double tank equipment

[Storker]

The last point assumes that the diver is already familiar with having a backup reg on a necklace and having an SPG by itself as opposed to being part of a console. What happens if diver is only familiar with the traditional recreational regulator configuration with a console that has the SPG, dive computer and compass?

Should I mention that I know people who use doubles with a short hose primary, a traditional octo and a console?

Again, it's not the number of tanks. It's total tank capacity, how you set up your system and how you dive.

 

[victorzamora]

Again, what with "the proper way to dive doubles" is different from "the proper way to dive a single tank"? Except remembering to keep the isolation manifold valve open, that is?

What size wing do you use? How do you set them up? Can you set them up without damaging the manifold or valves? How do you route your hoses? Where do you put the bands? What do you do if you're not trimming out right? What's the proper procedure for first stage or valve failure? How do you treat them for fills? There's a lot more to it than just the number of tanks. Certainly not rocket science, but seeking a competent mentor is a great idea.

 

[Adobo]

Should I mention that I know people who use doubles with a short hose primary, a traditional octo and a console?

Again, it's not the number of tanks. It's total tank capacity, how you set up your system and how you dive.

And I know manufacturers who sell BCs that are good for single and double tank diving. I also know people who got into the water with double steel 130s filled with nitrox wearing a wetsuit only.

Diving doubles is no different than diving a single tank for recreational dives - assuming that the diver is squared away when they get into the water. The thing is, the process is of getting squared away, as it relates to going from single tank to double tanks, is not intuitive to a diver who has no experience with doubles.

Let me put it a different way. A guy walks up to you and says, "I dive with this jacket BC with this reg, console and an Air 2. I just bought these steel 100 doubles with isolation manifold. Tell me everything I need to know before I jump in the water."

Is that going to be a 5 minute conversation?

 

[cool_hardware52]

Tobin, I know you have a lot more experience than me, so I'll say my piece and leave it at that. It seems as if an absolute statement with regards to simply asking a question was made. I'm not saying training or mentoring isn't wise, but without intent, asking a question is not irresponsible.

IF you just want more gas... then everything in your list has been covered in the OW class, or can be found in a 10 second google search (not specific for manifolds, but equipment failure is equipment failure and that was covered). Nothing irresponsible (yet).

-Jeff

No BOW class I've ever been a part of covered manifold operation, the nature of the failures, the remedies, and easily as important the proper operation of manifolds *out* of the water, i.e. at the fill station.

More than one recreational "tank monkey" I've encountered had no idea if the Iso valve should be open or closed when filling. I've had to educate more than one.

Would you expect a guy who doesn't know how many SPG's he needs to be well informed about proper procedures for filling doubles?

I once saw a guy er, uh, well, lets just say "brand new to doubles" starting to disassemble his iso valve (pull off the knob and start to back off the bonnet nut) on a filled set of tanks. He told it would be ok because all the valves were closed.

I also told him to seek competent training before he needed to have a valve bonnet nut surgically removed from his forehead......

Tobin

 

[Storker]

What size wing do you use?

Number of tanks is irrelevant. I use a 40# wing, since I dive dry with thick undergarments, and anything less wouldn't float my rig if I doffed it in the water due to the amount of weight I have to have on my BP. And I dive a single tank setup. If I were following popular opinion here on SB, I'd be using a 30# wing (max), but if I were, I wouldn't be able to doff my rig in the water without seeing it sink. Number of tanks isn't relevant, total configuration is.

How do you set them up? Can you set them up without damaging the manifold or valves? How do you route your hoses? Where do you put the bands?

Those are doubles-specific issues, I'll give you that. But once it's been set up by a competent person, it's not exactly rocket science to remember that setup.

What do you do if you're not trimming out right? What's the proper procedure for first stage or valve failure?

Same as when diving a single tank rig, provided we're staying within rec limits. For the latter, it's "get your buddy's secondary or CESA"

How do you treat them for fills?

Make sure three valves are open instead of one.

There's a lot more to it than just the number of tanks.

My point exactly. Number of tanks is irrelevant. Total gas capacity, weighting and proper practice is.

And I know manufacturers who sell BCs that are good for single and double tank diving.

That's just stupid. But, again, it's not the number of tanks, it's the total buoyancy of the rig.

I also know people who got into the water with double steel 130s filled with nitrox wearing a wetsuit only.

That has nothing to do with number of tanks, and everything to do with total tank capacity and gear config. As long as the diver takes care to stay within NDLs, and has a balanced rig, what has that to do with the number of tanks?

Diving doubles is no different than diving a single tank for recreational dives

Which is exactly what I'm trying to say. Over and over again.

assuming that the diver is squared away when they get into the water.

Well, I guess that's my problem. I assume that the diver is competent to do the diving they're planning to do. I don't automatically assume that the second someone straps two tanks on their back instead of one, all other things equal, they magically transfer to another universe.

Let me put it a different way. A guy walks up to you and says, "I dive with this jacket BC with my this reg, console and an Air 2. I just bought these steel 100 doubles with isolation manifold. Tell me everything I need to know before I jump in the water." Is that a 5 minute conversation?

Less. "Remember your NDLs, follow your computer, and remember to open all three valves. Have you dived with a BP/W before? No? Then we should talk about the difference between a BP/W and a jacket BCD". Now the latter issue is, again, independent of the number of tanks.

it's not the number of tanks. It's total tank capacity, how you set up your system and how you dive.

 

[Imla]

Now... To qualify Storkers comments... Here in Norway there has, in certain areas of the country been an inflation in the use of doubles. They are quite common!
One of the best dive stores in the country also happens to be highly proGUE. They also run the quickest internet-shop in the country.
So, basically, there is a lot of knowledge going around in the local clubs and "gangs".
Some of the most active dive-schools also push doubles to fresh divers. They are sold both as "bigger, better "single-tanks"" and as gear suited for technincal diving.
In other words... We're more used to seeing divers in doubles, than singles... (I hope this explains what I believe to be the background of his views)

(However... if you are _not_ in an environment where doubles are common practice and you have noone to mentor you, I agree with Tobin)

 

[victorzamora]

Now... To qualify Storkers comments... Here in Norway there has, in certain areas of the country been an inflation in the use of doubles. They are quite common!
One of the best dive stores in the country also happens to be highly proGUE. They also run the quickest internet-shop in the country.
So, basically, there is a lot of knowledge going around in the local clubs and "gangs".
Some of the most active dive-schools also push doubles to fresh divers. They are sold both as "bigger, better "single-tanks"" and as gear suited for technincal diving.
In other words... We're more used to seeing divers in doubles, than singles... (I hope this explains what I believe to be the background of his views)

(However... if you are _not_ in an environment where doubles are common practice and you have noone to mentor you, I agree with Tobin)

Having a community of divers near you to teach you how to use doubles, you say? Wouldn't that be the mentoring/training Tobin suggested? How is it different?

 

[cool_hardware52]

(However... if you are _not_ in an environment where doubles are common practice and you have noone to mentor you, I agree with Tobin)

From which environ would expect to find a diver asking "how many Spgs do I need" ?

Is it good practice, or irresponsible to assume the OP is surrounded by qualified mentors when there is zero evidence to suggest that is the case?

Tobin

 

[Adobo]

Well, I guess that's my problem. I assume that the diver is competent to do the diving they're planning to do. I don't automatically assume that the second someone straps two tanks on their back instead of one, all other things equal, they magically transfer to another universe.


Less. "Remember your NDLs, follow your computer, and remember to open all three valves. Have you dived with a BP/W before? No? Then we should talk about the difference between a BP/W and a jacket BCD". Now the latter issue is, again, independent of the number of tanks.

You're looking at the topic from the perspective of the diver knows everything. Others come from the perspective of "assume nothing".

If the diver knew everything, why would they be on scubaboard asking whether or not they need 1 or 2 pressure gauges? The question itself already implies complete lack of knowledge of how the various doubles configurations work. Or how their specific doubles configuration works. And if he doesn't have that knowledge, why would you assume that his BC is appropriate for his doubles? Or that his regulator is configured properly for doubles? Or that he knew that it is problematic to dive big steel doubles in a wetsuit?

Where in the process of learning to dive proficiently to 130 ft (~39m) in a single tank does a diver learn what they need to know to do the same dive in big double steel tanks?

 

[Imla]

Having a community of divers near you to teach you how to use doubles, you say? Wouldn't that be the mentoring/training Tobin suggested? How is it different?

This might also be a matter of english as a second language on my part. When I read Tobins comment, I understand him to mean "take a class from an instructor", which I really don't think is necessary if you have the right community.