Rebreather Questions

Any one currently dive with a rebreather?
If so, what make and model?
Best place to purchase or have one serviced?
And what type of diving do you do with it?

I am looking for a semi closed OR closed circuit rebreather, for use on technical dives less than 300fsw. (for submarine exploring and eventually doria trips.)
Thank You,
gjm

gjm,

I dive a Halcyon RB 80 (SCR).

Mostly on cave dives over 3 hours configured with AL 80's for exploration.

A few wreck dives to a max of 260 ft. configured with AL 40's, but probably wouldn't use it again for that as bottom times are short for ocean where I believe OC is safer and easier.

I purchased it from Halcyon.

I service it myself.

Happy and safe diving,
Shane

There is only one

the Insperation

A few wreck dives to a max of 260 ft. configured with AL 40's, but probably wouldn't use it again for that as bottom times are short for ocean where I believe OC is safer and easier.

Click to expand...

I am curious as to why OC would be safer in the Ocean but not in caves?

JT2,


We (my buddy and I) believe that for us OC is safer because in the ocean the surface conditions can change quickly. We want to keep the bottom times short to minimize deco. Also the RB adds complexity to the dive with gas switches and possible emergency procedures in open ocean. On OC we keep it simple with doubles and one or two deco bottles. In the ocean we would use the RB for cold water or where gas is not readily available.

In the cave we need to have much more gas available for penetration, exit, and emergencies. The RB gives us more bailout on our backs to get to our safeties and keeps task loading (due to the amount of extra bottles) down to a minimum. With OC in the cave we would have to carry much more gas than with the RB in case of emergency. In the cave the environment doesn't change (mostly) so the exit is much more predictable and we can plan accordingly unlike the ocean.

Shane

Thanks SLJ, That was a good explanation, and it certainly makes sense to me.

Certainly doesn't to me
<<We (my buddy and I) believe that for us OC is safer because in the ocean the surface conditions can change quickly. We want to keep the bottom times short to minimize deco. Also the RB adds complexity to the dive with gas switches and possible emergency procedures in open ocean. On OC we keep it simple with doubles and one or two deco bottles. In the ocean we would use the RB for cold water or where gas is not readily available. >>

Surface conditions are the same for all divers. On a rebreather you can kep your mouthpiece in and breath far longer than anu OC circuit diver, and as youre carrying far less kit, its easier if its rough

Rebreather complexity is something percieved by those not trained in them. A full electronic CCR requires no input from the diver other than an accasional check of the handsets

Thousand sof people are using rebreathers in the Open water, for much greater depth, longer duration, lighter carries etc. Most are doing this on fully closed systems as they offer far greater gas efficiancy and redundancy

For example on the Inspiration, you have 3 gas sources and can revert to semi closed mode (like a Halcyon) is you want to. You have triple redundant O2 sensors, and double redundant (some of us have triple) electronics and monitoring. It all happens automatically for you, but you can manually fly it if you want.

The nastier units have purely mechanical feeds, no oxygen monitoring and a nasty habit of not delivering enough O2 on the way up and on the surface, but many people still dive with them

Have a look at some of the web rebreather sites out there and read the rebreather manuals (most online) to get a true opinion rather than listen to most of the ideas passed around based or heresay and rumour. This web site will get you started and has links to many other sites
http://www.btinternet.com/~madmole/divemole.htm

Be careful though, once youve tried a rebreather you wont want to go back to those noisy, heavy, cold days you used to know.

Plus decos are shorter in general for a CCR than for an OC diver.. Doing a square profile where the OC diver is using the optimal mix (if he happens to get on the planned site and depth), at the end of planned BT the oc diver will have a bit less deco at that point (since CCR divers will back the PO2 opff just a bit usually running around a 1.3), On ascent the ccr's loop gets richer and richer during the ascent (it will keep the 1.3 thought the entire ascent) so the CCR diver ends up breathing the best mix all the way to the surface and gets out of the water well before the OC diver.. In fact most ccr divers will leave the bottom later than the OC diver would and probably still get oput of the water first.. I dread when having to go back to OC.. I ***** and moan all day usually..
The condtions I dive in (of NY) are very variable and usually rough.. I don't see any added complexity instead I feel its easier.. not having to change mixes while ascending, for optimal deco that would be at least 2 changes (one at 70 and one at 20), while my CCR does this all on its own all the way to the surface.. IF I get electronics failure.. then I fly it manually, no big deal..
Once experienced things like buoyancy control are simple and totally hands free(once you dump what little air you have in your wings).. Your OC diver has to worry about that throught the ascent. DO your last deco at 20ft and who cares how bad the surface is(I do this on OC also).. I have gotten back on board with 10ft seas without any problems as the gear is much lighter than I would have had to use for OC.

The Halycon is only an SCR it helps extend gas supply, not as quiet as other SCRS and has no other benefits, since your gas is pretty much the same as an OC diver.. If you dive this unit deep you will need to make gas switches also (not necessary on a CCR) and on an SCR a hypoxic event during ascent is a concern if you are breathing hard and ascending too fast.. A CCR will keep the oxygen at your setpoint PERIOD.

The only way to get hypoxia is turning your units off, running out of oxygen (highly unlikely, the 3l cylinders is about a 10 hour supply for most divers), stuck solenoid (but you should have seen this long before its an issue - and took the appropiate steps)or forgetting to turn the unit on when jumping in.. (there are idiots that have done this and paid the price).