Sharpie Schooner 42 with an outboard motor

Discussion in 'Boat Design' started by valery gaulin, Apr 6, 2018.

  1. chinaseapirate

    chinaseapirate Previous Member

    update....No, marine propulsion is so much simpler because there is no authority (other than self imposed) to overcome. Solomon Industries had 10 hsp engines that would push reasonably designed 45 ft catamarans 10 knot with 7 tons displacement and 18" propellers, must have been over 30 years ago.
     
  2. Angélique
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    Angélique aka Angel (only by name)

    My advice would be to study, and carry on . . :)
     
  3. Angélique
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    Angélique aka Angel (only by name)

    Like I said #119, it's all ready off the shelf available, thanks for adding this is for over 30 years the case now, so why bother yourself by trying to reinvent the wheel with limited knowledge about the matter, unless trial and error and wasting money by this is your hobby . . ;)
     
    Last edited: Apr 24, 2018
  4. Angélique
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    Angélique aka Angel (only by name)

    BTW, it's also over 30 years ago men flew to the moon, and came back alive, but this doesn't mean such an exercise would be easy today.

    [​IMG]

    Just like building electrical propulsion or improving a boat design, only not knowing what's involved could make one think it's easy.
     
  5. gonzo
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    gonzo Senior Member

    Current draw and capacity are two completely different things. Check the units and it will become obvious.
    Also, can you explain your claim that I got wet after mounting an outboard, etc.? Seems like you are resorting to outlandish untrue stories and personal attacks instead of providing technical information to back your claims.
     
  6. valery gaulin
    Joined: Jan 2017
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    valery gaulin Senior Member

    Wow this site is better than a soap orpera!!!

    electrical Power = volt * amp
    mechanical Power = Torque * angular velocity

    A battery is the energy source needed to create power. Gasoline or diesel is another type of energy that can be converted to power.

    My question was just if anybody is aware of someone trying to use a submersible motor, the one used on well submersible pump, to create an electrical propulsion system. I figured since everything as been done before, why not this one too!!!

    I will assume that no answer to this question would mean nobody is aware! Anothee possible answer would be yes, check this video or this site or this blog!

    No need to argue so much. Most of the answer so far have been good inputs, might not be always the direction or the solution that I need but you all make some valid point. I will sort out myself if someone gave a very bad suggestion. Most of you have good intention in the solution you provide and I like to get many different inputs. Even if your solution are not always base on engineering fact, I will sort it out myslef.

    Thank you all for your comments.
     
  7. Angélique
    Joined: Feb 2009
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    Angélique aka Angel (only by name)

    The torque calculations for electrical power works the same as for mechanical power.

    The below quote is posted for the bottom line, the rest is about where that came from...


    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

    ‘‘ Consumed P (Power in Watt) = U (Voltage in Volt) × I (Current in Ampere)

    P shaft = Consumed P minus the (estimated) yield losses.

    - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

    P = T × ω

    P = Power in Watt

    T = Torque in Nm

    ω = angular velocity = 2 π n/60 - where - π = Pi (3.14159265.......)

    (ω = angular velocity symbol represented by the lowercase omega)
    n = revs per minute (divided by 60 is revs per second)

    so - P = T × ω - becomes - P = T × 2 π × n/60

    T = P / (2 π × n/60)

    T shaft = P shaft / (2 π × n/60) ’’
     
    Last edited: Apr 24, 2018
  8. chinaseapirate

    chinaseapirate Previous Member

    I have no idea why you posted posted the scenario and said that I don't seem to understand any thing. I figured that is what you had done before or had first hand knowledge of somehow. I certainly did not suggest to ventilate the prop, if the outboard was installed at a depth where the plate was not required fine, if not, put it back on further up the shaft, obviously. I don't care what it sounds like to you Gonzo.
     

  9. Angélique
    Joined: Feb 2009
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    Angélique aka Angel (only by name)

    Re: post #127

    Please note that; 2 π / 60 = 0.10472

    So the simplified formulas become:

    P = T × n × 0.10472​

    T = P / (n × 0.10472)
     
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