Question Tri-Mix regulator questions

[PfcAJ]

Yes, they are safe. Take a class on one and you can learn there is plenty of safety in a rebreather. They only appear unsafe if you don't know them or only know a little bit about them.

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Do you really believe that? Or does it help you sleep more soundly?

 

[broncobowsher]

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Do you really believe that? Or does it help you sleep more soundly?

So what is your rebreather experience? Have you had any training on one?

 

[rob.mwpropane]

Personally I dream about RB's. They're fascinating and I'm sure I'll get there one day... but let's be honest. There's so much to see in the 100', 130', 160' range it'll be years before I need a CCR. Maybe by then they'll be simpler / safer / less expensive... who knows. I sure am enjoying the journey now though.​

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OP, just enjoy the ride.​

 

[grantctobin]

So what is your rebreather experience? Have you had any training on one?

 

[tbone1004]

But what about the start up costs for buying a rebreather and the training required to be able to do the depth you want? What about maintenance and the safety factor?

$10k to get into it, about $300/yr in annual maintenance.
6hr dive is the best way to compare it because it's a full scrubber.
Sorb is currently $3.86/lb from DGX so call it $4/lb for sorb. $24 to fill the scrubber.
You use somewhere between 1-2lpm of O2, so call it 2lpm for 360mins=26cf of O2 -> $12 of O2
I'm too tired to do the fill math but call 18/45 $0.60/cf and on that dive you'll probably use about 30cf for round numbers with inflation and what not, so call it $20 in Trimix.
Total cost of that dive is ~$60 in consumables.

To do that dive on OC.
Call it 1:1 ratio of deco at 6.5ata because I'm tired and this laptop doesn't have deco planner. 180mins at 6.5ata with 0.5cfm SAC ->~600cf of trimix used for the bottom mix -> $360 of trimix
Let's be generous because again too tired and say the rest of the 180mins is at 20ft on O2 ->170cf of O2 ->$80. Obviously the deco gas cost will probably be higher once you factor in EAN50 cost and total gas consumed, but all of these numbers favor the OC dive with the CCR numbers rounded up and the OC rounded down.
Total cost of ~$450 in gas.

Do that dive 25 times and the CCR and training just paid for itself *assuming you already have OC Trimix/ANDP. If it takes you 3 years to do those 25 dives then it's basically an extra dive/year to cover new cells/o-rings. Now that is an extreme dive, and the reality is that most people are only doing 2 hour or so dives at which point it's probably about 80 dives once you factor inefficiency in sorb use with unused sorb, but they will pay for themselves fairly quickly. If you factor in full trimix depths it's obviously that much faster.

 

[happy-diver]

So what is your rebreather experience? Have you had any training on one?

Mate he's not beating down on a steel rubbish bin lid next to your head after a nightshift

It's a great thought provoking question

 

[GF99/99]

Oh yes, many saving. Such frugal.

$10,000 rebreather…

But what about the start up costs for buying a rebreather and the training required to be able to do the depth you want? What about maintenance and the safety factor?

$10k to get into it, about $300/yr in annual maintenance.
6hr dive is the best way to compare it because it's a full scrubber.
Sorb is currently $3.86/lb from DGX so call it $4/lb for sorb. $24 to fill the scrubber.
You use somewhere between 1-2lpm of O2, so call it 2lpm for 360mins=26cf of O2 -> $12 of O2
I'm too tired to do the fill math but call 18/45 $0.60/cf and on that dive you'll probably use about 30cf for round numbers with inflation and what not, so call it $20 in Trimix.
Total cost of that dive is ~$60 in consumables.

To do that dive on OC.
Call it 1:1 ratio of deco at 6.5ata because I'm tired and this laptop doesn't have deco planner. 180mins at 6.5ata with 0.5cfm SAC ->~600cf of trimix used for the bottom mix -> $360 of trimix
Let's be generous because again too tired and say the rest of the 180mins is at 20ft on O2 ->170cf of O2 ->$80. Obviously the deco gas cost will probably be higher once you factor in EAN50 cost and total gas consumed, but all of these numbers favor the OC dive with the CCR numbers rounded up and the OC rounded down.
Total cost of ~$450 in gas.

Do that dive 25 times and the CCR and training just paid for itself *assuming you already have OC Trimix/ANDP. If it takes you 3 years to do those 25 dives then it's basically an extra dive/year to cover new cells/o-rings. Now that is an extreme dive, and the reality is that most people are only doing 2 hour or so dives at which point it's probably about 80 dives once you factor inefficiency in sorb use with unused sorb, but they will pay for themselves fairly quickly. If you factor in full trimix depths it's obviously that much faster.

@tbone1004 pretty much nailed it!! and if you live in a place like Indonesia where gas prices have gone up about 40% in the last 2-3 years and your doing sub 100m dives the cost between CC and OC is huge. I have worked it out many times and OC is about 10x the cost as CC

100m OC dive is about $1,000 is gas
100m CC dive is about $100 for gas and scrubber

10 dives on OC would have bought you a rebreather. Also $10k for a rebreather is for a new fancy unit you can always pick up used units for much less. Just clicked in the classifieds section and as of today the first post I clicked on is a JJ divecan version for $7,300. So that would drop you down to 7 dives. That it 7 dive on OC pays for a unit.

As far as "safety factor" well that's what OC bailouts are for and generally you plan OC bailouts very very conservatively I usually plan 45l/min for bottom gas 35l/min intermediate gas and 20l/min for deco gas. This is alot more safety factor then regular OC diving.

Lastly you if your strictly OC diving you will always have lots of partial trimix fills that you are always playing around with trying to figure out what to do with and they kind of dictate your dive profile. On CC you can just keep your dedicated bailout use them for a wide variety of dives and you only have little 3l tanks your constantly playing around with mix wise. Also less gas waste.

 

[tbone1004]

If we want to be really pedantic, then CCR is actually cheaper than nitrox diving too though, but you have to do a LOT of it to get it to work.

If we change the trimix over to Amigos current nitrox pricing it's about $40 for a scrubber/o2/nitrox to do a 6 hour dive.
If you were to do a 6hr dive in Peacock with an average depth of 2.5ata with a 0.5cfm SAC rate *no deco* you would use about 450cf of nitrox which is about $75 worth of nitrox.

Call that a $25 delta because of inefficiencies with not always being able to use a full scrubber and that's 400 scrubbers to break even or roughly 1500 dives with most peoples dives being around 1.5-2hrs. That's an insanely long ROI to get it to pay for itself with even very active cave divers only doing about 50 dives/year, but it would technically pay for itself eventually. I certainly wouldn't recommend buying a CCR if you're only doing shallow 2.5ata dives but if you already have the breather and are not wasting sorb, then it is technically cheaper per dive to use the breather even at Peacock.

 

[PfcAJ]

So what is your rebreather experience? Have you had any training on one?

I’ve done a few rebreather dives. Some of them pretty interesting.

 

[Wibble]

The OC twinset fill price answers you've seen on here aren't particularly accurate.

• The first fill costs the full amount
• Subsequent top-off fills are cheaper because it's not a full fill, just a top off. At least a third will be left over
• You do need to buy a second (third, forth...) twinset so that you've the flexibility to be gassed up for deeper dives, but have an air/nitrox filled one for shallower dives

Finally... Standard gasses are ridiculously expensive and few people, except those who follow the rools, will dive those gasses as they'll dive the right gas for that dive.

Example: 45m/150ft dive. The "true" gas would be 21/35. The pragmatic gas is 25/20 or thereabouts. Even a 'bit' of helium to knock off the narcosis would help: 25/15 or even 25/10. Those mixes are far cheaper than a standard mix.

It's all down to your personal disposition to narcosis, plus the type of dive (is it a pinnacle dive, much work at depth, need your head screwed on...).