Newbie Rebreather Questions

Halthron

I'm a newish diver (two years, Adv. Nitrox w/ Deco cert) that has gotten a bit tired of the effect of being an air hog and have started looking at the possibility of buying a rebreather. Since the answer to many questions is "it depends", my background and desires are listed toward the bottom. I'm rather nervous about just plunking down a lot of money on a unit.

What's a realistic cost assessment for comsumables and repairs? Naturally, you'll have to replace the lime, batteries and O2 sensors. That's sort of like buying a car and talking about gas, filters and brakes. How often does the transmission or clutch go out in these things and what sort of costs are involved? How do you know when to replace the sensors?

When comparing money saved on gas (trimix) to the cost of other consumables, is there still a net savings?

I know it'll probably vary by Rebreather but what sort of weight is needed to make a RB neutral in the water, assuming it isn't already?

At what point is someone "ready" for a Rebreather? I expect that the basic requirements are that you have Nitrox/Adv. Nitrox level knowledge and monitor your equipment during dives. Anything else?

How long does it usually take to qualify for the trimix level of training?

Electronic or manual? Besides the cost difference, should someone new start with the manual controls? Are there any upsides for the new Rebreather diver to starting with electronics?

I am forgetful, I'm guessing that a "pre-dive checklist" of some sort would be a good idea.

Can these units handle several months to a year of storage well?

What are some of the conditions that, if present, someone should just forget about using a Rebreather?

Thanks for any info you're willing to give.

Background

I've been diving for two years in a variety of environments. I learned in the cooler waters of the Med and while in the tropics have dives all over the range to 130 ft with a few overhead (wreck penetration, instructor escorted) dives. The plan is to get wreck certified this summer and expand my depth options. I don't have an interest to dive deeper just to dive deep, especially with the way I breathe gas, I prefer to see/do something. I expect to be heading back to Europe next year and hope to do more wreck penetrations.

I tend to be anal about checking the SPG & computer on OC, checking every couple of minutes just to be sure things are as they ought to be.

PeteS

Well I'll give it a go...... I'll give you my opinions. Just remember that opinions are like busses, there will be another along in a minute. For a proper answer, you're going to need to become unit specific, or at least decide semi closed or closed. There are some things that semis do well, and some things that closed do well.

This is an it depends kind of answer. It depends where you are in the world, and which type and make of rebreather you have. Sensors get replaced every 12 to 18 months. Batteries and lime are dependant on rebreather type and how many dives you do. And what type of dives you do - Recreational or techie.


Yes.


As in OC diving, it depends on the suit you wear. I vary between 0 and 1kg in tropical conditions with a 3mm shorty, to 10kg with a dry suit.


Not much else to add. Get in and do it!


You need to go from zero to hero and back to zero again. Then do your Tmx certs. You must have absolute control of bouyancy and an understanding of the risks with rebreathers and depth. And how to get out of the shit..... But having said that, I was Tmx certified before going on to an Rebreather, and within 6 months I was dark, deep, and dangerous again! And glad to be back on a gas that let me think about problems.


From my point of view, go electronic. It's a lot lower task loading for a beginner. Other people will disagree completely with this.


This would be dealt with in your training.


Provided you give it a clean first, no problem.


They shouldn't be a muppet. You need to think on an Rebreather, not just dive. This is like fat women being allowed to buy tight jeans or wear leggings. The shop assistant should say to them "I'm sorry, but madam has a fat arse, and is not permitted to buy these items for fear of offending public decency". Common sense should stop them doing it, but they still think they look good.....

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Halthron

Thanks!

decoweenie

Pete already done an excellent job answering most of your questions so there is very little I could add except:

• When doing about 50'ish trimix dives a year, it boils down to about US$10 per trimix dive for me NOT counting the boat fee, just the cost of running the Rebreather unit (i.e. gas, sorb, sensor, batteries, etc).
• Amount of weight depends on the actual unit used. Certain units are more buoyant than other, but in general very similar to the amount needed for OC diving once you are used to the unit. Same as OW class, in the beginnin you will tend to be more overweighted to compensate for lack of refined buoyancy skills.
• It is too easy and very tempting to go deeper (i.e. trimix diving) on a CCR too early since there is no gas issue WHEN everything goes fine. When they don't, it is harder to realize without having the experience to detect and deal with those problems. Take your time and develop the experience level and skills needed.

Dive safe!

JonnyB

Well i am only going to quote you on this, as it is quite important.
The machine can handle the storage without any problems. But most
probably you will not.
I know for a fact that there are a few agencies that have changed their policy regarding tech certification and you need to provide them with a log every year in order to get a renewed sticker. Some other agencies will probably follow.

Diving a rebreather is not much more complicated than normal diving, though it is much more important for you to remember the skills that you learnt.
It is not like OC diving, following a few gas rules, watching the gauges and then when you reach turn point you go back.
When things happen on a rebreather you need to have the motorskill to solve the problem without even thinking about it. And by staying of a unit for up to a year will not keep you efficient enough.

just my 2c

/Jonny

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Halthron

Regarding the storage, the intent isn't to store the device long term, I've encountered skills erosion before and don't like doing stuff twice if I don't have to. But the realities of my work are that every other year or so I do quite a bit of travelling for a few months. Then there's always the very real possibility of needing to go to one of the remote areas we have locations for a long term "temporary" assignment, often a place where the fresh water isn't and checkpoints can spring up instantly. Not a place I'm going to take a Rebreather. If it's as simple as cleaning and storing in a cool dry place then taking a refresher course on return, all's good.

rewrites

Being 'forgetful' could qualify as a good reason not to use an Rebreather. However, I would think that by admitting that, you have a good mindset about the good and bad points regarding your own diving (we all have them), so is a good starting point for your RB training.

Excellent advice from the posts above. JonnyB's advice is especially pertinent. As a newbie Rebreather diver myself (but trimix OC qualified), a pre-dive checklist is essential, and the need to practice, practice, practice your drills and acquire 'muscle memory' is fundamental to RB diving.

I like your analogy to owning a car. Rebreather diving is like driving one in some respects. Unlike OC where you simply breath the guess (apart from maybe a few gas switches later on), most RB's are 'working' for you all the time. You get to hear them doing it (solenoid firing etc.), and you feel the changes (loop volume change through your mouth etc.). Like car driving, you should aim to get to the point where you 'know' something isn't right just by the 'feel' of how it is operating - I'm still reaching that point

If you are likely to store your unit for up to a year - is it going to be cost-effective for you to buy an Rebreather? If cost isn't an issue and you are simply looking at ways of cutting down on gas usage, then it is probably the best way to go.

Have fun