The Economics of Rebreathers: unused gas costs?

[feldomatic]

So I (physics and submarining background) get the idea that a rebreather is cheaper in terms of actual gas consumed, but don't you have to pay for all that bailout gas every time anyway?

Or is there some reusability if you didn't bail out? (can take same bailout mix/fill on a subsequent dive)

Relatedly, what's the split for OC vs CCR in terms of the unused gas burden? In other words, for each system how much gas do you buy that (casualties notwithstanding) doesn't get used on the dive?

 

[grantctobin]

If we ignore the concept of dilout (using diluent from your bailout), bailouts often stay full for years.

In some traveling venues, you do pay for the full fill. Some operators will refund you some % of what is returned, some will not. There are other threads on the topic if you search around the forum.

 

[gordonscuba]

Fill the bailout bottle(s) once, keep it filled, use it on many dives.

 

[tbone1004]

So I (physics and submarining background) get the idea that a rebreather is cheaper in terms of actual gas consumed, but don't you have to pay for all that bailout gas every time anyway?

Or is there some reusability if you didn't bail out? (can take same bailout mix/fill on a subsequent dive)

Relatedly, what's the split for OC vs CCR in terms of the unused gas burden? In other words, for each system how much gas do you buy that (casualties notwithstanding) doesn't get used on the dive?

this will largely depend on where you are in the world. Most people that own rebreathers will have a set of bailout cylinders that they own and at least in the US, since VIP isn't a legal requirement, the bottles will basically stay full for ~5years until they need to go in for hydro. At that point, most of us have, or have access to booster pumps so the gas is transferred into other cylinders.
Most of the gas stations that we use charge by the cubic foot so you are only paying for what you use which is nice.

When you travel, typically you would rent the larger bottles and hold onto them until the end of the trip so it's not like you are paying for them to be filled every day.

TLDR, effectively 1 full tank of unused gas burden when traveling at worst case, 0 unused gas burden if you own your cylinders.

 

[Wibble]

Depends if you "own" the bailouts or not.

You don't use the bailouts on a dive, aside from test breathing, so they can (often) be topped up using air to get the pressure back up. As you don't use them, they may be full for years and often go out of test (another cost saving!).

Depending on your dive profiles, you'd probably have different sets of bailouts for different depths. Mine are:

• <30m/100ft -- single 232bar 7 litre ali with 32%
• <50m/165ft -- two 232bar 7 litre ali cylinders with 18/35 and 60%
• <70m/230ft -- two ali 80s with "full fills" of 14/55 and 60%

I've several sets of 3 litre cylinders for different diluent and spare oxygen.

If you are away and need to rent, it may mean you have to pay for the fill and cylinder rental. Some may credit you for unused gas, others will take that as their "tip" and get really annoyed if you "had to do a bailout on the final dive".

 

[lostsheep]

… others will take that as their "tip" and get really annoyed if you "had to do a bailout on the final dive".

If I paid for the gas on a trip I’m using my gas however I feel fit. One nice thing about a Choptima is the last dive can easily be done OC.

 

[Wibble]

If I paid for the gas on a trip I’m using my gas however I feel fit. One nice thing about a Choptima is the last dive can easily be done OC.

Had a discussion with a reasonably well known organiser of dive trips to remote locations who strongly made the case for charging for the gas and was mildly annoyed at my suggestion that it'll make ideal bailout practice on the last dive.

I'm very much a person who doesn't like hidden charges and hidden margins. I avoid hotels with "resort" charges and hate mandatory tipping.

 

[GF99/99]

So I (physics and submarining background) get the idea that a rebreather is cheaper in terms of actual gas consumed, but don't you have to pay for all that bailout gas every time anyway?

Or is there some reusability if you didn't bail out? (can take same bailout mix/fill on a subsequent dive)

Relatedly, what's the split for OC vs CCR in terms of the unused gas burden? In other words, for each system how much gas do you buy that (casualties notwithstanding) doesn't get used on the dive?

Everywhere in the world I have dove the operators have a posted cost/liter for He and O2 and then at the end of your trip you just pay for what you used. Mostly dive facilities just have standard mix B/O sitting around ready for customers to barrow. Some shops charger you a "rental" fee for the B/O others charge a "booster" fee, others just don't depends on where you are at.

I have never heard of or dove with a facility that charges you for the entire unused B/O. Most dive centers/Liveaboards are pretty good about posting on there website how there B/O gas cost work. Basically as long as you don't B/O or have some kind of massive free flow while zooming around on a DPV your B/O gas bill should be very very low to nothing.

 

[grantctobin]

I have never heard of or dove with a facility that charges you for the entire unused B/O.

Truk Master is one.

 

[GF99/99]

Truk Master is one.

Wow! that sounds really expensive.