Single to twins and weighting

Martin Burnard · February 2nd, 2006, 10:18 PM

OK just swithched from diving a single steel 15 ltr to diving twin 12 ltrs.

Change the wing (hug that Evolve) change the cylinders then sit in the front room waiting for morning to arrive so I can nip down the road for a dive.

Ponder bouyancy check in the morning.... why should it be any different?

I shall explain.

The only changes are cylinder and wing.

The wing is not going to have a significant effect when deflated, so what about the cylinders?

Well my 15 ltr cylinders weigh 17kg each when empty, so when diving single cylinder they are 2kg negative when empty.

Now my twin 12 ltrs weigh 13kgs each when empty. So each one is 1kg negative. 2 cylinders means 2kg negative.

SO in the comfort of my armchair I should wear the same weight.. I think.

So the morning arrives, I trundle down the road... and step into the sea.

Bouyancy check with 50 bar reveals...... I was right. Breathe in I float, breathe right out... then a bit more, and I slowly sink... marvalous.

So twins or singles just take my pick as I go out the door.

Isn't life great!

Is this typical or have I just been lucky with my cylinder selection?

Little Pete · February 2nd, 2006, 10:24 PM

Hey Martin, good to hear things went well with the first play on the twins.

I went onto them with 4kg on a belt (plus canister light and the usual rig) and it seemed fine. The weighting was pretty spot on for sea diving. Brian and I finished the second dive with a 1.5m stop being held with about 10 bar in the twins......

:p

So it's good to know the weighting was great though perhaps min gas was a little out :D

PS: Awesome dives, I miss Plymouth

Martin Burnard · February 2nd, 2006, 10:34 PM

50 bar for those times when it blows up rough at short notice.

Last year we went in on the Scylla with 2 foot gentle swell, surfaced after an hour with a 5-6 foot nasty swell, which became a 6 foot short viscous swell in the next half hour.

Good fun though.... wheres the boat?.... there it is..... where?..... there.... oh yeh!...... whoops looking down on the deck!..... oh long way above us now..... how am I supposed to get on that?...... oh I'm on it.

"Duggy is my biryani in the oven?.... whoops why are they being sick? Ummmm biryani is scrummy..... oh they are being ill again.... bless. Anybody want to share my grub?..... I'll take that as a no then!"

Oh what fun!!!!

*Brian Allen* · February 2nd, 2006, 11:22 PM

True! I had the same thing... singles to twins involved no difference in lead, but i got a huge benefit in stability!!! The twins are just rock solid in the water.

Dunno what pete was thinkin but on a non Deco dive i thought it a good idea just to check what we could get away with. 10 bar in the tins only involved an occaisional frog down to stay at 1.5m... either that or just crown me n pete as the princes of buoyancy haha lol :D

hmmmm... maybe we are :p

Quote: (Originally Posted by Little Pete)

Hey Martin, good to hear things went well with the first play on the twins.

I went onto them with 4kg on a belt (plus canister light and the usual rig) and it seemed fine. The weighting was pretty spot on for sea diving. Brian and I finished the second dive with a 1.5m stop being held with about 10 bar in the twins......

:p

So it's good to know the weighting was great though perhaps min gas was a little out :D

PS: Awesome dives, I miss Plymouth

February 2nd, 2006, 10:18 PM	#1 (permalink)
Martin Burnard(Offline) New Member Join Date: Nov 2005 Location: Plymouth, UK Posts: 580	Single to twins and weighting OK just swithched from diving a single steel 15 ltr to diving twin 12 ltrs. Change the wing (hug that Evolve) change the cylinders then sit in the front room waiting for morning to arrive so I can nip down the road for a dive. Ponder bouyancy check in the morning.... why should it be any different? I shall explain. The only changes are cylinder and wing. The wing is not going to have a significant effect when deflated, so what about the cylinders? Well my 15 ltr cylinders weigh 17kg each when empty, so when diving single cylinder they are 2kg negative when empty. Now my twin 12 ltrs weigh 13kgs each when empty. So each one is 1kg negative. 2 cylinders means 2kg negative. SO in the comfort of my armchair I should wear the same weight.. I think. So the morning arrives, I trundle down the road... and step into the sea. Bouyancy check with 50 bar reveals...... I was right. Breathe in I float, breathe right out... then a bit more, and I slowly sink... marvalous. So twins or singles just take my pick as I go out the door. Isn't life great! Is this typical or have I just been lucky with my cylinder selection?

February 2nd, 2006, 10:34 PM	#3 (permalink)
Martin Burnard(Offline) New Member Join Date: Nov 2005 Location: Plymouth, UK Posts: 580	Min Gas 50 bar for those times when it blows up rough at short notice. Last year we went in on the Scylla with 2 foot gentle swell, surfaced after an hour with a 5-6 foot nasty swell, which became a 6 foot short viscous swell in the next half hour. Good fun though.... wheres the boat?.... there it is..... where?..... there.... oh yeh!...... whoops looking down on the deck!..... oh long way above us now..... how am I supposed to get on that?...... oh I'm on it. "Duggy is my biryani in the oven?.... whoops why are they being sick? Ummmm biryani is scrummy..... oh they are being ill again.... bless. Anybody want to share my grub?..... I'll take that as a no then!" Oh what fun!!!!

February 2nd, 2006, 11:22 PM	#4 (permalink)
Brian Allen(Offline) GUE Instructor Join Date: Nov 2005 Location: London & Plymouth Posts: 594	True! I had the same thing... singles to twins involved no difference in lead, but i got a huge benefit in stability!!! The twins are just rock solid in the water. Dunno what pete was thinkin but on a non Deco dive i thought it a good idea just to check what we could get away with. 10 bar in the tins only involved an occaisional frog down to stay at 1.5m... either that or just crown me n pete as the princes of buoyancy haha lol :D hmmmm... maybe we are :p Quote: (Originally Posted by Little Pete) Hey Martin, good to hear things went well with the first play on the twins. I went onto them with 4kg on a belt (plus canister light and the usual rig) and it seemed fine. The weighting was pretty spot on for sea diving. Brian and I finished the second dive with a 1.5m stop being held with about 10 bar in the twins...... :p So it's good to know the weighting was great though perhaps min gas was a little out :D PS: Awesome dives, I miss Plymouth __________________ ...dive planning again ... GUE fundamentals and Halcyon Equipment Online www.ocean-explorers.co.uk

February 2nd, 2006, 10:24 PM	#2 (permalink)
Little Pete(Offline) New Member Join Date: Nov 2005 Location: UK Posts: 509	Hey Martin, good to hear things went well with the first play on the twins. I went onto them with 4kg on a belt (plus canister light and the usual rig) and it seemed fine. The weighting was pretty spot on for sea diving. Brian and I finished the second dive with a 1.5m stop being held with about 10 bar in the twins...... :p So it's good to know the weighting was great though perhaps min gas was a little out :D PS: Awesome dives, I miss Plymouth