Freeship starting model questions

Discussion in 'Software' started by valery gaulin, Sep 8, 2017.

  1. valery gaulin
    Joined: Jan 2017
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    valery gaulin Senior Member

    I just downloaded the Freeship software yesterday.

    I would like to know about the model that gets generator when starting a new project based on lenght, beam, draft that we input in the beginning of a new project.

    The model generated is it optimized already? If yes, optimized for what, least wetted surface, least resistance, best prismatic coefficient, best block coefficient, best displacement to lenght, freeboard, etc. Are all those design parameter taken in consideration when the first model gets generated?

    To me it seams that the untouch hull model generated looks to be the best compromise already! Am I wrong?
     
  2. TANSL
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    TANSL Senior Member

    I hope you are mistaken because otherwise the work of the designer would be of little importance. That software would be taking away the work of many professionals.
    How can a software optimize a design without having more data than lenght, beam, draft ?: Neither the best designer in the world would be able to do it. IMO.
     
  3. valery gaulin
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    valery gaulin Senior Member

    TANSL of curse you are right yacht designer would not be needed anymore if a software could de everything!!!

    But this is my main question what the model created is optimized based on the simple input data lenght, beam, draft.

    A designer as alot more work to do. Optimising interior room, waterline lenght performance vs the cost of a marina based on overall length. One of the most important factor for a yacht designer today is that it must be made for the wife first!!! Otherwise there is no sale!!! lol

    Really if you look at all the new Sailboat from big brand they are basically a sailing condominium! They have alot more technology in the sailplan and hull shape but don't actually really sail faster or better than much older design. But what they have is alot more room for the length.

    If someone is not limited by overall lenght to have all the comfort needed there is probably a general optimized hull shape for any given displacement and speed potential.
     
  4. TANSL
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    TANSL Senior Member

    Well, you rely on software until you have to stop trusting it. You decide if the model that the program offers you is better than the one you can do.
    You have to rely more on yourself and your ability to make things better than a machine. Star with this model, work on it and try to improve it.
     
  5. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    You seem to have some preconceived notions about design that frankly aren't correct, suggesting you need a lot more study on hydrodynamics and design, than evaluating a free design software package's abilities.

    Software doesn't design anything, nor does it optimize anything. The person sitting at the machine does this, assuming they have a clue about what to optimize. These low cost programs simply do some rudimentary math, volumetric calculations, etc., based (solely) on the input of the user.

    About the basic hull FreeShip provides. It's well not bad, though a pig in some circles, could be considered a "starting point" for many. It doesn't take much to distort it into something considerably better, though you do need to know where and what to "tweak", which is where the education part of the equation comes to roost.

    Given your assumptions, I'd hazard you really don't know what makes any particular sailboat design faster, more weatherly or more maneuverable than another. This means you're in need of some serious understanding on several subjects, before you start playing with the software. Okay, maybe a small little dayboat is fine, how bad can you screw this up, but before you invest a few years of construction and tens of thousands on a dream 35' sailing yacht . . .
     
  6. valery gaulin
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    valery gaulin Senior Member

    PAR you right that I know nothing about boat design! Otherwise I would not be asking questions on this forum about an open source software for boat design. Actually I give credit to the people that got this software together, amazing job they have done.

    Now since that you are a boat designer and have alot of knowledge, you should be able to answer my first initial questions. What is the model optimized for when first created with the initial input data, lenght, beam, draft. The algorithm is based on some knowledgeable assumption to come up with this model. Do you know what those assumptions are?

    The other aspect that you are right is that without any boat design background it would be completely stupid to start a sailboat building project without any design knowledge. Buying a plan for a reputable designers is the way to go, but for comparison between different sailboat plan available I need to understand the design basic before choosing a plan from a designer. All designer think they got their recipe right, but all their sailboat are different.

    I seams to favor shallow draft, the French called them "deriveur integral" and they sail around the world with those sailboat with very shallow draft and beaching capability most of the time built in aluminum. When you look in the USA designer market they favor deep draft for world sailing! Who got it right the French or the American??? Just different philosophy.

    My main objective is to understand the main design difference before I make a choice, and I want my choice to be a knowledgeable choice.

    So far my wants is a shallow draft cruising sailboat with a center cockpit that does not need to connect from the inside with a passage from the aft and forward cabin, actually I want water tight bulkhead separating those cabin. Two assymetrical daggerboard on each side and a long low aspect ratio lead keel for protection when grounding, beaching or drying out at low tide. I would like a staysail schooners rig with both stay sail on roller furling and self tacking setup. The newer shallow draft design favor large planning aft hull shape that comes from the newer racing fleet, mini 650, Imoca, etc. But for cruising I am not sure it is a good choice. I feel that I would prefer a more conservative hull shape in the aft part of the boat for more confort and seakindless motion. Lenght around 45 foot, beam 13-14 foot, draft around 3ft daggerboard up and 6-7 foot daggerboard down, 6'3" standing head room in the middle part inside the boat, I am 6' 2" tall. This one off DIY construction seams to be better with cold molded epoxy plywood construction or strip planking or both combine. Kevlar reinforce inside the hull below the waterline for impact resistance. Large single skeg hung rudder.

    If you have any plan that looks like what I have just describe, let me know. I will be interested.

    Thank you
     
  7. Dolfiman
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    Dolfiman Senior Member

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  8. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    The only person(s) that can answer your questions about the base FreeShip model, is the actual developer of the software package. Observationally, it appears to be a basic canoe body of average proportions, with a slightly narrower stern than is common today, a "U" shaped entry and modestly square midship section. The question is do you know why these decisions were employed, with the development of this as the base model? For example why would they want a "U" shaped entry section? This is the butt kicker with software packages, you have to understand why things are done, before you can make intelligent changes to them.
     
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  9. tmark
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    tmark Junior Member

    I might suggest learning the program by attempting to replicate the lines of a classic; something well known and well proven. Once you've learned to fair the hull start playing with the transformation capacities and see how they affect the hydrostatics etal ... have fun, you're not going to build the first thing you draw ... remember, it's a journey, not a destination.
     

  10. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    I disagree, the first thing you need to learn is hydrodynamics, structural considerations and yacht design basics. At this point, you'll have a chance at making more than pretty boat shaped pictures, with a CAD modeling package.
     
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