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REGULATOR Poseidon XStream Dive
I have no agenda against any particular brand of equipment but I confess to disliking the manner in which air is delivered by some Poseidon regulators. Its what I call the Captain Scott effect. I admit that there are many divers who seem to like the wind whistling round their tonsils. Not me.
     The Poseidon Xstream is little more than a year old now and I received an early model of this regulator that was specifically designed for use by deep technical divers.
     I was agreeably surprised. Its delivery of air was sublime. I pointed out at the time that, although Poseidon had deep tekkies in mind, there would be a greater majority of divers who had no intention of going anywhere near the 200m depth for which the Xstream Deep is certified but would like to own and use such a superior item of kit. To my surprise, I had become a Poseidon aficionado.
     Then Poseidon went and spoiled everything. For our top-of-the-range regulator test we were sent another example of the Xstream and our four testers each said it was horrible. I tried it and I had to agree. It was another tonsil-blaster in the old style.
     So what had gone wrong I can only think that in their rush to get a good result from our ANSTI machine, the fellows at Poseidon had tweaked that valve, but had forgotten that we were also going to have real people on the end of it.
     Well, looking back at my original test, I was right about one thing. There are just not enough deep-diving tekkies in the world to make a product specifically aimed at them financially viable. Mixed-gas diving is done by a very small minority in what is a small minority interest in itself (scuba-diving, that is).
     So diving-equipment manufacturers which want to stay in business are forced to look at the wider market. Hence we now have the Poseidon Xstream Dive, aimed at the discerning, air-breathing leisure-diver.
     Unused and plugged ports are seen as a potential failure point by purists with multiple tanks, but if you are diving with only one first stage you will need the five medium-pressure and two high-pressure ports supplied with the Xstream Dive.
     You will want an octopus second stage to sit alongside the one you are using. You will want a direct-feed to your BC, and possibly one to your drysuit too. You will want a take-off for a pressure-gauge and possibly one for the transmitter-unit of your air-integrated computer. I was pleased to find that there was space to fit this without the other hoses getting in the way.
     The Xstream is an upstream servo-assisted regulator. This means that the hose must incorporate a pressure-relief valve just in case it is subjected to full tank-pressure, and the servo valve has to take up the pressure when you first turn the tank on.
     This is why it is best to put your hand over the mouthpieces of the second stages to avoid them going into a dramatic free-flow.
     The loud sound of the rush of air escaping when turning on the tank each time resulted in many startled faces among the other divers in the boat. But once I had overcome this trauma and mastered the technique in such a way that the entire contents of the tank were not lost, all became well and I was able to return their frightened looks with a smug gaze.
     The Xstream first stage has a great coldwater design with a massive heat-sink in the form of an exposed spring that will put heat from the water presumably at a temperature above freezing and a lot warmer than the air from the tank.
     The mechanism is a balanced-diaphragm rolling ball-valve and uses fewer O-rings than most other regulator designs.
     Its second stage is one that can be used either way up, with the hose coming from the left or right. It exhausts exhaled air out to one side, well away from the face, avoiding the Jacuzzi-effect that is becoming so common on regulators with small exhaust-tees.
     Under water, I found that it was very light in the mouth and breathed as brilliantly as the original Xstream I had tried a year before. In fact, it gave me a broad flood of air at any leisure-diving depth to which I cared take it and, I even dare to say, this Xstream was extremely subtle in its delivery. Delightful!
     I now assume that some technician set that Xstream Deep to perform savagely for our earlier comparison, when what we want is a tame performance that leaves the diver feeling he has the whip-hand when it comes to inhaling.
The Poseidon Xstream Dive is not cheap. With octopus (and no other brand second stage will do, because of the higher than normal interstage pressure) it costs £653.
  • Poseidon 01420 84300, www.poseidon.se


  • Divernet
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    + Can be absolutely brilliant


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    - Rather expensive
    - Needs to be set up correctly