Additional cylinders mounted to doubles

[Digger]

If you're planning on 3 12s mounted as a triangle forget it. It was bad enough with a 7 when I tried it (in the interests of finding out for myself) and it's a nightmare, plus you honetly would have no way of reaching a 12 back there - I had enough trouble with a 7. Even hitching it up you wouldn't get there unless it was mounted so high you'd never dive it.

Get a bigger twinset. Twin 12s have a lot of buyers, big twinsets don't any more, as RBs are the way it's gone. So you should get a set for reasonable money. Probably about the same as you sell your 12s for.

That said if you need more than twin 12s it's either very deep or your SAC is very high. Personally I just adjusted my dive plan to suit the size of the tins - the deco tends to govern how long you can spend on the bottom once you've got a couple of stages on.

Either that or dive with a leaner first mix and larger tanks there, so you can switch sooner. But bear in mind the effect this will have on gas and deco planning. Obviously.

Digs.

[ian Price]

Actually I have done it! though for reasons I'll explain discarded the idea.

I set up my twin 12's to to triple (ie. take a 3rd cylinder). I got John at Kent tooling to modify a single adapter plate, and sorted the rods on my twinning bands with some spaces, I added in the cam bands and hey ho, I had a triple.

I used it with an Ali 40 and my Ali 7; due to their bouyancy characteristics, there wasnt much in water difference, I never actually tried it with my ali 80, even so it felt bloody heavy out of the water mind..

The advantages to my mind at the start of the process ... was it created a 5l or 7l bail out or gave me the option for a 3rd deco gas when trimix diving.

The disadvantages turned out to be - it needed a longer hose, as its quite aways back and coming over the shoulder as well meant it had to be clearly marked or banded to ensure I didnt get it mixed up with my main regs. -

Though it didnt create much more profile in terms of width it obviously was bulkier. -

The big disadvantage, was you can't get at the cylinder if there is a problem, no chance of shutting it down without taking the whole set off.

In the end I came to the conclusion, though it could be done with ali cylinders or maybe carbon fibre, steel would be a no no... and therefore it was just as easy to sling 3 cylinders in front where you can get at them and therefore check them more easily, shut down or discard / hand off, if there was a need to.

Therefore the problem could be solved more easily ultimately by a skill development (practice slinging and carrying 3 or 4 cylinders), rather than equipment modification.

still nothing ventured nothing gained, and at the time I had vowed not to go down the CCR route! Unfortunately I changed my mind on that one too... certainly the adapter and cam bands were considerably cheaper than the $8,900 the Megs going to be.

Hope this helps

Ian

[Noel Johnson]

Ahhhh sorry, I must not read posts under the influence.

[wreckweasel]

Can you turn the reg valve on/off.
Can you swap the 1st stages underwater (if need be).
Can you free any entanglement that might arise.
Can you take that whole rig off underwater and re-fit it.

If the answer to all the above is yes, then feel free......

Personally I wouldnt bother, side slungs are a whole world easier....

[Ivon]

Can I ask why your planning to do advance mix then get a rebreather?

You will be paying for two lots of training, will have to buy bigger side slungs, learn new skills and then go back to baisics when you get a rebreather.

In my oppinion it would be better to switch over as soon as you can as you need to take a season out of deep diving to master the rebreather to a sufficient level.

Just a thought.

Ivon

[kinetic]

Mark,

I was just wanting to try extending. There are some old wreck and car piles where I live that run down to about 70 metres. Diving them on twin 12s and stages is fine but there's a lot to see on one dive and I just wanted to give it a go with more gas just to spend more time to poke around down there...that was all.

Paddy - those brackets are interesting. I do like the doubles and the inverted 7 l cylinders bracketed to the side......looks heavy though. Just out of interest, are you diving steel or alis?? Also, the quick release system looks superb...I had not seen that before. I think I'll reconsider moving my battery pack to my cylinder too. I had not bothered locating it there as wiithout quick release brackets, that I currently don't have, it would have been a drag fitting and removing all the time. For the moment, I clip it to rings on my backplate so it sits slightly behind under my right arm.

Thanks again for the pointers.

kinetic

[Twinsetmad]

I had a mate that put a 7 between his 12's as you said, he spent the whole dive fighting for balance. When he was level, it tipped him forward, and when he trimmed back a bit, it tipped him backwards. Poor chap couldn't win.

[Capone]

A couple of my buddies have started doing this.
Twin 12s with a 3L in the middle of them making a sort of pyramid on their back..
I haven't seen it in action yet but will do down in Swanage this weekend if I can shift the cold & sore throat.

They are trying to get me to try it (peer pressure) but think I'll go for the tried and tested twinset on the back with stage bottle clipped accross the front on me.

I will see if I can get some video footage of one of them loosing their balance and "falling" over backwards......unaided of course

[Gav]

Don't know if you're planning to dive to 205m (!) but this article talks about Leigh Cunningham's quad of twin 18's plus twin 12's plus side slungs and Mark Andrew's triple 12's plus side slungs, very similar in what you seem to be talking about.

http://www.oceantechnical.com/worldrec.htm

[kinetic]

Gav,

Cheers for that....I'll have read through.

Not planning to be that deep for a while yet.

All the best.

kinetic