Why do you use a rebreather?

[Tomeck]

Why do you use a rebreather?

For a silence, to reduce stop decompression or to reduce the weight?

 

[sunkmail]

All of the above.

Plus the extra warmth of the breathing gas, longer dives, longer NDL, best mix all the time (Think nitrox blending station on your back)

And of course, Because it looks cool

 

[Mr.X]

And of course, Because it looks cool

"Extremely" cool was ten-twelve years ago. These days they are becoming commonplace.

A Cis-Lunar MK5p, MK 15, Inspiration or early Prism would spark instant lectures. They have certainly come a long way in a decade.

X

 

[Gilldiver]

The main advantage of a fully closed rebreather are extended gas endurance. It allows you to go longer and/or deeper without having to stage bottles or carry an excessive number of them with you.

A second advantage that many do not realize is that a rebreather lessens expedition complexity, both before and during a dive event. If 4 divers were to do 2 dives a day for three days of remote diving where they did not have a compressor, they might need up to:

If you figure that you will only burn through one set of deco tanks a day you still end up with:

2 sets of doubles x 4 divers = 8 sets (16 tanks)
4 80's of #1 deco gas = 4 tanks
4 40's of #2 deco gas = 4 tanks

24 tanks total

Total for 3 days of diving for 4 divers: 24 x 3 = 72 tanks

These are all tanks of 40 to 120 cubic ft - lots of weight, I hope you have a big boat.

Figure in the costs and time to get all these filled and the space they all take up in the truck or boat and the amount of work to get them to the dive site (walking to a cave?) and it is a lot of work.

In the real world, this is almost impossible, you have to bring a compressor and top off gas.

Do it on a Rebreather:

1 Dilutent tank per day per diver = 4 divers x 3 bottles = 12 tanks of 13 to 40 ft
1 O2 tank per day per diver = 4 divers x 3 bottles = 12 tanks of 13 to 40 ft

Plus a set of bail out of one 80 and one 40 for each diver (if you don't have to bail out, you reuse the same tanks

4 aluminum 80's
4 aluminum 40's

Total (Maybe)

24 20 cubic foot bottles of dilutient
24 20 cubic foot bottles of O2
4 al 80's of #1 deco gas
4 al 40's of #2 deco gas

So you now have:
48 small tanks for the rebreather
4 aluminum 80's
4 aluminum 40's

No compressor and top off gas needed.

It is just easier and a lot lighter and space savings, bBoth big factors on a boat.

 

[leapfrog]

So the bad guys don't see the bubbles on the surface.

 

[ScubaAl]

Maybe I'm missing something(hard to believe I know) but wouldn't it be 12 Del and 12 02 for the 3 day 4 diver 1ea per diver?

Also one of the great advantages is in fill prices. Helium is going for what at local dive shops $1.00 per cuft? Fill a double set of 120's vs a 19cuft dil bottle.

This past summer we did a 4 day trip to Isle Royale. Over the first 2 days I did 4 dives on one set ea of dil and 02. Used 2 of ea for the whole 4 days of diving.
Al

Do it on a Rebreather:

1 Dilutent tank per day per diver = 4 divers x 3 bottles = 12 tanks of 13 to 40 ft
1 O2 tank per day per diver = 4 divers x 3 bottles = 12 tanks of 13 to 40 ft

Plus a set of bail out of one 80 and one 40 for each diver (if you don't have to bail out, you reuse the same tanks


4 aluminum 80's
4 aluminum 40's

Total (Maybe)

24 20 cubic foot bottles of dilutient
24 20 cubic foot bottles of O2
4 al 80's of #1 deco gas
4 al 40's of #2 deco gas

So you now have:
48 small tanks for the rebreather
4 aluminum 80's
4 aluminum 40's

No compressor and top off gas needed.

It is just easier and a lot lighter and space savings, bBoth big factors on a boat.

 

[sunkmail]

"Extremely" cool was ten-twelve years ago. These days they are becoming commonplace.

A Cis-Lunar MK5p, MK 15, Inspiration or early Prism would spark instant lectures. They have certainly come a long way in a decade.

X

Just because it's more common, doesn't make it less cool :cool2:

And I get asked a lot of questions on my KISS almost every dive

 

[Mr.X]

Just because it's more common, doesn't make it less cool :cool2:

And I get asked a lot of questions on my KISS almost every dive

That's good.

X

 

[Gilldiver]

Maybe I'm missing something(hard to believe I know) but wouldn't it be 12 Del and 12 02 for the 3 day 4 diver 1ea per diver?

Also one of the great advantages is in fill prices. Helium is going for what at local dive shops $1.00 per cuft? Fill a double set of 120's vs a 19cuft dil bottle.

This past summer we did a 4 day trip to Isle Royale. Over the first 2 days I did 4 dives on one set ea of dil and 02. Used 2 of ea for the whole 4 days of diving.
Al

I was going for maximum absurdity, in the real world you are correct, it would be anywhere from 1 to 4 dil and O2 tanks per diver.

So min would be:
1 Dil and 1 O2, per diver total of 8 small tanks

max would be 4 dil and 4 O2 per diver.

You also have to add in a few cans of sorb, but that is minor compared to the tanks.

It all depends on the depth and duration of each dive.

Just as the number of double and stage bottles are max. What we would do is take 4 sets of doubles each with a rich Helium mix of 60 to 70% so that we can top off with air at least once and reuse each set.

I leaft Helium and O2 costs out, but as you noted the costs are considerable.

 

[Camerone]

I leaft Helium and O2 costs out, but as you noted the costs are considerable.

...and if you dive a lot of helium, it pays for itself in short order. Depending on the profiles you run and the local price of a K bottle of helium, a nice eCCR can hit the break even price in as little as 100 dives, less if you're diving an mCCR. Not only can you look cool, you can be smug in the knowledge that you're saving both dollars and the finite helium resources we've got

100 dives isn't even a year's worth of diving, so that's a pretty quick payoff...