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The Private, Exclusive Guide for Serious Divers Since 1975
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February 2014    Download the Entire Issue (PDF) Available to the Public Vol. 40, No. 2   RSS Feed for Undercurrent Issues
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DEMA Trade Show Follow-up

the latest innovations in rebreathers

from the February, 2014 issue of Undercurrent   Subscribe Now

While some sport divers, especially photographers, have switched from open-circuit scuba to rebreathers, their bulk and complexity make them a difficult choice for most traveling divers. They are not the sort of devices one can rent wherever one goes, so the travel hassle alone makes them unpractical for many.

Poseidon Se7enThat said, rebreather displays are still a significant element of the DEMA show, and the star of the show had to be the Poseidon Se7en. While not replacing the Poseidon Discovery MkVI, which continues on, this next-generation, closed-circuit rebreather (CCR) from the Swedish manufacturer looks more highly finished than its predecessor, with its works now enclosed in a smart casing with a carrying handle and lighting rails. That's just the icing on this cake.

Its new electronics, with entirely new firmware, is claimed to make the Se7en faster to set up, more flexible and more reliable. It can be configured as a limited recreational rebreather to 130 feet, or for deco diving to 130 feet, for trimix to 160 feet, for technical diving to 200 feet deep or even as a fully fledged 325-foot depth-limited CCR, simply by installing the appropriate color-coded battery, each with its own in-built electronics. Dive logs can be downloaded in seconds or settings updated as quickly, thanks to Bluetooth connectivity. Bluetooth also allows for faster and more convenient use of Poseidon's technical support. and detachable displays and sensors.

The mouthpiece that allows instant switching from CCR to OC has been upgraded, and the heads-up display features a green continuous function light, added to the red warning light familiar to those diving the MkVI. The Se7en can be combined with either a wing or standard style BC, and the technical counter-lungs have manual O2 and diluent addition valves.

I caught Bill Stone, the famous Florida cave explorer who originally came up with the concept for the Poseidon CCR, taking a coffee with equally famous deep diving ichthyologist Richard Pyle, who is known to be a proponent of the Poseidon. They both looked pretty pleased with themselves.

APD revealed a simple device that allows the Inspiration or Evolution user to validate the cells at 1.3 bar pressure in a unit. It has been introduced in the hope of avoiding any further unfortunate accidents in which people were tempted to dive with O2 sensing cells that were too old or otherwise not up to the job.

Of course, all the other established rebreather companies exhibited, including Inner Space Systems, KISS, JJ, and Hollis, with its semi-closed Explorer Sport and fully-closed Prism2. The Explorer Sport now has a vibrating warning device should the visual alarm not be responded to.

Many CCR manufacturers employ a Shearwater computer, such as the Petrel. Now, the complete computer information, notably more legible with both the Petrel and its predecessor, the Predator, is available as a true head-up display that for any diver with two good eyes appears transposed on the surrounding scene. Thanks to the optics employed, there is no need to refocus on a close-up image. Your eyes see the image as it would on a 32-inch television screen 15 feet distant. The display is unobtrusive, disappearing from view when you look past it.

Although the display part is obviously designed to fit on the breathing hose of a CCR close to the mouthpiece, it is available to conventional open-circuit divers too, and removes a lot of task-loading on difficult dives. The main electronics mount out of the way, behind the diver's head. I wasn't taken by the name though -- it's called the Shearwater NERD. It's expected to sell for $2,500. Again, this electronic marvel is Bluetooth-enabled, Shearwater desktop software is available for both PC and Mac, and a VPM algorithm is offered as an option.

PS: I got invited to the product launch of the Nikon 1 Awi, billed as "the first truly underwater interchangeable-lens compact digital camera that can operate down to 49 feet." Priced at $800 andwith 11-27.5mm f/3.5-5.6 lens, I thought this would be a digital Nikonos but alas, it is really an all-weather action sports camera that lacks a really wide-angle lens and has a depth-restriction of 49 feet. It is not really applicable to diving. A great disappointment.

John Bantin is the former technical editor of DIVER magazine in the United Kingdom. For 20 years, he used and reviewed virtually every piece of equipment available in the U.K. and the U.S., and made around 300 dives per year for that purpose. He is also a professional underwater photographer, and most recently the author of Amazing Diving Stories, available at

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