Anchor buddy/chum/angel/sentinel/kellet

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  • 14 Feb 2018 16:55
    Reply # 5736899 on 5730417

    Bonjour

    For the scientists there is a Excel model of the dynamic dehavior (with wind, blows  and waves) of a mooring.

    I'm sorry it's both in French and in metrics!!!

    Be carrefull, the compressed file is 14 Mo !

    For the others there are nice pictures on the blog, but from a pointy.

    http://artimon1.free.fr/docstechniques.htm

    Eric

  • 14 Feb 2018 15:17
    Reply # 5736704 on 5730971
    Annie Hill wrote:
    I must confess, though, that I do like a decent length of chain, myself.

    http://www.petersmith.net.nz/boat-anchors/catenary.php

    - to summarise, there isn't much benefit in having more than half the scope as chain, in a rode consisting of chain + rope, and actually, the more the weight of the rode can be concentrated near the anchor, the better. I have 10 metres of 6mm chain, and I would actually be better off, as far as holding power is concerned, with 5 metres of 10mm chain, or even 2.5 metres of 12mm chain. 

    Of course, holding power is not the only consideration, especially with an oversize 'new generation' anchor. Sailing around the anchor is reduced with a longer chain, but a chum can add this function, when necessary.

  • 14 Feb 2018 15:03
    Reply # 5736691 on 5730417

    A good article on when this device is, and isn't, useful.

    Basically, in extremis, it will do very little to increase holding power, and the better solution is to take the weight of the device and incorporate that weight into the anchor. Or, the biggest 'new generation' anchor that you and the boat can manage is the best way to maximise holding power.

    But:

    "Other applications:

    This is not to say that kellets are entirely pointless; they serve other purposes.

    They can contain and minimize swing radii in light conditions

    They can help dampen “sailing” at anchor

    They can keep a boat stationary when using bow and stern anchors

    They can help ensure that rode is kept down and away from the boat’s keel, rudder, and propeller."

    - and the last mentioned is the particular need that I have.


  • 13 Feb 2018 17:24
    Reply # 5734944 on 5730417

    The kettlebell was delivered today, and as I thought, it's going to be perfect as a chum/buddy/sentinel/kellet (how did so many names arise?). The handle is smooth and easy to grip to lift over the stemhead, as I'd expect for an item that is intended to be swung around (its origin as a cannonball with added handle is very apparent). It's well painted, so rust will not be an issue. The neoprene casing is thick, solid and tough, and will stand being thrown into the chain locker. I think probably the best thing to attach it to the rode is a http://www.gsproducts.co.uk/stainless-steel-winch-hook/ , lashed on.

  • 12 Feb 2018 17:40
    Reply # 5733377 on 5730417

    Another possibility is old sash window balance weights. These are cast iron and have a loop cast in at one end. They come in several weight sizes between about 4 and 8 kg and would be ideal for the job once coated with epoxy and then the neoprene rubber that is sold for coating tool handles. They can be picked up for very little money from most scrap yards.

    I cast the 5,000 kg keel for Arcadian and Arne is right about the moisture, we had quite an impressive boil from some hidden moisture that had got into the mould before we poured the lead. Also be aware that the fumes from molten lead are highly toxic so a suitable gas mask should be worn when working anywhere near the melting pot.

    David.

    Last modified: 12 Feb 2018 17:53 | Anonymous member
  • 12 Feb 2018 15:52
    Reply # 5733195 on 5730417
    Anonymous member (Administrator)

    Like  Phil, I regard casting lead to be an out-door job. Using old cotton clothes, is a good idea. What is super-important is that the lead bits that one drops into the kettle or can, are totally dry. If bits of wet lead is dropped into the 'soup', some impressive explosions will occur because of the expanding steam. The result is molten lead flying all over the place. I once participated in casting a 2500kg lead keel, so have first hand experience with it. The drops of lead are not hot enough to make cloths catch fire, but we anyway don't want the stuff to fly around.

    Arne

    Last modified: 12 Feb 2018 15:53 | Anonymous member (Administrator)
  • 12 Feb 2018 14:31
    Reply # 5733027 on 5732866
    David Tyler wrote:
    Arne Kverneland wrote:

    Cast your own chum


    It doesn’t take rocket science to cast a lead anchor chum. From an auto tyre workshop one is likely to get used balancing weights for free, or very cheaply.

    Then, all it takes is a gas or primus stove, a tin can of suitable size, and a ring bolt (dipping a stub of anchor chain doesn’t work as it floats in the molten lead). One could even cast the chum into a flattish shape (in a dry sand or cement pit), to give added hydrodynamic damping if the boat is pitching.

    Arne

     


    No, but it does take some attention to Elf and Safety considerations. Wear leather gauntlets, eye protection and natural fibre clothing, and keep the kitchen door open (for ventilation and to provide an escape route). Use a stainless steel saucepan, of the pot-bellied type (so that the lead will remain inside once solidified). Melt the lead and then leave it to solidify on the stove. Do not attempt to carry a pan full of 8kg of molten lead.

    Only worth doing if you already have 8kg of lead. Otherwise, just spend a few £ or $ on a kettlebell.

    The feedback I got from sailors on Facebook who have needed a chum is to look for second hand diving weights, and when you have enough, thread them onto a length of webbing.


     I used a discarded copper bottomed stainless steel tea kettle with the small spout lid removed and electric hot plate along with used wheel weights for a small job. I don't know if doing this way has any unforeseen greater risk but carrying and pouring should be less hazardous than with an open pot. It's an outside or highly ventilated area job. I worked to avoid the fumes, like a plague.  I'd want to coat the chum well with something (epoxy?) before handling and using it bare handed.
    Last modified: 12 Feb 2018 14:37 | Anonymous member
  • 12 Feb 2018 12:05
    Reply # 5732866 on 5732764
    Arne Kverneland wrote:

    Cast your own chum


    It doesn’t take rocket science to cast a lead anchor chum. From an auto tyre workshop one is likely to get used balancing weights for free, or very cheaply.

    Then, all it takes is a gas or primus stove, a tin can of suitable size, and a ring bolt (dipping a stub of anchor chain doesn’t work as it floats in the molten lead). One could even cast the chum into a flattish shape (in a dry sand or cement pit), to give added hydrodynamic damping if the boat is pitching.

    Arne

     


    No, but it does take some attention to Elf and Safety considerations. Wear leather gauntlets, eye protection and natural fibre clothing, and keep the kitchen door open (for ventilation and to provide an escape route). Use a stainless steel saucepan, of the pot-bellied type (so that the lead will remain inside once solidified). Melt the lead and then leave it to solidify on the stove. Do not attempt to carry a pan full of 8kg of molten lead.

    Only worth doing if you already have 8kg of lead. Otherwise, just spend a few £ or $ on a kettlebell.

    The feedback I got from sailors on Facebook who have needed a chum is to look for second hand diving weights, and when you have enough, thread them onto a length of webbing.

    Last modified: 12 Feb 2018 13:27 | Anonymous member
  • 12 Feb 2018 10:29
    Reply # 5732764 on 5730417
    Anonymous member (Administrator)

    Cast your own chum


    It doesn’t take rocket science to cast a lead anchor chum. From an auto tyre workshop one is likely to get used balancing weights for free, or very cheaply.

    Then, all it takes is a gas or primus stove, a tin can of suitable size, and a ring bolt (dipping a stub of anchor chain doesn’t work as it floats in the molten lead). One could even cast the chum into a flattish shape (in a dry sand or cement pit), to give added hydrodynamic damping if the boat is pitching.

    Arne

     


    Last modified: 12 Feb 2018 10:30 | Anonymous member (Administrator)
  • 11 Feb 2018 10:41
    Reply # 5731504 on 5730417

    Bonjour

    An other way would be to use a weigted rope BUT to turn the weighted end to the deck.

    Eric

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