stuffing box for pedal drive

Discussion in 'Boat Design' started by tom melon, Aug 25, 2022.

  1. tom melon
    Joined: Aug 2022
    Posts: 8
    Likes: 1, Points: 3
    Location: UK

    tom melon Junior Member

    I have been looking over different designs for pedal boats, i was wondering how much drag or problems stuffing boxes create. should i expect a lot of drag if it is well set up?

    is there commercial stuffing boxes for small shafts, say 10-20mm?
    is it easy to DIY your own?
    can you get away with no drip seeing as pedal drive wont do over say 100rpm?
    what are peoples experiences with this?
     
  2. gonzo
    Joined: Aug 2002
    Posts: 16,230
    Likes: 1,365, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

  3. fredrosse
    Joined: Jan 2005
    Posts: 436
    Likes: 80, Points: 38, Legacy Rep: 56
    Location: Philadelphia PA

    fredrosse USACE Steam

    I have used common tubing compression fittings, with an O-ring inserted instead of the metal furrel to seal the shafts of a few large model boats. For example, if you have a 3/8 inch diameter shaft, buy a 3/8 inch outside diameter tube compression fitting, typically pipe threads on the other end of the fitting. Drill through the fitting a 3/8 inch bore for the shaft to pass through. Use an O-ring with 3/8 inside diameter, and approximately 1/2 outside diameter. Lubricate the O-ring with grease or Vaseline, and tighten the compression nut to retain the O-ring. There you have a stuffing box that will reasonably seal water out. A simple clamp will keep the compression nut from rotating off it's threads. Compression tube fittings are available in all USA sizes, 1/8, 3/16/, 1/4, 5/16, 3/8, 1/2, and 5/8 inch sizes are common.

    I have done virtually the same thing, on a larger boat using a Home Depot plastic drainage pipe compression fitting for a sink drain. This is for a one inch diameter shaft, and I installed it on a 14 foot electric boat swinging a 14 inch diameter x 17 inch pitch 3 blade propeller. I replaced the plastic ring that forms a static seal on the plumbing tube with greased yarn, and tightened the plastic compression nut on this packing. That packing has been in place since 2004, and since I converted this boat to steam power last year, it has just started to leak.
     
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