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Author Topic: Ballast tanks  (Read 1886 times)

6705russell

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Ballast tanks
« on: July 27, 2009, 11:43:18 AM »

Has anyone built ballast tanks in their larger models to get it down to the waterline?  Any info/ideas on materials used would be appreciated...

Thanks

Russ
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Subculture

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Re: Ballast tanks
« Reply #1 on: July 27, 2009, 12:09:48 PM »

Build your tank first. You can make this from whatever material you like,but plastic or GRP would be preferable, and I would choose the later as you can mould it to the shape of your hull which should enable you get the lowest centre of gravity.

Fit a schraeder (tyre) valve to the top of the tank, and ensure the tank is vented at the bottom and exposed to the water surface. A few small(ish) holes should be sufficient to allow flooding. To fill the tank, depress the valve, and the water should start to flood the tank.

To empty, just connect a small air pump (i.e. a bicycle pump) to the valve,and blow the water out the way it came.

if you don't want to drill holes in your hull, then you will need to use a water pump of some description.

A centrifugal pump will shift water at the highest volume, but you will need two, or a valve arrangement, as the these pumps are not bi-directional. A geared pump will pump either way, but they are a lot slower.

boatmadman

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Re: Ballast tanks
« Reply #2 on: July 27, 2009, 12:19:26 PM »

Russ

Have a look at the build log for Blue Marlin Semi Submersible ship - I used a combination of free flooding and pumped ballast tanks.

Ian

http://www.modelboatmayhem.co.uk/forum/index.php?topic=9014.msg87341#msg87341
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if at first you dont succeed.....have a beer.....

g6hfk

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Re: Ballast tanks
« Reply #3 on: September 07, 2009, 10:24:45 AM »

Russ,
 One of our club members pumps watewr in and out of his Chant, people think its sinking.
 I can email his name he will tell you how he did it.
 I was thinking of plastic water bottles with pumps for in and out working from tranny
   Les PMBC
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6705russell

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Re: Ballast tanks
« Reply #4 on: September 07, 2009, 10:53:31 AM »

Thanks Les,

Sorted now using home-made acrylic tanks and pumps  :-))

Russ
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