Brain Teaser: Renewable Powered ‘Flying’ Yacht

Discussion in 'Boat Design' started by zstine, Mar 31, 2022.

  1. zstine
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    zstine Senior Member

    I’m looking for out of the box thinking for this concept…

    Stated Need (SOR?): This is for a cruising yacht with living space for 4 (similar living space to a 38ft sailing mono), though typically operated by a couple in the Bahamas/Caribbean for 6mo at a time. Of primary concern is decoupling the habitable space from sea state during passage. A submarine is not allowed. Plateau operations up to 6.5ft (2m) wave height and contour operations to 10ft (3m) swell. Shallow draft (~5ft) operations for anchoring and ‘getting over the bank’ are required. The primary propulsion source must be renewable (wind/solar/other?). Price of build (not including design/engineering) is $300k max. Min cruise speed 9knts. Min range without sun/wind is 25mi. Max length is 50ft and max beam is 30ft.

    I’d like to hear any ideas that fit the above. I fear my 2 cents below may hamper your creative juices, so feel free to skip it and just create! However, my description below may add some detail to the above statement of need.

    Decoupling: This can be ‘flying’ over the sea like a hydrofoil, HSWATH, SWATH, etc. or a fully active suspended Hab space, but not a submarine. Please address scalability issues if you go with a SWATH concept, or speed/power issues with hydrofoils, etc.

    Power: solar and wind would be primary sources of power. Maybe others ?"wave generation" i don't know. It’s up to you on how to capture it. Obviously active suspension or powered lift devices have to come out of your power budget, in addition to propulsion. The selected cruise speed and max length allows for Fn<0.4 operation, so low-ish drag.

    Appendages & Draft: If your design requires deep appendages, please explain how they retract, fold, deflate, etc. for littoral operation.

    Devil is in the details. The more you can provide the better. I hope you are welcome to a critique of your ideas. I believe a back-n-forth conversation is the best way to identify the best concept and its Pros & Cons.

    Thanks!
    Zach
     
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  2. gonzo
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    gonzo Senior Member

    Can you elaborate on what you mean by decoupling the living space? There are gyroscope stabilizers that will reduce motion. An SOR should not have as many constraints to start with. For example, at the modest budget you specify, something else has to give. A diesel would be the cheapest to buy and operate, with sails as the main propulsion (wind energy as you ask for).
     
  3. portacruise
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    portacruise Senior Member

    "So feel free to skip and just create..." "Out of the box... " Used blimp, if you can buy it at the right price surplus, adapt to wind and solar power, haha?
     
  4. zstine
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    zstine Senior Member

    By decoupling the living area, I mean that up to 6ft seas there should be very little impact on pitch, roll, yaw, or heave induced in the living area by the sea while under way. And I accept heave (contoured flight) from 6ft to 10ft seas. Yes, gyroscopes are a valid/acceptable way to actively control pitch and roll. I'm not sure they do much with heave though, so another method would be needed there. I'm not aware of the power consumption of those gyros, but if you can balance the power budget with renewables (solar?), then using gyros is a winner. As for the budget constraint, that would be the first of the requirements I'd be willing to stretch on. But a diesel is a non-starter. with a 25 mile range, you hardly need a diesel! Sails are of course an obvious choice for propulsion, but they can throw a wrench in the 'decoupling' from sea state. A SWATH for example, would have a hard time maintaining its stability with the over turning moment of a sail up a mast... a kite maybe. As for other requirements, I didn't spec displacement, tankage, hull form, material, propulsion type, power type other than renewable, sea-decoupling method and only a max length and beam... There's room to get creative. no?
    Thanks for the reply gonzo
     
  5. zstine
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    zstine Senior Member

    Yes, That is out of the box! I like it... Though I'm not sure how safe it is to fly those in the trade winds. That said, some sort of lighter than air pod could be coupled with a vessel to reduce water displaced volume and help decouple the vessel from the sea and could provide a propulsion force too. There's lots of available hydrogen around in water.. hmm, I'll have to think on that. your not out to lunch. It could make for easier deployment and more reliable flight in light air compared to a kite sail.
    thanks portacruise
    And yes, I consider solar powered electrolysis with Hydrogen capture a renewable energy source.
     
  6. portacruise
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    portacruise Senior Member

    On the trade winds, the balloon part could be multi-chambered, in such a way that it changes a fashioned crude foil shape ( using drop stitch if not too heavy?), as different chambers/ sections are inflated... It might take some time to do your own scale model experiments, but perhaps the perfect shape for an adaptable balloon sail could be configured to accommodate Tradewinds? Or a cable tied balloon sail could be moved higher or lower to help find the best match for wind conditions?
     
  7. gonzo
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    gonzo Senior Member

    In general, power consumption for propulsion is less than that for other uses. Most liveaboards stay in one place for long periods. I think that a power consumption analysis is necessary before deciding on anything else, since you set it as a constraint. For example, do you use AC? That will require more power than your main propulsion.
     
  8. zstine
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    zstine Senior Member

    Over the long term at anchor (weeks), I agree house loads would add up to more than propulsion. But you need a lot of juice all at one time for propulsion. So I think that demand would dominate... When we were living aboard a few years ago, our 530W solar array was more than enough to keep up with house loads. Full SOC by 11am in general. No AC. Refrigeration is the biggest draw <100Ahr. Add making RO water, charging devices, etc and we used about 150-160Ahr (~2kW) a day. But we were cooking on gas. I'd like to cook on induction now. That said, I'm expecting this concept to have many kW of solar and batteries in the 10's of kW... how else are you going to meet that 25mi range with no wind or solar? Even if you can make the 9knt cruise speed with just a 10kW motor draw (unlikely, per Gerr a 50ft, at just 7ton could do it), you need almost 30kW in the battery for that range. Unless you can think of another way to move the boat 25mi?
     
  9. zstine
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    zstine Senior Member

    Yup, that's what I was thinking, like a bulbous parachute/para-sail. And if i read you, it could vary in size based on how many chambers you want to fill. If you used this design, I'm guessing you'd have a launch system something like SkySails ( https://skysails-group.com/wp-content/uploads/2021/05/SkySailsYacht_Brochure_EN.pdf ) and would only use the Hydrogen kite at low/moderate wind speeds when it's buoyancy would help keep it aloft in lulls, if not help lift the vessel. In heavy winds, it would have to be too small for the buoyancy to be effective, but then you would just fly a 'standard' kite.
    Lighter than air kite, "gets pushed up by gravity" haha... https://www.airbornecomms.com/helikite-aerostats#:~:text=The Allsopp Helikite is lighter-than-air like a balloon,much or gets too strong for their adjustment.
    The lighter than air kite to power a boat is not a novel idea. image from project.kiteboat.com (though i think this is a pic of the above Helikite)
    [​IMG]
     
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  10. tlouth7
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    tlouth7 Senior Member

    Reduced motion implies a small waterplane area for a given displacement. So basically a traditional heavy displacement hull form. The problem is reconciling that with the shallow draft requirement. I see three options: a lifting ballast keel, water ballast for passages, or an inflatable sponson to raise the boat in "local cruise" mode. The last of these is the most outlandish but could provide a pleasing liveaboard platform. Water ballast takes up a lot of space so is probably not a good solution. A lifting keel is of course a mature option.
     
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  11. zstine
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    zstine Senior Member

    Hi tlouth7,
    Yes, Small waterplane area is one of many ways to reduce motion. Active suspension, gyros, hydrofoils, hybrids, etc. are other options... I'm sure there's more that I can't think of.
    As for converting a deep draft/small waterplane boat to shallow draft operation, there are many ways to do this. Yes, The lifting 'keel'/demihull is likely the most 'normal' or mature way. But that certainly doesn't mean it is the best way. And even if you do go for a retractable or lifting keel, there's a lot of different ways to make that happen. I like the idea of an inflatable sponson to raise the craft up to reduce draft and would hardly call that 'outlandish' as it is maybe easier than a retracting keel. Of course the opposite is possible, inflating the demihull tubes during operation and deflating them for shallow draft, where the boat would sit on the main hull/bridge deck. Like an inverted inflatable wing sail!
    I wouldn't just discount water ballast. The tankage could/would be located in the demihull/keel and not in habitable space. One issue with small waterplane is scaling it down to a sub-50ft size and maintaining good stability. How would you do that? Also, the mature propulsion for renewable power would of course be sail. But the small waterplane does not play well with the over-turning moment of sails. So, If you think small water plane is the best choice, what do you think is the best way to power it?
     
  12. portacruise
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    portacruise Senior Member

    Can solar powered electrolysis produce a significant amount of hydrogen, is the question. Will there be enough for regular topping off a balloon? Will there be enough for minor fuel uses like cooking or for 25 miles with a hydrogen combustion motor, or to use for fuel cell power?
     
  13. zstine
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    zstine Senior Member

    As for topping the kite and cooking, that's an easy 'yes, there's more than enough solar to make Hydrogen for that'. As for propulsion, let's explore what a few to 3 hours endurance means. The boat 'energy observer' is a Electro-Hydrogen Hybrid with 24/7 endurance (compared to my 3 hr SOR endurance!) and aux sails. So, if you are willing to wait at anchor a day or 2 to fill up H tanks and you only need enough to go 25 miles, then you could have a small fraction of the Solar compared to Energy Observer and still produce plenty of Hydrogen. 3hr of endurance on say 15kW motors (Gerr method for 22,000lb 50ft lg at 9knts), is 45kW-hrs. Google says electrolysis is 80% efficient, but turbo-ICE is only about 33%. So you need about 160kW-hr of Solar production to satisfy the range using Solar Electro-Hydrogen ICE. If you have 2 days (10 hours) of solar production to fill your tanks, you need a 16kW array. That easily fits on the footprint of a 50' x 30' boat. 21% eff panel makes 20W per sq.ft. which mean 800sq.ft. array is needed, compared to a potential deck space of 1,500 sq.ft. So if you filled the whole deck space you could almost make enough Hydrogen in 5 hours (1 solar-day) to go 25miles every day. I think the main issue with Hydrogen is the size of the equipment for electrolysis, compressing it, and storing it and the cost of all that stuff. Perhaps this is not that big of an issue if you only need to store enough fuel to go 25-30 miles. That is 'laboratory' size equipment vice the industrial scale stuff on Energy Observer, still expensive though. The main 'pro' of hydrogen storage over batteries is the weight is much lower. Obviously, using it as buoyancy in a balloon-wing is another potential advantage that batteries can't do.

    Check out Energy Observer. They post energy balance data showing how much power they made and how it was distributed between house, propulsion, and control systems. They also show how much energy came from wind(sail), solar, and hydrogen. They have articles on Electro-Hydrogen power... pretty cool stuff. www.energy-observer.org
     
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  14. zstine
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    zstine Senior Member

    Storage space needed for 160kW-hr with 2.7kW-hr/L is only 60L (15 gallon) tank. This slide says "Storage System Cost" is $2/kW-hr or just $420.. don't buy that Brooklyn Bridge. These are old slides and the aforemented is 2015 goals.. Using the 2005 actual in-service data, which I'm sure is antiquated, you would need 133L or about 33gallons (160kW-hr x 1.2kW-hr/L ) and it would cost $6/kW-hr or $960 for the "storage system" which is probably just the tank, a valve and maybe a pressure gauge I'd guess. BUT still a 30 gallon H-tank is small and cheap compared to a 160kW-hr battery bank!!! oh you actually need 135kW-hr storage. the 160kW was solar production, but you waste 20% of that in converting it to H... anyway, these a rough ball park figures.
    source https://www.hydrogen.energy.gov/pdfs/review05/st1_satyapal.pdf

    Just a thought. My 33% eff ICE is based on gasoline oxidizing 'air', but with electrolysis, pure O2 is available and may be able to run at much higher eff... idk?
     
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  15. portacruise
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    portacruise Senior Member

    My guess is that using the oxygen won't help efficiency that much, and might introduce more things that can go wrong.

    Most of the energy in a gallon of gasoline (or hydrogen) is released in the form of wasted heat, with an ICE, from what I understand. I think it's mostly the explosion part that drives ICE forward, and that may only amount to 30% or less of the total energy, according to some sources. I don't see how pure oxygen would help that, unless the explosions somehow become more violent for the same chemical reaction? Heat and nitrogen oxides produced by a hydrogen ICE are not helpful to the environment, if that be a consideration. On the other hand, electric power plants are more efficient compared to ICE, probably because they use the heat part and not so much the explosion part, as well as scale. Fuel cells can be closer to one hundred percent efficient because they are not heat engines, and they produce much less, (if any),of Heat, nitrogen oxides, or carbon when run on hydrogen fuel. Of course everything has Cradle and Grave consequences which need to be considered, haha! Thanks for the interesting links above!
     
    Last edited: Apr 4, 2022
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