Saturday 24 September 2016

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.

diver with camera surrounded by fish, single tank and bcd, recreational diver

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 diver closes the manifold to shut down cylinders
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.

sidemount diver with 2 cylinders extended in front practicing skills underwater

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

Saturday 3 September 2016

PADI Open Water Course- Reviewing the new stuff!

padi logo. Blue world, red diver

We have been teaching the revised PADI Open Water Course at Scuba Tech for approximately 2 years now, which I think is plenty of time to get to grips with the changes and how to adapt it to different types of student, which means it is a great time to do a review of the changes.

What changed in the PADI Open Water Course?

diver showing buoyancy and trimThe main difference in the whole course is the focus on Buoyancy and Trim and taking more
responsibility for yourself underwater.

While the older course saw most divers kneeling on the bottom of the pool for the majority of the skill exercises, the new course aims to have divers completing the skills mid-water, which, let's face it, is where we usually have to do them when we are actually scuba diving.

So, although we still begin teaching the skills with a solid base below us, throughout the training, we look to bring divers up so they can demonstrate mastery while hovering off the bottom.

More attention is paid to making divers responsible for their own dives. Checking air supply regularly and being aware of how much air you have remaining at any given time and how much air you are using throughout the dives alongside all the pre-dive planning are all aspects of diving that were not really compulsory for the old course. This meant divers out in the real world with no real idea of how to plan their dives besides using the RDP.

recreational dive planner

The idea of training Open Water Divers using computers is a nice addition, as we have also seen plenty of divers out here that have bought their own computers and yet have no idea how to use them. However, I also like to teach them in conjunction with the Dive Tables because I feel that the tables give the students a better picture of what is happening with no-decompression times and pressure groups.

I think the whole course has shifted to try and create thinking divers rather than just a diver that can follow a guide.

However, I still feel that Open Water Divers would do well to dive with other more qualified divers for the first few dives after certification until they have a little more experience and are a bit more comfortable in the water.