjusted. It has to be approximately 1 meter in length plus or minus 1/8". The Rocker or keel line profile curve I would like to maintain if possible. The Beam of the boat can definitely be reduced. Now with these parameters defined, one could simply begin a slight cross-sectional reduction at each station, taking into the fact that there may be less freeboard now available hence lowering the sheer line of the boat. Or just reducing the curve but still maintaining the curve profile. With the right adjustments at each station, the freeboard could be maintained and the keel line profile could be maintained as well while only really reducing the Beam of the boat. This is what I am hoping for. With some drag testing software, Im hoping for some clean lines and a good estimated speed projection. All these things are available, I know, on Hull Design Software today. I would just prefer to have a pro do it and have the security of consulting with them about it.
     
    Last edited: Aug 31, 2013
  6. abAndad
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    abAndad Energetic Naval Architect

    Why don't you scale it to a smaller size?!
     
  7. TANSL
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    TANSL Senior Member

    RumnCoke, what you need is what is called an "affine transformation" of the ship, which is not a change in scale but a transformation that changes the dimensions of the base model unevenly, keeping as smoothed forms as they were previously. This is very normal in shipbuilding and certainly, I can help you do it. I know how to do it and I have the required software.
     
  8. RumnCoke
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    RumnCoke Junior Member

    Definitely what I was looking for even if I didn't state it clearly. How may we talk further?

    Thank You :D
     
  9. TANSL
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    TANSL Senior Member

  10. Mr Efficiency
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    Mr Efficiency Senior Member

    If the only restrictions are overall length and sail area, I'd advise you switch to a catamaran ! Has to be more than that surely.
     
  11. johneck
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    johneck Senior Member

    CFD software has advanced amazingly over the past 10 years and we can now look at wavemaking drag as well as pressure and frictional drag in a very efficient manner. Obviously, reducing wetted surface is a primary goal. However, I suspect that with a 5-6lb displacement hull, you will need to include the effect of the fins in the drag calculation. The displacement of the keel might even change the most efficient longitudinal buoyancy distribution.
     
  12. RumnCoke
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    RumnCoke Junior Member

    Sorry, I only mentioned those two. Class rules for that boat are on the theamya.org website.

    These boats are racers and a development class with few restrictions... allows more freedom than old one design boats. Its a popular class with many boats and therefore a more competitive class than others.
    RC Cats have their place but not much of a following. Kind of like this years AC racing lol.
     
  13. RumnCoke
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    RumnCoke Junior Member

    Thanks for the interest Johneck. The Keel is very important to this class and there have been many designs because of it. The open design of this class does change keel requirements. Very astute of you. Most keels average between 28 sq in and 34 sq in. and the flotation element is noted. Most go for a neutral buoyancy. Keels are designed mostly with Reynolds profiles and most appear as a fin type with straight edges and a 12 degree rake on the leading edge. Ballast is as a torpedo shape also done with Reynolds profiles. Rudder profiles and surface area are calced by the good builders. Reducing wetted surface area to minimums is an advantage.
     
  14. messabout
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    messabout Senior Member

    Sounds like you intend to finesse the IOM or USOM class. There are a bunch of hull designs for both those classes as you know. The IOM class, in particular, has been exposed to some very lengthy and intelligent design tweaks. Any improvement that you might make will likely be incremental as all the ones before. Not to say that one should ever stop thinking and working toward better and better hull design.

    You know, of course, that you can narrow the hull or reduce the draft by fiddling the section shapes. In either case you may need to increase the bulb weight or depth to compensate. A dilemma that could be fun to solve. Hang in there and do it RumnCoke.
     

  15. RumnCoke
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    RumnCoke Junior Member

    Thanks Messabout,
    I was wondering if I would run into someone from Model Yachting on these forums. Ive had designs and complete boat ideas running thru my head for 25 years. I have not been capable of realizing them until this time.
    The IOM class has so many restrictions its kind of defeating and old as the class has not progressed with time. I mean c'mon fiberglass hull, and aluminum mast, and worst of all 8.75lbs minimum weight. All in the name evening the playing field for amateurs and keeping costs down. Well Costs of a complete boat rival that of even the most expensive exotic boats in any class, so keeping costs down isn't really happening. The weight ridiculously out of line with a 1 meter design unless you want to regress in time back to the 60s and 70s. A revamp in the IOM class would be a dream come true.
    US1M gives more latitude and I happen to live in the most populous US1M area in the US. Anyway the IOM idea is just to see If I can compete with it. Another challenge. Talk is cheap... doing is another, and Im sending US1M plans today for review and to get the ball rolling. Who knows what the future will bring... a lot of testing and exploration of ideas. I have a box full of trophies competing against the same boats that are still alive in that class today. I have every confidence that my thumbs are as good as any skipper out there today. Yes Ive been watching.
    Today is a good day. Thanks for the interest.
     
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