Small electric outboard: endurance – real world experience

Discussion in 'Boat Design' started by Jon E, Jul 29, 2015.

  1. Jon E
    Joined: Jan 2005
    Posts: 54
    Likes: 3, Points: 8, Legacy Rep: 22
    Location: Norway

    Jon E Junior Member

    The boat is a 17 feet displacement rowing/motor monohull with Torqueedo 2.0 electric motor (Input power in watts 2000, propulsive power in watts 1120). Total weight including boat, engine, batteries and driver is around 350 kg.

    [​IMG]

    All results below is at constant 600 watt input power, mesuared over 5,5 hours and 48,4 kilometers. Batteries: Sønnak EP1500 EXIDE DUAL AGM: 2 x. 12V 180Ah

    It consumes 1% of battery every 3.65 minutes
    100% consumption of battery = 6 hours 5 minutes
    Speed 8,8 km/h - 4.75 knots

    Note: After a 5,5 hour long trip and 48,4 kilometers, i still have 17% left on the battery. My solar panel fleet are rated 981 watt (optimal), and on a sunny day here in Norway - it will charge 500 to 600 Wh to my bateries.

    Pictures and video here >>



    UPDATE:
    Friday 31. july i mesuared average speed (with and against current). Total weight ca. 400 kg. Distance (only) 300 meter, so this is not 100% accurate, but wery close.
    Input power 150w=3,0 knots
    Input power 300w=3,7 knots
    Input power 450w=4,3 knots
    Input power 600w=4,75 knots
    Input power 1000w=5,1 knots
    Input power 1500w=5,3 knots
    Input power 2250w=5,65 knots



    Cruise 2.0 R Technical Data (from the manual):

    Input power in watts 2000
    Propulsive power in watts 1120
    Comparable petrol outboards (propulsive power) 5 HP
    Comparable petrol outboards (thrust) 6 HP
    Maximum overall efficiency in % 56
    Static thrust in lbs* 115
    Nominal voltage 24
    Total weight in kg 15.3 (S) / 16.2 (L)
    Shaft length in cm 62.5 (S) / 75.5 (L)
    Standard propeller
    v = speed in km/h at p = power in watts v19/p4000
    Alternative propeller options v30/p4000, v8/p350
    Maximum propeller speed in rpm 1300
    Control Remote throttle
    Steering Provision to connect to standard remote steering; lockable
    Tilting device Manual with grounding protection
    Trim device Manual, 4-step
    Integrated on-board computer Yes
    Stepless forward/reverse drive Yes
     
    Last edited: Jul 31, 2015
    2 people like this.
  2. Jamie Kennedy
    Joined: Jun 2015
    Posts: 541
    Likes: 9, Points: 0, Legacy Rep: 117
    Location: Saint John New Brunswick

    Jamie Kennedy Senior Member

    Great stuff. Your units aren't all that clear when you mean KWh vs KW or Wh vs W.

    I think you mean you ran the motor at a constant 600 watts, measured by electrical power in. This would make sense given your gross capacity of 2 x 12 x 180 = 4320 watt hours. 4320 / 6 hours = 720 watts drained, so you are indicating a loss of 120 watts or 20% of the 600 watts when draining your batteries at a 6 hour rate, which makes sense.

    I think the actual hydrodynamic resistance on a 350kg 17 foot hull might be in the 450 watt ballpark, do that mean a combined motor and propeller efficiency in the 75% ballpark which is pretty decent.

    Thanks for the numbers, and the pictures and videos.
    Sweet little rig. Are you planning any long distance camping expeditions?

    If you can go 50km in 5.5 hours on 500-600 kwh you could probably do 70-80km in 12 hours by slowing down a little.
    It would be fun to see how far you can get over a multiple day cruise on solar and battery alone, optimizing your speed for sun, wind, and tide. :)
     
  3. Jon E
    Joined: Jan 2005
    Posts: 54
    Likes: 3, Points: 8, Legacy Rep: 22
    Location: Norway

    Jon E Junior Member

    Hi Jamie. Thanks for the correction and Nice Words! I am not that good on watts and watt hour..:) My boat is sort of a test bed. I have bigger plans, wich includes a Kookaburra rowing Shell wich i am currently building. Only to test speeds and weight. My ultimate goal is a all solar Powered catamaran. New Pictures added to the link above.
     
  4. Jamie Kennedy
    Joined: Jun 2015
    Posts: 541
    Likes: 9, Points: 0, Legacy Rep: 117
    Location: Saint John New Brunswick

    Jamie Kennedy Senior Member

    Sounds fun. I really love that little lapstrake launch though. :)
    Thanks for the extra pics.
     
  5. BertKu
    Joined: May 2009
    Posts: 2,461
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    Location: South Africa Little Brak River

    BertKu Senior Member

    Very interesting Jon. What wave heights did you encounter at the 8.8 km speed? Also what can you say about the current experienced, against you or with you?
    Love to hear from you. Well done.
    Bert
     
  6. Jon E
    Joined: Jan 2005
    Posts: 54
    Likes: 3, Points: 8, Legacy Rep: 22
    Location: Norway

    Jon E Junior Member

    Hi BertKu. Wave height is almost non-existing at that speed. Top speed is only around 5,65 (speed edited 31. july) knots at 2.200 watt input Power, and that With pretty big waves..!

    At 600 watt: With the current: 9,75 km/t – 5,26 knots, against the current: 7,83 km/t – 4,23 knots. There is a detailed diagram, if you click the link in the first post.
     
    Last edited: Jul 31, 2015
  7. Heimfried
    Joined: Apr 2015
    Posts: 325
    Likes: 34, Points: 28, Legacy Rep: 37
    Location: Berlin, Germany

    Heimfried Senior Member

    Hi Jon,
    thank you for the pics and the information.
     
  8. BertKu
    Joined: May 2009
    Posts: 2,461
    Likes: 39, Points: 58, Legacy Rep: 223
    Location: South Africa Little Brak River

    BertKu Senior Member

    Thank you Jon, my apology that my Norwegian is non existing and I overlooked that graph. Nicely documented. My weather is always from yr.no, although, we live in South Africa. They give me the most accurate weather forecast for this part of the world. I was able to use a translation program. Thanks, your reply has helped me greatly. Bert
     
  9. Jamie Kennedy
    Joined: Jun 2015
    Posts: 541
    Likes: 9, Points: 0, Legacy Rep: 117
    Location: Saint John New Brunswick

    Jamie Kennedy Senior Member

    I still think it would be fun to pop those panels onto the boat and go a-viking. :)
     
  10. alan craig
    Joined: Jul 2012
    Posts: 225
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    Location: s.e. england

    alan craig Senior Member

    That's a nice looking boat and a very successful electric conversion. Have you considered a towed array of solar panels?
     
  11. AndySGray
    Joined: Jun 2014
    Posts: 296
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    Location: Cayman

    AndySGray Senior Member

    Seemed very quiet...

    Hmmm :!: :idea:

    I'd be tempted to shorten a couple of oars - leave only the bit from the handle to the rowlock and pretend to be rowing as you pass other boaters :p:D:p:D:p

    Great work, have some reputation
     
  12. Jon E
    Joined: Jan 2005
    Posts: 54
    Likes: 3, Points: 8, Legacy Rep: 22
    Location: Norway

    Jon E Junior Member

    UPDATE:
    Friday 31. july i mesuared average speed (with and against current). Total weight ca. 400 kg. Distance (only) 300 meter, so this is not 100% accurate, but wery close.
    Input power 150w=3,0 knots
    Input power 300w=3,7 knots
    Input power 450w=4,3 knots
    Input power 600w=4,75 knots
    Input power 1000w=5,1 knots
    Input power 1500w=5,3 knots
    Input power 2250w=5,65 knots
     
  13. Heimfried
    Joined: Apr 2015
    Posts: 325
    Likes: 34, Points: 28, Legacy Rep: 37
    Location: Berlin, Germany

    Heimfried Senior Member

    Thank you Jon, your numbers are - may be - graphically displayed even more impressive:

    [​IMG]

    speed versus power (from Jon's table above).


    To draw more than about 500 W means wasting battery power.
     

  14. BertKu
    Joined: May 2009
    Posts: 2,461
    Likes: 39, Points: 58, Legacy Rep: 223
    Location: South Africa Little Brak River

    BertKu Senior Member

    Indeed very impressive and gives the confidence that actual little electric power is needed when using brush-less motors versus engine power. I read somewhere that an electric automotive car needs 1/3 electric power of that of an mechanical engine with approx the same performance. Bert
     
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