Electric Inboard

Discussion in 'Inboards' started by penguin78, Dec 15, 2013.

  1. penguin78
    Joined: Jan 2010
    Posts: 14
    Likes: 1, Points: 3, Legacy Rep: 22
    Location: aus

    penguin78 Junior Member

    Hi,

    I am building an Electric inboard drive system and keeping a Blog.
    http://tctec.wordpress.com/
    I'm interested in advice as well sharing what I have done.

    It is 5Hp (3kWatt).
    Using the latest and best battery technology (Li Fe )
    Low Cost (but very reliable) BLDC motor


    Putting the drive shaft together has been a challenge because I want to use low cost readily available parts.
    But what I have done so far looks promising.

    PVC pipe and low cost fittings (to be fiberglass)
    Greased thrust bearing and home-made epoxy seal at the top
    Cutlass bearing at the bottom.

    I've attached a pic of the Hull, displacement hull, fiberglass.


    Tec
     

    Attached Files:

    • boat.JPG
      boat.JPG
      File size:
      116.4 KB
      Views:
      870
  2. michael pierzga
    Joined: Dec 2008
    Posts: 4,862
    Likes: 115, Points: 0, Legacy Rep: 1180
    Location: spain

    michael pierzga Senior Member

    Sounds cool. A challenge will be keeping all your gear dry. Perhaps a waterproof engine room with a full time scavenging bilge pump powered by the prop shaft.

    The same with air supply...something filtered to keep spray or dust from clogging up your gear.

    What will be your shaft speed..rpms ?
     
  3. penguin78
    Joined: Jan 2010
    Posts: 14
    Likes: 1, Points: 3, Legacy Rep: 22
    Location: aus

    penguin78 Junior Member

    Hi,

    Speed 2000 rpm,

    Yes, it is a water cooled motor so fairly splash proof.

    I would like a closed water cooling system.. a small pump running water around from a tank.


    The top of the shaft and the motor will be above the water line, in the centre of the boat at the end of a 1.5Metre shaft..
    The shaft is hollow aluminium tube for lightness and stiffness.
    Someone said 'forget it, the aluminium tube will corode'
    But, boats are made from aluminium, and so are outboards..if there is any problem I plan to just slip it out and replace with stainless tube.

    It does have a seal at the top of the shaft also.
     

    Attached Files:

    1 person likes this.
  4. michael pierzga
    Joined: Dec 2008
    Posts: 4,862
    Likes: 115, Points: 0, Legacy Rep: 1180
    Location: spain

    michael pierzga Senior Member

    2000 rpm prop shaft speed ??
     
  5. johneck
    Joined: Nov 2011
    Posts: 247
    Likes: 14, Points: 18, Legacy Rep: 117
    Location: New England

    johneck Senior Member

    Even at 1500 RPM, the prop is likely overpitched, 8" might be better.

    Is the shaft solid?
     
  6. CDK
    Joined: Aug 2007
    Posts: 3,324
    Likes: 148, Points: 63, Legacy Rep: 1819
    Location: Adriatic sea

    CDK retired engineer

    Looks like an interesting project!
    You can omit the water pump if the tank is not far from the motor and both in and out tubes are below the water level. Once primed the system will provide enough circulation without wasting electricity in a pump.
     
  7. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 488, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    I'd think an aluminum shaft would work, though stuffing box and cutlass wear on the usual alloys will be a constant issue. Maybe some sort of imbedded bearing surface.
     
  8. penguin78
    Joined: Jan 2010
    Posts: 14
    Likes: 1, Points: 3, Legacy Rep: 22
    Location: aus

    penguin78 Junior Member

    Shaft is hollow, will try two props

    Yes the shaft is hollow 32mm diam, 3mm-wall Al-tube. (1 1/4inch)

    mmm,so the prop has probably too much pitch.
    I can try a large low-pitch trolling motor prop also (I have drilled it out)

    The Water cooling is just a hollow block on the motor without a pump.
    I have to push water through it.

    Plan for a stainless insert into the end of the shaft where the prop connects and for the cutlass bearing surface.
    I have a quote to make this, and it isn't very expensive..
    I have made up something equivalent with stainless threaded rod and PVC pipe that can test the system.


    I will have a picture of the complete shaft assembly soon to show.

    And should really spin it at 2000 rpm before I go much further..
     

    Attached Files:

  9. parkland
    Joined: Jul 2012
    Posts: 700
    Likes: 6, Points: 18, Legacy Rep: 40
    Location: canada

    parkland Senior Member

    I think electric trolling motors spin 1000-2000 RPM, and they don't have 5 hp.
     
  10. penguin78
    Joined: Jan 2010
    Posts: 14
    Likes: 1, Points: 3, Legacy Rep: 22
    Location: aus

    penguin78 Junior Member

    Test in Water

    I've tested in water :

    https://www.youtube.com/watch?v=XGdy8UBmBvs&feature=youtu.be



    With the 10" prop.
    At 12V (1/4 maximum RPM)
    Normal SLA 12V battery (not the LiPo pack yet)

    The boat was cruising at a fairly nice speed.
    8" prop would probably be better as suggested, for higher RPM.
    Still have to try the trolling prop.

    Vibration in the shaft...
    Still have to clamp it near the motor with a U-Bolt.
    It is just a cutlass bearing and a trailer bearing, I will see how long they last.
    easy to replace.


    The shaft seal seemed ok , and the top of the shaft-tube is just above water line with two people on board.
     

    Attached Files:


  11. Toolate
    Joined: Sep 2013
    Posts: 38
    Likes: 1, Points: 8, Legacy Rep: 19
    Location: CT (Western)

    Toolate Junior Member

    You still at this? Any progress?
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.