Battery based Ferry boat design! HELP!!!!

Discussion in 'Boat Design' started by koman, Jun 29, 2009.

  1. koman
    Joined: Jun 2009
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    Location: HK

    koman New Member

    Please help!!!

    my boss ask my to design a commercial electric ferryboat for 30 passengers and work at the sea. However, I am not understand anything in this area:confused: . Where can I find related data? What is the first step should I do?

    The required data of the boat:
    - Commercial electric boat working 12-18 hrs/day (not hybrid, charging 2 times per day can be charging at night and at lunch time)
    - working at the sea
    - 3mins to 3mins 30 sec. per each travel (very short distance) waiting time is about 3 to 5 mins (ship sail when passengers full)
    - normal speed required is about 8km/h (max is about 12km/hr)
    -Battery ( I already find some information, http://www.thunder-sky.com/products_en.asp?fid=66&fid2=70 )

    For the boat body, it may make from china (cheap and near)

    Please teach me how to design and select , and what should I consider when design a boat body. Also, some suggested supplier (close to Hong Kong is better)

    Thank you for your attention and hlep! and please help me, i am really alarmed:( !
     
  2. gwboats
    Joined: Sep 2005
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    Location: UK

    gwboats Naval Architect

    Commercial Electric Boat

    koman,

    Unless I completely misunderstand you, are you saying your boss (not teacher, lecturer etc.) wants you, as a totally unqualified marine designer, to design a sea-going passenger vessel?

    If this is the case, then I would go back to him and insist he use an experienced and qualified designer or Naval Architect.
    You will be responsible for the safety of 30+ people if you carry on with this project and that is not something to take on lightly.

    Just the vast amount of safety regulations for passenger boats can be overwhelming to the inexperienced, not to mention stability, strength and systems engineering involved.

    It is very distressing to see the frequent loss of overcrowded, unsafe passenger boats around the world. Please don't add to the statistics.

    I apologise if I have misunderstood your intentions but this is a subject I feel strongly about.

    Graham Westbrook
    Naval Architect
    www.westbrookmarine.co.uk
     
  3. peter radclyffe
    Joined: Mar 2009
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    peter radclyffe Senior Member

    what a coincidence, i was going to advise him to contact you, after tony wager & my sister sas told me about your work
     
  4. mydauphin
    Joined: Apr 2007
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    mydauphin Senior Member

    koman,

    Give it a try, why not? You design a seagoing vessel, I will do open heart surgery on you. As long as we try our best, what does it matter?
     
  5. peter radclyffe
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    peter radclyffe Senior Member

    great joke
     
  6. koman
    Joined: Jun 2009
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    Location: HK

    koman New Member

    Sorry about I write not clearly. My boss would like me to calculate the power supply part. However, it got no data!!!! He just tell me the boat body will made by a company in China. But the company say, I need to provide the detail of the boat. In my mind, I know that the first step sould be design the boat shape,etc. 2nd, choose a suitiable motor and propeller. 3rd, calculate the power(battery power) required. However, I got nothing...... How can I start to desidn the motor part and power part? can any one give me some suggestion? Or give me some sample for me to cal.
    The main concerm of me is the how to choose a dc motor for the boat and choosing propeller thus get the speed of the boat. Also, can cal. the battery power.

    I am sorry about I am not good in this area and course this big misunderstanding. Thanks for all of you!!
     
  7. masalai
    Joined: Oct 2007
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    Location: cruising, Australia

    masalai masalai

    koman,
    Electric will not really go fast but a relatively narrow and long hull should be easily driven, then you need to know the loaded weight of the boat and therefore the sort of thrust that would be needed to propel it at about 6 knots (what is often loosely called "hull speed") and then you can calculate the size of the motor and how much battery power to get one return trip, then the shore based power-supply and how long to recharge the batteries for the next run (do not forget it may be called to do 2 or more return runs without an opportunity to recharge, and this factor must also be considered)... A good bet on batteries may be those used in golf buggies - largish 6 volt units set up in series to give the required voltage ?48vDC? and parallel these banks to cover the energy needed before recharge/down time - technology is still very young - so do not expect much if regular trips are anticipated - current technology for batteries is very expensive and not good at heavy loads for extended periods... (no regeneration - no hills/breaking, constant speed not stop/go as in an auto-mobile...)

    Source for electric motors is difficult what with the global downturn and that this technology is just starting to develop, I intend to use Torqeedo and at 4000watts peak from 48 volts can deliver something like 90kg of thrust (check the website I may be wrong - memory not good) and using pulse-mode speed control - I am using 2 on my boat and will be very happy with 6 knots on a no wind calm seas situation and OK with 4 knots there, but batteries are STILL a very big and difficult issue... The Torqeedo system is guaranteed for 2 years and each 4.0R engine is the equivalent of a 9hp petrol outboard...
     
  8. kerosene
    Joined: Jul 2006
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    kerosene Senior Member

    I think it is admirable that you have the patience Masalai, however it is quite useless. We have here a person who is seemingly way over their heads and should not be designing boat to carry passengers.

    The brief is totally ambiguous and quite unrealistic. 30 passenger boat needs some serious power for electric. Lunch break is not going to charge much batteries for one thing. What is the cost to power even 100 hp motors for 6 hours? 100hp=73kw 6hx73kw=438kWh battery pack.

    LiFePO4 batteries go for like 500$/kWh (really good price as far as I know). Also said batteries need quite sophisticated management systems.

    Now maybe you don't need 100 hp on slow vessel but still. Even if regular coasting could be done with lower power - you need quite reserves - what if its a windy day? do you just stop early that day as batteries empty? as batteries get older they will eventually lose some capacity so they can't be fit too close to your typical day's need.

    Let alone the characteristics of a boat that was just "design the boat shape,etc."

    anyways - we get these once a week
     
  9. masalai
    Joined: Oct 2007
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    Location: cruising, Australia

    masalai masalai

    It is almost do-able, 8 kmh is less than 4.5 knots, 30 people is about 3000kg (3 tonnes, bare boat and batteries about 6 tonnes if a swath cat it may just do it but not the range/motor time between charges.... But I would not like to be the designer certifying it:D:D:D

    Now this Flinders Island brie goes very well with a nice drop of wine - both with a delicate flavour, so neither overpowers the other... Like this, nothing is too much bother to try to help:D:D:D
     
  10. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    Your first step was correct: contact people with knowledge. The second one should be to hire one to do the calculations
     
  11. Jeremy Harris
    Joined: Jun 2009
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    Jeremy Harris Senior Member

    Although the power required for modest speeds will be low, this is a ferry, so won't there be a significant margin of excess power needed for safe manoeuvring?

    I'd have thought that a ferry would need a fair bit of additional thrust available to be be economical, as the ability to dock/undock quickly in a wide range of conditions might be crucial to successful operation.

    Just a thought from someone working on a low-power electric propulsion system; I'm far from being an expert on powered craft though.

    Jeremy
     
  12. mydauphin
    Joined: Apr 2007
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    mydauphin Senior Member

    This would be one slow, dangerous ferry. Imagine crossing just 10 miles at 5 miles per hour. Nobody would sit there for that. Or even if you got it up to 8 knots, your still talking hull speed and you still need like 400hp that is a lot of power for a electric motor on batteries. What is distance, if distance is less than 1 mile, I have another idea that will work better.
     
  13. apex1

    apex1 Guest

    What was that?
    I doubt that any yard or boatbuilder, even in China, will ask a complete novice to make any sort of power calculations! Let alone some "design".
    You have been right Koman to be "alarmed"
     
  14. apex1

    apex1 Guest

    A bridge?
     

  15. mydauphin
    Joined: Apr 2007
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    Location: Florida

    mydauphin Senior Member

    No, actually when I was a kid we used a cable powered ferry boat between mainland and our little island. Something like that would work very easily.
     
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