Narc Boy 1 project

[kidspot]

As some of you have probably figured out, I'm trying my hand at building a rebreather this summer... dunno if it will be a sucessful project or just a time consuming way to throw some money away while having fun.

There are no photos yet, as I have not begun construction, but I wanted to post a link to the website where I'll be keeping my chronicle.

http://www.alohashoredivers.com/proj...boy/index.html

And ask you all to feel free to post ideas and criticism here. When there are updates and tests I'll post the news here.

Things are still in the planning stages, but your input is greatly appreciated.

Aloha, Tim

P.S. The basic idea and schematic is there, and while I have already decided on several possible changes, your comments are appreciated.

[rjack]

40cf dil and O2 cylinders are definately overkill for the scrubber size. Actually I suspect they are overkill for any divable RB, people needing that much are probably going off-board anyway.

What are you using as a constant mass valve and how will it adjust for you?

Are you going to train yourself on this thing? Since you have no prior RB training that seems rather, "risky". You don't know what you don't know.

[kidspot]

Great questions rjack:

40cf, because at the moment I happen to have 2 of them, and nothing smaller ... I can always change them for smaller cylinders once I like the rig and decide if I'm going to keep it or not (using what's available). Plus 40cf means I won't need a bailout bottle for non-deco dives. Once I put a smaller cylinder on (probably 19's or steel 23's) then the 40's become my bailout bottles.

For training, I started my training last week for an Inspiration eCCR, then a combination of self-teaching and a buddy that dives an mCCR to figure out the nuances for diving mCCR (I'll also ask my instructor to focus on manual flying during class)

For the orofice, I'm looking at a 75 micron from http://www.lenoxlaser.com/shop_cart/...tml&lang=en-us .

Honestly, there is a LOT to still consider and think about. Which is one of the big reasons I'm doing this. Figure that if I build it, I'll gain a solid understanding of the variables along the way. Been a month getting to where I was ready for some outside input, and that time has now come where I have a grasp of where I want to go, but might need some redirecting at times

Aloha, Tim

[rjack]

I would be very very hesitate to say your dil is your bailout. That's alot of eggs on that one reg's basket and doesn't really conform to industry standards (as I marginally understand them).

Schematically from 30,000ft it "looks" like a RB80 crossed with a manual Meg. But its not in any way shape or form "DIR" despite the funky long hose coming off the dil. Since you were clearly influenced by that SCR you might want to check out Clare Gledhill's posts over on DIRx about their RB80 training and now ongoing usage.

[kidspot]

Dil as bailout is no more suspect than single tank diving ... same limitations. Recreational no overhead limits, rockbottom etc.. Once any limitation is exceeded you now have a need for doubles/external bail-out.

Longhose is definitely overkill ... and may dissapear, but as you noticed, reflects the RB80 influence (doesn't really work unless the dil meets Rock Bottom requirements) If moving to small cylinders and a bailout the bailout now becomes a passable bottle, thus no longhose necessary. . . least as far as my limited understanding takes me.

I seem to recall reading that post on DIRx, but am suffering from brain "mush" from all the RB information I've been collecting the past few weeks... feels just like when I first took up Scuba - lol.

btw - I really appreciate your thinking as these are issues I need to make sure have been considered. (which, in this case I have ... though double checks are always appreciated as mistakes in logic do happen far too easily.)

Aloha, Tim

[Dive-aholic]

Looks interesting, Tim. I've recently become interested in RBs, but only for OW. Not sure I want to deal with the added risks of taking one into the overhead. The only thing keeping me from looking further into it at this point is the cost of 2 of them! What's your projected cost for this project?

[kidspot]

Projected cost is tough as a lot of the parts I already had laying around (extra regs, valves, etc..) but if I had to rebuy those parts it would run about $1200. If you bought a commercial BOV you can add another $900 ($300 for a basic DSV) and another $900 for a commercial PO2 monitor (just monitor, no computer) ... you get the idea. I'm really trying to do all these parts from scratch (PO2 monitoring is first step)

I may build the tough to fabricate parts twice so that if I wanted to build a second one I could, while just buying the rest as I have the finances for it.

Aloha, Tim

[rjack]

Dil as bailout is no more suspect than single tank diving ... same limitations. Recreational no overhead limits, rockbottom etc.. Once any limitation is exceeded you now have a need for doubles/external bail-out.

Yeah but you have to continually monitor your diluent usage to ensure it stays above a RB level which is about 20cf assuming you're limiting yourself to 100ft. I wouldn't be using bailout on an ongoing basis like that. Contradictes the redundant "reserve" concept of bailout. Just have an offboard 40cf of bailout with its own reg.

I also don't know if you're diving in mixed teams or not but if you are... You have to close the loop, throw it over your head, donate the long hose, then go back to the loop. Complicated, comparatively easy to screw up. The RB80 protocol is similar but has a bungied backup if the loop were to partially/fully flood in that process.

[kidspot]

Still debating the bungeed backup ... giving it serious thought, but haven't made a decision yet... figure it was a concern that could be dealt with later (just add a reg and hose) - For the initial prototype with a DSV instead of BOV a bungeed backup is going to be necessary, so it will be there, even if not shown on the schematic (yet).

As to "reserve" my buddy did a 2hr 40 minute dive a couple weeks ago (third rebreather dive, max depth 70 fsw) and used a LOT of dil during the dive according to his instructor. Wound up being about 10 cf. Rock Bottom from 100 fsw is 20 cf, which leaves you 2 dives easily before hitting rock bottom. Course a lot of this has to do with the skill and comfort level of the diver on the machine (which I won't have for quite awhile) so a little padding will be in order. A second boat dive around here is usually to 40 fsw, so rock bottom drops to a little under 4 cf. (not telling you anything you don't know, just for consistency here) Any time you dive a single tank rig you are using your "reserve" bottle, but only to a point - nothing changes here. When you go past Recreational min-deco/single tank limits the rules change ...

Monitoring of gas pressure is just like always, regular intervals. Probably clip O2 and Dil gauges together and check both at the same time. PO2 checked along with depth/time - so with a little experience it should not be much more involved than diving OC. (this is me guessing ... take it for what little that is worth)

Remember the 40's are for the testing period (which will be unlikely to exceed 100fsw) ... if I need a bailout I'll just sling an [ugg] 80. Once I'm satisfied that this is going to be my future diving style I'll invest in new cylinders... unless I really like the way the 40's dive Then I'll pick up another 40 for when needed.

This is really a good process, so keep 'em coming

Aloha, Tim

[rjack]

I guess the fundemental concept of "using" bailout on a routine basis seems "not right".

So I would just find some used AL13 or 19s and set it up properly to begin with. With completely separate bailout that can be managed independently. Seems like the typical routine, certainly much more so than a long hose underneath the loop. Then again I think RBs are essentially death traps and only justified for huge dives where the OC requirements are so hairline that the CCR risks are actually smaller, so what do I know.

I'm curious what Chickdiver and Brian think of the concept of "integrated diluent bailout".

[kidspot]

Then again I think RBs are essentially death traps and only justified for huge dives where the OC requirements are so hairline that the CCR risks are actually smaller, so what do I know.

I'm guessing as much as I do, if not more

I'm curious what Chickdiver and Brian think of the concept of "integrated diluent bailout".

It would be good to find out - so few divers using rebreathers from a UTD mindset.

I don't know if they are death traps or not yet, but the idea of a 6 hr shallow shore dive, or always having helium on dives below 60fsw are both VERY appealing to me.

Aloha, Tim

[rjack]

the idea of a 6 hr shallow shore dive, or always having helium on dives below 60fsw are both VERY appealing to me.

Its gonna suck shallow (well you'll just need a lot of diluent) any little up and down to the reef will vent your loop and that adds up. And you'll constantly be dealing with the ppO2 drops on ascent too. While I haven't (ever) dove a RB, that sounds like a pita to deal with. I know I couldn't focus on those elements after hours in the water. I saw this recently, figured you might not have seen it:
http://www.cavediver.net/forum/showp...8&postcount=10

Long shallow dive? That's like a MX cave. A set a double 80s down there lasts me way longer than my pruny body can handle. What are you going to see in hour 5 that you didn't see in hour 3?

It would be good to find out - so few divers using rebreathers from a UTD mindset.

Are you building more than one?

[rjack]

Since this has the long hose concept going on for now, and the RB80 is the only RB out there typically rigged with a long hose, you might find this interesting.
http://www.direxplorers.com/dir-trip...-try-dive.html

[kidspot]

Good article, I've never been to cavediver.net ... probably better stay away as the last thing I need right now is another good forum - lol.

One of my regular buddies (about my only regular buddy I should say) is going to be diving RB more and more often (he loves it for his photography) but the rest of the time I'll be in a mixed group. I'm guessing at least my first 100 dives or so will be RB exclusive just to learn the skills and then decide if I want to go back and forth, or stick with RB most of the time. May turn out that I really hate the things... remains to be seen.

And if I like the way it dives, yes, I'll be building a second one over the next year or so (which is why I want to fabricate twice what I need of the difficult pieces)

So much of this is just an experiment, which if I don't like it - will have been an interesting adventure.

Aloha, Tim

[kidspot]

yup - the DIR-xplorers dive report was a good read. So much of this is foriegn to the way I've learned to dive OC, so it takes a lot of consideration.

Aloha, Tim