Project Log - New Keel, Who Dis? (Pearson 26 to Electric Cruiser)

Discussion in 'Boat Design' started by Jeff in Boston, Apr 23, 2021.

  1. Jeff in Boston
    Joined: Sep 2020
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    Jeff in Boston Junior Member

    I think the calculations were for watts at the prop, like a gas outboard. Looking at the power / speed results others are getting on YouTube with trolling motors, I don't think they are wildly off.

    As for the hybrid approach, I suspect you may be correct. We will see! But it is clear I can cruise around at 3 to 4 MPH with electric.

    I understand the issues with lead batteries, but at the current price points using lead carbon to tolerate slow and partial charging (and I can afford more Ah to reduce the Puekert effect!) I feel it may be worth it. But if I use a gas motor this year, I can wait to see what the lithium prices are next year!

    Yes, for the Navy 3 they tested that with a small skiff. :)
     
  2. Dejay
    Joined: Mar 2018
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    Dejay Senior Newbie

    Depending on product and use case, Lithium 18650 packs might already be cheaper than good lead acid batteries if you include actual usable capacity and lifecycle recharge cycles.
     
  3. kerosene
    Joined: Jul 2006
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    kerosene Senior Member

    The more exotic LiPos are imo no go for amateurs. With big packs catastrophic events are serious stuff. LFP are way safer.
     
  4. Jeff in Boston
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    Jeff in Boston Junior Member

    There are ways to DIY LFP, but even then, I'm not interested in doing that. I'm staying the hell away from LiPOs on a boat.
     
  5. Jeff in Boston
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    Jeff in Boston Junior Member

  6. Dejay
    Joined: Mar 2018
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    Dejay Senior Newbie

    That price seems pretty good. For my project (48V and more of a house battery for aliveaboard cruiser) I want to DIY with LiFePO4 prismatic cells. Mostly because I'd like to be able to understand and replace each individual part. Ideally I'd want the charger and BMS to be open source so I could replace something like a busted capacitor myself.

    Also theoretically DIY and using a better and maybe wireless BMS can give you more safety. Not sure if this is true or even applies to lifepo4 but I read a comment that some battery packs use cheapest BMS that can fail and then no longer balance or protect the battery pack.

    For safety I've been wondering too although I'm not that worried with LiFePO4. But maybe there is some kind of design for an external pod. Or placing battery so they don't easily get hit. And is not in the bilge in case of a bit of flooding. And if they catch fire the heat can escape without setting the rest of the boat on fire. Boatsmith mentions a seawater pump to flood the batteries to douse them. A bit extreme but should provide best protection for the boat.
     
  7. Jeff in Boston
    Joined: Sep 2020
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    Jeff in Boston Junior Member

    The custom ordered trailer exists!

    IMG_3123.jpg IMG_3124.jpg
     
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  8. Dejay
    Joined: Mar 2018
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    Dejay Senior Newbie

    That's one sexy trailer! Do you know how much it weights / gross weight it can carry?
     
  9. Jeff in Boston
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    Jeff in Boston Junior Member

    10400 lbs GVWR - which should be plenty for a 5000 lb boat.
     
  10. Jeff in Boston
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    Jeff in Boston Junior Member

    Assuming I can get the trailer and the boat to my yard tomorrow first step will be pulling the seacocks so I can rehab them.
    20210115_113526.jpg
     
  11. Dejay
    Joined: Mar 2018
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    Dejay Senior Newbie

    Thanks, nice. I'm just curious about the weight of an aluminum trailer compared to steel. Do you know the weight by chance?
    Maximum gross weight for a trailer for a normal car and drivers license here in Europe / Germany is 3.5t / 7700lb and the steel trailer I'm looking at weighs about 580-720kg depending on length. The aluminum trailer I've found isn't lighter in weight either.

    Sorry for derailing your thread - but with a trailer like that how do you expect anyone to talk about your boat?? ;)
     
  12. Jeff in Boston
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    Jeff in Boston Junior Member

    The maker thinks about 1600 lbs.

    I'll weigh it and the boat eventually.
     
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  13. Jeff in Boston
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    Jeff in Boston Junior Member

    The trailer has been delivered to the yard! Now to register it! And pay taxes on it.
     

  14. Jeff in Boston
    Joined: Sep 2020
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    Jeff in Boston Junior Member

    I have finally trailered the boat to my local storage yard!!! The trailer looks good. I won't be able to start on the keel until I have it at my house for a few weeks and get it jacked up, but there is plenty of other stuff to do.

    20210602_143855.jpg
     
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