Inverted twins

[Mark Chase]

<font color='#000F22'>I have over 100 dives logged on my twin set and I still cant confidently reach the central isolator valve without a great deal of effort.

I dive a CD TDK single bladder wing. I have to release the waistband and push the tanks up my back with my right hand and reach back and over with my left hand to do it.

This is too slow for my liking so I use a slob knob and take the flack from people who can (or claim to) do it.

Two things I found:

Reaching back at a horizontal hover is easier than kneeling on the bottom

Having something that you CAN grasp and working back form there is a big help. In my case thats the slob knob hose. I walk my fingers back along the hose to reach the isolator. Obviously this is only ever necessary if my slob knob fails.

Side valves are reasonably easy to reach and if you cant do it quick enough at least central isolation saves 1/2 the remaining gas.

Inverted twins are a good fix for these problems but the kitting up issues and the custom hoses have prevented me going that rout. I do invert my pony bottle when it's on my back and I can reach the valve with no effort. &nbsp;

Another silly point is inverted rigs are difficult to stow on a boat as the fixing is usually a bungee that wraps around the pillar valves.

Mark Chase

[And]

Hi

I have found that if you can reach the top of your backplate (positioned at about your second verterbrae) with your drysuit, undergarments etc. then it is easier to reach your valves. For me this involved tightening my harness quite a bit. My bands are then positioned so that when horizontal looking straight ahead means that my head rests against the isolator.

This was pointed out on the DIRF course. Before I could reach my valves but it was a bit of a struggle. As soon as my harness was tightened it made a big difference. I even had to lower my cylinders in the bands. They are now right at the top of the cylinder, just before they start to taper.

Now I just have to practice getting the harness off !!

HTH

WL

[Mdemon]

ROFWL Heads UP!!! &nbsp;And I guess if you're doing it properly you should have a buddy close at hand...

I think with much stress I probably could walk my arms back along something. &nbsp;The harness thing doesn't work for me though - I always like the harness to be close fitting and it didn't help. &nbsp;Bottle placement might, however, but then we're into pitch problems.

I think I would rather bite the bullet and get a system that I know I can use quickly and without effort. &nbsp;I'm not sure how essential shutdowns are on indies, but when/if I change to a manifolded twin, I need to be able to deal with problems easily.

Sooooooo... Inverted it is. &nbsp;£40+ for new hoses (thanks for the info previously Hobby) and an interesting time pursuading someone to weld me a valve protector/stand. &nbsp;So far the design is simple, but I'm wondering what the best way of fixing it to the necks of the cylinders is - collar and bolt seems likely. &nbsp;Without SS bands, it needs to be adjustable too... Any ideas?

[Hobby]

Mdemon,re.the valve guards.
For what Probe diving(Oldham) were flogging them for I would'nt bother trying to fabricate one.They worked on a collar clamp arrangement,from memory, 2 x sepeate recessed Allen bolt fixings each side of the collar,hence 4 screws per cylinder.Tubular stainless costruction.Check though mate,am not 100%
HTH,Hobby.

[Dr Stevil]

Originally Posted by [b

Quote[/b] (Mark Chase @ Mar. 09 2003,19:12)]Inverted twins are a good fix for these problems but the kitting up issues....


Another silly point is inverted rigs are difficult to stow on a boat as the fixing is usually a bungee that wraps around the pillar valves.

<font color='#0000FF'>I understand your point about the hoses (yet more cash, c'est la vie...) but would you like to expand on the 'kitting up' bit?

Re on a boat, on Saturday I just laid mine flat on the deck, but I could have gotten the bungee around the valve guard easy enough

Chee-az
Steve
PS the feeling of being able to reach your pillar valves 'easy as pie' is well worth the extra for the hoses etc, feels very, very safe indeed

[Hobby]

You'll probably find Mark,that the custom hoses are no longer than the &quot;long hose&quot; now commonly found/available.It's also possible to invert and use standard length hoses too, as SteveW will now be able to confirm!
If you retain the boots(either on of off the cylinders in dive bag etc) the cylinders can be stored as any others,as Steve did though,the cylinders should be lay down wherever possible anyway.
Hobby.

[Steve S]

Hi All, just to add my two'penorth, yesterday at 38m I had my first ever freeflow, it was also the first time that I had worn my twinset inverted and all I can say is that whatever problems you may have with with configuration, stowage etc don't matter at all when you can switch off an offending reg as quickly as I was able to.

On the question of hoses I was able to invert my rig and get away with buying only one extra long hose.

Safe diving,
Steve.

[Angleseyskipper]

hi all if anyone is considering goin inverted i 've got an unused set of aluminium collars/clamps with 12mm stainless bar screwed in and A2 hex bolts on the collars.
all you need to finish is bend the stainless rod to make the halo ring decide on the spacing and weld.its all there.
i had the bits machined for two twinsets and only welded the one as i sold me open circut gear over 2 years ago and bought a rebreather.
I run inverted for about 3 years it was ok but i always felt a little bit arse heavy with all the regs, valves and cage at the bottom.
still it was worth putting up with for the valve access
if you can stick weld use 316 rods ,you can have it its no good to me cos i ain't ever going back.
the finished thing looks the part and best of all its cheap music to any divers ears

[Mdemon]

Hi Butty Box,

Pardon me, but I'd like to bite your hand off! I'm just in the market for a valve guard, as you may have gathered. &nbsp;How easily does stainless steel weld, by the way?

[JohnK]

As a `not lost my virginity yet` as far as the iso valve is concerned, I can boast some heavy petting. I reckon another inch (isnt it always the way) of tank will get me to the promised land.

Like me dad used to say `these women are all right but you cant beat a slob knob`!!!

If the other inch doesnt get me there then I`m going for the real thing - a slob knob