PfcAJ
Contributor
50s are sweet for anything off a boat.
DIR- GUE GUE CCR Discussion (split from Tec Pass Thread)
- Thread starter helodriver87
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PfcAJ
Contributor
I just don't see a good reason to use dil/BO combined for ocean / great lakes dives.
Getting a single 3L refilled is easy (or bringing a bunch of them) plus I can dive however much helium I feel like even on shallower dives. 10/70 dil for any contingency? No problem just pick the 80 of deep BO that suits the dive. I never end touching my BOs, they never need top ups. I can bring a BO gas from 32% all the way down to 15/55 plus a 80 of 50% and a 40 of O2 and I'm covered for basically any plausible dive from 20ft to 260ft
I know plenty of people pushing it on what they do on backmounted 50s because topping them up is a pain and hard to do with a baby booster. And tons of places won't overfill them which is a serious cramp.
bubblemonkey2
Contributor
As someone who hasn't put the 50s on yet, despite having some--100cuft of dil/BO on the back seems convenient in that it's one less BO cylinder to clip/juggle, and could be plumbed into a BOV without any spaghetti off the stages or QDs. Does that count as streamlining?
I guess the idea of the 2x50's is to do your regimented "25(+) experience dives" at a time, with a fixed "standard gas" under specific parameters (depth/time limits)?
How many dives worth of dil and wing fill can you take off the 2x50s before they are deemed insufficient for a Minimum Gas Bailout Ascent(tm?) Is it problematic to top up a mostly full trimix cylinder(s) for Minimum Gas purposes?
Does one do a "practice BO ascent" or something just to get rid of (waste?) 50+cuft of the current mix in favor of the next 'deeper' mix? Or else, keep it in there, and do what is alluded to/quoted above?
Locally its a pita the top off 50s and no shop will go above 2650 either. So you got people doing trimix dives starting with 2000psi (or less). And on top of that its 18/45 for everything because its too much hassle and expense to have multiple sets of 50s with a variety of mixes. Plus you lose helium through the Teflon hose flexible manifold so last month's 18/45 turns into 18/38 or something if you forget to shut off the isolator posts. Plus the whole thing is ghastly heavy which is ok if your boat has a lift or a great ladder with ideal step distances. But hauling it back aboard a RIB is a 2 person job for sure. And so-so ladders and narrow door openings are an extra mess because of the weight and the width.
Every system has flaws, including the 50s.
PfcAJ
Contributor
bubblemonkey2
Contributor
What if someone were to just keep diving them at less than full, and carry extra BO cylinders if/as needed? Resourceful, back-breaking, or worst of both worlds? I heard that once you're in the water you don't even notice them?
Do people visit the shop for a top-up to 2650 after every single dive then?
PfcAJ
Contributor
id generally vote no for that.
the whole point of backmounted bailout is to have a large supply immediately accessible. Carrying extra stages to make up for the missing volume due to a surface logistics issue isn’t the best method, in my opinion. Option 1: don’t dive.
Maybe diving with less than full tanks is ok for shallower stuff, but anything in the hypoxic gas range needs full ones. You can math it out and decide for yourself. I still would shy away from taking a stage though.
I was invited to participate in a multi day open water project involving very deep rebreather diving. I went as far as sourcing a 2nd set of lp50s configured for the rb80 because I didn’t want to dive with less than full tanks. I could have transfilled from al80s, but I still wouldn’t end up with the volume of full (3300psi+, 2640 is NOT full) Lp50s. Unfortunately the ‘rona has gotten in the way and I won’t be able to participate this year
unwise for the same reason the backmounted 50s are only for baby cave diving
The reality is that if you need frequent top offs especially if you cant get FULL fills in the first place. So you are dependent on having a good booster around not a itty bitty CCR bottle booster. And you also need banked gas because its not that easy to accurately mix 600psi of 18/45 or 15/55 etc. Better to make up an al80 of the desired mix then top off from that. Which sounds simple... Except lots of back of the boat or back of the pickup mixing stations aren't really that sophisticated. And there are plenty of CCR charters filling 10/50 as a default dil because its so simple. So asking for 15/55 gets you lumped into the hassle diver bin. The 50s, slightly low on gas, and needing to be topped up to 3600psi is just not a very flexible and adaptable place to be.
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