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Thread: Research on anchor chain and rope

  1. #16

    Re: Research on anchor chain and rope

    It is actually quite surprising just how much weight can be dragged across the bottom. I work for a tug company. On the project we are on currently the anchors in use for the moorings are either 3 or 5 tonne units. If these foul in the chain during deployment and a tug is moored to them (admittedly a 400 tonne tug) they will quite happily move across the bottom in as little as a metre of swell.

  2. #17

    Re: Research on anchor chain and rope

    Neale,
    join the club. It's not a precise science, depth, wind tide direction make it tough. Takes a while for the thing to get to the bottom and then dig in.
    When it digs in your swing round distance varies with the amount of rope out.
    All you (I) can hope for is that by go #10 you (I) are a bit better than on go #1. By then eyeballing how far upwind/tide to chuck it out should be a bit better.
    Might have to chuck two out if you want to hold a spot without the swing.
    I've left a couple behind on the bottom.
    Soon learnt that one of the so called guru's espoused method pulling the anchor up from the back of the boat was a good way to sink the boat motor first.
    Now only pull from the front and cut the rope if nothing gives. Usually a prong straightens out and up it comes. Go for the thinnest prongs that will hold the boat.

  3. #18
    Ausfish Platinum Member bigjimg's Avatar
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    Nov 2006
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    Moorooka, Brisbane.

    Re: Research on anchor chain and rope

    I use a simple rule. My chain is 8mm @ 7m long and warp is 12mm attached to a Lewmar 6Kg plough. I have 10m increments marked on the warp with spay ink. If for instance I am in 15m of water I will move off the mark a known distance, in this case .025 of a Nm or 46 meters.
    So 15m squared =225 and 46 meters squared = 2116. 225 + 2116 = 2341. Square root of 2341 = 48.383 meters of rope +/- depending on conditions. Using these sums and with my setup I have never dragged anchor. Once you get to know rate of drift you should be able to set your anchor positively by backing it in. Jim.
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  4. #19

    Re: Research on anchor chain and rope

    just on all things anchored, does any one use this hole for what it was intended?
    Sand%20Anchor.jpg

  5. #20

    Re: Research on anchor chain and rope

    That's there so you set the anchor up to trip in snaggy areas. The chain is shackled to that hole and then layed along the anchor and either cable tied as previously mentioned or attached with cord or wire that will break if required so the anchor will come out backwards.

  6. #21

    Re: Research on anchor chain and rope

    thanks all. before i buy a new anchor, i will try lengthening the chain with a smaller diametre as Dignity mentioned and shorten the prongs to 20cms and give that a shot.

  7. #22

    Re: Research on anchor chain and rope

    Very good scott. I knew what it was for but wondered how many others knew. Getting the right length of chain between the 1st and 2nd holes in the secrete. I made one up with to much chain between the holes and if landed the wrong way would not open the flukes because the chain got in the way...I use a stainless key ring instead of cable ties.

  8. #23

    Re: Research on anchor chain and rope

    Quote Originally Posted by nealeboy View Post
    thanks all. before i buy a new anchor, i will try lengthening the chain with a smaller diametre as Dignity mentioned and shorten the prongs to 20cms and give that a shot.
    What you are trying to achieve with the chain is enough weight/length so that there is always a belly in it. Having enough rope in the water helps but if you have enough length of heavy chain you can generally keep ropes fairly short. If the chain is pulling perfectly straight in any sort of wave action or current the snatching or jerking action of the boat against the anchor will pull it out of the bottom or prevent it getting a hold. You can use a surprisingly small anchor if you have sufficent chain to achieve this.

  9. #24

    Re: Research on anchor chain and rope

    Had the same problem and easy fix. I don't like the idea of long chain as it can easily get caught on, in, or around reef and bye bye anchor or worse tip your boat when trying to retrieve. 2 mtrs is plenty. What you need is a heavy as anchor, i got a welder to make me some using solid rod about 3 foot long with reo prongs. Also 12mm rope is to much, i use 8mm on a 6.2m platey. Rope floats so the thicker the rope the more it will float which isn't what u want when your trying to keep your anchor down.

  10. #25

    Re: Research on anchor chain and rope

    Quote Originally Posted by bigjimg View Post
    I use a simple rule. My chain is 8mm @ 7m long and warp is 12mm attached to a Lewmar 6Kg plough. I have 10m increments marked on the warp with spay ink. If for instance I am in 15m of water I will move off the mark a known distance, in this case .025 of a Nm or 46 meters.
    So 15m squared =225 and 46 meters squared = 2116. 225 + 2116 = 2341. Square root of 2341 = 48.383 meters of rope +/- depending on conditions. Using these sums and with my setup I have never dragged anchor. Once you get to know rate of drift you should be able to set your anchor positively by backing it in. Jim.
    I guess I had better start eating my cornflakes again so that I can get my Kelloggs degree in maths.

  11. #26

    Re: Research on anchor chain and rope

    Quote Originally Posted by Dignity View Post
    I guess I had better start eating my cornflakes again so that I can get my Kelloggs degree in maths.
    Oh come on Dignity - The square of the hypotenouse of a right angle triangle is equal to the sum of the square of the other two sides. On second thoughts - My calculator's sh*t itself - just drop the heavy bit and let out some rope. LOL

  12. #27

    Re: Research on anchor chain and rope

    I knew it was too simple, the first part I couldn't get as I had no idea what hippo's had to do with anchoring but the second part is what I do, I usually find a mark, let the boat drift a little to work out which way the wind and tide might be pushing me, head back over the mark and whatever the depth is I go twice the distance and drop the pick with 3 times the depth of water (more in rougher conditions). Works most times and is simple enough for me to work out, my line has coloured twine spliced at 20 m intervals so I can tell at a glance what amount of rope is out there.

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