questions for a college design project

Discussion in 'Boat Design' started by rmalone33, Nov 17, 2010.

  1. rmalone33
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    rmalone33 New Member

    So first off I wanna say thanks for anyone that takes the time to answer, and secondly I apolagize for a lack of vessel design background. Im in a college project based 'green design' course and we are currently assigned working on renewable energy ocean-going vessels. Probably inspired by the new completely solar powered ship trying to circumnavigate. Ill pitch a few of our ideas and id love for you guys to rip em apart and see what directions, if any are viable.

    Anyway, the challenge is to produce an electric yacht-esque vessel that is safe and sound for ocean voyages, with a lowest cost being one of the 'win' conditions for this project. The solar ship I mentioned I believe was upwards of 16mil? I think, or something like that. So we had thought rather than completely design a vessel from the ground up, could pre existing ships be retrofitted.

    Our first idea was to take a suitably long(65ft+ maybe) mono-hull sailboat, and afix a large surface area of solar panels to either side of the boat, with these regions supported by pontoons. The boats diesel engine system would have to be redone as an electric motor and battery bank system. The masts could maybe be left in place and used for wind turbines? Again not sure. Forseeable problems were rough seas causing too much strain and breaking the joints, but could that be accounted for with either hinge attachments or some sort of non rigid attachment, like how floating docks attach to bulkheads etc..

    Other ideas using the solar panel spreads were maybe using a large ocean barge that would be able to be stable at sea with the panels, but because they're not really built for locomotion, would a barge move well if an electric motor system was rigged up. I feel like it might have more room for rooms/living space as well as the panels and battery bank, but at the cost of speed being near a crawl.

    The third option was to take a stable enough surface, maybe a large barge again or a really large cat, and using tall wind turbine towers, which are supposed to be more efficient then solar panels. But the logistics of getting a surface stable enough at sea that could support wind towers were pretty daunting, so if that's not one you guys wanna deal with no worries.

    Well, thanks again for the read through, like I said a little out of our comfort zone when it comes to these types of designs, so if these are just ridiculous qquestions i'll understand
     
  2. gunship
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    gunship Senior Member

    I am by no means an old salt, but these are a few things that comes to mind.

    "Completely safe" Usually includes a trusty backup diesel....

    Wind turbines driving generators driving electric motors (or via batteries) sounds awfully more complicated than a sail rig, that nowadays can be automated, and probably solar powered automation if you want. Not as ground-breaking, but that's what I would shoot at.
     
  3. rmalone33
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    rmalone33 New Member

    Yea that was the first point brought up, that sailboats already used renewable energy, but its really just to get us thinking outside the box, so the prof wants electricity being generated etc..

    There could always be a diesel powered generator on board as a backup I would think would work as well
     
  4. fcfc
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    fcfc Senior Member

    Why

    Are not sailboats "green" :confused::confused: :?::?:

    Check the figures :

    The 22 ft sailboats in the mini transat race have a far lower price, and higher average speed on Atlantic crossing than the swiss project solarnavigator if I remember well. Nearly twice, something like 7 kts for mere sail vs 4 kts for expensive electro sh.t.

    Also look the average speed in atlantic crossing of recent "Route du Rhum" winner. You will find that the electro solar b.llsh.t cannot even reach that for 5 seconds TOP speed.

    If you need more, check also "Vendee Globe Challenge" for a race around the world.

    If you want green (ie without fossil energy), low cost, proven and reliable, go wind and sail and forget electric.

    That not politically correct, nor marketable, but that technically sadly true. Again, check the average speed figures.
     
  5. gunship
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    gunship Senior Member

    Hmm, yes as it's kind of experimental I think a backup would be recommendable. Kind of how the early steamships had sails.

    And yes, by all means go for the generator(s) but I don't think it would be as effective as sails, except possibly dead to windward and downwind. Mainly, the conversion of wind energy to moving the generator, converting that movement to electricity, and converting that electricity back to movement, converting it to forward motion via the propeller, seems like alot of conversions of energy, all involving some losses.


    EDIT: fcfc, he stated that they were aware of that, but they're going "outside the box" to see if it's possible.
     
  6. fcfc
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    fcfc Senior Member

    :p I agree that's hard to think out of the box for something that has some millenium history.
     
  7. fcfc
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    fcfc Senior Member

    If you want to go electric and low cost, check ocean crossing rowing skiff. They are non sail boats that use the lowest energy to move.
     
  8. rmalone33
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    rmalone33 New Member

    Haha to be fair swords had several millenia of history too.

    But I agree with you, sailing is a completely satisfactory method of transportation, and maybe we'll do a side write-up detailing the effectiveness of modern sailing but that's not the project.

    Gunship what u mentioned about making a sailing ship automated via solar and wind generation might be acceptable but I feel like if that could be done it would have been right? Maybe a rigid solar array around the entire deck would be enough to power such a system, id have to take a look at the numbers of consumption for rigging/sailing motors etc..

    Our initial thought was basically taking a mono-hull and converting it to a trimaran to maximize solar surface area. Which after goin through these forums seems like a bad idea. But if its no longer under sail-power, do those limitations still hold true.

    5-6 knots would be acceptable, maybe even less. As long as we could make an argument justifying it, 'fastest' wasn't a win category cause it'd be hard to prove
     
  9. Stumble
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    Stumble Senior Member

    RM,

    the fundamental problem is this... Solar, wind, and battery power combined cannot generate enough electrical power to be used as propulsion for any reasonable yacht. The efficiencies are too low, and the power demands are too high.

    Just as an example, take th Dashew 64. Which is a very efficient long range cruising powerboat. It was specifically designed to be highly fuel efficient and operate on a miniscule amount of power relative to other boats its size. It uses a single 175hp engine to move a 64' boat at hull speeds, and doesn't even try to achieve a faster speed.

    The problem with your design requirements is simply this... To generate 175hp (or 130kw) for a 24 hour period of operation requires a solar system that generates 130*24=3,120 KW a day. Setting aside inefficiency, lets take a best case scenario that your panels generate full power for 8 hours a day. That means you need to generate and store 9,360Kw in that eight hour period. or 1170KW an hour. Now the best price I could find was around $5.50/watt installed so your initial price just for the solar cells is $6,435,000 (though this the installed price).

    In addition you will need to make room for all of these solar panels. Again needing 1170KW of production, using commecially available panels you would need to make room for this vast array of solar panels somewhere on the boat. Then you will also need to find the room and weight budget for thousands of pounds of batteries to store this much power being generated so quickly.

    Now we need to address the safety issues in having very high voltage DC power systems operating on a vessel. Since the hull is conductive and DC power is deadly you need to make very sure there can never be a short in any of these systems of people will die. Not sure how you do it, but for a comercially available boat it must be a priority.


    The reality is that electrically powered boats are not an option at this point in time. Neither the on-site power generation, nor the storage capacity of modern batteries (and their alternatives) comes anywhere close to that of diesel fuel. I would actually argue that the most 'GREEN' boat would actually be a highly efficient diesel powered boat since instead of spending all of that energy and material making renewable energy systems you could use the same energy budget directly to power the vessel for a long time to come. Not to mention the lifetime energy budget of the vessel would go down (From CNW Marketing Research, Inc. at http://www.cnwmr.com/nss-folder/automotiveenergy/DUST PDF VERSION.pdf).
     
  10. gunship
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    gunship Senior Member

  11. rmalone33
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    rmalone33 New Member

    Thanks to both of those last two posts, definitely things to consider
     
  12. Stumble
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    Stumble Senior Member

    After a few minutes I had a thought...

    If the project is to design the most energy efficient vessel possible over the lifespan then you really need to consider a steel hull easily driven boat.

    If the project is to create a renewable energy vessel then nuclear decay, or nuclear steam is the only possible contender without using fusion or something equally rediculous.

    And do the numbers on my post above, I am not an engineer so I might have missed something.
     
  13. gunship
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    gunship Senior Member

    Nuclear power is not renewable. its very fossil, and very unenviromental, but its ridicilously effective.
     
  14. Submarine Tom

    Submarine Tom Previous Member

    Where does the wind come from?

    Ultimately... the sun. Therefore, a sailboat IS solar powered.

    This is the "low cost", "green" way to go.

    Sailboats are also well proven.

    Good luck to you and your school project but you will eventually end up back at sailboats as your solution.

    -Tom
     

  15. fcfc
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    fcfc Senior Member

    No. There was a swiss project on that. Eco prao, or something like that.

    The first was plywood from local species. (no material transport).

    The second was surprisingly carbon fiber on pvc sandwich. Rather non eco friendly material, but build the absolute lightest boat, with a big margin. ie minimum building materials and minimum power needed to sail.

    Steel was second to last (protective paint toxicity, and heavy power needed) and aluminium was last. (very high energy for production).
     
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