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Small, yet perfectly formed...
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3,299 Posts
Discussion Starter · #1 ·
Soo all you smart alecs out there.


How would you calculate the change in bouyancy you would expect between tywin 7 232s and single 12 232?

I have about 6kg in my shot belt for sea diving and this is going to be fresh water.

Any idea how i would go about estimating if my weight is going to be ok???

jUles
 

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16,363 Posts
No weight change for me. There's about the same amount of steel etc. I reckon.

I'd go with the 6kg just to make it possibly slightly on the heavy side, but not much.

HTH.

Digs.
 

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No longer open water diver
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1,319 Posts
hi jules,

in my experience i need to add an extra 3kg lead when i go from 2x7 232s to a 12. 7kg with twin 7s, 10kg with a 12. This is in sea, i have no idea what the weighting would be in fresh.

hth, al :)
 

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never odd or even
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286 Posts
Faber Steel Cylinder Measurements

Capacity (Litres) Diameter (mm) Height (mm) Weight (Kg)
3 100 580 4
7 140 685 8
10 177 635 11.2
12 (std) 177 750 13.6
12 (dumpy) 203 622 13.7
15 203 724 16.9

Hope this helps
 

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Small, yet perfectly formed...
Joined
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3,299 Posts
Discussion Starter · #6 ·
Faber Steel Cylinder Measurements

Capacity (Litres) Diameter (mm) Height (mm) Weight (Kg)
3 100 580 4
7 140 685 8
10 177 635 11.2
12 (std) 177 750 13.6
12 (dumpy) 203 622 13.7
15 203 724 16.9

Hope this helps
Well it would if I knew what forumla to apply to them! :)
Someone must know what forumla you would apply or do people really just test it empirically?
 

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Exiled in Scotland...
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6,286 Posts
Well it would if I knew what forumla to apply to them! :)
Someone must know what forumla you would apply or do people really just test it empirically?
Jules what he's saying is that at present you have 2*7ltrs which is 2*8kg = 16kg. Your hoping to dive with 1*12ltr, which is 13.6kg, which is 2.4kg lighter, hence you might need ~2 - 3kg more in your shot belt. The manifold might add a little but it might be negligable.

Hope this helps.

Faber Steel Cylinder Measurements

Capacity Diameter Height Weight
(Litres) ----(mm) ----(mm) --(Kg)
---3 -------- 100 ----- 580 --- 4
---7 -------- 140 ----- 685 --- 8
--10 -------- 177 ----- 635 --- 11.2
--12 (std) --177 ----- 750 --- 13.6
--12 (dmpy) 203 ---- 622 --- 13.7
--15 -------- 203 ----- 724 --- 16.9
As for Fresh water, I don't dive anything different, but then I'm happy being a little more heavy in fresh.
 

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Small, yet perfectly formed...
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3,299 Posts
Discussion Starter · #8 ·
yes i realised that but isnt displacement (ie external volume) also a factor? Archimedes n'all that...

jules
 

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Exiled in Scotland...
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6,286 Posts
About 4kg in the same water between twin 7 (and backplate) and single 12 for me. So take off 2kg for fresh and you have a 6kg difference.
Don't forget Jules displaces a LITTLE less water than you.
 
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