Doubles etc.

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Quite honestly, I think you're over-complicating things. You've told us about your intended gas management, now tell us about how you're going to manage if you have to rescue a buddy from 100ft with that tank you're breathing down to 500psi? Will both of y our independent doubles have hoses long enough to donate? Will you leave both tanks on all the time? If someone comes up and grabs the reg out of your mouth because they are OOA, can you deal with unstowing the hose off the other tank and getting it to your mouth before you drown? How will you deal with a failed reg? If your regulator fails on one of the tanks 40 minutes into your dive, and now you effectively have a single tank with no redundancy 100ft from the surface?

I'm not saying independent doubles can't be used effectively, they most certainly can. But nothing in your reply mentions the safety of your dive buddy... only yourself.
 
NJScubaDoc:
These past few responses have been stellar. Thanks for the thoughts.

As AquaW mentioned, you really can't begin to scratch the bottom? of NJ wreck diving without getting into decompression. Many of the larger wrecks lie in deeper water, and to spend some worthwhile time on these you have to start thinking about decompression. Which is what I'm doing. I deal with a great shop (Divers Two in Avon-By-The-Sea, NJ) and they employ some of the most talented instructors around, especially when it coms to technical diving. I like getting opinions and feelings from various sources though, hence the reason for this thread.

Onto some questions posed, and my feelings...

The boat(s) I dive off are well equipped to handle doubles, so that won't be an issue. I'm still young (22) and in pretty good shape. The extra weight is something I can handle at this point. As for shore diving with doubles, perhaps I mislead, most of the shore dives are done in water that is 20fsw deep or less. Using double 95s for that is something I just would rather not do.

If there is one key point that I take from all the posts thus far is that decompression diving requires proper training, equipment, and a certain mentality. When the time comes that I want to get into decompression diving I certainly have a good sense of what to expect and how to go about it. Thanks.

In the meantime (read while I amass more funding) I need to increase my gas volume allow me to reach the maximum limits of my NDLs as provided by the Nitrox I'm diving ($15 a fill). The best way I can figure to do that is to take my four tanks and dive them as 3 sets of independent doubles (for potentially 3 boat dives). In practice, I would take 2 full 95s on my first dive, breathe them down in increments of 500 psi. At the end of dive number one I would have one tank with 1500 psi and one with 500 psi (i'd breathe the last 1000 psi off a single 95). For dive two I would take a fresh tank and the 1500 psi tank from dive one and breathe the full tank down to 1500, then switch off to the half full (always an optimist) tank from the first dive, and breathe the final 1000 off that. For dive numero tre I would simply repeat the same procedure as with dive #1.

The first thought is probably, my that's an awfully complicated amount of gas management. I don't think it is though, and I think the same level of competency in gas management and ability would be required for decompression/technical diving anyway. I think I'd also sling my 30cft which I'm currently using as a pony. Aside from it offering me another redundant air source, I think it'll get me used to diving with bottles in that configuration.

The whole thing seems like it could work, and would allow me to accomplish my immediate goals without a huge investment, while also not limiting me in my variability when it comes to gear configuration (I.e. single tank shore diving).

Any thoughts, are as always, welcome. :D
Consider getting a transfill whip. Double up one set of 95's (using the standard manifold method), and use the other two tanks to transfill gas between dives.

It's a simpler solution to your problem ...

... Bob (Grateful Diver)
 
NJScubaDoc,

Some questions
How do you intend to rig two 95's and a 30cuft bottle with little to no investment?

Your wing is designed for singles. Do you have a wing designed for doubles? Do you intend to use your current wing?

How are you going to attach you extra tank to your body?

Do you have three 1st stage regulators, 3 2nd Stage regulators, 3 SPGs and all the hoses for your regulators?

Your Gear
Apeks WTX Harness with a SS Backplate, Oxycheq M-5 40 lb wing, legend LX reg, titan on the 30 cuft pony, air2 , and a bunch of other fun toys.


Some advice
Patience! At age 22, you have an entire lifetime of diving ahead of you. This sport is dependent on equipment, training, knowledge, and skill. To go deeper and stay longer you need a lot of it. Take your time, make the right investments and you can enjoy this sport for your entire life. Take short cuts and make compromises and go to fast and sooner or later it will catch up to you.

Jonathan
 
PerroneFord:
But nothing in your reply mentions the safety of your dive buddy... only yourself.

Very good point. When I, and those others on the boat dive, we are independent of each other. We do not operate in buddy teams and try to stay out of each other's way. I realize that last statement has probably got some baffled, maybe even outraged. Let's save that discussion for another thread though. Your sentiments do not fall on deaf ears, Ford, and are some things I've been contemplating regarding diving since I started.

AndrewJD:
How do you intend to rig two 95's and a 30cuft bottle with little to no investment?

Your wing is designed for singles. Do you have a wing designed for doubles? Do you intend to use your current wing?

How are you going to attach you extra tank to your body?

Do you have three 1st stage regulators, 3 2nd Stage regulators, 3 SPGs and all the hoses for your regulators?

I orginally said, "without a huge investment" Nothing in diving can be done with "little to no investment" save for maybe...ya I dunno...hehe

In terms of my wing, yes I would have to get a horseshoe wing for the doubles set up, as my current wing wouldn't be able to provide the appropriate lift for the heavy tanks.

When you say extra tank, I assume you are talking about the 30. I would attach it with bolt snaps to my harness, basically slinging it with a regulator wrapped up in bands.

In terms of regulators and hoses, I currently have 2 first stages, 2 second stages, and all the necessary hoses. I have 1 spg, would have to get another. I'd also have to get another regulator, but that's an investment I'm willing to make, as it will be applied to future applications.

As for your advice, it is certainly noteworthy, and yes I do have an entire lifetime ahead of me. My career has progressed to the point where the moves I'm trying to make would serve as an appropriate intermediate step.

Transfill whips......how much gas can you actually get to transfer from a full tank to a near empty tank? Basically, how well do they work in application?
 
Just remember to get a pizza stained shirt to go with your new doubles.
 
NJScubaDoc:
Transfill whips......how much gas can you actually get to transfer from a full tank to a near empty tank? Basically, how well do they work in application?
A transfill whip will equalize the pressure in both of the tanks it's connected to. For me and the friends I dive with, it's proven a very useful way to get an extra dive out of a set of doubles while boat diving.

... Bob (Grateful Diver)
 
NWGratefulDiver:
A transfill whip will equalize the pressure in both of the tanks it's connected to. For me and the friends I dive with, it's proven a very useful way to get an extra dive out of a set of doubles while boat diving.

... Bob (Grateful Diver)
Which in real world terms...means 1/2 full.

I would just use stages and leave the backgas for last. But thats just me.
 
NJScubaDoc:
When I, and those others on the boat dive, we are independent of each other. We do not operate in buddy teams and try to stay out of each other's way.
Agreed, that's the way we do it here. BUT, a couple of years back I had an OOA diver, from the same boat, that I needed to donate to and I'm guessing he was glad that I had the backgas to oblige. ;)
 
JeffG:
Which in real world terms...means 1/2 full.
Not necessarily ... if you're filling a pair of 95's off of a single 95, the equalizing pressure won't be halfway between where the two started (assuming an isolated set of doubles with isolation valve opened).

... and I'm talking about getting adequate gas in your doubles to do another recreational dive ... for practical purposes, this can mean you don't need more than 1,200 psi or so in the doubles to do the dive and end with an acceptable reserve.

JeffG:
I would just use stages and leave the backgas for last. But thats just me.
Probably ... ;)

... Bob (Grateful Diver)
 

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