drawing needs scale

Discussion in 'Boat Design' started by sandpiper32, Aug 28, 2014.

  1. Rabah
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    Rabah Senior Member

    Hello PAR,
    I have seen that is in the Internet for Presto 30 sharpie, then has once again tested that I have made and have seen that did not pay attention to that fact that the deck in the image has more indicative deck sheer in the bow and the stern than at model Delftship. For this purpose windows of the superstructure are covered. Now has corrected deck sheer of model and I think that that's all right.
    The draft for total displacement T = 0,69m has defined so that the length of water-line LWL=8,64m was received.
    A series of models Delftship is tested in hydrodynamic pool in the University and meets the requirement about minimal water drag at movement of the vessel. So that I do not have any doubts in contours of the underwater part.
     

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  2. PAR
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    PAR Yacht Designer/Builder

    Again, it's obvious you're unfamiliar with the Presto as a "type". The Presto 30 is a recent production boat and not especially Presto like, except in topside appointments to a degree. Even at that, you're doodling isn't even close.

    [​IMG]

    This is the Roger Martin version of a Presto, though it's not really.

    The type evolved as the good commodore worked out the asspects.

    [​IMG]

    This is a showing of some of the typical shapes employed on a presto type. The blue one is fast, but not especially sea kindly, the teal one is Ruel Parker's version and has better sea keeping features, the red one is the original Presto and the green one the commodore's last version in developing of the type.
     
  3. Jammer Six

    Jammer Six Previous Member

    So, if Roger Martin can design a Presto that doesn't meet your standards, I'm thinking that Rabah can, too.
     
  4. PAR
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    PAR Yacht Designer/Builder

    Roger Martin designed a boat that resembles a Presto enough that a marketing team can use it as a sales tool. It's a good boat and a well thought out design, but isn't very close to a Presto, even the later versions Monroe developed. Attached is what a Monroe Presto would look like, so tell me how does this compare to the Martin design or the DelftShip rendering? If you can't see the significant differences, the issue is moot, but in reality, there are huge difference in the posted DelftShip rendering and a Presto, even the modern versions, such as those from Parker and Martin. The Martin is a narrow canoe body, with Presto topside influences, while the Parker sharpies more closely match the Monroe shapes. Craig Walters has a good design too. Parker's designs typically carry more quarters power and better form stability, than the originals.
     

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  5. TANSL
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    TANSL Senior Member

    Returning to the initial question of sandpiper 32, I think what is crystal clear is that there is no reliable way to turn up the brochure sketch to a scale to work with.
    Latest posts (I agree a lot with what he says PAR) only demonstrate that the method used by Rabah not lead to anything that could be used by sandpiper32.
     
  6. rwatson
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    rwatson Senior Member

    Oh, I dont know. If he had stuck to what he could see, he could have done a good job.

    Its when you try to make it up out of your head. it gets pointless.

    From a purely aesthetic and rigging point of view, it may have been interesting for the OP to 'adjust' as a styling exercise, and make a wooden model from.
     
  7. TANSL
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    TANSL Senior Member

    Of course you're right, rwatson. All I want to remember is the initial question : "Does anyone know how I can scale the drawings up or down to a convenient scale?"
    I am also able to do many things which little interest to the OP. I do not want to make an exhaustive list of my abilities because it would take too long.
     
  8. Rabah
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    Rabah Senior Member

    Dear PAR,
    In modification3 you will find that search. This time I have taken for a basis total displacement 3,356t and have received the draft 0,437m and LWL=9,378m. I send IGES file too. But as I do not like the fore I offer mod4 with D=3,351t,T=0,44m and LWL=8,996m.
    You can see different between my hull end Presto.
     

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  9. TANSL
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    TANSL Senior Member

    Rabah, I think you've done a very creditable job.
    The problem remains the same because, not knowing where to measure the total length, breadth or depth, we can never ensure that the created model is correct, although the displacement match.
    As you well know, even knowing these three dimensions (+displacement, +longitudinal profile), you can create infinite different hulls.
     
  10. PAR
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    PAR Yacht Designer/Builder

    I think we're all on the same page in regard to the issues associated with trying to generate lines from brochures, etc., but this isn't my point.

    [​IMG]

    This comparison shows how far off the rendering is, suggesting a lack of understanding about the type, who's lines and plans are available from several sources.

    The lack of understanding about the type is the early hull form conformation, rather than the evolved and developed versions. The fit should be obvious with the DelftShit version having a U shaped entry, instead of the finer V of the Monroe, the flat midship floors of the Monroe, compared the deadrise of the new version and the exit that's all wrong with a much shallower run and buttocks. Just not even close, again suggesting an exercise in pretty picture drawing, instead of an understanding of the type and the affects subtle "modifications" can have on the performance envelop, not to mention type conformity. This is particularly interesting, since the plans are available from several locations, why the uneducated guess work, about the type and it's shapes, is entirely unnecessary.
     
  11. Jammer Six

    Jammer Six Previous Member

    Yes, we know. Your point is that you have too much business.
     
  12. sandpiper32
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    sandpiper32 Junior Member

    To my eye Par, "Neena" is very close to the red in under body, especially the short keel where 2500 lbs. lives. She doesn't have quite as much flare though. Today under just the fore, she sailed her self up wind in 15 to 20 knots, hard on the wind, tacking through about 100 degrees, doing 3.2 knots. My bilge boards won't go down all the way so performance suffers up wind. On the broad reach home, we averaged 5.
     
  13. Rabah
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    Rabah Senior Member

    Hi PAR,
    Sirs with which we discuss in the forum are very right - you have changed the primal problem of the discussion.
    Not in the beginning and a little bit later sandpiper32 has published the side elevation drawing, but there did not suffice the information:
    -The depth neither as the image, nor as definite size was not clear
    - There were no other two projections
    It was necessary to share the discussion on two parts:
    1. How to copy from the shown image contours of the superstructure and sails
    2. How to change the chosen model so that he responded to the prototype
    I have proved that the point 1 is easily feasible irrespective of furious attacks in the forum.
    For performance of a point 2 I used the ideal possibilities of program Delftship - it is necessary to transfer the control points in the three projections so that contours of model have coincided with it in the image. You already were convinced what it is possible to make quickly. Certainly it is possible to change still contours but to me has already bothered.
    Personally I do not divide your enthusiasm. It is visible that you very much like original design Sandpiper 32. I am not an adherent to such stems. Anybody any more does not project and does not build a yacht with upright stem. If I projected a yacht I shall never pattern contours so that have coincided on 100 % with the prototype. It signifies to be hidden behind the prototype and to not bear any personal responsibility as the author of the design.
    I think that already is time to stop talking. That to which is not pleasant that I have made it is time to show itself as necessary to make. For this purpose I dispatched IGES file. You want use it, you want no. If you are too Designer, show what you can!
     
  14. TANSL
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    TANSL Senior Member

    Rabah, I think you should open a new thread in which to expose everything you're saying. I say this because in this thread no one has raised the following issues:
    • 1 How to copy from the image shown contours of the superstructure and sails
      [*]2 How to change the chosen model so that he responded to the proto
      type
    I think:
    - You have not shown anything that we did not already know.
    - You have shown us, it is true, that "it is possible to make quickly". But no one knows what "it".
    - Nobody asked you how you design it, because we do not want to know.
    - No one has asked you to assume personal responsibility for anything.
    Therefore, let me repeat that you've done a great job:
    - Nobody has asked you for.
    - I do not know what it does.
    - Shows that you are not able to properly analyze the problems. You give solutions to problems that no one has raised and misguided solutions.
    - Let me tell you that we do not need to show you "what we can".
    This is in short what I mean on this issue and I think we've (unfortunately and with much effort) killed this thread.
    Cheers
     

  15. PAR
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    PAR Yacht Designer/Builder

    Why is it necessary to recreate something that currently exists? The sail plan for the Sandpiper 32 is available . . . The hull form, lines and construction drawings are also available . . . so what is there to regenerate, particularly if interested in the qualities of the type, rather then "interpretations" of it?
     
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