weight/bouyancy changes from 15 liter to 12.2 liter cylinder

[kawaboy]

Hello all

I'm downsizing my 15lt steel cyl to a 12.2lt steel.
My question is:

Everything being equal, what changes will I have to make to my weighting when I change?

Here are the numbers from the Faber website:

12.2lt
MT weight 13kgs
Buoyancy in SW MT 1.27kgs
Buoyancy full -2.01kgs
Real weight 14.27kgs

15lt
MT weight 16.5kgs
Buoyancy in SW MT 1.1kgs
Buoyancy full -2.92kgs
Real weight 17.6kgs

As far as I can figure, the difference between the swings is about .72 kg.
I got this by taking the difference between sums of the MT and full buoyancy figures, thus:

(1.1 + 2.92) - (1.27 + 2.01) = .72

Is my logic correct in saying that effectively underwater there will be .72kgs between the two, therefore, I will save lugging around about 3kgs of steel on the surface?

I hope I did the maths right...

Thanks for your info/comments.

Cheers

Joe

 

[H2Andy]

i think the key is going to be buoyancy when empty

in this case, at the end of the dive you will be .17 kgs lighter ... so ... you MAY need .17 kgs of added weight to retain your current buoyancy at the end of the dive

that's less than half a pound, so you probably won't even notice it

 

[kawaboy]

Thanks Andy. That's good news that I'm sure my back will appreciate.

Next thing is to do the same with an al80 that I might be able to get from a mate of mine.

Cheers

Joe