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I'm a bit of a newbie - being not long qualified (but logged 70 dives) and have been looking to move from a 15l and pony to a twinset - primarily because I dont like the unbalanced feeling that I get from them.

I have been offered twin 7l 300bar MDE manifolded twins with SDS bands plus a 45lb lift OMS wing with stainless steel backplate - for £500.

Is this a good deal?  My thoughts were that if I didnt like the wing, then I could split the kit, keep the twins and sell the wings.

I've also been offer Apex TX40 valves (DIN) as well - do these have to be specifically for 300 bar cylinders?  If the valves offered are only for 200bar cylinders, is there an easy/cheap way to convert them to 300bar.

Any thoughts or comments would be hugely appreciated
 

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Hi Sam

The rig you describe should be a good setup and should see you well into the future unless you wish to go deeper for longer where upon a bigger set of cylinders may be required, but for now you'll have more gas than your original 15ltr and enjoy the full redundancy of running manifolded twins.

From some of the deals I've seen floating around just recently I wouldn't say that you were getting a great price at £500 I'd personally want them a bit cheaper.

There's a guy on here selling a Diverite Classic wing and BP for £150 and you can pick up twinsets for around the £225-£250 all day long so I'd haggle the price If I were you.

The TX40's will go straight onto the cylinders no problem, the fact that your cylinders are 300 bar will mean they have a deeper thread on the pillar valve (seven threads instead of five I believe) but that won't cause any issues with the TX's

On a side note, I've heard that when calculating gas with 300 bar cylinders that they don't actually contain what the maths would give you because of the non linear gas laws, but others on this forum with more knowledge than me on that subject will no doubt fill you in.

Regards
Dave
 

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Off topic, but why does a single and pony make you feel unbalanced? I've used a single and pony for years without feeling the least unbalanced. I've now changed to a bigger pony (3L x 300 bar) and still cannot notice any change in my balance (tried it for the first time last evening). I've heard people say a pony makes them feel  unbalanced before, so you're not unique, but I've never understood why. Could it be that you mount your pony a little too far from your body?
 

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Quite true, Dave. The curves for the ideal and real gas laws intersect at 232 bar. Above that pressure you "lose" some gas. For 300 bar you have to deduct 10%.
I have a single 10L 300 bar cylinder, giving me 2700L of air, and a 3L 300 bar pony, which contains 810L.
 

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Discussion Starter · #5 ·
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John /Dave
thanks greatly for your comments - much appreciated and exactly the sort of response I was hoping for.  I'm going to look at the kit later on today so will let you know how I get on.  One point probably worth mentioning is that I've just been told that the cylinders are about a year out of date so i assume that that would have an impact on the price - any idea how much it costs (on average) to get cylinders tested?

As for being unbalanced with a pony - not sure what the cause is.  I've tried mounting the pony differently - bands and straps, different sides, heights and distance from my body but I've never felt truly comfortable.  I currently use a ND Guardian BCD which is slightly too big for me, so perhaps this may be part of the problem.
 

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Sam if those puppy's are out of test then the deal seems even less attractive, if they need both a visual and a hydrostatic then you could be looking at anywhere between £50-£80 to have them sorted.
 

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Sam,the others are correct in what they say,take note of Dave's point particularly,if the tanks are out of test they're basically just big paperweights until stamped up and the price should reflect that.Not saying that they're not going to be any good,they maybe mint,however if they are the seller should test them.It's a bit like buying a car to go to work in without an MOT,you can't use it legally for it's intended purpose so in effect it's scrap.Mike at Trearddur Bay charges about £30 odd quid for a full test.Dependimng where you're based may dictate how much it will cost you.If you can find an industrial set up that tests Fire Brigade gear etc.(there's one at Knottingley)it will be cheaper than the local scooby shop.Hope this helps,Hobby.
 

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Just for reference, I bought secondhand twin 232bar 10s with MDE isolator manifold, newly tested (tanks were two years old in pristine condition for £220, my mate sole
d 300 bar MF twins for about the same price (slightly older though still in test for 3-4 months)

Diverwarehouse will do you a BRAND NEW  Single 45lbs bladder + Aluminium Backplate & webbing  for £268

either of these twins plus new BCD would come in at less than £500, so if I was you I'd keep shopping. Plus you can save by getting a Combro(?) SS backplate for about £25, and webbing can be bought cheaply "off the reel".

And if you need more comparisons, here's a complete twinset kit for sale by a guy I know, C/w his e-dress
Cheers
Steve
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
For Sale

Complete Twin Set (All that is required is one regulator)

· 2x12L Cylinders (In test and 02 service) with MDE Valves
· MDE Manifold with remote isolator
· Custom Divers Twin Valve Protector
· Custom Divers Wing (New Bladder, August 02) with Stainless steel back plate
· SL4 Torch and Knife on shoulder sleeves
· Rigid D Rings (for attaching stages)
· Stainless Steel Twining Bands
· TX100 with suit feed (Apeks)
· Metal Sub Mounting Bracket (if required)

V. Good Condition.

Price £800 ono

Contact Nick at

[email protected]
 

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Re gas laws - the simplified reason for the decline in capacity is that above 232bar the gas is so compressed it begins to act as a liquid, which as we all know means it is virtually incompressible.

Re unbalanced pony with a single - yes I always felt lopsided with single + pony, plus having a pony in a canvas bag meant it shifted a bit during dives.
 

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I too have used a Pony, but this was held rigidly in place by bands. I have also used the canvas bag set up. I would agree that the canvas bag does tend to allow some movement and therefore a feeling of being unbalanced. If your in a position to move weight around I always found that having an extra couple of pounds on the opposite side to the pony helped.
On the 300bar twin 7's I have a friend who is always feeling that her tanks aren't full enough..easy tiger...
This is partly due to many shops thinking that 300 bar actually means 280, plus she tends to dive with guys carrying twin 10 300bars.
One of the considerations to make is what type of diving platform. If it's a crowded rib large twin tanks don't go down too well, but you will probably get away with smaller twins. On a hard boat size tends not to matter. All to be considered when choosing your tanks.
 

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Discussion Starter · #11 ·
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Just thought I would give you all a wee update on my original post.

Basically after having had a look at the kit, a chat to the seller and a chat to one of the instructors at my club I decided to buy the kit.

The twins turned out to be 4 years old and only 5 months out of test - but as they only had had 2 years of use they were immaculate - only minor scratches on the cylinder body and the manifold and pillar values were still shiny bright.  The wing was only 2 years old, and again immaculate - no wear or tear on any parts plus it had the OMS adjustable harness which I believe is non standard and a bit pricier than the norm.  I also got a pony, weights, BCD knife and strobe torch for the slightly cheaper price of £450.   Probably not the best bargain around, but based on the current second hand market up in Scotland I'm really happy with the price.

Thanks to everyone for all their comments - much appreciated.
 
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