Making best use of shore and passive power sources

Discussion in 'OnBoard Electronics & Controls' started by jamesgyore, Jun 10, 2013.

  1. BernardG
    Joined: Aug 2013
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    Location: France

    BernardG Junior Member

    :) Don't miss read me. Sorry to quote myself, but here is what I wrote:
    What I mean by that, is that your electric engine will be
    1. the biggest "consumer" of electricity on board, when you use it
    2. the biggest "producer" of electricity on board, when you don't use it

    obviously, this is all in the context of electricity on board, and not in the context of the whole boat.

    if you prefer, and to say it differently, that big pole in the middle on the boat, with that fabric attached to it, beside "propulsing" the boat, will also produce electricity by the mean of that electric engine which turns into a generator while the boat is moving under sails. :)

    As this thread subject is "best use of passive power sources", it seems to me that this source cannot be taken out of the equation.

    HTH,
    Bernard
     
  2. michael pierzga
    Joined: Dec 2008
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    Location: spain

    michael pierzga Senior Member

    Ive sailed many miles with a well thought out low friction free wheeling propshaft that powered an alternator. At speeds below 4 knots no energy was generated. 8 knots was the sweet spot...perhaps 15 amps

    8 knots is pretty fast for a sailing boat.

    One advantage of the free wheeling prop shaft alternator is that it also produced energy when motoring, this means that only one alternator was needed on the front end of the engine.

    Front end real estate is precious. Refer compressor...high volume water pump.....PTO
     
  3. BernardG
    Joined: Aug 2013
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    BernardG Junior Member

    the swedish company, which I am using numbers from, gives 40 W at 5 Knots, 600 W at 10 K, and 2000 W at 15 K produced by their engine. From those numbers, it seems pretty obvious that it's not a straight relation to speed, but an exponential curve. I don't know below 5 K, there is certainly "something", but not much.

    Even if those numbers should be taken with a pinch of salt, it would seem to me that an optimized, fixed installation, could be seen as more efficient than other systems.

    It also suggest that a system like this might be better in a fast catamaran than in a small monohull. (But to be fast, catamarans needs to be light....Damn vicious circle! :p )

    Regards,
    Bernard
     
  4. michael pierzga
    Joined: Dec 2008
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    Location: spain

    michael pierzga Senior Member

    I think the key is to not be overly optimistic when considering energy generation.

    Add plenty of extra capacity
     

  5. BernardG
    Joined: Aug 2013
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    BernardG Junior Member

    Certainly true, but you can also (should?) optimize energy consumption. For example, instead of having a fridge running 24 hours per day, it might be better to have an ice cube making machine, and an icebox. I don't know, I have not checked the numbers. There are tons of possibilities. One has to search, compare, evaluate. Brute force, like doubling the number of batteries to double the capacity, might not be the smartest move....

    Regards,
    Bernard
     
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