Need ideas with trout research mini-boat design

Discussion in 'Boatbuilding' started by tjxtreme, Nov 28, 2007.

  1. tjxtreme
    Joined: Nov 2007
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    Location: Cape Cod, MA

    tjxtreme Junior Member

    Hi All,

    I am conducting a trout research project that requires weekley canges of 4 marine batteries that power an antenna. The easiest way to get to the site is by wading. I am looking to build a boat that can float the batteries, and one that rides low in the water so that it will pass under the antenna.

    Info:
    Batteries: 4 x 55lbs. LxWxH=12.75x6.75x9.5
    Antenna height above water= 6 inches

    Even a box-shaped boat would work (assuming calculations are easier that way), but I don't know how to calculate for weight and displacement.

    Thanks!

    Andrew
     
  2. Kay9
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    Kay9 1600T Master

    Might seem simple, but how about an innertube with a pice of plywood in the middle?
     
  3. tjxtreme
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    tjxtreme Junior Member

    perhaps... but I think that would ride too high in the water, despite the 220lbs of batteries).

    Ideally, I could figure out a design that would allow the batteries to ride as low as possible without taking on water.

    Thanks anyway!
     
  4. Kay9
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    Kay9 1600T Master

    Well you state your max height is 6 inches and your max load is 220 Lbs.

    The hieght of your Batts is 9.5 inches. So nothing you build isgoing to go under your antenna. I think the best you can hope for is next to your antenna, and then some muscle power.
     
  5. tjxtreme
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    tjxtreme Junior Member

    I was thinking of something that will displace water, and therefore allow the batteries to ride at least partly below the surface.
     
  6. grizzlyone
    Joined: Nov 2007
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    Location: Vancouver Island

    grizzlyone New Member

    Here's a start...

    Water weighs 62.4 lbs/ cu ft.

    Four batteries and your hull will probably displace in the order of 4 cu ft. +/- 7000 cu inches.

    You will want the cg low so make it draw 8"

    7000 cu inches/8" draft= 875 sq inches total projected area.

    60" LOA... 875/60=14.5" beam

    5 " freeboard max...total side height 13"
     
  7. DGreenwood
    Joined: Aug 2004
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    Location: New York

    DGreenwood Senior Member

    tjxtreme
    Your requirements are not difficult. Grizzlyone is on the right track.
    There is a little more info required to achieve a workable minibarge for your batteries. Are they lead acid batteries. If so they require ventilation so a snorkel tube would be a good thing as a water tight lid would also be helpful for a vessel that rides that low in the water. With a little plywood and epoxy you could make this thing pretty quick.
    I would run the power source through a cordgrip or water tight gland so that it is 100% water tight. Buy batteries with threaded lugs for quick change and I think you will be all set. Also, I am assuming you will drag this thing to shore to change the Batteries?
     
  8. tjxtreme
    Joined: Nov 2007
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    Location: Cape Cod, MA

    tjxtreme Junior Member

    thanks for the help...

    So, here is what it would look like?

    (and please trust me that my construction skills will be better than my computer sketch...)

    60"x14.5"x13" LWH

    PS the boat will only be used to transport batteries, the data loggers are on land. Getting to the site by water is the easiest way.
     

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  9. DGreenwood
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    DGreenwood Senior Member

    I might give it something of a bow so that it drags through the water nicer. Like a barge...leave the end square in plan view,but sloping in side view from top to bottom. This will not increase the free board much but will insure an increase in buoyancy if you go through some rough water. It will also be easier to drag in the water and on land. The only other thing I can think of is maybe some UHMWP strips on the bottom to make it easy to drag around on rock or beach and will keep bottom from getting damaged and losing integrity. The point of a rock would play hell with a 240 lb plywood box.

    Edit: I just realized that you only transport the batteries with this boat. I was thinking the batteries lived in the box during operation. So ventilation and a power feed are not necessary. Is it fairly slow moving water you transport across?

    Good luck with your project.
     
  10. Fanie
    Joined: Oct 2007
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    Location: Colonial "Sick Africa"

    Fanie Fanie

    Why don't you sit the batteries on land with a cable to your electronics , or make a simple structure ie stainless steel where the batteries sit on ?
     
  11. tjxtreme
    Joined: Nov 2007
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    Location: Cape Cod, MA

    tjxtreme Junior Member

    thanks for your help again. after making a scale drawing, the boat seems like it would be tippy.

    Using the same 875 in^2, can I divide that by 33 to allow for the batteries to be stacked in a square rather than in a line?

    New dimensions would then be about 33 x 26 x 13 LWH, if I am not misusing a formula...

    THANKS
     

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  12. grizzlyone
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    Location: Vancouver Island

    grizzlyone New Member


  13. tjxtreme
    Joined: Nov 2007
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    Location: Cape Cod, MA

    tjxtreme Junior Member

    not a bad idea... cheap and guaranteed leakproof
     
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