"Guided" 200' dive with a single AL80?

[JeffG]

...not if you have a rebreather.

yea, but I remember seeing a thread on the "real" cost of going rebreather. The consensus was around $10,000 - $15,000

That can buy a lot of helium for open circuit dives.

Basically...Its hard to use the price of helium as justification to buy a rebreather.

 

[Cave Diver]

yea, but I remember seeing a thread on the "real" cost of going rebreather. The consensus was around $10,000 - $15,000

That can buy a lot of helium for open circuit dives.

Basically...Its hard to use the price of helium as justification to buy a rebreather.

I'm justifying the cost of buying one as the opportunity to expand my diving in areas that are now logisitically prohibitive. Using current open circuit setup, certain dives will require either multiple sets of doubles, numerous stages, or both. I'm looking at the rebreather to extend the distance and duration of certain dives while reducing equipment considerations. Reduced gas costs are just an added bonus.

Plus I just want one!

 

[PerroneFord]

I'm justifying the cost of buying one as the opportunity to expand my diving in areas that are now logisitically prohibitive. Using current open circuit setup, certain dives will require either multiple sets of doubles, numerous stages, or both. I'm looking at the rebreather to extend the distance and duration of certain dives while reducing equipment considerations. Reduced gas costs are just an added bonus.

Plus I just want one!

You know, I just can't see it this way. I've been going back and forth on getting a rebreather before the jump to trimix. But here's the problem.

In cave, you have to plan for that RB to fail at the distance of your maximum penetration. If I am swimming in a cave at 100ft deep, and I am 3000ft in, I now need OC bailout to go 3000ft. Assuming I swim at the average 60fpm, I am 50 minutes from the door, plus deco. If it's 50 minutes out, it was 50 minutes in (assuming no flow). So my deco is for 100 minutes at 100ft. I cannot assume my oxygen tank will be there when I get back, so I have to run worst case and plan the deco with the oxygen and without. For a 100ft dive, I'm going to be on EAN32.

Vplanner puts me at 40ft for a minute, 30ft for 10 minutes, and 20ft for 60 minutes.

For my SAC rate, 50 minutes at 100ft puts me at ~160 cuft of gas. So I need ALL of 2 AL80s plus a bit to get to the door, plus another 80 for deco on 32%.

The benefit to the RB is that I actually can make it to 3000ft pen. on thirds with ease. But the bailout plan is exactly the same as if I'd had done it on OC.

In OW, things get a bit easier because I have no horizontal distance to travel, and bailout only has to cover my ascent. And since I am carrying all my gas with me, the likelyhood of "losing the gas" is far less. Other than an o-ring failure on the tank, I am going to have my gas.

So I just don't see this massive savings of gas unless you are doing recreational level dives with no, or minimal deco where you could get away with just carrying a 40 or an 80.

 

[Mike Edmonston]

So I just don't see this massive savings of gas unless you are doing recreational level dives with no, or minimal deco where you could get away with just carrying a 40 or an 80.

This should really get split into a "Rebreather bailout considerations" thread.

Your point is valid Ford, but there are alternatives. You can choose to stage a couple of 80's in the cave as you go, and have a 40cf bailout on you for emergencies. You can use the 1.5 team rule, or you can sidemount a pair of 80's if you like.

The thing to remember with a rebreather, is that it doesn't go by the "clock" like OC.
By clock I mean, gas pressure, sac rate, 1/3's etc... It really gives you more freedom to explore.

Also in remote areas (central America in my case), it really makes more logistical sense to get 23cf of Helium, and still dive for 2 days.

IMHO, Rebreathers are SAFER than OC in the long run. On OC, your life is "Timed" to the amount of gas in your tanks vs your sac rate. On a Rebreather, the rate is determined by the body's ability to metabilize o2 and expel co2. In oc, if you lose a majority of your gas, your existance underwater is dramatically shorter. On a rebreather, if my o2 decides to freeflow, shoot off my back and imbed itself in a cave wall, I can still run the machine SCR and make it out with plenty of gas for DECO. Rebreathers give you time to think, assess the situation, make informed decisions, and get out alive.

Even if I had a complete loop failure and flooded the stack, I now have bailout and staged cylinders to still get me out alive. It just turned into an ordinary OC dive.

Now, in certain regions of the world, 80's are all that you're gonna get. So, staging them at intervals is alot easier that trying to find a pair of OC doubles to dive with.

Cheers

 

[PerroneFord]

I am not arguing the "safety or convenience" of RB. I am a fan. But that said, whether I am staging, sidemounting, or whatever, those tanks still have to get filled. Thus the cost savings is dubious as a reason for buying a RB.

-P

This should really get split into a "Rebreather bailout considerations" thread.

Your point is valid Ford, but there are alternatives. You can choose to stage a couple of 80's in the cave as you go, and have a 40cf bailout on you for emergencies. You can use the 1.5 team rule, or you can sidemount a pair of 80's if you like.
Cheers

 

[Cave Diver]

I am not arguing the "safety or convenience" of RB. I am a fan. But that said, whether I am staging, sidemounting, or whatever, those tanks still have to get filled. Thus the cost savings is dubious as a reason for buying a RB.

-P

Filled yes, but not necessarily used.

I'm also talking about the hassle of either carring a lot of bottles vs. having to run back to the dive shop and fill the only set you have with you. Depending on where you choose to dive, either you carry all the gas you need to do several OC dives, or you waste a bunch of time going back and topping off.

As I stated it, I'm looking at it more as a convenience standpoint than a cost savings.

 

[porsc]

for those who wondered, there is training outside of padi, naui, ssi, dir, ect.....

living in the south pacific, we trained every day to dive deep, and it didn't have anything to do with padi or any of the other agencies that people hold so high on this side of the world. there is a whole other world out there, and people are not limited to what padi thinks you should and shouldn't do. lol.
now, when i am working as an instructor, i follow padi standards, and those of the local gov. but padi doesn't have a damn thing to do with what i do with my personal diving. in the south pacific, deep diving, training with local divers who have been diving everyday of their lives, for 40 or 50 years takes you well beyond what padi teaches and solo diving is also very common. i don't mean it to be offensive to anyone here, so please don't take it that way, but in my opinion and in most people's opinion who have lived over there, the dive philosophy in the south pacific is light years ahead of that around the north american region. and i say that in part, because a lot of the things that are common over there for decades, are usually adopted over here sooner or later (usually later).
remember, when nitrox first came out, padi called it a death gas. and was deadset against it for years and years.
anyway, i don't want to start a big mess here, that is not my intention. but i am just trying to say that people over here tend to get there underwear in a wad sometimes, over simple things, that most of the world doesn't consider crazy or wild. so that's all i have to say about that.

and thanks for the welcome SCUBA_VIXEN. i have been in st thomas for almost two years, but that was my first trip to st croix. and i am jealous. st croix looks much nicer than st thomas.

actually it was the salt river canyon, and it was beautiful. it reminded me a lot of the walls in belize, specifically lighthouse atoll, at half moon cay, in a dive site called dolphin pass.
i'm not sure what you meant about remembering, but it was a nice day of diving.

if you come to st thomas, let me know. the witshoal is a really nice wreck to dive. and of course there is the trip to the bvi, and the world famous rms roan. there are a lot of nice wrecks and reefs. thanks for the welcome.

and by the way, i love your avatar!

 

[Scuba_Vixen]

for those who wondered, there is training outside of padi, naui, ssi, dir, ect.....

living in the south pacific, we trained every day to dive deep, and it didn't have anything to do with padi or any of the other agencies that people hold so high on this side of the world. there is a whole other world out there, and people are not limited to what padi thinks you should and shouldn't do. lol.
now, when i am working as an instructor, i follow padi standards, and those of the local gov. but padi doesn't have a damn thing to do with what i do with my personal diving. in the south pacific, deep diving, training with local divers who have been diving everyday of their lives, for 40 or 50 years takes you well beyond what padi teaches and solo diving is also very common. i don't mean it to be offensive to anyone here, so please don't take it that way, but in my opinion and in most people's opinion who have lived over there, the dive philosophy in the south pacific is light years ahead of that around the north american region. and i say that in part, because a lot of the things that are common over there for decades, are usually adopted over here sooner or later (usually later).
remember, when nitrox first came out, padi called it a death gas. and was deadset against it for years and years.
anyway, i don't want to start a big mess here, that is not my intention. but i am just trying to say that people over here tend to get there underwear in a wad sometimes, over simple things, that most of the world doesn't consider crazy or wild. so that's all i have to say about that.

and thanks for the welcome SCUBA_VIXEN. i have been in st thomas for almost two years, but that was my first trip to st croix. and i am jealous. st croix looks much nicer than st thomas.

actually it was the salt river canyon, and it was beautiful. it reminded me a lot of the walls in belize, specifically lighthouse atoll, at half moon cay, in a dive site called dolphin pass.
i'm not sure what you meant about remembering, but it was a nice day of diving.

if you come to st thomas, let me know. the witshoal is a really nice wreck to dive. and of course there is the trip to the bvi, and the world famous rms roan. there are a lot of nice wrecks and reefs. thanks for the welcome.

and by the way, i love your avatar!

The Grainton and the Wit Shoal are the two I'd like to do. The down side is that to make the trip over worth while, I'd have to be able to do them as tech dives, and as you've seen, the VI dive ops aren't exactly what you'd call "tech friendly". As far as I know, I've still got the only trimix fill station here.

The Rhone is a nice dive, we spent a day diving her on a sail trip to St Marten a few years back.

On your Salt River wall dive, do you recall if it was the east or west wall?
The west wall has lots of nice topography and swim thrus and I have more fun there, while the east wall has better reef and more vegetation and critters.

What makes for an outstanding dive is to go in on the east side, and swim over to the west side at close to 200' (bottom is at ~300'). You can see the canyon bottom and way out towards the open ocean on a really clear day. Just trust your compass and you'll gradually see the west wall come into view after a bit of a swim. It's an awesome sight.

It's the "Wall at Cane Bay" that most people think of when talking about wall diving on St Croix., It's a nearly bottomless wall (about 13,200') that starts in about 60' of water only a couple hundred yards off the beach. Much of the cool stuf is at the top of the wall at recreational depths from 60' to 125' or so. Then it's pretty plain and boring till you get to the 225' and beyond range.


If you want, drop me a PM and let me know what shop you work for and if they are cool with doubles and deco.



Darlene

 

[Scubakevdm]

for those who wondered, there is training outside of padi, naui, ssi, dir, ect.....

living in the south pacific, we trained every day to dive deep, and it didn't have anything to do with padi or any of the other agencies that people hold so high on this side of the world. there is a whole other world out there, and people are not limited to what padi thinks you should and shouldn't do. lol.
now, when i am working as an instructor, i follow padi standards, and those of the local gov. but padi doesn't have a damn thing to do with what i do with my personal diving. in the south pacific, deep diving, training with local divers who have been diving everyday of their lives, for 40 or 50 years takes you well beyond what padi teaches and solo diving is also very common. i don't mean it to be offensive to anyone here, so please don't take it that way, but in my opinion and in most people's opinion who have lived over there, the dive philosophy in the south pacific is light years ahead of that around the north american region. and i say that in part, because a lot of the things that are common over there for decades, are usually adopted over here sooner or later (usually later).
remember, when nitrox first came out, padi called it a death gas. and was deadset against it for years and years.
anyway, i don't want to start a big mess here, that is not my intention. but i am just trying to say that people over here tend to get there underwear in a wad sometimes, over simple things, that most of the world doesn't consider crazy or wild. so that's all i have to say about that.

and thanks for the welcome SCUBA_VIXEN. i have been in st thomas for almost two years, but that was my first trip to st croix. and i am jealous. st croix looks much nicer than st thomas.

actually it was the salt river canyon, and it was beautiful. it reminded me a lot of the walls in belize, specifically lighthouse atoll, at half moon cay, in a dive site called dolphin pass.
i'm not sure what you meant about remembering, but it was a nice day of diving.

if you come to st thomas, let me know. the witshoal is a really nice wreck to dive. and of course there is the trip to the bvi, and the world famous rms roan. there are a lot of nice wrecks and reefs. thanks for the welcome.

and by the way, i love your avatar!

I don't think anyone is saying that dives to 180-220 feet are impossible, I just think that some are saying that the way you are doing them is unsafe. I personally would not call diving to 200' with a single tank light-years ahead of what's going on in North American technical diving, but it may just be that I'm not aware of some of the South Pacific techniques. If you could share more about them, I might understand better.

 

[MikeFerrara]

. i don't mean it to be offensive to anyone here, so please don't take it that way, but in my opinion and in most people's opinion who have lived over there, the dive philosophy in the south pacific is light years ahead of that around the north american region. and i say that in part, because a lot of the things that are common over there for decades, are usually adopted over here sooner or later (usually later).

I'm not sure what you're basing this statement on. You're right, there is lots of diving beyond anything that PADI teaches and to get an idea of where so many diving inovations have originated you only need to look at the history of cave diving. US cave diving figures promenantly in the deleopment of lots of equipment and techniques.

remember, when nitrox first came out, padi called it a death gas. and was deadset against it for years and years.

Of course I remember.

from Nitrox FAQ

A major step was taken in 1970 when Dr Morgan Wells of the National Oceanic and Atmospheric Administration (NOAA) began experimenting with nitrox. He recognised the advantages of nitrox for the type of diving that NOAA divers were carrying out. Dr Wells was responsible for the (now) standard nitrox I (published in 1978) and nitrox II (published in 1990) mixes. It is largely as a consequence of NOAA's decision that we have nitrox in the recreational diving scene today.

Dick Rutkowski formed the International Association of Nitrox Divers (IAND) in 1985 to teach nitrox to sport divers. In 1992 the name was changed to the International Association of Nitrox and Technical Divers (IANTD). The T was added when the European Association of Technical Divers merged with IAND. Prior to founding IAND, Dick Rutkowski worked for Dr Wells and was director of the diver training at NOAA. This was the first organisation to offer international training to recreational scuba divers.

Trimix/heliox...from Trimix and heliox diving

1970:
Hal Watts performes dual body recovery at Mystery Sinkis (126 m).

Several cave divers (ie. Sheck Excley and Jochen Hasemayer) use heliox on even 212 m of depth.

1987:
First mass use of trimix and heliox: Wakulla Springs Project.

Exley teaches non-commercial divers to trimix usage at caves.

1991:
Tom Mount developes first trimix training standards (IANTD).

Look at all the US guys listed there...specifically Florida...and there were meny more on that leading edge with them.

anyway, i don't want to start a big mess here, that is not my intention. but i am just trying to say that people over here tend to get there underwear in a wad sometimes, over simple things, that most of the world doesn't consider crazy or wild. so that's all i have to say about that.

No "mess" but I don't think you have your facts quite straight. In glancing back through the history of some major inovations in civilian diving, I don't see the South Pacific mentioned at all.

For extra credit, look into who is credited for the first alternate reg, manifold, BC and so on.