Rebreather - Cost of Ownership

[doctormike]

[USER=15922]@doctormike the rig isn't that bad. I have a rack with 50's, a pair of 3l's *one more than the GUE setup*, and a meg in it. It's no worse than a set of big doubles *LP120's* and IMO a helluva lot less cumbersome than a "Standard" rebreather and sidemounted 50's.

[/USER]

Yeah, clearly a tradeoff, putting some of your bailout on your back instead of sidemounted. Just basing this on lifting my buddy's rig compared to mine. I dove BM doubles for years, I definitely think that it's more cumbersome than that. I guess I can see the advantage.

But my point was that the OP doesn't HAVE to adopt that non-standard configuration just because his prior training was with GUE.

 

[tbone1004]

@doctormike fair. Total rig weight is no worse than cave filled PST 104's, and while it is a couple of inches taller on your back, it is SO much nicer when diving off of boats than the sidemounted bottles. That configuration is truly amazing which is why I went to it immediately after Mod1 class

 

[doctormike]

@doctormike fair. Total rig weight is no worse than cave filled PST 104's, and while it is a couple of inches taller on your back, it is SO much nicer when diving off of boats than the sidemounted bottles. That configuration is truly amazing which is why I went to it immediately after Mod1 class

Hmmm... maybe I'll try it!

One issue is that I would have would be the need to fill two 50s and my O2, as opposed to 2 3L bottles that fit in my messenger bag (important for NYC based divers). I don't have much trouble clipping off an 80 on the boats - I sidemount between a heavy bungee loop on the plate and the very useful JJ stand.

I guess you get used to recalculating your available bailout over a weekend as you use dil.

 

[rjack321]

Hmmm... maybe I'll try it!

One issue is that I would have would be the need to fill two 50s and my O2, as opposed to 2 3L bottles that fit in my messenger bag (important for NYC based divers). I don't have much trouble clipping off an 80 on the boats - I sidemount between a heavy bungee loop on the plate and the very useful JJ stand.

I guess you get used to recalculating your available bailout over a weekend as you use dil.

Getting refills of a small set of doubles on a rack (the 50s) is a pita compared to boosting from a banked bottle of trimix with a tiny cheap booster into a 3L

 

[rjack321]

Personally, I do somewhere around 20 technical dives per year. All of my tech dives were on 18/45 with 50% deco gas. Filling my back gas and deco gas averages anywhere from $120-$140 per dive. Gas wise what savings in gas expenditure can I expect?

My gut feeling is that the "savings" math will never pencil out at 20 tech dives a year.

My other gut feeling is that you will end up doing 30 or 40+ tech dives a year on CCR compared to what you do now.

If you can afford the upfront costs and want to dive mix whenever you want get the CCR. If your family (buddies, weather, boats etc) is really the limiting factor and you realistically are never doing more than 20 tech dives a year anyway then staying with OC is probably the wiser move.

 

[tbone1004]

Getting refills of a small set of doubles on a rack (the 50s) is a pita compared to boosting from a banked bottle of trimix with a tiny cheap booster into a 3L

agreed, I do have a booster so keeping them topped off is easy for me, but with that much dilout, you aren't going to need fills often. Standard AL80 with 75cf of gas in it, double 50's have around 130cf total. 3l has 23cf if you get a full fill.
The standard GUE configuration uses the 50's as "dilout" and they have a normal sized drysuit bottle in the usual configuration. I thought that was ridiculous and hated the unbalanced look, so I put a second 3l on the back that I used for wing and suit inflation. You can see the splitter in the picture below that went to wing and drysuit. You could easily use that plumbed in the same way the standard 3l's are plumbed in though and not have to worry about filling the 50's. If you are diving trimix, you can still use the 3l for wing inflation and/or dil, then use a drysuit bottle on your left hip.
You can see the size below with 50's. Overall width is maybe 2" wider than a set of 8" doubles, and it's about 2" deeper. That's basically the equivalent of diving 10" doubles instead of 8" doubles. For everything but DPV cave diving, it's the tits since it is almost fully self-contained. The only thing you need is deco bottles if you can't do it on backgas.
In a cave it's not terrible and I put a bunch of hours on it in the caves, but it is quite restrictive for me being used to OC sidemount not going where I want to go because I don't fit. On a DPV, it's also the equivalent of an air brake on a fighter jet, and you can feel the drag and can feel it pulling your head up which takes some getting used to to sort with your fins. I didn't put LOLA valves on it because it was a temporary cave unit for me until I got my smCCR up and running and for OW I didn't see the need in spending the money on the manifold.

This is the actual GUE JJ configured with the second 3l. A buddy of mine was diving his with a single bottle and bitching about the size of the drysuit bottle for cave diving so I showed mine to him and he stole it. I think the GUE JJ is a little bit thicker because of the orientation of the LP50's. The rack on mine puts the bottles right up against the backplate and look to be a bit farther forward than they are with the JJ, but that may be an adjustment you can make.

One other thing to think about that I'm planning to do and have seen a few times in cave country. You can dive doubles or even singles as dilout, and use a sidemount CCR with an O2 bottle mounted to it and dive it as a sidemount bottle.

 

[Superlyte27]

I break this down for you guys every year. Based on 300 hours per year underwater, your cost per hour at any depth is under $10/hour.

That includes EVERYTHING except initial purchase and training.

 

[rjack321]

The standard GUE configuration uses the 50's as "dilout" and they have a normal sized drysuit bottle in the usual configuration.

Part of why I don't like this is the dilBO concept in general.

On my "normal" 180 to 240ft kind of dive I bring 15/55 BO in an 80. It's been full for years.
And jack the helium in my 3L. 18/45 or 10/50 is the least helium I really ever use. For bigger dives I just use 10/70 even if its "only" 240ft. The 50s are just not that versatile so you have to "pick a dilBO" and unless you have multiple racks its hard to change. I can have a collection of 2L and 3L dil bottles that I bring on a trip. Refill my O2 from my booster, swap out to a fresh dil bottle suited for the depth/duration and just keep the one 80 of 15/55 as BO. (plus deco gas)

If you only have the 50s and you do progressively deeper dives over a long weekend you end up doing your deepest dives with the least amount of BO. They are a challenge to top up with a mini booster even if you bring along some premix. If I had a more industrial scaled booster my attitude might change, but they are still nearly impossible to haul over the tube of my RIB without help (double 130s are also a major pita)

 

[tbone1004]

@rjack321 diving out of a rhib I'd certainly consider a different option. For that I'd probably go for small doubles of dilout and sidemount the rebreather, but I have an AG30 in a pelican case and only need 110v power to run it.
In your situation I'd probably do double 100's and a sidemounted breather just due to the rhib issue, but off of a big boat with a ladder.
The baby boosters not liking going much over 3000psi due to the 25:1 ratio are a bit restricting indeed.

 

[Jack Hammer]

@Jack Hammer where are you buying your cells from if they're that expensive? $75 each from DGX.

I just used a generic price guess with shipping and taxes. Actual JJ Vandegraph cells currently range from about $100-$130 ea depending on where you get them. The DGX sensors are made by Analytical, not Vandegraph. Some folks prefer the "factory" sensors over "aftermarket", some folks dont care.