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Thread: Float-plane Tie-Down Anchors and Lines?

  1. #1
    Member BluNosDav's Avatar
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    Question Float-plane Tie-Down Anchors and Lines?

    Looking for advice on the best type of aircraft tie-down anchors & lines to use for a C172 float-plane?

    The lake has a recessed docking area that is indented from the shoreline, rectangular in shape, approximately 25 ft long X 15 ft wide X 2 ft deep. So, the airplane will float in it's own little harbor, with nose pointed out toward the lake, and the wings & tail overhanging the grass on three sides. I plan to bury the tie-down anchors into this somewhat moist ground and run the lines up to the wings & tail rings, as opposed to tying onto the floats. Or is that a bad idea?

    AIH offers two different types in a few sizes of each:

    Dukbill - which uses a rod to drive the anchor into the ground attached to a steel cable that extends back up the surface.
    https://www.aih.com/storefrontCommer...umber=DUK10305
    https://www.aih.com/storefrontCommer...umber=DUK50012
    The cables sizes are either: 0.125" X 30" X 1100# rating, or 0.25" X 41" X 3000# rating

    Braber Rod - which looks like a big eye-bolt, with a wide propeller blade at the bottom, that is screwed down into the ground:
    https://www.aih.com/storefrontCommer...umber=PWA11073
    Sizes are: 3" diameter blades on either a 16" or 28" long shank, or 4.5" blades on a 36" long shank (no # ratings)

    Are there other types of ground anchors that I should look at?

    Also, which type & thickness of tie-down lines do y'all recommend: Double-braid or 3-Strand? / Half-Inch or Three-Eighths?

    Final Question: Does anyone use line "snubbers" or short bungees with their tie-down lines, in order to let the plane rock gently with the waves that roll across the water?
    https://www.westmarine.com/buy/west-...2?recordNum=14
    https://www.westmarine.com/buy/green...10?recordNum=8

    Thanx, Dave.
    "Luckily, enforcement reads these forums, and likely will peruse this one...Especially after a link of it is forwarded to them....." - AlaskaHippie.

  2. #2

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    When I built my place on Firelake in Buzzard Gulch, Alaska (aka Eagle River) I cut a 55 gallon steel drum in half and rigged rebar for attachment, and took them the Klondike Concrete, and asked that they be filled with their end of the day excess concrete (which is cheaper). After the lake was well frozen, we slid them to where I wanted for a winter (taxi through) tie-down. Attached floats to chain end. Maybe some modification of this, if using Duck-bills, I strongly suggest the biggest you can order. I suggest chain rather then cable whatever you do. I have bad experience with Duck-Bill type anchors.

  3. #3

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    Without knowing the ground/subsurface, it's hard to say what anchor is best. I would get the biggest of whatever you choose. The screw-in type likely won't work if the soil is gravelly, and I have bent the drive rod trying to put a duckbill into rocky soil. You may have to excavate. I've used half-inch rope forever, and it held in 75 mph gusts when other planes flipped. I don't think I used snubber bungees when I was on floats many years ago, since my dock had tires on the side - not a bad idea, but you could make something for less than the $100 ones in the link.

  4. #4
    Member Float Pilot's Avatar
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    I used to have a spot like that where my wings were over the ground. I just buried an old tire 2/3 into the ground ( standing up with a chuck of 2x4 running through the hole. ) so I had a nice rubber loop to run a line through. That way it would flex downward if it was hit by a snowplow in the winter.
    Float-CFI, Photo Guide, Fishing Guide, Remote Kayaking
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  5. #5
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    I've used Duckbill's at the cabin for 25 years...had great luck with them holding either a C-180 or the -12 in some pretty serious blows....landplanes only though.

    However, the ground there is perfect for that system: good gravel, layered with clay, then more good gravel, then more clay, etc. Duckbills wouldn't be my first choice for anything looking like marshy ground. If you do go with Duckbills, get extra drive rods, go with the biggest you can get, and (addressing the marshy ground), I'd suggest adding some additional cable and burying the anchor deeper than the standard cable allows.

    If possible, I'd go with the method posted by AGL4now.
    Back in AK

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