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Thread: Make me faster

  1. #1
    Join Date
    Apr 2021
    Location
    Uk
    Posts
    2

    Default Make me faster

    Hi there.

    I have converted one of my dads old 70s nitro boats to electric using an Aquastar 3974-2200kv

    it?s currently fitted with a X440 prop but the performance is pretty disappointing on either 4 or 5 cells

    its takes a long time to get on the plane with a lot of cavitation and overrevving and once going isn?t that fast

    can you offer me some advice to make it better, some have suggested dropping the surface prop and going submersible prop

    boat specs. 31 inches long 11 inches wide and weight 6.8lbs with 5 cell 4000 on board

    19349820-BD4F-41EE-BECE-19ACA9006A45.jpgE3707FA4-0802-4280-948D-E0F4DDB34AAC.jpg03C64596-7939-45A7-B430-16D9F25D9FDA.jpg0F96B536-CB7A-48FC-BF77-C4EB6CEAEF8E.jpgEC5A5C43-E10E-4E4C-9BBB-25EB3516D1A6.jpg

  2. #2
    Join Date
    Apr 2021
    Location
    Uk
    Posts
    2

  3. #3
    Join Date
    Apr 2007
    Location
    AZ
    Posts
    8,009

    Cool

    Where to begin? That hull is very draggy with a lot if wetted area which will slow the boat down. The motor is better suited to a hydro rather than a mono. The cavitation is because the prop is too small, but a larger prop will probably overheat the motor and ESC. There is no gap between the drive dog and the strut, this causes huge amounts of frictional losses.

    What to do? Lots of possibilities, I would recommend the same sized motor with a Kv of 1500-1600. Run an x445 prop on 4S. Have the balance point 10? ahead of the transom. That should help, but there will be minor tuning from there.




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  4. #4
    Join Date
    Sep 2007
    Location
    NC
    Posts
    2,778

    Default

    Assuming that prop in the picture is the one you are running with you need to sharpen and balance it. Dull props will cause all sorts of headaches.
    Given the large wetted surface, make sure the bottom is scuffed with 400 wet/dry sandpaper to remove any shine. You want a nice dull surface.
    Tyler Garrard
    NAMBA 639/IMPBA 20525
    T-Hydro @ 142.94mph former WR

  5. #5
    Join Date
    Jun 2011
    Location
    FL
    Posts
    789

    Default

    All of the above good suggestions. A 440/2 does not have a lot of blade area and may be slipping a bit carrying the wetted area and weight. I would try a 3 blade either X440 or try a 42/3 CNC from OSE. More blade may create heat so monitor temps.
    Mic

    Mic Halbrehder
    IMPBA 8656
    NAMBA 1414

  6. #6
    Join Date
    Jun 2010
    Location
    Mi
    Posts
    738

    Default

    The strut looks level when the boat is on the stand.
    When the boat is on plane, wont it will basically ride as if the boat is on a table (balanced left to right) ?
    If so, then it look like the strut may be pushing the nose down, which would explain why it would take so long to get on plane.
    the strut should be flat when the boat is resting in a table.
    Cheetah, Super Rio, (Mod) Starship (Mod and sold),

  7. #7
    Join Date
    Mar 2017
    Location
    VI
    Posts
    371

    Default

    I think the problem is the hull. It will run very wet no matter what you do. And it will cause alot of prop slippage.

    That boat have a setup that should be running over 50mph. But that hull will not allow you to get that speed.

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