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Inverting a Twinset

Most people consider inverting as a consequence of being unable to reach the valves for shutdowns - beit good injury or other reasons - or it is out of preference to all that stretching and reach learning drills. The high maintenance of remote (slob) knobs - or premature failure of these because of not doing very frequent maintenance is an expensive driver that is the straw that breaks the camels back.

So you want to invert... then address the follow:-

1. The hose length on Inflators and DV's needs to change from 70cm to ideally 90cm. Their routing needs to ensure they are on the inside of the wing otherwise they can be damaged or cause entanglement hazards.
2. The valves and 1st Stages need to be protected so the Custom Divers (for example) Halo Guard is ideal as you're more likely to smack these on the deck or harbour wall. This in itself adds line snag hazards to your rig that you must avoid at all costs...
3. Slob Knobs require regular greasing and hence are high maintenance - I had one got rid and never looked back. its all about stretch exercises and rig setup, have you tried using your other arm to lift and push away the bottom of the twinset, thereby bringing closer to your head that central isolator? There is not that much lattitude when inverted. if you need to use a slob knob then take it apart every six to eight dives and grease it well. It will last for years then, if you don't do this they have a nasty habit of rusting inside and seizing up.
4. An inverted rig moves the centre of gravity of the whole rig away from behind your ribs in the upper centre of your back to that very concerning lower centre of your back - directly on your lumber region where you don't really want it.
5. Now conventionally it is a good idea to set your rig up so you breathe off the long hose and that is on (your) right hand shoulders' valve - that way any rope/cave or wreck structure slowly rubbing it as you travel forward will switchoff the valve and this will be swiftly detected. I always avoid crossing over valve function so this right hand valve also does primary inflation of the (double bladder) wing. The left hand valve is all the backup functions - so the secondary reg (around your neck via a reg lanyard), drysuit/second bladder inflator (1 hose, same sytech/schrader valve nipple) and a single SPG on a HP hose this side only. When you invert you will reverse all this on your tank BUT you will be best to keep this all the same side of you as above. Take care to rig the stages such that they don't bash the hell out of your MAIN 1st stages/Valves. Also keep reels away too (for the hoses sake). Ensure that whatever guard you put on the twinset does just that from the Cave, Wreck, your own Stages and other accessories such as Reels.

On balance I do think the non-inverted normal upright configuration is best; Look at the seams on your drysuit to see if they are restricting your movement. I do shutdowns by first reaching outwards then bending my elbow directly onto the relevant valves - I've found this sorts out the twists in the seams and that of the fabric of the undersuit/base layers and gives me a much better and more flexible reach.

If you still have problems and you have adjusted your twinset up and inch and/or down an inch on the harness/backplate then and only then go for the inverted style and be sure to sort each of the above points out in turn.

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