Why do I dive a Twinset?

I first tried a twinset in my first year at Scuba Tech when I was a Divemaster Trainee. 

I did a discover twinset dive with my instructor, Peter Crane. I went on to complete my PADI Tec 40 and 45 in the last couple of years, both courses were conducted with a twinset. Since then I haven’t looked back!

A twinset is two scuba tanks manifolded together, with an isolator in the middle of the two valves.

The misconception with twinsets is that they are only reserved for technical diving and exploration. This is wrong; anybody can use a twinset with the right training, whether you are recreationally or technically minded in diving.

The two main reasons for using a twinset are...

One, redundancy – having that extra peace of mind and security underwater as you have two tanks instead of one.

Two, to extend your bottom time. Having two tanks is a great way of increasing your gas supply.

My twinset, without a doubt, is my favourite way to dive. 

I love the balance underwater and the stability of two tanks on your back instead of one. When weighted correctly, this is a very comfortable way of diving as well as a simple, streamlined set-up. 

However, they are very heavy, and do take some getting used to at first.

Furthermore, I want to be self sufficient underwater, I know I will never dive solo and that I will always have a buddy there to help me. However, if it ever comes down to a situation when my gas supply is compromised, I want to be able to have control and to be able to rectify the issue.

Diving a twinset can help me do this, as I can manipulate the valves and breathe off independent regulators.

This is what is known as a shut down – a way to close the valves in order to save your back gas in the event of an emergency.

If you do not know how to work the twinset properly and be able to perform these skills and drills, the twinset will only give you false security. It is so important to learn how to dive a twinset properly in order to receive the benefits!

Once you make the decision to dive a twinset, you know you are committed to diving as it is an expensive investment; you now need two of everything! 

I feel it is an excellent transition in my diving career as I grow as a diver as well as a professional. It may be expensive in the short term but it is worth it in the long run! 

A twinset brings comfort, control and flexibility in your diving whether you are in the shallows one day, or conducting a tech dive another. 

Technical Diving vs Scuba Diving- What is the difference?

I have had a few emails over the past couple weeks asking me what is the difference between a recreational diver and a technical diver, so for those of you unsure, here is some clarification as to how we differentiate between the two.




Recreational Divers are regular scuba divers who are qualified with a diving agency such as PADI,
BSAC or CMAS.  Their depth limit for diving is usually 40m and they usually dive with just a single cylinder and complete their dives within the no-stop limits offered by recreational dive planners or dive computers. If necessary, the dive can be ended at any point with a direct ascent to the surface without an excessive risk of DCI.

The vast bulk of divers fall into this category.



Technical Divers however, use more complex diving equipment. They may dive a twinset or Sidemount configuration and they are trained to use it properly.

Tech divers have the training, equipment and skills to dive beyond 40 metres and often make decompression dives, which means they cannot make a direct ascent to the surface.

If you exceed your no-decompression, no-stop times, the decompression stop is mandatory and if you miss it, you will put yourself at an unacceptable risk of DCI.

However, just diving beyond 40m and going beyond the no-stop limits to make decopression dives does not make you a tech diver.

Technical divers learn how to use more sophisticated dive gear so, in the event of an emergency when a direct ascent to the surface is not possible due to overhead environments or decompression obligations, they can try to solve the problem underwater to allow them to ascend safely.

For example, a second stage free flows underwater and you are losing gas. In recreational gear, you would swap to your dive buddy's alternate air source and make a direct ascent but tech divers, whether on sidemount or twins, can shut the offending cylinder down and breathe from the other one while they complete decompression obligations or reach a safe depth to breathe a richer, decompression mix.

Mixed gases are another mark of a technical diver.

Nitrox is pretty standard as a breathing gas these days and in and of itself, does not distinguish a tech divers. Most recreational agencies only qualify divers to use up to 40% nitrox.

Tech divers can use up to 100% Oxygen to allow them to optimise off-gassing of Nitrogen (or indeed Helium). If diving to 45m, they could breathe a 25% nitrox mix on the bottom (or a 25/20 trimix), switching to 50% at 20m and then to 100% at 6m. This is known as Accelerated Decompression.



Over the years, the lines between rec and tech have been blurring. Some agencies such as BSAC and
CMAS train their divers to make decompression dives and to dive to 50m using air. Many recreational divers now carry additional cylinders in the form of a pony cylinder or a stage to allow them additional safety options. Sidemount diving and Twinset diving is becoming more mainstream in the recreational market for those wishing to dive with extra gas and nitrox is readily available practically anywhere in the world.



There is even talk of offering rebreather training from the very first dive. That would mean no open circuit training at all. I think that would be a bit further into the future but who knows with the way technology and diving  is advancing...

...now where did I put the keys to my hovercraft?