Twinning questions

[Sipadan]

would agree with big andy about 300 bar 7s. i also have a set of twin 12s for more serious dives, but they are horrible out of the water.

[G man]

I would have thought that twin 7's are a pain in the arse, few places fill to 300 bar. Surely it would be easyer to get some 12's there is 1000l more gas when fillled to 232 compared with a set of 7's filled to 300 bar.

G.

[Sipadan]

Originally Posted by G man

I would have thought that twin 7's are a pain in the arse, few places fill to 300 bar. Surely it would be easyer to get some 12's there is 1000l more gas when fillled to 232 compared with a set of 7's filled to 300 bar.G.

i've never had a 300 bar fill and am not arsed about getting one. 300 bar cylinders trim out nicely and require less lead. there is nothing easy about 12s out of the water very few (of my) dives actually require them.

[Woz]

Yep 12's are a pain out of the water but I find 300 bar 7's trim very neck-heavy.

[Big Andy]

Originally Posted by G man

I would have thought that twin 7's are a pain in the arse, few places fill to 300 bar. Surely it would be easyer to get some 12's there is 1000l more gas when fillled to 232 compared with a set of 7's filled to 300 bar.

G.

I know what you mean but access to 300 bar hasn't been a problem for me in the places I've visited around the UK. Yes, more gas is true but I've never even got close to using all of my 7s in 1 dive and you can always top up...

[nigelH]

Originally Posted by G man

I would have thought that twin 7's are a pain in the arse, few places fill to 300 bar. Surely it would be easyer to get some 12's there is 1000l more gas when fillled to 232 compared with a set of 7's filled to 300 bar.

LOL
Well if you do insist on living in the back of beyond...

I dived 300/10 twins for many years.
If I was in a hurry for a fill it cooled a bit short but most places knew this and asked if I was in a hurry and were quite happy to top them off if the queue didn't run right twice round the shop.

Now I fill my own and the lazy wotsit can never be bothered to do the extra to get it right up.

[G man]

The diving I do I use two 10's as Deco cylinders with 18's for back gas. Lots of gas for the dive plenty in reserve and some for spidge bags.

But that wouldent suit the original poster so to answer his questions.

You need good quality seam welded wide bands to stop the cylinder flexing.
A good quality manifold

size the cylinders for your dive and your body size, so when you sit on the boat the cylinders touch the seat and can still be nice and ballanced ( 18's are perfect for me).

Regards Grant.

[PapaBear]

Thanks loads to everyone who has posted, some really good advice that I'm going to have to think about some more.

TBH I had pretty much ruled out 300bar cylinders as my club compressor cant do them (though I do already use DIN regs)
As many have you have said think the best thing will be to get myself to a familiarisation day!!