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Student Design, critique?

Discussion in 'Yacht Renderings & Plans' started by vling, Oct 6, 2009.

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  1. vling

    vling New Member

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    Hello YF,

    My name is Vaughan, I'm a transportation design student working on a yacht for my term project, and was hoping to get some constructive feedback from the knowledgeable folks on YF. The design is ~320 ft length, inspired by the Greek Trireme, using sail (Dynarig) and solar power. Above deck is supposed to be mostly open air with large overhangs for shade. My main concern for the design is: Will the long nose or keel placement be problematic for balance/handling of the ship? The design is still in progress, so any feedback is greatly appreciated!

    Thanks, Vaughan

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  2. 84far

    84far Senior Member

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    Vaughan,

    first thoughts are 'star wars' :D . second, instead of having the single blade (keel) in the middle, have two seperate blades, still have both blades connected to the bulb. the New Zealand America's Cup team tried it (concept) one year... not to sure if it works, but it would look good... unless thats the traditional/modern look your going for?
    theres no reason for that bow not working, u would just have to be careful with it.
    if u made it a planning hull that would be nice.

    overall, pretty cool imo

    far
  3. AMG

    AMG YF Moderator

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    I have just one question, which way is it going..?
  4. Henning

    Henning Senior Member

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    The greater problem with the handling of the vessel will be the balance of power around the longitudinal center of balance. The way she is rigged, she will always want to drive off the wind meaning she will always need to have helm applied to keep her nose up which will cause drag until the rudder stalls without her being pointed up very high at all. As for solar power, are you talking photovoltaic or thermal transfer/steam? I wouldn't personally bother with either. Do a bit of research on a ship Phillipe Cousteau built some time back with a rotary vane turbine sail which drove the props. Rather than harnessing the wind and redirecting it (with the restrictions of aerodynamic foils and stalling) for propulsion under Newtons 3rd law, the wind spun a vertical turbine which went through a gear box to the shaft. The variable position of the turbine housing and stators allowed the ability to sail at any point of the wind.
  5. 84far

    84far Senior Member

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    what about a forward canard, standard centerboard/bulb and rudder at the back?

    far
  6. Henning

    Henning Senior Member

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    What purpose would the canard serve? I know what it is and what it does, but why use one? It's just extra drag. Better off balancing the drive IMO.
  7. 84far

    84far Senior Member

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    its just a suggestion, and well it could also act like a second rudder, given the length of the boat, and the length of the keel it may need an extra hand turning (tacking).
    u could also reduce the size of the rudder cause u have the canard up front (reduce drag). and due to the depth of the keel, she wouldnt have to much under the water when shes on a heel, so it could help there to? your thoughts?
    and would u say this boat could use some more sail area and less bulb? thoughts?

    far
  8. vling

    vling New Member

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    Thanks for the suggestions so far. I discussed the balance issue with my professor today and will be making adjustments to the proportions of the hull (shortening the "nose") and lengthening the rear, bringing the sails and keel more to the center. BTW he had trouble figuring out which direction it was going too, so hopefully the new proportions will help that.
  9. 84far

    84far Senior Member

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    in the first pic the bow is on the left?

    far
  10. vling

    vling New Member

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    bow on the right
  11. NYCAP123

    NYCAP123 Senior Member

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    At first glance that's what I thought and saw Star Trek's Enterprise as inspiration. Then I looked harder at what looked like a bow sprit and said 'no, that has to be the bow'. Radical. Should be interestting to watch it evolve.
  12. 84far

    84far Senior Member

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    bows on the right, thank god. the balance should be ok. i would like to see more sail area though.

    i was thinking more a 'Naboo Royal Starship'. and if u could do all the portholes with the same tint as the hull, that would look pretty **** sexy to... your project though :D

    far
  13. vling

    vling New Member

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    84far - An earlier version of this looked very Nabooey, but got Xed for practicality and more greek trireme looks. Also, can you explain what bulb is? (more sail less bulb)

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  14. 84far

    84far Senior Member

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    vling.... WOW! out there!... ok, a little to much sail area ;)

    the 'bulb' is the lead weight at the bottom of the centreboard. and basically if u make the sail area larger and less 'bulb', u will find a happy medium as far as boat speeds, etc goes. but thats more for the naval architect to work out.

    far
  15. Henning

    Henning Senior Member

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    Interesting.... I'm going to assume you haven't spent any time at sea. I think you have a bright future in Hollywood CGI. If you can make the designs into shiny metal objects, I think they may sell well as sculptures. As functioning vessels, not so much so. Study boat designs as they exist, and look at them through the centuries. You'll notice that there really isn't any radical change going on. The biggest changes are really in the details, because the major form issues are governed by the immutable laws of physics. The major form variables are all a trade off between drag and mission (volume, load carrying ability, range, speed, stability, sea kindliness...) requirements. As vessels for a "Transportation Project", I'm trying to figure out what missions the forms can fulfill. As art I think they are very nice, for a vessel though, form is driven by function to a great extent and function is determined by mission, so I suggest you first think about "What is this vessels job?" and with that you also have to consider "Where would the person with the mission she meets want to take her?" That will also dictate various limitations such as draft (might need to make that centerboard retractable) and even mast height for bridge clearance.
  16. NYCAP123

    NYCAP123 Senior Member

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    You need to get that thinking back into the small yacht arena. It's all speed and how does it look at the boat show. Black hulls, light composites, fancy furnishings. Sea worthy? What's that?:rolleyes:
  17. CODOG

    CODOG Senior Member

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    :) Well, you asked for 'critique', and you got some. Your crime it seems is to start with the fantastique, bypassing the basics. Easily fixed if you have the stomach for it.
    How will you be marked on the project ? If a pass is down to aesthetics then ignore us and stick with the bling...if the project demands some substance then do some research into sail boat design. I'd guess the software you are using can punch out some figures for an enclosed volume ? A realistic relationship between volume, mass and balance with a heady mix of force and levers thrown in may seem rather out-there straight off, but at your stage in life it pays to gain advantage over the rest of the class. Enough info to get a great heads-up is out there if you really want it.
  18. vling

    vling New Member

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    Henning, thank you for the valuable feedback. You'd be right to assume I haven't spent time at sea, except for once when I was little we went fishing on a family friend's catamaran.
    This is a conceptual charter pleasure yacht, for use in the Mediterranean mainly, with main inspiration for the hull coming from ancient Greek Triremes, although I know this form is probably not as efficient as it could be. In this revision, I have moved the center of the sails and bulb to the Beam WL, which farther back than most ships. (and behind the CLP, which is another problem I'm wrestling with) The Beam is also farther back than the Beam WL. (does this create more issues?) I was looking at aircraft carriers and how the hull spreads out at the top to accommodate a large flight deck. This hull does spreads in the same way at the rear but to a lesser degree.

    Here's a couple screenshots how how it's looking now. Again I really appreciate the feedback guys, I hope by the time this is finished, it will be somewhat believable :p.

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  19. CODOG

    CODOG Senior Member

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    I reckon the spear-like bow will dig in when the hull is heeled over and tend to turn the hull away from the heel with considerable force. IMO its not a good hull shape for a rig that heels the boat. Triremes relied mainly on oar power...they had basic sails that worked best with the wind behind them, they cant have heeled much or the oar ports would have been underwater.
    There is no rudder....I assume you plan to have one.
    The appendage connecting the keel bulb to the hull looks extremely large (is that a stairway inside it ?) This large appendage will have a large volume...this large volume will give a lot of buoyancy directly under the hull, which will directly counteract / negate the weight of the keel bulb...obviously having an affect on the amount of sail you can carry etc.
  20. Henning

    Henning Senior Member

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    Ok, that top view brings up another issue. When a sail boat works to weather, it inclines, figure it will lay on its side about 30 degrees. Now, consider that and how far aft you've placed your maximum beam, which controls your longitudinal center of bouyancy. When you combine that factor with your fine bow entry and the fact that it is reversed, you will quickly realize that when she heals over, you will drive the bow deep under water due to the combined leverage and lack of forward bouyancy.