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Just not enough dive time.
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I have been thinking of replacing my 12l with a 15l as I need more gas for more bottom time as I have the Nitrox quals done. However I have recently damaged my back but it seems to be responding to treatment so it looks as if I shall be able to dive again soon (yippee!). I dont want a 15 now as I think hauling it out of the car might wreck my back and being nervous about the prospect will make me tense which will almost certainly damage my back again. So 7's or 10's run as indies, so I can lift them out of the car one at a time is I think the way to go for me.

7's as 232 or 300,
232 are lighter than 300 but neutral when empty and dont really have enough gas, I could also side sling a pony for extra bail out, but that would tempt me to run the 7's to the point of empty, which isnt really good gas management.

300's are heavier but negative in water so weight comes of the belt and have enough gas.

10's (232) a bit heavier than the 7x300 but lighter than 12l but twinned up a lot heavier than the 12&pony but have more than enough gas. Might even be possible to get 2 dives from one fill.

300's harder to get a proper fill, especially Nitrox, doubt if a boat compressor would go to 300 either.
232 - easier to get a fill

Prices - all about the same, give or take 20 GBP.
Resale value - anybody's guess

Anybody else deliberated over this one, which way did you go in the end?

Thanks for any help on this one.
Matt
 

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To dive or not to dive - that's not even an option
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You've deliberated exactly the same way I did. Ultimately I did not make the switch as most of my dives are comfortable on 12s and I have 15s if required, always with a pony.

The biggest single thing for me was that many UK dives from rib or shore mean having two cylinders for two dives as there is no compressor to hand. If I had twins, (10s x 232 would be my choice), then I would actualy have to make both dives on these and actualy get less bottom time.

I like the idea of twins, I just can't convince myself it's right for me or even practacle for most, but James Bond would never agree!

James 003

 

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Just not enough dive time.
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Trouble is James I dont want to have to lug a 12 or a 15 around. I can live with the inconvenience of having to come back for a fill but not with a damaged back preventing me from diving.

Twin 10's are 5kg heavier than a 12 and you cant lose that weight off the belt either as they are just about neutral at the dives end.

Matt
 

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"hardly ever here"
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<font color='#000080'>depends a bit on your gas consumption.  i've just started on indy 232 sevens and i can get two 15-20m dives out of them no worries (my normal diving).

do you think it is likely that you will be doing a lot of diving where you will need to get a fill between dives? (i.e. two deepish dives with no chance to fill up, or two heavy-breathing dives with no chance to fill up).

if not, i wouldn't worry about getting a lot of gas so you can get two dives out of them. i would just get whatever is lighter and better for your back - you said the 300 sevens are lighter than the tens so i'd get them.  even if you can't fill them to 300 you can still fill them to 232, which should be fine for most dives (unless you are a heavy breather or if you often can't get a fill between dives - back to my point above)

hope that was vaguely helpful!
 

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Ok. Twin 7s are not too good if you want two full dives without a fill, eg a 25m followed by a 20. But they're fine if you do something like Brighton pier as a second dive

So, you have to decide what category most of your diving fits into: On a boat for two full dives; on a boat for a deep and a shallow dive; dive, get a fill, dive again; etc

Since you're running indies, you have got the option of having three (or more)  bottles and taking the fullest two on a dive with you. You could also consider taking a full 12 and decant whip along on trips where air isn't conveniently available.

Since you've done Nitrox, I'd assume you're looking into getting longer bottom times - so I'd say 232 7s are probably out. 10s have a small amount more gas capacity than 300 7's, but will require more lead as they're bigger.

Overall, a 300x7s rig will probably be lighter, and since they're more streamlined, you'll probably find your SAC decreases enough to compensate for the reduced volume of gas available. So I'd say get 300 7s, so long as you're confident that you can get decent fills most of the time.
 

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This is where Matt's wife finds out htat not only does he spend all day posting on here, but he is a heavy breather too!..........

Go on Matt, own up before it's too late!
 

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Just not enough dive time.
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I must admit I am looking really hard at the 7 300's, they weigh a tad more than the 12 BUT the weight can come off the belt as they are negative all the time. Very tempting, and the idea of a third bottle hadnt passed me by either, that would definitely allow for two dives without a refill.

Hmmm!!!

Heavy breather and tartan trunks, oh the shame of it all.

Matt
 

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Jonah
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Matt, have you checked how much a rebreather weighs?
 

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<font color='#000080'>OK quick question as i'm looking at tanks too at the momment, weight wise how do 300 7s and a 12 plus pony compare (out of water).
 

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3 boats down from the candy
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Matt , i am in the same sitiuation as you , i upgraded to a wing and so far have managed to borrow twin 10s which i find great, but often with the depth and length of dive it is not practical to get two decent dives out of one fill.this is only a problem if you are out on a boat with no refill possible and a second dive gone begging. someone mentioned taking a 12 litre and a decamp whip but i am not 100% certain how that works , if someone knows please explain.
one thing i do know twins are a lot better than my 15l and 3l pony, better balance etc
cheers paul
 

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www.divefaber.com for all you cylinder weight inquiries.

Decant whip for a twinset - it's a HP hose with DIN (or A-clamp) fittings at each end. Oh, and a bleed valve.

So you take your down-to-50-bar twinset, hook it up via the whip to a 232 bar 12, and let it do it's thing.

(If you're really nerdy, you close the isolator and fill each cylinder on your manifolded twiset separately, thus getting an even better fill)

You won't get a FULL twinset out of it. But you'll get maybe 150 bar into twin 7s - plenty for most second dives.
 

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Not as tall in real life
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[b said:
Quote[/b] (Mary @ Jan. 20 2004,12:29)]OK quick question as i'm looking at tanks too at the momment, weight wise how do 300 7s and a 12 plus pony compare (out of water).
Well just off the top of my head.

300 bar 7l is about 10.3kg empty.

232 bar 12l is about 13.8kg Empty.

232 bar 3l pony is 3.8kg empty.

These weights vary depending on supplier but are approximately what mine weigh.

The thing to bear in mind is the difference in weight vs water displacement.  Twin 7 300 bar due to being more negatively buoyant require less weight on the harness or belt so the package as a whole is probably comparable weight wise when all factors are considered.

Daz
 

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<font color='#000080'>Ok, so looking at the faber website (thanks dom),

300 bar 7 weighs 10kg empty
232 bar 10 weighs 12.2kg empty,

pony and 12 combination weighs 17.8kg

I'm trying to decide what would be the best use of my money, a single 12 £114 or some 6 month old 300 7s for £180.

Weight issues are I guess that 7s would be slightly heavier out the water but due to the weight/volume displacement i would get rid of some lead so my total weight out the water (ie tanks and lead combined) would be less than 12 + pony.

Have I got this right?


Just wondering as have some saying i wouldn't be able to handle the weight but the 7s would weigh less than 232 10s and the 10s would need more lead, or have i completely confused myself now??
 

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OK this is all just off the top of my head....

But with a single 12l and Pony I can get away with 8kg of weight (maybe 7kg at a push)

With the 300 bar 7's I can get away 2.5kg (Backplate weight) at a push or maybe a extra 1.5kg just to make holding stops a bit more comfortable.

All based on fresh water trials.

The main difference is that with the 12, it was possible to put my weight on and then someone would usually help me to put the 12l on and then clip the pony on,  so all gradual additions to the weight.

With the 7's (23kg ish not including air) it is everything in one go,  so I have mastered a way of doing it on my own rather than relying on people to have to struggle to pick the whole lot up and hold it while I try to put it on.

However I am sure if you flutter your eyelashs you will not have any problems getting some big strapping guys to help you get it on (as it were)  
  Failing that it's not like it is very far you need to get it off the floor is it?  


Daz
 

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[b said:
Quote[/b] (daz @ Jan. 20 2004,14:48)]However I am sure if you flutter your eyelashs you will not have any problems getting some big strapping guys to help you get it on (as it were)  
  Failing that it's not like it is very far you need to get it off the floor is it?  
<font color='#000080'>Are you volunteering your manly physique to give me a hand?


OK well at the moment I have to hoist 12+pony onto back of the car and can get then on from there, and the same with 300 7s when i tried diggers. I'm just trying to workout why people keep telling me that they are too heavy for me if they weigh not too much different, it's just the weight isn't split into lead and tanks.

Anyway I'm very tempted by the 7s. What's more worrying is that i have a great desire to paint them barbie pink, somehow i don't think the DIR boys would approve.

ooOOooo that's a question, what colour wuold hot pink look like underwater?
 

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Just not enough dive time.
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Discussion Starter · #17 ·
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Mary
do these people who tell you that thet (7 300s) are too heavy actualy have them or is it my mate down the pub stuff.
The advantage I see in the 7's is that if you need a fill its far easier to carry two light(ish) tanks down to the filling station than one heavy(ish) single 12. Plus the 7's will be closer to your back so less turning moment as you walk to the waters edge.

If you have a second set of 7 300's at 180 quid I'll take them off your hands, new they are about 260.
I am seriously tempted, Incidentally Faber 7 300's are 9.7Kg, 232's are 8Kg. My 12 & pony weigh 17.7 but neutral in water whereas the 7's will be negative by about 2 Kg so that can come off the weight belt.

Credit card at the ready, off I go
Matt
 

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Just as a FYI:

7 300s weigh from 8.2 to 11.6kg each
10 232s weight 10.9 to 12.4kg each.

Buoyancy-wise, that means (empty & in the sea) you're looking at:
Neutral to over 5kg negative for twin 7 300s
1.5kg +ve to 1kg negative for twin 10 232s

So if you needed 5kg to get down, your total cylinders + lead for the combos out of water is:
Light 7 300s: 16.4 + 5 = 21
Heavy 7 300s: 23.2 + 0 = 23.3
Light 10s: 21.8 + 6.5 = 28.3
Heavy 10s: 24.8 + 4 = 28.8

So there you have it - 300 bar 7s are lighter than 10s when you take lead into account as well. Woohoo.
 

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wibble
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<font color='#000080'>I have just got my second twinset, im a light breather too.  Now have twin 10's and twin 12's, plus a 7.5l stage and a 3l stage.  Dunno if i can walk with the 12's though.  Only a minor technicality tho....
 
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