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That’s Wrong: Technical Diving Misconceptions



By John Bentley and Brian Shreve

Perusing internet forums on technical diving can be an entertaining way to waste a few moments of a lunch hour, but it’s disheartening to see the amount of misinformation perpetuated online. Just recently, we’ve seen some of these recurring topics, and thought it might make for an interesting article.  So what have we seen?

I can just do whatever I want for decompression, because it’s only loosely understood

This one isn’t really a misconception, at least not completely. Decompression theory isn’t thoroughly understood from a physiological perspective. This is being mentioned because the looseness of our understanding is taken as a free pass to bypass the rules. Guess what? Science doesn’t really understand much when it comes to physiological interactions at that level but we still follow the research and data that is available. Saying “it’s just a theory” doesn’t justify aggressive gradient factors, skipped deco, or diving with antiquated versions of tables. While it is true we’re our own crash test dummies on dives that push boundaries, that can’t be taken as carte blanche to do whatever on every dive. There’s a good body of evidence of what works for most technical dives, and a prudent diver will keep within that range of ascent strategies.

CNS loading isn’t a real thing

People, more and more, seem to devalue CNS tracking for repetitive decompression just because they know of explorers pushing 500% of their CNS clock. This shows a clear lack of understanding to the actual value of that percentage and what it represents. 100% does not mean “CNS toxicity happens here.” 100% is a recommended value over a period of time. Sometimes that value is pushed further and done so successfully with specific considerations being met. The fault here is probably the units (percentage) chosen to represent this loading. We’re used to 100% being the maximum in a dataset, while the time variable in CNS loading makes that not the case. Just because 100% is typically used as a maximum value and can be surpassed significantly does not mean that the idea of a max CNS load is invalid. Divers doing repetitive decompression dives with accelerated deco should be tracking their CNS and should stop waylaying data in favor of anecdotes and conjecture.

Buoyancy control and trim

“If I’m not in a cave trim, it isn’t a big deal.”

Really? No. If an open water student can be horizontal in the water you can too. Vertical diving comes from a time of over-weighted technical divers whose equipment literally wouldn’t let them be trim. Now, with balanced rigs and standardization of gear it’s simple to be flat in the water. There really isn’t a good excuse for this anymore, especially considering that SDI instructors are consistently producing entry level scuba divers with horizontal trim.

Helium doesn’t require a full class, it’s just a new gas

Hopefully this is only a popular one among the internet divers, which is where it’s seen the most. A helium class’s necessity coming in question really shows the lack of respect towards years and years of fatalities and accident analysis. Helium is different. We’re all glad you have Google and read something about isobaric counter diffusion.  The skill sets developed in a trimix/advanced trimix course, and the evaluation of those skills, is a vital part of a self-regulated industry. Your self-evaluation is important before a course, but the idea that self evaluation and an exam makes a trimix diver is not valid nor is it supported.

While talking to your favorite internet diver don’t forget to take wild anecdotal evidence with a heaping grain of salt. Training, experience and research make a great instructor as well as a great diver. Those two things can’t be replaced by marginalization of facts and data that appease egos and mitigate hard work.

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To find out more about International Training, visit



From its humble beginning in 1994 to today, the group of training agencies Scuba Diving International (SDI), Technical Diving International (TDI), and Emergency Response Diving International (ERDI) form one of the largest diving certification agencies in the World – International Training. With 24 Regional Offices servicing more than 100 countries, the company today far exceeds the original vision the founders had when they conceived the idea on a napkin, sitting at a kitchen table in the early 1990’s.


Get moving with the new RAID DPV training programs



The thrill of speeding through the water behind a diver propulsion vehicle (DPV) is an experience that really gets the blood racing. Using a DPV provides divers both immense fun and the means to achieve goals that would be impossible without their use.

RAID is proud to announce the new two-tier DPV training program with certifications for DPV and Advanced DPV.

Why DPV and why now?
Recreational and technical divers are using DPVs to access sites that would be difficult to reach and explore using traditional propulsion methods; to help propel large amounts of heavy equipment; to increase the safety of dives in areas of strong current; or just for the pure exhilaration of shooting through the water at speed and performing underwater acrobatics.

By extending your capabilities and extending your range, using a DPV opens new vistas for exploration and fun.

This certification option is aimed at the recreational diver who wishes to learn how to use a DPV to enhance their diving by using mainly natural navigation.

Advanced DPV
This certification option is available to anyone who is familiar with longhose configuration, has logged a minimum of 20 dives and is certified as Navigation specialty divers.

This certification option is aimed at the slightly more experienced diver with preexisting navigational training and diving on a single, twin or sidemount setup with a longhose. Although this level is slightly more challenging, the more advanced navigation exercises provide an important base for more complex types of DPV diving within a team.

You must:

  • Be a minimum of 12 years old.
  • Be certified as RAID Open Water 20, Junior Open Water or equivalent.

Just visit to put some extra dash into your dives.

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Marine Life & Conservation

Beers raise cash for ocean clean-up



The Driftwood Spars Brewery, a pioneering microbrewery based on the North Cornwall coast, is donating a percentage of all profits from its Cove range of beers to Fathoms Free, a certified charity which actively cleans the ocean around the Cornish peninsula.

Each purchase of the small-batch, craft beers – there are four different canned beers in the Cove range – will help generate funds to purchase a remotely operated vehicle (ROV) and fund retrieval dives; every brew will raise the equivalent cost of a fully-funded dive. 

Fathoms Free is a Cornwall-based charity whose day-to-day mission involves dives from their fast-response specialist vessel to recover ghost fishing gear; abandoned nets, pots, angling equipment and other plastic causes severe damage to the marine environment and the death of countless seabirds, seals, dolphins and other sea life.

The campaign to raise funds for an ROV is a new initiative which will take the clean-up work to a new level; the highly manoeuvrable underwater vehicle will be used to scour the seabed, harbours and remote parts of the coastline for abandoned fishing gear and other marine litter.

Project Manager Natallia Paliakova from Fathoms Free said: “Apart from helping us locate ghost gear underwater, the ROV will also be capable of recording underwater video which is always great for raising awareness about marine pollution issues.”

She added: “We are really excited to be partnering with The Driftwood Spars Brewery and appreciate the proactive support of Mike and his team in bringing the purchase of an ROV a step closer to reality.”

Head Brewer Mike Mason personally approached the charity after their work was featured on the BBC 2 documentary, ‘Cornwall with Simon Reeve’.    

He said: “As a keen surfer I am only too aware of the problem of marine litter and had heard about Fathoms Free, but seeing them in action prompted me to find a way of contributing. The scale of the challenge is scary, but the determination of organisations like Fathoms Free is inspiring.”

Photo by Beagle Media Ltd

Photo by Beagle Media Ltd

The Driftwood Spars Brewery was founded in 2000 in Trevaunance Cove, St Agnes; the microbrewery is just a few steps away from it’s co-joined brewpub, The Driftwood Spars; both pub and brewery are well-regarded far beyond the Cornish cove they call home. 

You can hear the waves and taste the salt on the air from the door of both brewery and pub, and the rough seas along the rugged North coast often throw up discarded nets and other detritus; Louise Treseder, Landlady of The Driftwood Spars and a keen sea swimmer, often collects washed up ghost gear on her daily beach excursions.     

Louise commented: “This is a great partnership to support a cause close to our hearts – I know the money we raise will have a positive and lasting impact. The Cove range was inspired by our unique surroundings and the artwork – by local artist Jago Silver – reflects that. Now donations from each purchase will contribute towards the vital ocean clean-up taking place right on our doorstep.”

The Cove range can currently be purchased online here, and is available in good independent bottle shops in Cornwall.

To find out more about Fathoms Free visit their website here.

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This is the perfect start to your 2021 diving season… and at an incredible lead-in price of just £885 per person.

Jump on board the latest addition to the Emperor fleet and enjoy diving the famous sites of the Red Sea with this fantastic special offer. This itinerary takes in the wonderful South & St Johns from 26 February – 05 March 2021.  

Subject to availability – limited flight seats at this price so don't delay!

Call Diverse Travel on 01473 852002 or email to book your spot!

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