Let's begin by defining what extended range diving is and what the training involves.

Extended range diving involves making dives beyond the limits of a single cylinder and no decompression time limits. The whole point of completing an extended range course (also known as Technical Nitrox) is to allow us to stay on the wreck longer and then use a rich decompression gas to reduce the decompression requirement. To stay on the wreck longer we are going to need more gas. This will involve the use of a manifolded twinset of at least 20 litres WC in total. Obviously the longer we stay on the bottom, the more gas we need, so maybe even a set of double 12's or 15's may be used depending on the dive. With an extended bottom time, we will undoubtedly run into a longer decompression. This can be reduced by using a richer decompression mix in a separate cylinder. Again the longer the decompression, the larger the cylinder. As with any type of advanced diving, accurate planning has to be considered to make sure that you have enough gas for both phases of the dive, and also enough gas in the event of a failure within the team or your partner. During the training you should cover these aspects of dive planning.

I have come across differing opinions amongst divers as to the merits of extended range diving and the training course. There is some doubt as to whether an extended range course is actually necessary and most advanced divers see it merely as a stepping stone to Trimix. In most cases this is actually quite correct, but it really depends on how thorough your ERD course was. As standards change within training agencies, the ERD course starts to merge into the Advanced Nitrox course, and overlaps with the Trimix course. I know of a few Instructors who recommend that a diver is better off completing a longer Advanced Nitrox course, gaining a couple of seasons diving in twinsets and stage bottles and then doing a week long Trimix and ERD course together. I count myself as one of these Instructors.

However the ERD course is ideal for divers who maybe have completed a Basic Nitrox course, and have been using twinsets for a season or so and are looking to further their skills with the equipment they have purchased. The ERD course will develop their skills with the gear, and expand their knowledge of diving physiology.

What does a typical course involve? Nearly all the Instructors I know will run their courses in the sea. At the end of the day we are trying to get more dive time in and there is limited interest in a fresh water quarry!

The 4 day course will start with a day of theory topics such as Nitrogen narcosis, 02 Toxicity, Extended range dive planning and gas management to name but a few. Equipment configuration is a topic hot on the press at the moment. There is a need to have the correct gear configured correctly for the job. The only way to pick up good advice about kit configuration is to talk to divers who are actively diving and see what their set up involves, then go and look at other gear configurations and see if you can spot the difference. It doesn't hurt to make comparisons and at the very worst you will be told to mind your own business! There is no point in having five of everything - sometimes less is definitely best.

Over the remaining 3 days you will be putting your theory training into practise, in particular the dive planning procedures. At the end of the day it's pointless sitting around a table all day talking about it - jump in the water and get on with it. With this in mind make sure the course you enrol for is high on in-water time. Avoid short cuts wherever possible, they don't work out in the long run.

With all courses, whichever the agency, there should be a written minimal standard that you have to achieve to gain certification. Obviously it is a training course and you will not be expected you to get it all right first time, that is why we need as much time in the water as possible to consolidate the training. I have copied the practical standards from the IANTD Standards and Procedures manual to give you an idea of what's involved. With 3 days to get it all done, there should be plenty of time to practise and make perfect. IANTD have a scoring scheme that grades your performance rather than just a verbal debrief. This works quite well as you will be able to see an improvement in your scores as the training course progresses. It's also quite nice to receive a written assessment sheet at the end of it all as it helps with the next level of training.

IANTD TEXHNICAL NITROX PROGRAM CONTENT:
A confined water session must be conducted prior to OW dives
This is to get you warmed up prior to jumping in at the deep end. It also gives us a chance to practice skills for a longer period of time before the deep dives. For your Instructor it means that they can check you out to see if you can do what your present level of certification suggests you can!

Open Water - 100 minutes of bottom time made within four to six dives. Two of the dives may be in depths from 50 feet (15 meters) to 90 feet (27 meters) for skill development. Two of these dives are to be to depths deeper than 100feet (30 meters) to a maximum depth of 170 feet (51 meters). It is not necessary to exceed 130 fsw (39 msw)
With the availability of Trimix these days, there is no point in using deep air. If we are going to dive below 40m use Trimix, it's far safer.

At the Instructor's discretion, dives, as specified in the Standards, may be credited. With the maximum credited dives from other Technical Programs (Cave, Wreck, or Advanced Deep Air) and/or experience, 60 minutes of bottom time must be completed.

This is why the course has to be 4 days duration. With one day for theory and another taken up with Kit configuration and Confined water training, we are going to need another 2 days to do the 2 deeper dives (1 per day with a shallower second dive in the afternoon) The next section describes what we have to do during the dives.

WATERSKILLS DEVELOPMENT
1 Demonstrate proficiency in propulsion techniques.
2 Two divers are 50 feet (15 meters) apart, with blacked-out masks, or eyes closed on a count of 3, and while simulating an out of air situation, locate dive partner (use side of pool, rail on wreck, guide line, etc. for orientation) and begin gas sharing via long hose. Take 3 breaths at rest. While mask is removed, swim sharing gas for 2 minutes.

3 Air / gas shutdown and regulator switch. Student is to simulate air failure. Change regulators and shut valve of primary regulator, then re-open valve and repeat as if the other regulator had malfunctioned. Repeat until skill (both regulator shutdowns and valve openings) is completed in less than 1 minute.

4 Close eyes, remove and replace stage bottle and make regulator switch to stage bottle and back to primary.
5 Gas shutdown at least once per dive. (It is not necessary to remove mouthpiece on these practice runs.)
6 Remove and replace stage bottle(s) on one dive.

7 With 2 buddies swimming side-by-side, on Instructor's signal, both divers stop taking a breath, while slowly exhaling. One diver remains stationary until the other diver has performed 3 kicks. At this time, the stationary diver swims to buddy and signals need for gas. Gas sharing is then started and maintained for 2 minutes.
8 Use of a safety reel with deployment of a lift bag.

9 Demonstrate good dive technique and swimming (SCUBA) abilities combined with correct buoyancy control.
The whole point of doing these skills is not to satisfy the perverse desires of your instructor, but rather to show that you have complete control of your equipment and the right attitude towards extended range diving. By successfully completing these skills you will feel much more confident in using your gear and the skills learned during the ERD course will be amplified during further levels of training. So how do you know whether an ERD course is for you? If you are diving routinely on wrecks in the 30 to 40m mark, using a twinset, and generally feel like you would prefer a little more time on the wreck and a little less time hanging around during deco, then there is a good chance you will benefit from the training. To give you some ideas of different dive profiles, I have planned a 40m dive in 3 different ways.

Dive1 - 40m for 40 minutes using air for the bottom and air for decompression.
40 minutes on the bottom and 47 minutes of decompression
Dive 2 - 40m for 40 minutes using EANx 28% on the bottom and EANx 50% for deco
40 minutes on the bottom and 24 minutes of deco, quite a saving.
Dive 3 - 40m for 40 minutes using EANx 28% on the bottom and 02 for deco
40 minutes on the bottom and 19 minutes of deco.

So by using ERD techniques and training, our air diver will be out of the water 28 minutes quicker! Not to mention the reduced risk of DCI and increased repetitive dive quality. If these advantages appeal to you, pick up the phone.

To enrol on an ERD course you have a few choices. IANTD, TDI and BSAC all run an ERD training program. No doubt in the near future you will have a wider choice available. There should be no difference between the training programs but sadly there is. Best bet is to ask around and try and find out what you are going to get for your money, you may be surprised!
For a list of Instructors contact: BSAC HQ, IANTD (UK) or TDI Europe.

By Richard Stevenson.