Best material for autonomous transatlantic boat

Discussion in 'Materials' started by andy47, Oct 10, 2016.

  1. andy47
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    andy47 Junior Member

    Hi,

    I am designing a 2-metre autonomous sailboat that will attempt to cross the Atlantic ocean. I am trying to find the best material for a foam-filled hull, a rigid foam-filled sailwing, a keel with lead weights and a rudder. I am considering between fiberglass, carbon fiber and Kevlar. The cost of material is not important in this project. Based on several articles and forum threads I have read, I decided to use these materials:

    1) Hull: fiberglass

    The hull has to survive extreme conditions like storms and hurricanes, but also impacts (e.g. rocks, icebergs, a floating piece of wood, transportation, etc). As I understood, carbon is more brittle and it would not tolerate impacts as well as fiberglass. Fiberglass is also more flexible than carbon fiber. However, I have seen similar projects that use carbon fiber instead of fiberglass.

    2) Sailwing: carbon fiber, then one layer of Kevlar and then another layer of something (carbon fiber?) for UV protection

    The sailwing has to be lightweight (!) and rigid (perfectly symmetrical), therefore I go for carbon fiber. The outer layer of Kevlar would improve abrasion resistance and prevent breaking the sail in a strong wind or high ocean waves.

    3) Keel: carbon fiber and a layer of Kevlar

    The keel must be rigid and it's absolutely critical that it won't break apart.

    4) Rudder: carbon fiber

    It must be rigid and lightweight.


    I will appreciate any feedback.
     
  2. mydauphin
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    mydauphin Senior Member

    I would built from foam outer hull with aluminum skeleton housing the electronics. It would be a self-rightin trimaran. I would coat it in a 100% silicone coating to protect it and keep it as clean as possible from marine growth. Of course the biggest danger is a container ship running over it... game over
     
  3. andy47
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    andy47 Junior Member

    Silicone-coated foam won't be impact-resistant. Also the whole sail must be rigid.
     
  4. TANSL
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    TANSL Senior Member

    mydauphin, what do you mean by "a self-righting trimaran"?, could you show a sketch?
     
  5. andy47
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    andy47 Junior Member

    He means a trimaran that won't flip over. That's exactly what I want to make.
     
  6. TANSL
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    TANSL Senior Member

    Thanks a lot. My question was because, for me, "self-righting" means that, once overturned, the catamaran returns to its upright position by itself. This seems difficult to achieve.
     
  7. andy47
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    andy47 Junior Member

    Yes, it will turn to the upright position. It can be achieved by a keel, because the sailwing floats.
     
  8. upchurchmr
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    upchurchmr Senior Member

    How does your current boat choose and control the direction it is sailing?
     
  9. andy47
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    andy47 Junior Member

    It has a GPS, compass, wind sensor and computer. I set up waypoints and the computer controls the rudder position based on the heading offset.
     
  10. upchurchmr
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    upchurchmr Senior Member

    Do you adjust the angle of the main and jib?

    Your tracker seems to show the boat going in circles.
     
  11. lyda
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    lyda New Member

    I am not experienced in boats in any way, but am a software engineer (oh dear). An earlier post mentioned container ships being an issue and elsewhere debris was mentioned as an issue. Are there any sensors available for boats that can detect objects that you could use to route around obstacles?
     
  12. andy47
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    andy47 Junior Member

    The probability of hitting a boat is very small, but I am working on detecting the boats having AIS. Besides that, it can't detect obstacles (maybe in the future). The debris is not such a big issue for sailboats as it is for motorboats.
     
  13. andy47
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    andy47 Junior Member

    To make the first attempt simple, I don't adjust the sail. The geometry allows to use just the rudder.
    Yes, the boat has had issues described in the comments in the tracking map. Hopefully, it will continue sending updates to recover the boat one day.
     
  14. mydauphin
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    mydauphin Senior Member

    You can incorporate a way to flood one arm, then reinflate it, in conjunction with a float on mast. I have seen this done on catamaran and tri. There are hard foams that aready very tough. The metal frame within will serve as skeleton but also as rigging. An A frame could be used for both float and sail. Purpose of silicone is basically encase everything in a shield against moisture. My idea is this thing is going to be floating for months in a very hard environment. It must be extremely sealed. Heat can be dissipated via aluminum as a heat sink.
    Let me know size your looking for and I make a sketch.also a tube for a sail might be good. And make it more reflectIve so less chance of getting hit.more important you can transmit your location via ais.
     

  15. upchurchmr
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    upchurchmr Senior Member

    You will never make real progress without adjusting the sails.
    Have you ever learned to sail? Personally?
     
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