Paul Taylor describes his kit configuration for diving on open circuit Trimix. Paul has been diving since 1994 and is a BSAC Advanced Diver, Advanced Instructor and a TDI Advanced Trimix Diver. Paul also is an Area Coach for the North-East Region.

My Standard Configuration

I use twin 10 litre 232 bar manifolded cylinders for my main gas (usually a mix of Nitrox i.e. EANx28), twin 7 litres cylinders do not hold enough gas according to the rule of thirds allowing one third reserve, ideally the max depth of twin 7's is probably 25-30m. My cylinders are stainless steel banded and bolted to the aluminium back-plate of my wing. I also employ the use of a side-mounted 7 litre cylinder for decompression gas (i.e. EANx50). 7 litre cylinders do not hold enough gas for long decompressions so I would recommend this set up for 40/45m max. Shallower depths I would boost the strength of Nitrox accordingly and loose the side-mount.

Deeper than 45m up to 75m I would only use twin 12 litre 232 bar manifolded cylinders (10 litre twinsets do not hold enough gas (including adequate reserve) to complete the dive safely) for my main gas (usually a mix of Trimix i.e. 16:45) these again are stainless steel banded and bolted to the aluminium back-plate of my wing.  I  employ the use of two side-mounted 10 litre cylinders, one for travel gas (i.e. EANx36) and another for decompression (i.e. EANx60). Divers tend to choose smaller cylinders for comfort, often cylinders hold inadequate gas for a reserve, it is very important that divers are aware of having a reserve of one third gas, if things do go wrong you have this backup, to dive without allowing a one third reserve is plain suicide!

 For my BCD I use an OMS single bladder wing with IQ Pack integrated weight system, this wing I feel is very comfortable during extensive dives, and is very versatile with different types of diving. Although I use my drysuit for buoyancy, the wing provides a superior lift at the surface.

Also important is weighting; divers often dive so over-weighted they can not break the surface as there is so much air trapped in their suit/BCD keeping them afloat. When I am diving with my full Trimix kit, I  use only 2lb of lead, this plus the weight of my kit is adequate enough for me to achieve perfect neutral buoyancy, remember cylinders are heavy and also four regulators are heavy. When I dive with one stage I use approx 4 lbs of lead to compensate. Weighting is very important when undertaking Trimix/Technical diving, it pays off to check in the shallows if you can break the surface without a weight-belt, add a little lead if required.

I mainly employ Poseidon regulators, I have two different 1st stages on my twin-set, a Cyklon and a Jetstream, and strictly speaking there is less chance of both failing if they are different models. For my travel stage I use a US Divers/Aqualung Calypso regulator. For my decompression stage I use another Poseidon Jetstream. My regulators have colour coded banding on the regulator hoses and on the body of the regulator housing, Red for Trimix, Yellow for Travel and White for Decompression.

When diving Trimix, it is important to remember that if the drysuit feed comes from the twin-set, helium in the mix will chill the body (traditional set up) especially on long decompression times and as helium is a very expensive gas it is not cost effective to use the gas a suit feed. For this reason on Trimix dives, the drysuit feed should come from the travel gas stage, not the decompression gas stage, wasting decompression gas is very irrational. Small argon cylinders can be utilised for drysuit inflation purposes, this however can also prove expensive, the suit has to be fully flushed with argon before the benefits can be felt therefore a lot of expensive gas will be wasted flushing the suit, also a small cylinder and regulator for argon would be expensive, no 2nd stage regulator/breathing apparatus must be fitted to the argon cylinder.

I use decompression software to calculate run times, I use a customised slate and a dive timer. Also I use Delta-P's brilliant multi-gas decompression computer the VR3.

I am a firm believer in streamlining, subtraction of excess hoses that are not essential, stowage of regulators and general configuration to ensure no hoses are trailing. For instance my inflator controls for my wing are routed under my arm and connected to a bungee cord on the opposite side, keeping the controls accessible, tidy but more important, easy removed in case of an accident.

I have bungee loops on my wing to stow my regulators that are not in use. On my stages the regulators have loops cable-tied to the body of the second stage, this loop is placed over the valve, simple, cheap and effective. Bands of bungee are placed over the cylinder and the other hoses are neatly fed into the bands to prevent snagging. The stage clips have a small amount of bungee fitted, this allows a slight amount of play when fitting on the surface, underwater they hang horizontal with my body. Having a slight degree of play proves very useful when swapping stages with other divers or when fitting stages from the multi level trapeze (if required). Also when back on the surface, it allows some play when removing the stages to pass back into the boat.

I use a hands-free torch system that I commissioned from a canoe helmet, simple, inexpensive but effective, also I have a powerful HiD umbilical torch that I can use when required. I have two reels both with DSMB's and an assortment of tools and gadgets, these are all stored neatly with nothing dangling to snag on the wreck.

The last thing I have to add is, that this kit configuration works for me, use my suggestion, or don't take my guidance, either way it may not suit everyone, but it works very well for me. Remember no one's kit configuration is faultless and do not take one person's advice, the best way is to look at as many diverse ways as possible, try them, pilfer ideas from one person and thieve ideas from another and see what works for you.

Safe Diving!

Paul Taylor