Results 1 to 6 of 6

Thread: new project

  1. #1

    new project

    New to this site
    Looking for info on a new build.
    I have built a full size airboat from the hull to the rigging and all that goes with it.
    I also build airplanes and have five in my hanger at this time.
    Here is what i got.
    A 14 ft X48 inch wide bottom alumacraft.
    a 33 hp Generac engine with polished intakes ,High performance carb, LP pistons, and a special cam.
    It puts out about 41-42 hp.
    A 72 inch X 45 inch pitch Tennessee prop, with a 2.2/1 reduction drive.
    The engine spun the prop at 3600 rpm's when it was on the aircraft.
    I plan on building all the rigging with 6061 aluminum for weight.
    Will this set up push my boat---respectfully----???
    You guys have much more knowledge than I and was hpoing for your thoughts.
    Thanks

  2. #2
    Administrator Papee's Avatar
    Join Date
    Jan 2008
    Location
    PA/GA
    Posts
    2,721
    Welcome to the site! Everything sounds good except for the size of the prop compared to your hull width. If you have a 48" bottom the hull is most likely not wide enough to accept that prop with the needed clearances. A wider bottom would be better but I so no reason it would not work if you found a shorter prop that would work with your setup.

    Using a shorter prop would also allow you to mount your engine lower and wouldn't be as top heavy with the 48" bottom.
    Please check out our YouTube channel and subscribe! Our YouTube Channel helps fund the site. Check it out at https://www.youtube.com/channel/UCTv...FrJP7yQVFVZnyA


  3. #3
    KWAZY old Southerner... Duane Scarborough's Avatar
    Join Date
    Feb 2009
    Location
    Wilson, NC
    Posts
    1,688
    Chippawariverrunner,

    Welcome to the Mini Airboat Association forum.

    It sounds like you'd got a lot of aviation fabrication experience. I'm betting you can make a NICE Mini Airboat.

    Papee gave you some good advice. Listen to him. He's been there, and done that. You can learn from him.

    Here's MY 0.02 worth:

    Honestly, a 48" wide hull is on the narrow side. Yeah, it CAN be done. But it WILL be VERY unstable. You'd be safer with either a much wider hull, or a much narrower prop.

    To put a 72" prop on a 48" hull would be asking for a lot of trouble, IMO.

    I assume that your Alumicraft hull is a typical wide Jon Boat, which has strakes/ridges in its bottom. There have been many small airboat built that way. It all depends on what you expect of it.

    If you want a boat to just putt around in, it'll probably be O.K., IF you reduce the prop to about 42".

    IMHO, you'd be better off to get a different hull, one that is meant for airboat use.

    The Generac engine is kinda' new to the Mini Airboat world. Reviews are mixed about it.
    But if you intend to use a 72" prop, you'll HAVE to use a reduction drive.

    We have a member who's been working on a souped up Genarac.

    Hopefully he'll chime in before long.

    Anyway, WELCOME to the forum.

    Duane
    A KWAZY old Southerner... and darn PROUD of it.

    Airboat Pros MiniPro 116 / Frog Spit
    SS rigging - with side by side seating
    Teledyne 4A084-4 engine
    Solex H30/31 Carb
    Arrow Prop 1.73:1 reduction
    67" Whirlwind 2 blade Mini Prop

    under construction

  4. #4
    Administrator Papee's Avatar
    Join Date
    Jan 2008
    Location
    PA/GA
    Posts
    2,721
    Duane,I was assuming when he said "A 14 ft X48 inch wide bottom alumacraft" the bottom of the boat was 48" which would make it around 60" at the top of the gunwales. He has a reduction drive on it. If he could clear a 60" prop it may work for him. I'm sure being into aviation he is familiar with the prop width/length/pitch deal so I didn't go into detail.

    Any way, if you have more questions just shoot.
    Please check out our YouTube channel and subscribe! Our YouTube Channel helps fund the site. Check it out at https://www.youtube.com/channel/UCTv...FrJP7yQVFVZnyA


  5. #5
    Thanks guys
    I don't want to waste my time with this set up if it won't work.
    I will just fabricate a surface drive mud motor with this engine.
    The boat is 48 inches wide, at the top its 67 inches which would mean a few bends in the cage to get me out to a good clearence.
    I would really like to use what I have, but again, don't want to waste my time.
    All my airplanes have an adjustable pitch prop, along with my big airboat.
    I bought this prop because an engineer said it was the right set up for the application.
    I changed out this engine for a 119 hp motor which is alot more fun, now what to do with this thing sitting on my shop floor.
    Appreciate all your advise, keep it coming
    Thanks

  6. #6
    Administrator Papee's Avatar
    Join Date
    Jan 2008
    Location
    PA/GA
    Posts
    2,721
    Will it work? Yes
    Would I tell someone to do it? Probably not.
    Would I try it? Yes
    If I were doing it I would make a temporary stand at the height you need for the prop then take some measurements.
    Keep the engine as low as possible keeping some of the prop below the transom.
    I would not allow any part of the cage past the gunwale. IF the measurements you come up with allowing for prop clearance are not to far off from your width you could add some tapered gunnels to widen the boat slowly. Seating would have to be kept low.
    Please check out our YouTube channel and subscribe! Our YouTube Channel helps fund the site. Check it out at https://www.youtube.com/channel/UCTv...FrJP7yQVFVZnyA


Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •