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Poseidon Discovery Review

No-one knows what future dive-gear will look like, but Poseidon is sure it will leave no bubbles. Its closed-circuit rebreather the Discovery VI is the breathing gear the Swedish manufacturer hopes will revolutionize diving.

IN THE 1990S, Audi developed a new small car model. It took a bold step in deciding to bolt the bonnet shut. It concluded that today’s car engines were too complicated for the owner to fiddle about with, and that there was little the driver could or should do.

So the A2 model was built with an openable front grille, so that the driver could check engine oil and brake and cooler fluid, and refill the screenwash. That’s it. The A2 was for those who wished to focus on driving – and nothing else.

Jonas Brandt and his crew in Poseidon’s R&D department followed similar principles when they developed their new rebreather. Discovery VI is a fully closed, fully automatic rebreather for sports divers who want to go to a maximum of 40m without decompression. The number of procedures to be performed by the diver has been minimised – to decrease the risk of “human error”. Poseidon believes that the typical Discovery diver will be a middle-aged gentleman who has been diving for some time and wants to “spice up” his diving, but is not interested in submersing himself into technical diving, great depths and prolonged decompressions.

Poseidon also wanted to design a breathing “machine” that could be handled by someone who had never even tried diving before. As long as the Discovery functions normally, the user should feel no need to pay more attention to it than he would to the pressure gauge with open-circuit scuba gear. An experienced diver should need to spend no more than 15 minutes assembling his Discovery, and preparing it for the dive.

A closed-circuit rebreather is an advanced and complicated piece of equipment. Up to now the intended customer base has been relaxed about fiddling with settings, preparations and pre-dive tests. So how do you design a rebreather for those who are less relaxed?

According to Poseidon, the solution is called “Pre Dive”. The Discovery VI needs slightly more than two minutes to pass a self-test of approximately 30 items before you are allowed to start the dive. The test includes leak checks, oxygen sensors, gas pressure, battery condition, software and so on. Unless everything is OK, the message will be “Stop”.

We encountered this ourselves before we could splash into the Poseidon pool on our try-out dive. The Discovery needed three test runs before it was entirely satisfied with the set-up. Among other things, one of the O-rings in the gas loop turned out to have a tiny leak.

To minimise the risk of errors in refilling and packing of the scrubber, Discovery is supplied with ready-to-use scrubber canisters that last for three to six hours. The price of a scrubber canister is about £21. Add to this the cost of refilling the gas supply, and you have a running cost of around £8 per hour.
“We were pleasantly surprised when some interesting and unexpected customer groups started making requests. We didn’t have those in mind when we developed the Discovery – military units and rescue services. They have shown a keen interest in our ‘plug and play’ concept,” says Jens Sjöblom, Poseidon’s Sales Manager.

The Discovery has a unique design, in that it has only two oxygen sensors, but these are subject to constant recalibration while it is in use.

This is done using micro-valves that blow minute amounts of pure oxygen and air alternately across the face of the cells, so giving two calibration points. It was a system originally conceived by cave-diving veteran Bill Stone, the inventor and designer of the original and very complex CIS-Lunar rebreather.

Initially it had been intended that the Discovery would have a single sensor, so reliable was this concept thought to be. Market research since proved to Poseidon that the diving public had yet to be convinced that a solitary cell would be up to the job, and a second cell was therefore added to the design.


Finally it was time for the test dive…..Continued


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