hub lengths for inboard props?

Discussion in 'Props' started by Deering, Jun 20, 2015.

  1. Deering
    Joined: Feb 2005
    Posts: 481
    Likes: 24, Points: 18, Legacy Rep: 44
    Location: Juneau, Alaska

    Deering Senior Member

    I must be missing something obvious, but where do you find the hub lengths for inboard props? Are they all a standard length?
     
  2. NavalSArtichoke
    Joined: Oct 2013
    Posts: 431
    Likes: 8, Points: 0, Legacy Rep: 83
    Location: GulfCoast

    NavalSArtichoke Senior Member

    Have you tried contacting the prop manufacturer or distributor?

    There's no big secret about the length of a prop hub. The hub is usually cut off as close as possible to where the blade root fairs into the hub, thus hub lengths vary depending on the blade geometry.
     
  3. Deering
    Joined: Feb 2005
    Posts: 481
    Likes: 24, Points: 18, Legacy Rep: 44
    Location: Juneau, Alaska

    Deering Senior Member

    Thanks. That's my next call. I couldn't find it published with any of the other prop data, so I assumed it was a standard size.
     
  4. jehardiman
    Joined: Aug 2004
    Posts: 3,208
    Likes: 667, Points: 113, Legacy Rep: 2040
    Location: Port Orchard, Washington, USA

    jehardiman Senior Member

    They are sorta-kinda standards, having to do more with power absorbed to shaft diameter to shaft taper to hub material. Generally both shafts and props are designed based on power or torque inputs. For the hub and shaft material there are consistent rules of thumb for taper given a specific power. All of this tends to drive hub size and length to be similar between props designed to absorb a specific power. Which is a good thing for most commercial and commercial fisherman applications. You still should check it, always allowing for push up on the shaft.
     
    Last edited: Jun 20, 2015
  5. JSL
    Joined: Nov 2012
    Posts: 811
    Likes: 62, Points: 28, Legacy Rep: 41
    Location: Delta BC

    JSL Senior Member

    There is a SAE size chart that prop mfrs follow
     
  6. NavalSArtichoke
    Joined: Oct 2013
    Posts: 431
    Likes: 8, Points: 0, Legacy Rep: 83
    Location: GulfCoast

    NavalSArtichoke Senior Member

    1 person likes this.
  7. Deering
    Joined: Feb 2005
    Posts: 481
    Likes: 24, Points: 18, Legacy Rep: 44
    Location: Juneau, Alaska

    Deering Senior Member

    Yes! That is exactly what I was looking for. I knew that they were tapered to an SAE standard, but I hadn't seen it dimensioned out so clearly. Thank you.

    Now all I need to do is figure out how far the blades project behind the hub (rake, shaft angle and so forth) and I'll be set. Goal is to place rudder shaft for appropriate spacing between prop blades and leading edge of rudder. Gerr suggests about .15 x rudder dia.
     
  8. gonzo
    Joined: Aug 2002
    Posts: 15,768
    Likes: 1,195, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    You need to first specify the propeller. They are many designs that will give you different clearances.
     

  9. JSL
    Joined: Nov 2012
    Posts: 811
    Likes: 62, Points: 28, Legacy Rep: 41
    Location: Delta BC

    JSL Senior Member

    15% prop dia. Or make sure you can pull the prop without having to remove the rudder
     
    Last edited: Jun 21, 2015
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.