Diving doubles recreationally

[Lobzilla]

A 2-4in shorter hose solves this problem. MK25 routes really well, you just have to put the 7ft hose on the swivel, and backup reg on the bottom port. Most people seem to point the reg down and it doesn't route as well (it's even on GUE's site in the less desirable position, idk why).

Thanks for the constructive reply on the topic of doubles vs singles.

I tried shorter hoses but at some point you cannot fully look to the left anymore. Yes, the Mk25 makes the hose routing easier but if I bet my life on a single reg in cold water (Massachusetts) I prefer the Mk17.

 

[Rhone Man]

Yes, but you are only counting the tanks themselves. How about a double wing, additional regulator set (1 set at least, possibly 2 if you don't want to break up the single setup).

Yep, fair points.

 

[rongoodman]

Not sure it really needs to take any time at all. If you are diving within recreational limits, I'd strap 'em on and go. You are going to be a bit wobbly for your first few dives, but it 'aint rocket science.

That might work if you just want to consider them as a large single tank, but without some knowledge of and practice with the valves and failures, you'd be giving up the redundancy they offer.

 

[Lobzilla]

double post

 

[Lobzilla]

Oh crap. I did my OW through YMCA? What ridiculous analogy will you come up with for them? YMCA multi-engine rating?

I have no problem with your certification, your instructor, or his/her agency. What I have a problem with is if people get the McDonalds version of dive education and then have to defend this philosophy because they are to proud to admit that they wasted their money/time.

I know exactly how much the realization of being short-changed hurts. I have sunk twice as much money into SSI for a fraction of the value compared to what I spent on and got from GUE. What do you want me to do now? Recommend SSI? Or suggest that you get your doubles set up by your dentist?

But would they have you? That elitist attitude makes me think I'd rather pee in my drysuit than endure a day on a boat with such snobbery from fellow divers. Seriously man....

But pounding on your "experience" chest is OK for some reason? Snobbery would be to look down at you for not having shelled out the money for a p-valve. The rest is about the legitimate pursuit of excellence. Which, if I remember correctly, made this country great before nobody was supposed to be hurt in their feelings through constructive criticism.

What you are missing here is that I am in no way knocking what GUE is teaching or their methods, and certainly not any GUE instructor. I think what they do is great. I have no issues at all with GUE.

At least you do not pick battles you are guaranteed to loose.

What I, and many others, often find off-putting is when people like you, with basically little to no experience, save a fundies class under your belt, preach down upon those divers who haven't taken fundies as if you are the Noah of all that is diving, here to save the flock from the great flood of Air2 octo-inflators, poor trim, and ankle weights.

There is the humble, charming, and socially acceptable "experience" chest pounding again.

But do not worry. I am going to switch SB back to 'read only' mode and let everyone else figure it out for themselves. Heck, it's only their time, money, and health at risk - not mine. Just make sure that you profit from endorsing or defending the Air2, ankle weight, and kneeling on the bottom BS because I surely do not profit from talking people out of it. In your analogy I am not Noah, I am just a critter pointing to The Ark that prominently sits on top of the hill.


As far as the original topic of doubles for recreational diving is concerned, why even bother with heavy single tanks? Just shove a couple of Spare Airs in the cavernous pocket of your BC jacket and you will be golden.

 

[oldogre]

I normally dive single Faber 15L steel, air or 32%. (Recreational Holiday Diver about 40 dives per year plus Pool practice). On my last trip I was offered twin steel 8L to try (make not known) belonging to dive centre owner, the total wt. was LESS than my usual Faber 15L! I needed more lead. They were nice & stable, trim was easy to adjust so they will be getting more use. ( Tank rental & fill cost that I pay for a RIB dive is the same for any of these configurations).

 

[elan]

Although Im not a tech diver I normally dive doubles on my rec dives. For two boat dives I woukd usually take a set of 72 or 85s plus one Al80 stage or just a set of 108

That would allow me to do 2 dives to the NDL on 32.

The issue with the doubles is that you have to take more factors into account to find a tank that is good for you say for me the shorter tanks like 95 or 118 do not work well as they are short.

I dive them for stability and redundancy as half of my dives here are in 40f water and redundancy is needed some charters will not even let you on the boat w/o redundant config.

 

[elan]

Nope. We do this quite often. Math:

100' dive, let's call min gas (conservatively) 40cf. That leaves 90cf usable. MDL at 100' is 30 minutes on 32%. Assuming a rather *terrible* SCR of 0.75 cf/min/ata that gives: 90/(4*.75) = 30 minutes. For any SCR better than 0.75 (i.e. everyone I know), you're MDL-limited, not gas-limited for a 100' dive with a HP130 with 32%.

0.75 is not terrible. I have just a bit better 0.6-0.65 SAC on dives in 38f low vis water. Whereas I can get down to .35 in warm and nice conditions and a lazy swimming

 

[Rainer]

0.75 is not terrible. I have just a bit better 0.6-0.65 SAC on dives in 38f low vis water. Whereas I can get down to .35 in warm and nice conditions and a lazy swimming

As I said, it's worse than that of *everyone* I dive with. It's still 25% worse than your low average for cold water. *I* would personally be having a terrible day if I were breathing that high.

In any case, most divers aren't going to have an even higher SCR than that (as suggested by the diver I quoted). That's all.

 

[James R]

IWhat I have a problem with is if people get the McDonalds version of dive education and then have to defend this philosophy because they are to proud to admit that they wasted their money/time.

I agree completely. I have personally taken "specialties" that were ridiculous. That said, I am not here to say that any agency overall is bad. You should not equate one instructor doing the bare minimum to get a c-card in your grubby little hand with the agency as a whole, you know? Broaden your perspective a little bit.

But pounding on your "experience" chest is OK for some reason? Snobbery would be to look down at you for not having shelled out the money for a p-valve.

You're completely missing my point. I'm not pounding on anything. What I am saying is that at this point you shouldn't be. Simple as that. I guess you can't see the forest for the trees. I am genuinely happy that you took fundies and I am not surprised that you got your butt kicked doing so. I am sure that like many others you learned more than you could have ever expected and that it made you a far better diver. That is definitely a good thing.

By the way, I have a p-valve. Yet again, you missed my point completely.

Just make sure that you profit from endorsing or defending the Air2, ankle weight, and kneeling on the bottom BS because I surely do not profit from talking people out of it.

You're really reaching now, and that's pretty far out there, considering I have never personally endorsed any of those things in this or any other discussion. I have said in other threads that an Air2 isn't as bad as people make it seem, but I did NOT say it's ideal - actually the opposite. Please, do tell how one could profit from doing so as well...it'd be a better use of time, wouldn't it?

As far as the original topic of doubles for recreational diving is concerned, why even bother with heavy single tanks? Just shove a couple of Spare Airs in the cavernous pocket of your BC jacket and you will be golden.

Man this whole time I thought you had no sense of humor...


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OldNSalty - I apologize for the bs/drama that has derailed your thread.