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Re: [bolger] Re: Long Micro launched!

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  • John Gilbert
    What at this wonderful math fails to take into account is what happens, if you hit a rock at speed. The solid lead casting will absorb the impact, along with a
    Message 1 of 23 , Nov 21, 2007
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      What at this wonderful math fails to take into account is what happens, if you hit a rock at speed. The solid lead casting will absorb the impact, along with a brief radical change of trim. Whatever filler you use to bind your bits of lead together, (cement, epoxy, congealed snot), will not serve as well. Concrete will transmit the impact pretty much directly to the hull, epoxy perhaps(I think) a little less. In a life time on the water I have hit a rock at speed twice, once with a lead keel and the other with cement/iron blend. The lead was better in every measurable respect. It did pean over a little but a thump was way easier on the hull and crew than a jarring THUMPP with the cement.
      I'd personally go for the casting. The savings in cost and or perceived trouble are negligable when you invest a year or three of spare time and some thousands of dollars in a boat of your own creation.
      Good luck.

      ----- Original Message ----
      From: Kathy Kreamer <kreamers@...>
      To: bolger@yahoogroups.com
      Sent: Wednesday, November 21, 2007 2:00:38 PM
      Subject: RE: [bolger] Re: Long Micro launched!

      I gleaned the following from the internet. Your mileage may vary.

      If you take a bunch of spheres, say marbles in a jar, they will randomly
      pack in what is called Random Close Packing (RCP). This has been shown to be
      about 64 percent of volume fraction.

      If you shake the jar hard enough to allow for migration and re-arrangement
      of marbles, you might get to the maximum of 74 percent that is called
      Hexagonal Close Packing (HCP).


      Spherical particles of equal size theoretically may be packed in five
      different ways, e.g. (1) cubical with a theoretical void space of 47.64%,
      (2) single-staggered or cubical-tetrahedral with a theoretical void space of
      39.55%, (3) double-staggered with a theoretical void space of 30.20%, (4)
      pyramidal, and (5) tetrahedral; the void spaces in the latter two are
      identical, 25.95%.

      Secondary, ternary, quaternary, and quinary spheres each set smaller than
      its predecessor, may be fitted into the voids in this last type of packing
      and the voids reduced theoretically to 14.9%.

      The use of very fine filler in the remaining voids will then reduce the
      voids theoretically to 3.9%.

      - Bill


      From: bolger@yahoogroups. com [mailto:bolger@yahoogroups. com] On Behalf Of
      Sent: Wednesday, November 21, 2007 10:21 AM
      To: bolger@yahoogroups. com
      Subject: Re: [bolger] Re: Long Micro launched!

      In a message dated 11/20/2007 9:47:53 PM Central Standard Time,
      kingw@bgnet. <mailto:kingw% 40bgnet.bgsu. edu> bgsu.edu writes:

      But anyway, what I remember was
      that using shot and epoxy made for a much lighter keel.

      If you use lead shot...all of the same size beads/balls. ...you'll get a keel

      about 70 percent the weight of a solid lead one...so, make the keel a few
      inches deeper and it should even out...but do the calcs yourself and a test
      batch to confirm the numbers....also i'd suspect lead shot would cost ALOT
      than bulk or scrap lead....but I dont know that for a fact....

      Has anyone suggested this route?

      Make a mold for the keel....the mold is flat on its side....with the upper
      face/side of the mold non existent.... or in other words the mold is like a
      gaint shallow pan...

      Now, just melt your lead a small pot at time....pour into mold....do it at
      your leisure...over days/weeks/months if necessary..

      You'll basically end up with keel made up of many thin sheets of
      lead.....and if you clean and or gouge/roughen up the surface between pours,
      those thin
      "sheets of lead should be VERY well bonded....or stand up a bunch of nairs
      thier heads before the first pour....that should also bond the sheets
      together very well..

      Just an idea of avoiding the scary prospect of melting/handling/ pouring
      massive quantities of molten lead all at once....

      Also, be careful about ventilation, fumes, safety glasses, gloves, boots etc



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