Do I need it

Discussion in 'Boatbuilding' started by Iron Lady, Dec 20, 2006.

  1. Iron Lady
    Joined: Dec 2006
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    Iron Lady Junior Member

    Hello
    Thanks everybody for reading this thread.
    I have a 10.5m ( 34 ' ) steel cruiser, Built in mid 80's, Plans came with boat when we purchased 3 yrs ago are from BUILD - A - BOAT PLANS Co. There is an addition to the keel that looks like a whale tale just forward and below the prop ( not shown in plans ). Can anybody tell me what this is and purpose if any:?: I would like to cut it off as this will reduce the boats draft by approx 300mm ( 1' ) but worried it may affect stability. I will try and attach some photos.
    Can anyone tell me the hull type, I am not sure if its a medium or semi displacement. The plans say displacement is 6.92 Tonne but our mate on the travel lift says 8 Tonne ( new lift ). The extra mass is problably from thicker side and deck plating than nominated on plans, plus a 200 HP cummins and all the wifes luxuries of life ( junk ). She cruises at 7 - 8 Knts and flat out at 9 - 10, uses 10 - 15 L per hour at cruise and thursty when flat out
    Thanks for any help on the above. If anyone needs more info please let me Know
    Regards Richard
     
  2. Iron Lady
    Joined: Dec 2006
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    Iron Lady Junior Member

    Having trouble attaching pictures, will get some help as soon as possible
    Merry xmas and happy new year to everyone
    Regards Richard
     

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  3. Iron Lady
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    Iron Lady Junior Member

    I am over the limit and cant attach any more pictures:confused:
    If anyone is interested I can email them to you
    Thanks Richard
     
    Last edited: Dec 20, 2006
  4. SouthernCross
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    SouthernCross Junior Member

  5. marshmat
    Joined: Apr 2005
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    marshmat Senior Member

    I've never seen anyone attach pictures in zip format before....
    If you have JPEGs or other common formats, uploading's pretty easy (just make sure to actually click upload in the attachment window after you're done browsing.... a list of attachments will appear below the reply box).

    I believe the purpose of the skeg-fin thing in the photo is mainly to protect the prop. If the boat is grounded, or if it's hauled out and set down on blocks, or if it's allowed to dry out at low tide, that skeg ensures the propeller stays well clear of anything that could be dangerous to it. A hull like that can take a surprising beating, but if the prop is dented or broken it will vibrate so much that you'd be unable to move under power. It's deep and beefy like that so you're assured of hitting it- and thus stopping the boat, allowing you to safely back out- if you get into sufficiently shallow rocks as to put the prop at risk.
     
  6. Iron Lady
    Joined: Dec 2006
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    Iron Lady Junior Member

    Thanks for the comments Marshmat, I agree that the skeg is for prop protection. A few have said it is for stability but I don't know enough to disagree.
    On Lake Macquarie the bottom is mainly sand, I have run aground a few times and got the skeg caught but was able to back off without damage.
    The real fear for me is crossing the Swansea bar ( entrance to lake ) because it has a coal seam at 2m deep, The boat has a 1.5m draft, The bar is protected from SE swells most of year, but if swell was big enough the skeg could hit and possibly dig into the seam.
    If I cut the existing skeg off and built a skeg to run under the prop the draft could be reduced by approx 300mm
    The skeg being flat would slide over opposed to digging in.
    I should get advice from a Navel Artchatect or Shipwright before doing anything.
    I'm still working on the picture attatchements but don't worry I will get there one day.
    Thanks for any input
    Regards Richard
     
  7. Tim B
    Joined: Jan 2003
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    Tim B Senior Member

    It's an interesting looking bit of work isn't it?

    I think Marshmat's right, it's most likely for protecting the prop. I don't think it's there for any stability purpose. There's nothing to stop you re-designing a prop-guard, but the prop looks to be a long way back, so that may cause some problems.

    Tim B.
     
  8. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Cut it off. I'd recommend a stout skeg to protect the prop and rudder, but that thing looks stiff enough, to hold the boat up when on the hard, possibly left over from use as a construction brace. You may get a slight decrease in fuel usage and possibly a slight speed increase too, with that "kick stand" torched away. Fair things in nice and smooth and keep her off the hard bars of coal.
     
  9. Iron Lady
    Joined: Dec 2006
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    Iron Lady Junior Member

    Thanks everyone for their input.
    Not real sure what a stout skeg is but I will do some research.
    Think I might talk to some local people before deciding on action.
    Sounds like it might be worth the effort.
    I'll keep everyone posted.
    Regards Richard
     
  10. Popeye
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    Popeye Junior Member

  11. hansp77
    Joined: Mar 2006
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    hansp77

    wow that does look strange, sort of alien...

    just thought I would attatch the photo for you so we can all see.
     

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  12. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    I'm reasonably sure that is a support leg, left over from construction. It should have been torched away and faired, but got left in place with the excitement of the launch, I'll bet.

    Iron Lady, a skeg is an appendage that offers protection to the running gear (shaft, prop, strut, bearings, rudder, etc.). It's found in many different forms, but many just by looking at it, you can see how it would protect the running gear from groundings, object strikes, etc. Look around the marina and you'll see them hanging below the butts of many boats (not all, by a long shot). You can install one or brave the untamed soul of the sea and wish for the best without one. Replacing running gear can be costly, so it's a good investment, though you may never need it. The moment you do need it, you be very glad you put one on.
     
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