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Thread: Prop KV and amp draw help

  1. #31
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    i'm not sure i even know which hull you're talking running those electronics in.
    Vac-U-Tug Jr (13mph)

  2. #32
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    That makes 2 of us. I don't know what the hull is other than looking at it.the pictures are up in the thread.

  3. #33
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    Quote Originally Posted by fweasel View Post
    i'm not sure i even know which hull you're talking running those electronics in.
    We are talking the 48” cat hull Ryan.
    Jimmy, I think I’d be more in the 50mm range on props, perhaps 47mm. I don’t think id worry about the amp draw with 6s on 1250kv. You should be good there. I think 75 amps is where I’m at with 447’s and 1700kv Motors. Might even be less.

    A few things to add to Ryan’s comments,
    #1: I think the silicone would work fine in this situation. I did it on my little boat WITH flood tube when I started having sealing issues. Two years and no issues.
    #4: I haven’t done the ‘annaeling’ process as I find the bends usually gentle and can be gently worked into shape. One size over and under tubing helps to get leverage.

    And I was looking at the pics you posted and you’ll have to glass up that hatch but then I think that lid should seal pretty well. Bit of foam tape perhaps.

  4. #34
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    Jimmy, do you have a pic of the stinger you speak of? Perhaps a strut would be better.

  5. #35
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    Thanks for the prop size recommendation. Given your setup with higher kv, you're probably right I need something like x450. I think I'll try that first.

    I'm definitely glassing the hatch. It likely won't look pretty for now since I don't have a ton of time, but I'll get her sealed up.

    I don't have pictures of the stingers since they are in the mail. But these are what I ordered. I don't want to do a strut simple because I've done that before and wanted to try stingers.

    https://www.ebay.com/itm/3-16-left-r...-/142314976890

  6. #36
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    Ok yeah Promise hobby is good to deal with. The tubes I usually run the tube just inside the stinger. Enough to go inside but allow the stinger to move up and down a little. Should only need a few degrees of travel positive/negative.

    You shouldn’t really need to move the brass tube up and down within the hull.

    CNC for 50mm props. I just got some from RCboat bitz I believe.

  7. #37
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    Those are fairly expensive compared to Octura for $12. Is it just because they are already balanced? Since I'm still not sure on the size I might go with cheaper props until I know what size I'm going to stick with. I'll still balance and sharpen though.

  8. #38
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    Quote Originally Posted by Jimmypooh View Post
    Those are fairly expensive compared to Octura for $12. Is it just because they are already balanced? Since I'm still not sure on the size I might go with cheaper props until I know what size I'm going to stick with. I'll still balance and sharpen though.
    Oh I guess you are looking at plastic ones. Yeah they would be fine too as your not spinning 40k

  9. #39
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    Sorry looks like that correct size is $15 from here on OSE site: https://www.offshoreelectrics.com/pr...?prod=oct-x450

    I don't mean to be too cheap, but in the next couple months I'll be buying at least 4, maybe more.

  10. #40
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    Jun 2019
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    IMG_20190720_142054.jpg

    First boat is complete. This is a fiberglass 32 inch Dumas Deep V 40 that someone made from a plug of my Grandfather's wood version. It's far too heavy because the fiberglass was laid too thick which is why it was given to me for free years ago. I call it the tank.

    It weighs 4.3kg (10lb) all up and uses a 4074 2000kv Goolrc motor with a Seal 130a esc and Banggood special 40 x 1.9 prop with 2p 5000mah batteries. It draws 55amps peak jumping in and out of waves. My guess is that it does about 30mph, but I will clock it later using my 1:1 boat. The speed is about perfect for the rough conditions I plan on running it in. I may go up in prop diameter while going down in pitch, but this prop did fine.

    For my test run I taped some plastic to waterproof it, but now that I know the boat works I need something more permanent. I'm open to suggestions for simple cowl materials. The tough part will be dealing with that weird front and back lip.

  11. #41
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    I'm getting close to finishing the 48 inch Cat. I just ordered x447 props (right and left handed). Here are the specs. Can anyone see any glaring issues?

    All Up Weight: 18.5 lbs
    Dual 4092 1250kv SSS motors
    Seal 130a 6S ESCs
    x447 Props
    10,000mah 6S battery
    CG at 30% from the transom

  12. #42
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    All looks good to start. Just watch the startups with that heavy of a boat and only 130amp ESC’s. It’s gonna takes bit to get it up and moving. Hopefully 447’s are up to the task

  13. #43
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    Jun 2019
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    Thanks. It's getting cold here now, so I might not get a chance to run this boat until next year.

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