Electric Hydrofoil Powerboat

Discussion in 'Boat Design' started by intrepid71, Dec 28, 2015.

  1. intrepid71
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    intrepid71 Junior Member

    http://candelaspeedboat.com/

    Revolution in boating or another half-baked idea?

    This outfit has the most well thought out approach to designing and marketing a recreational hydrofoil powerboat that I have seen. Going all-electric utilizes the efficiency benefits of hydrofoils to their greatest advantage. They are marketing it as a Tesla for the water, which I think is brilliant angle for luring wealthy buyers who want to feel like they are being environmentally conscious. The full foil retraction incorporated into an attractive and functional boat design takes away many of the problems inherent with hydrofoils and leaves the advantages. Success will depend on two main issues IMO:

    1. Will it actually perform as advertised?
    2. Can it be built at a reasonable price?

    Thoughts?
     
  2. messabout
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    messabout Senior Member

    We will have to wait and see. My first impulsive reaction is to answer your questions: No and No.

    The video shows a rinky dink little prop that is supposed to propel that boat up to 40 knots. I wonder if it can deliver enough thrust to make the boat foil bound. .............
     
  3. gonzo
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    gonzo Senior Member

    They always fail to address the two main problems:
    Firstly, the energy has to come from some source. Most likely it will be a coal or gas burning power plant. Secondly, they have no plan on how to deal with the toxic waste created by used Lithium/Ion batteries.
     
  4. intrepid71
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    intrepid71 Junior Member

    They mention a 42 kW motor. That is only 56 hp. Making 40 knots with a 25 ft boat will be quite a feat. They don't provide a weight. I guess that is still being worked out.
     
  5. intrepid71
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    intrepid71 Junior Member

    Those issues haven't stopped Tesla from being quite a success. And by success I mean a small start-up company gaining the market cap of GM.

    I agree the environmental value of all-electric is going to depend on what produces the electricity. In Sweden there is more chance that electricity is coming from a wind turbine.
     
  6. Timothy
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    Timothy Senior Member

    I have no idea if this design will perform as advertised but if Germany is any indication of what is to come then it is likely that most electricity will come from solar arrays. It follows that presuming energy storage technology advances keep up , most cars and boats will then be electric.
     
  7. kerosene
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    kerosene Senior Member

    -electric power IS more eco friendly even if done by coal (which most isn't)
    -electric makes really rarely any sense in watercraft left alone performance watercraft
    -electric makes sense where about half the battery capacity gets used frequently (like a well matched commute) and lack of reserve capacity is not a major concern
    -pleasure craft is a really bad candidate for E powertrain as the hour of use per annum simply are miniscule. The expensive batteries are not getting utilized.
    -weight is such an enemy of efficiency on boats that gas simply makes a more economical boat. If gas powered 50kw boat is matched with e-drive it needs so much batteries that the boat will be heavier and need more power and need more batteries and need more...
    -batteries are not toxic like claimed above. We often hear stories how batteries (or wind turbines) need more energy to construct than the lifetime benefit. These claims are not correct - but on a boat that gets used 40h/yr this very well can be true.

    I think this boat apples to apples is not comparable to gas powered equivalent, even near. The 2.5h range (note no distance mentioned) is probably at low cruising speed. The video gave zero specs and all emotion. I don't think the physics got redefined here. Planing boat and e-drive don't match except on rate occasion for marketing or soothing ultra rich person's conscience (thx to lack of understanding on his/her part).
     
  8. intrepid71
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    intrepid71 Junior Member

    They are saying nearly 3 hrs at 25 knots.

    As far as whether a recreational powerboat is a good use for expensive batteries... maybe not. Will they likely be under-utilized? Yes. However, you could make the same argument for any recreational boat. It is an expensive piece of equipment that will likely be under-utilized, regardless of whether it has pistons or batteries.

    My interest in this is really the retractable, fully submerged hydrofoil aspect. That coupled with a handsome boat design is very appealing to me. I think the smooth ride, reduced noise, zero wake and vastly improved fuel efficiency using a four stroke outboard rather than an electric motor would be quite revolutionary.

    I realize they are going all-electric because that is what really generates interest. They claim to have nine preorders and I doubt that interest would be there if it was not all-electric. So they have quite a challenge making the heavy batteries work in the context of a light-weight boat design. Obviously they are going all carbon fiber on the hull to offset the battery weight as much as possible.
     
  9. kerosene
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    kerosene Senior Member

    my point was kind of what you are saying: for a business case (marketing and product interest) electric can make sense even if the practical reasoning really doesn't.

    3h at 25knots is pretty good.
     
  10. kerosene
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    kerosene Senior Member

    i was checking on a mobile device earlier and the website didn't work quite right.

    Range ~ 60 nautical miles ( 70 US miles)

    Motor: 42 kW

    Battery: 40 kWh Lithium ion NMC

    Forward foil: Automatic fully retractable double wing

    Aft foil: Automatic fully retractable stabilization wing

    40kwh battery pack. At lets say 70% drain you have usable battery capacity of 28kwh you have 40 minutes of full power drive. Its better than some attempts earlier.

    I still think that the same boat with 42kw gas engine and drastically lower payload would make more sense - that is all. And that the fuel cost would be tiny fraction compared to the price of all electric gear.
     
  11. JSL
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    JSL Senior Member

    Interesting project: could be a 'dream' but worth pursuing. As already pointed out, prop looks a bit small and there are a few other things like autos don't use as much hp/lb as boats. Keep in mind the Tesla is AC powered (Mr. Tesla discovered AC) so I don't know if this affects the numbers etc.
     
  12. WestVanHan
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    WestVanHan Not a Senior Member

    And from Intrepid "They are saying nearly 3 hrs at 25 knots. "

    The Tesla 85 battery pack weighs about 1400 pounds I think,so if they're counting discharge and kwh the same ways,this battery pack ought to weigh 650 pounds or so.

    So working backwards from all this ( 28 kwh is about 9 kwh for 3 hours) they say they can foil the boat at 22 knots or so on about 12 hp...
     
  13. messabout
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    messabout Senior Member

    I am most skeptical that a boat that large with a power delivery system that heavy, could hope to get itself foil bound with a measly 12 HP.
     
  14. FAST FRED
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    FAST FRED Senior Member

    Those issues haven't stopped Tesla from being quite a success. And by success I mean a small start-up company gaining the market cap of GM.

    Tesla has financial success not from selling cars or batterys ,

    but from selling INDULGENCES to the other car mfg.

    Gas Hog mfg pay dearly for the indulgences , as they are cheaper than not selling cars.

    Electric cars will be a success when they can go 400 miles at 75mph , charge up in 10 min and cost what a Diesel Golf costs , not 500% more.
     

  15. Joakim
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    Joakim Senior Member

    They are saying in the >60 M at 25 knost so more like 2.5 hours

    40 kWh for 2.5 hours means 16 kW electrical power. With good electrical and propulsion design they could get 70% of that to propulsive power so say 11 kW propulsive power. At 25 knots that is 850 N thurst. With hydrofoils you should easily get 10:1 lift to drag ratio, maybe even 20:1 is possible. So you have to get total weight down to 850 kg (or 1700 kg).

    The 40 kWh battery will be 200-300 kg.

    Under the "Info" (in Swedish) they mention 280 kg, which I guess is the carbon hull weight. They also say that for every extra kg in the hull they need 300 g more batteries for the same reach.

    Under "Company" they mention 900 kg, which I guess includes batteries, engine etc. Maybe even the driver? Anyway they seem to be well within that 850-1700 kg range so it should be feasible, but will be expensive.

    This is another Swedish foiling project that has had a working prototype for a few years: http://www.foiltwister.se/index.php/en/foiltwister
    Their 5.8 m aluminium boat uses a Honda 50 HP and gets 0.34 l/M at 24 knots thus probably using about 25 HP at that speed. Still more than the electric one should, but they use a much simpler foil design and thus probably not optimal lift to drag ratio. They claim 75% reduction in fuel consumption, but seems more like 30-50% compared to normal aluminium boats at that size.
     
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