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Between the Devil and the Deep

It has taken a while and a lot of work but we are, at long last, heading toward the point where you can actually have a copy in your hands. Please feel free to share and do have a look at the web site to check on how we are trying to fund this project. It is being done with a sort of crowdfunding but if we don’t hit the target you won’t loose any money so please do pledge to buy a copy, thank you.

_MG_7891 copy

When we plan how much bailout gas we need there are a number of different strategies, ‘bailout philosophies’, we can employ. It is also perfectly fine to combine strategies depending on the nature of the dive, how many divers there are on the team, how many support divers there are to help etc. Here are some of the options. The pros and cons of each and how to plan the set up will be looked at in a further article.

Individual bailout. This one is fairly obvious, each diver carries all of their own bailout gas. They each enough gas to get them through the ascent and decompression from the furthest and deepest point of the dive. On some dives this could mean carrying a lot of gas!

Staged bailout. Using this technique, some or most of the gas requirements are placed in the water in advance of the dive. This could be on a decompression stations or shot-line or placed in the cave etc. We can combine this with individual bailout plans or a team bailout philosophy.

Drop cylinders/support divers. By using a prearranged time or a pre-planned signal to the surface support divers can deliver gas to the dive team. For example on a deeper dive you can signal the surface cover at a pre-planned depth and support divers can descend and take away all the deep trimix bailout cylinders which are no longer needed and exchange them for shallower decompression gasses. This means you don’t have to carry absolutely everything throughout the entire dive regardless of how you have calculated your gas volumes. This system can also be used to cover emergencies. A separate emergency signal can be used to alert the support dives and have them commit to deliver gas in advance of any pre-planned depths or times if something has gone wrong and one of the team has had to bailout.

Team bailout. Using this philosophy, the gas requirements are split between the team in accordance with the guidelines below. It is very easy to incorporate team bailout into staging cylinders or the use of support divers.

First to put it in its simplest terms, calculate the gas needed to get one diver safely through the exit/ascent and decompression to the surface. Multiply this volume by 50% (the ‘enough gas for one and a half divers rule) and that is your gas volume requirement. This is the standard ‘1 ½ diver rule’

This is then divided amongst the team with the following provisos:-

Firstly, every diver in the team must have an OC bailout gas suitable for the deepest part of the dive. It needs to be a life sustaining volume of gas, not just the right mix.

Secondly, (and this is optional, not every dive team would adopt this part) no matter how many people you have in your team, you divide the gas as if there were only two team members. For example, in a team of three, each of the three potential pairings would have enough gas for one and a half divers between them.

The gas mixes can be decided upon based on likely OC bailout decompression, but whenever we can we base all our gas mix choices on the inert gas ratios in the rebreather to keep any transitions from one gas to another (if on OC bailout) as smooth as possible and avoid any inert gas spikes.

The subject of using inert gas ratios to pick ideal bailout gasses is on the list for future blog topics.

With a little planning and imagination you can carry all sorts of gas mix combinations to optimise the decompression obligation if someone has to go to OC bailout and stay on OC bailout.


Hollis recognition crop.pages It has taken a little while to come through (we have been running Hollis approved Prism II and Explorer Instructor courses since late 2013) but it is still nice to get my letter. My thanks to John Conway for sending.


Mount Fuji overlooks the dive site

Mount Fuji overlooks the dive site

After a long flight, although not as long as going to Australia, I arrived in Nagoya, Japan to be met by Nobuyuki-san for dinner.  The next morning we drove to Osezaki in Shizouka Prefecture to start a Tec 40 CCR Diver course for Nobuyuki and Yosuke.  I was surprised how much life there is here in the ocean despite the sea bed being quite black (the ‘sand’ and gravel is basically volcanic, we are diving in sight of Mount Fuji) and barren in places.

The dive site is in a very sheltered bay so even on very windy days the sea is fairly flat and we can still dive 🙂  Diving is not the only lesson, I am learning some Japanese and of course, getting to know the local cuisine.


Se7enPoseidon Diving Systems will be hosting a program for Poseidon Rebreather Instructor Trainers who are also Tec CCR Instructors to become Poseidon MKVI/SE7EN Tec CCR Instructors and Trainers (dependent upon experience).

The courses will be run by PADI Designated Instructor Trainer and Technical Field Consultant, Martin Robson, who has been instrumental in the development and launch of PADI’s rebreather and tec CCR range.

The Courses will take place at Poseidon HQ in Gothenberg, Sweden.

Courses, Dates and Course Prices:

1. Tec 40 CCR Instructor 18-21st August 2014 – GBP750

2. Tec 40 & 60 CCR Instructor 18-22nd August 2014 – GBP1000

3. Tec 40, 60 & 100 CCR Instructor 18-23rd August 2014 – GBP1250

To book your course, please contact directly. Spaces are limited and subject to minimum numbers.


Current Teaching status PADI Rebreather Instructor Trainer on the Poseidon MKVI/SE7EN

Tec CCR Instructor on a Type T CCR (or qualifying certification) and have taught at least one full course and issued at least one certification at each level you wish to attend.

These courses will also meet the requirements for the practical elements of the Tec CCR Instructor Trainer course, successful completion of the practical sections will enable you to complete the remainder via webinar.

For questions about pre-requisites please contact

Poseidon Diving Systems have put together several options for accommodation and transport:

1. Comfort living

Single room 1290 SEK/day for accommodation and breakfast at Gothia Towers in city center

2. Economy living

Single room 820 SEK/day for accommodation and breakfast at Hotel Poseidon in city center

3. Super economy

Single room 695 SEK/day for accommodation and breakfast at Hotel Ibis Style Mölndal outside city center

4. Transport packages

2000 SEK for pick up and drop off at airport, transports between Poseidon Diving Systems and hotel every day and transport to lunch

1500 SEK transports between Poseidon and hotel every day and transport to lunch

For information on accommodation, transport and equipment, please

Candidates will need to have copies of all required PADI materials and bring or hire all required equipment. Diluent and oxygen cylinders are available to borrow from Poseidon Diving Systems. Poseidon Diving Systems have kindly offered to coordinate the hire of bailout cylinders for the group.

For Tec 40 and 60 CCR equipment requirements please check the unit register:

Requirements for Tec 100 CCR have not been finalised by PADI yet, however, in addition to the 60m unit requirements, the requirements will include (at least) a Poseidon SE7EN enabled to 100m.

Poseidon Diving Systems will offer course attendees a special deal on equipment – contact for details.

Contact Details:

To book your course, please contact Spaces are limited and subject to minimum numbers.

For questions about pre-requisites please contact

For information on accommodation, transport and equipment, please





It won’t be long now.  I’m looking forward to attending and speaking @TEK DiveUSA.


PS.  If anyone is definitely coming along to my talk, I could do with someone capturing it on video.

Hollis SpainHome from a great week running Hollis Explorer and Prism II Instructor and IT training.  It was still technically winter so we were lucky with the weather and diving conditions and managed to complete everything we needed to do.

Planning to go back next year for Tec 60 CCR and Tec 100 CCR Instructor training.

New Blog

Having got the new website up and running I thought it would be a good idea to move the blog to the same address.  I will still try to post here but you can now read the blog on the main website at

Just click on the drop down list under ‘more…’ and you will find the link to the blog or you can go straight there using

Thank you – hope to see you on the new site.


New Website

The address has now been redirected and points at the new website.  Amazing stuff this internet and it all connected a lot sooner than my web hosts suggested.

1827004 is back up and running.


The Eau2 website has had a facelift. Not too much, I am not that good at web design but a bit lighter, brighter and more information. The old address will start redirecting in a couple of days. In the meantime you can take a peak here:-

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