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Silent Knight
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It's my first forays with a twinset (twin 12 Beaver steels, 5mm steel backplate) this weekend and I'm wondering what weight I should begin with. Of course I will be conducting relevant weight and trim checks over the course of my first dives and obviously continuing until I am happy but I'd just like a pointer of where to start really.

So, if you're fairly similar to the following weight stats or even fancy a thoughtful guess at roughly where I should be I would be grateful.

Stats: (all based on a single 12 litre cylinder /BCD)

I am 5'9 and weigh 13.5 stone
In a 5mm wetsuit in salt I need 6 kilos
In a O3 2.5mm compressed neo drysuit and arctics I need 10 kilos in fresh
In a O3 2.5 compressed neo, one layer of O3 PBB's in I need 9 kilos in salt

I will be diving in a muddy puddle, so freshwater and my buddy can take extra weight for me (although I'm trying not to overload her as she is the wife too after all and wont hear the end of it!) I would normally take 10 kilos on a single 12 /bcd combo for this dive. What guess you on twins?

Cheers lads and ladesses :D

Graham


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Try somewhere between 2-4 kg depending on what other bits and pieces you have and whether you have a full or empty twinset.

That is on a rough comparison to your single set up and mine and my weight compared to yours.
 

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Finless: You couldn't invent him...
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Try somewhere between 2-4 kg depending on what other bits and pieces you have and whether you have a full or empty twinset.

That is on a rough comparison to your single set up and mine and my weight compared to yours.
You don't weigh 13½ stone! Do you???

Wow, puts my weedy 10 stone weakling but getting fat so really 11 stone weight to shame? :):):)
 

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Finless: You couldn't invent him...
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OK ............... I'll guess 8 kilos.

Of course, don't forget to the weight check with almost empty cylinders .... 'grandmother' you say ............. 'suck eggs' you say?

Also, don't be too disappointed if you find your previously admirable trim shot to pieces. It might be an idea if you take some temporary means of adding weight to the back of your cylinders?
 

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I'd say a max of between 1 & 2 kg.

The bp is going to weigh 4-4.5Kg.
The manifold is around 1kg.
The buoyancy weight of the new cylinder is around 0.75kg.
Then you have the reg first stages another 200-300g.

Suggest trying with 1kg.

If you go buoyant at 3-6m then note the pressure. Take off 30bar. Multiply the remaining number by 24. Multiply that by 1.23 and divide the result by 1000.

Eg. You go buoyant at 90bar. 60x24x1.23 = 1771. divide by 1000 = 1.7Kg to add.

Hope that helps.
 

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Nigel Hewitt
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7,142 Posts
In a O3 2.5mm compressed neo drysuit and arctics I need 10 kilos in fresh
In a O3 2.5 compressed neo, one layer of O3 PBB's in I need 9 kilos in salt
OK based on that you need a total weight check.
Your kit is too variable.

Remember you new twinset contains 6Kgs of gas so if you get the right weight to hold position at about 1 meter deep just by how you breathe with the wing/bcd empty with the cylinders full you need another 6Kgs of lead to hold a stop on empty.
It's best to do the test on the last bit of gas (say 50 bar) and add a kilo.

Without that you breathe the rig down and bob up like a cork. Weighting is not so simple once the weight of the gas becomes serious.
 

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Finless: You couldn't invent him...
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With a 5mm backplate I'd say nothing at all in terms of extra weight. you may end up with 1 or 2 kg but I'd be really suprised if it was more than this.
Don't forget he uses that special lightweight lead!
 
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