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Launch with a low prop shaft

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Launch with a low prop shaft

Home › Forums › Steam powered models › Launch with a low prop shaft

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  • 17 April 2016 at 13:35 #64669
    Martin Field 1
    Participant
      @martinfield1

      I have a hull which I am making into a steam launch, but the prop shaft will, I'm sure, end up below waterline level. I've not had that before and wonder how you all seal a shaft where that's the case. Is a tube full of grease enough?

      Martin

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      17 April 2016 at 13:35 #7341
      Martin Field 1
      Participant
        @martinfield1
        17 April 2016 at 16:08 #64675
        Kev.W
        Participant
          @kev-w

          Silicon washer at the prop end, the thrust from the prop going forward will help stem water ingress, I also put a helical groove on the shaft, that helps push any water back out of the tube.

          It works for me, but I still get a small amount of water into the boat, so try to incorporate a bulkhead to limit the forward progress of any that gets in & keep your electrics forward of the bulkhead if possible.

          17 April 2016 at 16:12 #64677
          Martin Field 1
          Participant
            @martinfield1

            Thanks, Kip. A helical groove? How the Hellical do you cut one of those? My wee lathe doesn't have screwcutting on board.

            Perhaps some absorbant material in the bilges may help, but I take your warning and will keep the electrics well tucked away.

            Cheers,

            Martin

            17 April 2016 at 16:22 #64680
            Dodgy Geezer 1
            Participant
              @dodgygeezer1

              Another trick is a thin-walled silicone tube – ID slightly less than the prop-shaft. Push it on over the prop-tube at the motor end, and let 1/8" or so overhang the prop-tube onto the shaft, so that it makes a seal. See below:

              img_5007.jpg

              17 April 2016 at 16:24 #64681
              Kev.W
              Participant
                @kev-w

                I cut my helical groove with nothing more than a junior hacksaw ( where needs must, man finds a way ) wink

                It took a bit of time and a steady hand, but it worked.

                17 April 2016 at 16:26 #64682
                Kev.W
                Participant
                  @kev-w

                  Thanks DG, will note that one down to try, will save a lot of time & effort if it succeeds. smiley

                  17 April 2016 at 16:32 #64683
                  Colin Bishop
                  Moderator
                    @colinbishop34627

                    Getting a little bit of water in under those circumstances is pretty normal but it will only be a small quantity and, as Kip says, you can build in a small dam inside the hull to stop it spreading.

                    Colin

                    17 April 2016 at 17:40 #64687
                    Martin Field 1
                    Participant
                      @martinfield1

                      Gentlemen, once again, thanks. A hacksaw eh? A man of my own kind there!

                      Just modified the old wood in the hull to accept a nice waterproofable area for any drips, but I like the silicon tube idea as well and will see if I can find any. But on this model the shaft is "nutted" close up to the tube.

                      Martin

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