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Sentinel sensation 15 November 2008

Posted in Diving.

Simon and his VR Technology Sentinel Closed Circuit Rebreather

There are a few articles on my blog about Closed Circuit Rebreathers and of course you hear of them going wrong all the time. This is a quick article about my new Sentinel, what happened when it went wrong and why I bought the bloody thing...

My fellow 'tritone', Tony Bridge, recently wrote a piece about the training so I thought I had better justify why I plumped for a Sentinel.

It is also a great time to do it: 2309 on a Tuesday evening in the Isle of Man, sitting in my office which overlooks the bay, a large glass of red wine on my desk and listening to 'In Rainbows' by the mighty Radiohead.

If you follow my ramblings you may have seen my article where I nearly bought an Inspiration. In fact I had already booked the course and was just about to send the cash. It was at this point that I re-read my own diatribe and changed my mind; there must be something better!

As you will see from my previous writings, I had done a lot of research in rebreathers and once I had decided against the inspiration, I had another look around.

I had seen the Sentinel at the Dive Show last year and it did look very well built. However, following a very 'difficult' experience I had with my VR3 (also by VR Technology Limited), the poor service and the tales of woe and despondency from divers who had been foolish enough to purchase the fearsomely expensive Ouroboros, I really was not going to look again.

BUT I spoke to a few of my diving buddies and following excellent reports, I went to take a look again, first hand: see Tony's article).

What does it have to make me buy one?

Here is a riveting video: Kevin Gurr, the main man himself, talking you through the unit...

So, my key features:

  1. CE Approval: I can only teach when using a CE approved unit
  2. Single rear mounted counter-lung with good work of breathing: YEEEEAAAHHH, I have retained my clear front!!!
  3. Lithium polymer rechargeable batteries: with a 60 hour life and a six hour recharge time. It can also be recharged with our optional solar charger (which will also charge my iPhone and other peripherals - nice)
  4. Integrated Bail Out Valve (BOV): If you choose to use it, the unit has a Poseidon Extreme Deep fitted to the bottom of the mouthpiece; this is connected into the onboard diluent cylinder
  5. It has a primary colour display with full trimix diluent capability, a separate backup PO2 display along with a vibrating, Heads Up Display (HUD) and rear mounted buddy HUD
  6. Automatic oxygen cell calibration
  7. A Thermal Profile Monitor (TPM): licensed from the US Navy to measure the temperature of the absorbent in the scrubber. This information is displayed as a graph on the primary display indicating the remaining life of the scrubber
  8. Great software: counts the number of solenoid 'fires' and calculates a percentage remaining based on O2 metabolism
  9. Fantastic quality materials: Poseidon Extreme first stages, stainless steel pipework, Kent tooling backplates and the superb miflex hoses as standard
  10. Swagelok connectors: for attaching bail out gas into the diluent or oxygen sides of the system yes you can connect your stage directly into the loop without unapproved modifications
  11. 100m depth rating
  12. Beautiful Delrin body: yes, I am sad but it's turned really well
  13. Lovely connectors and breathing hoses
  14. Gas switching blocks for manual operation
  15. Ability to fully recover from a fully flooded loop: now you're talking...

Err... It's also black.

What happened when it went wrong

The week after I had completed my training I attended a RYA Coastal Skipper Course and Examination and then moved straight out the Isle of Man.

Of course once I had settled in (four hours), I wanted to take my new unit out for a spin.

I excitedly charged and prepared the device then attempted to fire it up. Nothing happened! I checked the charger, finally establishing the unit would only partially boot when the charger was attached and even then the menus would not work correctly!!! I was furious. On a positive note, the secondary handset (showing the PO2 from the three cells), was still working. If this happened under water you could drive the unit manually; actually, a very easy thing to do.

I called technical support and Al Wright, from VR Technology, talked me though swapping round the magnetic switches to establish if it was one of those. Whilst we were diagnosing the problem, he posted a 'reboot' connector which, when plugged in to the TPM connection port, surprisingly enough, reboots the system.

As promised, it arrived the next day! This appeared to be good customer service; I didn't see that one coming...

Unfortunately the reboot didn't work; I sent a mail to Kevin (Gurr), Freda and Al; I was getting overheated.

Whenever I buy anything I always go mad on spares and had bought everything that was recommended for the expedition diver. Of course, as the handsets and electronics are sealed into the head (very sensible - no connectors), the ultimate spare would be a backup head!

Anyway, I received a call first thing in the morning and Al offered to send me Kevin's head. I thought this was a little extreme, after all we are not in the 15th Century, but after further investigation Al meant Kevin's Sentinel head! The 'Vlad the Impaler' in me had almost accepted too...

It arrived the next day and I packed up my head and sent it back with the carriage costs credited against my account. Great service and again, not at all what I expected.

The factory quickly established the fault was a reed switch in the main handset. They swiftly replaced this and shipped my head back to me; I can now think straight.

So, the upshot is...

It's a fabulous unit but goes wrong like any other re-breather. The difference this time is that I really think Kevin has his service bang on... Well done VR Technology Limited.

I will keep everyone posted on my progress but if you want to know more of our exploits visit the expedition section of this site, our Triton Oceanic site and for more Sentinel training photos, visit my Flickr...

1 comment

Mike Taylor on 20 Nov 2008 at 2:21

No worries Simon.  If it goes wrong out here in Asia, simply slip local tap water into Tony’s Evian bottle and use his for the remainder of the trip while he’s on the loo

He spent most of the first week here chez bog, and I didn’t even need to borrow anything off him

Glad that you like the unit. Tony’s looked really well put together, and simple to use.  And, rather annoyingly, he looked very comfortable in it. Diving with you must be doing something for him.

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