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Wibble's CCR odyssey

Discussion in 'General Scuba Diving' started by Wibble, Jul 5, 2020.

  1. Wibble

    Wibble Fish don't talk
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    Had a wonderful dive today on a submarine. Beginning to feel comfortable with the rebreather and enjoy the dive and what’s happening outside, not just focusing on the box.

    Fish seem to be far less bothered with CCR than when blowing bubbles.

    I’ve a real soft spot for blennys and this wreck is covered with them. One though had a penchant for nibbling on our dry gloves if you invade it’s space.

    Reviewing the dive log, the ascent seems reasonable. Seems that the time spent on the platform has paid some dividends.
     
  2. Dave Whitlow

    Dave Whitlow Super Moderator
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    An interesting sub?! Which one was that ? I recently revisited a memorable (for me) sub dive (HMS Sidon was my BSAC Sports Diver 35m progression dive, and the first time I saw a SAR helicopter in anger!). I found it was as dull as I remembered (long tube with a lump on top) and went gathering a bag of scallops as compensation. The ascent was useful practice for holding stops. I even followed my recent advice and let go of the reel and used it as a reference point, rather than a buoyancy prop :)

    Just remember when ascents go wrong on CCR (as I've seen they can - never tried it myself :) ) there are more things to put right so the wrong is harder to correct. On CCR, as the diving is so simple, it is usually complacency that creates the fateful incident.
     
  3. Wibble

    Wibble Fish don't talk
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    I find submarines both sad and interesting. Their only purpose is death and destruction. They only appear as a dive site as the tables were turned and they were the prey.

    The are the pinnacle of contemporary technology at that moment.

    Now getting the hours and ascents in. Definitely not complacent yet — still very new.
     
  4. Wibble

    Wibble Fish don't talk
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    Managed to pass the 25 hour milestone on the Revo and I’m still alive. Not only that but I’m absolutely loving the experience. No bubbles; undisturbed animal life; lack of crap (percolation) falling down from above as bubbles disturb rust and silt; less time spent preserving gas and more time spent enjoying the diving.

    The descent and bottom phases are fine, buoyancy's now pretty much cracked. As predicted the ascent phase is most challenging to control the buoyancy and wind the spool, whilst monitoring and injecting the right amount of oxygen. Although a statement of the bleeding obvious, found that taking things easy whilst doing slow and controlled ascents works best.

    Have added the first modification to the Revo, sidemount bungees to get the bailout cylinders back and streamlined. Bailouts now have modular valves, so just a matter of adapting the existing sidemount skills To CCR diving. So lots more bailing out drills to practice.


    The intention is to get to 50 hours on the unit by the end of September.

    A small but very significant Billy Bonus is how cheap it is to run. Have now started down the helium path and to have a set of fills and a scrubber fill costing less than £20 is brilliant. As is not having the back-breaking task of carrying a twinset and multiple stages.

    The next set of dives are in the 30 to 40 metre range. Beginning to optimise the bailout gas for when a failure occurs to force a bailout at the end of the bottom phase. Just a matter of applying the standard ANDP/normoxic backmount planning.

    Well chuffed with progress thus far.
     
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  5. Iain Denham

    Iain Denham Active Member

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    If I`m honest I always find subs a tad boring.
     
  6. Dave Whitlow

    Dave Whitlow Super Moderator
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    Agreed. I filled a space yesterday and dived U322. It had a pointy end, a conning tower, and a propeller at the back. There were a few other features and a hole where the depth charges had done their work.
    The take home features were the 5lb lobster out for a walk and the 4lb crab looking for a change in scenery. I didn't trust them to play nice so they had separate accommodation for the journey to the final phase of their life.

    The annoying part of the dive was that my OSTC cR and Vision didn't agree on my TTS. Usually they are pretty consistent. I'd been fiddling with it the day before (including setting it to OC and air as I was thinking of doing a shore dive). It was set to CCR mode, it was using sensors to monitor ppo2, the GF values matched the Vision (60/85), and the gas mixes were the same. I was puzzled. The OSTC cR was adding TTS faster than I'd expect for a 50m dive (should be just over one minute per minute). At 40 minutes the Vision was showing TTS of 50 minutes but the OSTC cR was showing 80 minutes putting me close to the 2 hour runtime I'd told the skipper. At 100 minutes the Vision cleared whilst the OSTC had clocked down to 50 minutes. Rather than bending the OSTC (that would be rude) I switched it to the alternative GF of 100/110 and it decided 7 minutes TTS was now required. I let it clear and then took my time surfacing. As @Wibble would appreciate I like to gradually get shallow and practice holding very shallow stops. I surfaced at promised 120 minutes and was greeted by a full boat so no waiting around! Pretty picture added for you @Wibble

    At home I checked the computer and found two settings in a menu I rarely visit had each received a single button push (oops). The 'Desaturation' setting was at 60% rather than 100% and that fully explained my annoyance.

    [​IMG]
     
    #66 Dave Whitlow, Aug 17, 2020
    Last edited: Aug 17, 2020
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  7. barrygoss

    barrygoss Active Member

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    Somebody did Mary Poppins

    Single 15l OC for me, I went shopping on Peveril ledges. Scallops
    Got home and paid my medical insurance (the next door neighbour is the bloke who decides if you get ventilation or palliative care at Northampton general, his wife loves scallops) and then cooked the Mrs dinner.
    Back again bank holiday weekend.

    B
     
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  8. Vanny

    Vanny Well-Known Member

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    Aeolian sky for me and my son. Great dive , good vis followed by lifting scollops off lulworth banks , some will go to the boat yard man. Happy days
     
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  9. barrygoss

    barrygoss Active Member

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    Where do you keep your boat?

    B
     
  10. Dave Whitlow

    Dave Whitlow Super Moderator
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    Always do. I rather enjoy it, it saves a lot of winding, and minimises ongassing on the way to the first stop. I also wasn't sure how much TTS the GF switch would give and I didn't want to bend the computer, or be late.
    Nice to see club diving still happening.
     
  11. Vanny

    Vanny Well-Known Member

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    Ferrybridge.
     
  12. barrygoss

    barrygoss Active Member

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    Bill for the weekends rib diving £22
    Oh and £10 a month for two ribs, a pool twice a month in summer, 3 times a month in winter.
    The DO doesn’t care as long as you’re safe, all the free training you want and SDC’s organised for whatever you want.

    B

    p.s. I’m the DO ;)
     
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  13. barrygoss

    barrygoss Active Member

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    George got a couple of dozen Sunday as well ;)

    We’re the rib with the ladder ;)

    B
     
  14. Vanny

    Vanny Well-Known Member

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    Ah nice. We’re the rib that’s always flat ! George is spoilt.
     
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  15. Wibble

    Wibble Fish don't talk
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    Nice curves

    What gases were you using?
     
  16. Tribal Chestnut

    Tribal Chestnut Well-Known Member
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    How old is your son?
     
  17. Vanny

    Vanny Well-Known Member

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    He was 16 in June
     
  18. Tribal Chestnut

    Tribal Chestnut Well-Known Member
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    Same age as my little one. I can’t tempt her into UK sea diving though.
     
  19. Vanny

    Vanny Well-Known Member

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    My son loves uk Diving , his twin sister isn’t so interested. Her kits here but she hasn’t been fussed to dive. I’ve got to take her out again on the Rib though to look for the dolphin. If we were abroad she would’ve had a dive or 2.
     
  20. Dave Whitlow

    Dave Whitlow Super Moderator
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    Sim
    :eek: That feels like a question from OC thinking as I suspect the profile wouldn't change much with different gases.

    I have banked oxygen and 15/55. The diluent had a slight air top and was 16/41. Bailouts were bottles of 15/55 and 62% that I take on many journeys, and hope to never use.
     

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