Can solar energy power a catamaran?

Discussion in 'Multihulls' started by EscapeArtist, Sep 4, 2016.

  1. Timothy
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    Timothy Senior Member

  2. groper
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    groper Senior Member

    Looks good, looks expensive... spend the same money on a sailboat and it will still be far more suitable and practical for private coastal crusing :)
  3. Stumble
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    Stumble Senior Member

    They took an old racing catamaran (sail) added a bunch of length, stripped the sailing gear and added solar power... The all up budget for this is something in the $5m range.

    I will bet you right now that the new boats best distance per day is <50% her old record under sail. And that her average trip speed will be a fraction of what it was before the refit.

    Obviously multihulls should be faster than a monohull, so compare her to the fastes monohull on the water right now (Commanche). They are both 100', both have transatlantic range, and both cost a fortune to run, Commanche on her worst day will cover more ground than this expensive 'proof of concept.'

    I'll put $100 down right now that a reasonably fast 40' sailboat will have a higher average crossing speed than this 100' solar sailor.
  4. groper
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    groper Senior Member

    The interesting concept they are employing is the hydrogen energy storage system as opposed to a battery. Excess solar and wind energy is converted to hydrogen via electrolysis membrane - presumably one of the latest higher efficiency types which may net them upto 50% round trip efficiency. About half the efficiency of lithium battery energy storage, but hydrogen energy storage has a much higher energy density- surpassing diesel. The weight of the fuel cell and electrolysis system has to be accounted for however.

    A different approach, i guess it's in the name of improving the hydrogen technology. That is, reducing it's size and weight, researching it's application, and sorting out bugs... interesting developments ahead, but the current state of the art is not ready for market yet.

    Back to the original discussion, provided one can accept a hybrid propulsion system, which could be fossil or sails for example, a solar boat could be feasible for just about any purpose. The main problem with solar alone is the sun only shines for approx 6 useful hours on a clear day- that is the amount of energy available is very small outside the 3 hours either side of midday.

    In the interests of safety and practicality, a coastal or ocean boat must be able to run when the weather gets bad or when the sun is over the horizon. Without the ability to do that, it's not a very practical or safe boat...
  5. Stumble
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    Stumble Senior Member

    Ya I am not sure what the point of the hydrogen storage really is. Even assuming the batteries are full I would think it would be more efficient to burn off excess power production as speed rather than generating hydrogen. But maybe the goal is to reduce on board weight... Somewhere there is a cross over point, where removing X amount of battery weight is worth the inefficiency, I just wouldn't have thought it would be this low.

    But then they are also using inefficient wind turbines, so maybe it's supposed to just be a demonstration platform.
  6. groper
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    groper Senior Member

    I read the comment from the financier / manager , when there is no wind or sun, they can use the hydrogen. I guess the energy storage is for when they are dead in the water...

    Another interesting possibility of the hydrogen energy storage is due to the low weight, the amount of energy they can store could be quite large. So when they have favourable strong winds blowing them down wind, theyre propulsion needs would be very low, almost non existent, so nearly all of the solar and wind turbine energy goes into hydrogen storage. Then when conditions change, say several days later, they have a large reserve of energy available to them to battle head winds or no wind scenarios. The amount of energy they can store is unknown, but in theory it could be over 142 times greater than the same weight lithium battery system...

    If the boat follows the trade winds around the world, they could be building up a huge amount of energy in large hydrogen storage tanks. Who cares if the conversion is only 50% efficient, with 40kt winds pushing you across the southern ocean, the wind turbines would be going nuts generating shed loads of energy 24hours a day... burn this later when they need to cross the equator...

    Above all tho, its probably all about publicity. Hydrogen energy storage is being considered for grid energy storage on a large scale. The potentnial money available to companies selling this type of technology is phenomenal. Hence this boat project is probably an attempt to make them more visible compared to competitors...
  7. Skyak
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    Skyak Senior Member

  8. Ilikeboats
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    Ilikeboats Junior Member

    When you can unwind thin film solar off the back of your boat like a fishing net then drag it behind your boat and it stays afloat undamaged is when everything goes that way .. just my opinion
  9. GaryJones
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    GaryJones Junior Member

    Not a cheap choice (but then when is a 64' powerboat cheap), here are some details on probably the leader in solar luxury catamarans:

    Does the Solarwave 64 make solar-powered boating a reality? - Motor Boat & Yachting

    It would probably be one of the best platforms for being at a location but would definitely involve compromises on getting there. I also think you could make tradeoffs with regards weight, luxuries, solar coverage and 'flybridge style' to alter the balance in a different direction. My personal preference would be: leaner, lighter, simpler, cheaper and a bit more solar.
  10. lucdekeyser
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    lucdekeyser Senior Member

    Rick's design is probably the best engineered in that sense with a good bit of solar. It is a stabilized monohull thus earning a place in this multihull section. Waves remain as usual an issue.

  11. pacific green
    Joined: Oct 2017
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    pacific green Junior Member

    So after five years of planning and outfitting we launched our solar electric catamaran two years ago now. The first summer of cruising we did not get to participate in. This year was a way different story. We clocked close to 40 days out and made some interesting gpx tracks around the Pacific North West. During the entire time we never used a traditional anchor once as we relegated those duties to the 36volt subsystem in charge of the gps enabled trolling motor. We had some amazing anchorages. By our calculations we could have easily gone over 100 km in a day had we cared to. Some legs on battery alone were downright impressive.

    What was interesting is that we produced over 400 videos of the trip where you can see the voltages and current usage overlaid on top of the navigation software.

    My Youtube channel is Solar Catamaran and as I release more videos they will eventually become unlisted.

    Here is a video of us crossing English Bay after being out over twenty days.

    From a performance aspect of the boat we like the original owners of the boat could always count on the catamaran to get us anywhere at 4 knots of speeds and the fact that it did not have a sailing rig did not seem to matter to the catamaran. In fact we would have been at a disadvantage had we been geared with a sailing rig. We saw very few sail boats actually sailing in the Pacific North West this summer.

    Some other observations we made were that it did not matter the conditions we could always make headway even into extreme conditions because we always had the torque available even at 2 or 3 knots into 15' waves over the Sand Heads shoals one day alone by myself. That is another story but to me it served as a good indication of what the catamaran was actually capable of if we wanted to push her. We found in rough conditions that like many others even with traditional sail boats they too choose not to venture out into those conditions as these two videos relate:

    Into 20-30kts wind and tide 8' rollers

    That is crazy slow progress - Turn around

    We burned only 140 liters of gasoline in our economical Honda 2000 generator and if we would have had another one we could have turned prop at times for over 80 amps continuously which to us seems absurd at times but we will see what next year brings. I have all the exported gpx tracks but can't upload gpx tracks unless I zip them all and add them as a zip file.
    Last edited: Oct 27, 2017
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