First Time Diving Doubles

[tstormdiver]

I am asking this mostly to other ladies who have dove, or are diving double tanks about your first attempts at it. I'd just like to compare notes & get some ideas. Today I dove my doubled LP85's. I have been diving the tanks as singles for the last couple of months & was getting quite comfortable with them. At the urging of my technical instructor I had them doubled up for my Adv. Nitrox class. The first dive was terrible. We descended to a deep boat in the quarry (I reached near the bottom at 89'). I wore no extra weight & managed to still sink like a rock. Between sinking so fast, trying to balance the tanks, filling the wings & drysuit to slow myself & help with squeeze & clearing my ears, I became overloaded with the tasks. I also wouldn't be surprised if I wasn't a bit narc'd. My breathing became very rapid & was quickly becoming hyperventilation. Unable to control my breathing, I aborted the dive & began to ascend with my buddies right behind me. Afterwards I sat out for about 5hrs to compose myself. The second dive I stayed shallow (about 25' max). My buddies & I putted around some of the attractions. I worked more on balancing the tanks & also worked on hovering. In the end I was able to better control my buoyancy, but had a horrible time with my attitude in the water. One moment I would start going to the left, then to the right, then nose dive, then heads up. My buddies gently admonished me for using my hands too much to correct myself & that even though I felt like I was trying to invert, I was actually swimming at a heads up 45 degree angle, making harder on myself. any other ladies have this problem? Any tips to practice & help me? Thanks in advance. I really appreciate it.

 

[ScubaRandy]

I am asking this mostly to other ladies who have dove, or are diving double tanks about your first attempts at it. I'd just like to compare notes & get some ideas. Today I dove my doubled LP85's. I have been diving the tanks as singles for the last couple of months & was getting quite comfortable with them. At the urging of my technical instructor I had them doubled up for my Adv. Nitrox class. The first dive was terrible. We descended to a deep boat in the quarry (I reached near the bottom at 89'). I wore no extra weight & managed to still sink like a rock. Between sinking so fast, trying to balance the tanks, filling the wings & drysuit to slow myself & help with squeeze & clearing my ears, I became overloaded with the tasks. I also wouldn't be surprised if I wasn't a bit narc'd. My breathing became very rapid & was quickly becoming hyperventilation. Unable to control my breathing, I aborted the dive & began to ascend with my buddies right behind me. Afterwards I sat out for about 5hrs to compose myself. The second dive I stayed shallow (about 25' max). My buddies & I putted around some of the attractions. I worked more on balancing the tanks & also worked on hovering. In the end I was able to better control my buoyancy, but had a horrible time with my attitude in the water. One moment I would start going to the left, then to the right, then nose dive, then heads up. My buddies gently admonished me for using my hands too much to correct myself & that even though I felt like I was trying to invert, I was actually swimming at a heads up 45 degree angle, making harder on myself. any other ladies have this problem? Any tips to practice & help me? Thanks in advance. I really appreciate it.

Tammy,

Personally I would go get in a pool somewhere first and get used to the characteristics of doubles.... It is like starting to dive again, as you have seen.

First off, let me state that I am working off of the Faber LP85 buoyancy specs... 2400 psi with a 10% Overfill Rating to 2640 psi, 7 inch Diameter, 26" Tank Height
33 lbs. Tank Weight, negative 6 lbs full / Neutral empty Buoyancy in salt water
Triple Coated with spray galvanize, epoxy paint and polyurethane coating

You have introduced 6 more pounds of buoyancy swing in there by adding the 2nd tank. At first you are negatively buoyant since the tanks are full... This is why you were sinking like a rock.

When you breathe, you are breathing gas out of both tanks, the trim is affected since both tanks are losing volume. Remember when you first started diving and you had trim problems at first? Well, the same item here, except it is much worse because of the doubles.

You did the right thing on the second dive by staying shallow and concentrating on the trim aspect of your diving.... And that is really what it is about.

Back when I dove doubles, I played around with the position of the tanks to help with the trim aspect... You want and need to be able to get to the valves of course for shutdowns... You might have them mounted too high or too low on the BP... Try moving your weights around on your weighting system... I cannot stress enough it is like learning to dive all over again...

Hope this helps...

Randy

 

[Fionab]

At the urging of my technical instructor I had them doubled up for my Adv. Nitrox class. The first dive was terrible. We descended to a deep boat in the quarry (I reached near the bottom at 89').

Frankly I would get another instructor, I am surprised your instructor took you to 89' / 30m for your first venture in doubles. I agree with Randy a pool or shallow area would have been a better place.

 

[tstormdiver]

I was not with the instructor on those dives (although he was there diving with some others & he did admonish me for my poor judgment call there). His urging was only that I get them doubled up, not to go deep with them on my first tries. I was with a couple other divers that have been diving doubles for quite a while & were also trained by the same instructor. Believe me, they helped out as much as could be expected both with advice & physical help when I was struggling. I agree, in hind sight, it was foolish to go so deep on the first dive. We discussed this at length after surfacing & we all agreed that it was a bad decision on all of our parts. It was a learning experience that I won't soon forget. As for my weight system, with both tanks, I need no weight, but you may be right in the part that I may need to make adjustments to tanks & wings to smooth things out. Right now, I can reach the valves, if needed. After the first experience, it will certainly be the quarry shallows for me for a while, as I do not have ready access to a pool. Thanks for your input. I'm learning this & am open to any helpful suggestions.

 

[Hemlon]

No offense, Tammy. But it sounds like poor planning.

The prudent action is always to buddy up closely when trying out new gear or planning new skills.

 

[shoredivr]

So, hemlon, she's already said it was poor planning.......plus she did have buddies......

tstormwarning, sounds like staying in the shallow end, like you've decided, is the best chioce till you get comfortable.

 

[TSandM]

Tammy, I'm not going to talk about the dive you did, because you know what went wrong there. I'll just share my experiences with transitioning to doubles.

First off, it takes a couple of descents to get used to how negative you are -- The first time or two, I dumped all the air in the wing, got roaring downward, and discovered that it took a LOT of air to get stopped. My guess is everybody has an embarrassing "splat" story to tell, if they'd admit it. I've learned a couple of things -- It's not necessary to take all the air out of the wing to descend, and it's really important to keep the descent rate under control, especially if you aren't sure how deep the bottom is, or you aren't going to be able to see it until just before you hit it, which is typical Puget Sound conditions. I figure that, if I can't just about stop my descent with a deep breath, I should be putting air somewhere. (A slower descent makes it easier to keep the team together, too, which is a nice side effect.)

A second thing I learned is that the harness has to as tight as it can be and let you get out of it, if you are diving doubles. You can get away with a sloppy harness with a single tank, but once you get all that mass on your back, any slack in the harness lets the tanks move around with respect to your body, and it's very unpleasant. I did several dives where I felt like the tanks were swimming around and all I was doing was trying to position myself underneath them -- yuck! Make sure the wing nuts are tightened down a LOT, too. If there's slack there, again, you get tank shifting. Once you get everything tight and stable, you'll actually find that doubles are LOVELY to dive. They're very stable as a platform above you, and their inertia makes buoyancy control much easier than a single tank. But you have to get everything adjusted properly for it to feel that way.

Finally, the trim stuff. I started out in a set of 72s, because they were small and relatively light. I can't balance them out, even now. They're too short and sit too high on my shoulders, and I'm just enough head-heavy that I can't stay in horizontal trim and not move. So I end up diving 30 degrees head-up to try to balance them. And if you look around you at new doubles divers, you'll see a LOT of people out of trim for this reason.

I now dive a set of Worthington 85s, and from the first time I went in the water with them, they felt SO much better. But I can't really imagine diving them without any weight at all -- I dive with 16 pounds on a weight belt, and that trims me out perfectly. On the other hand, I've dived a set of Al80's with an 8 pound V-weight and no other weight, and they trimmed out beautifully (this was in fresh water). If you can't trim out the steel tanks, you might want to try a set of aluminums, to allow you to put some weight on where you need it to balance. Oh, and that reminds me of something else -- Are you using a SS backplate? I had to go to an aluminum plate to let me move four pounds down my body.

Anyway, you're not unique in finding it a challenge to achieve the same level of comfort and competence in doubles that you have in a single tank. But I'll tell you, if I could get somebody ELSE to schlep them to and from the water, I'd never dive a single tank again. I love my doubles.

 

[Belmont]

Tstormwarning, thank you for the precise description of your experience. I will be diving in doubles in a few months, twin HP 130's, should be interesting. It reminds me when I first tried my BP/W and a single 130. Like you I was all over the place, using my hands, lifting up the bottom, up and down, the works. It has since improved a lot, so do what ScubaRandy said and for my part I will also abide by his recommendations when the time comes.:14:

 

[tstormdiver]

A second thing I learned is that the harness has to as tight as it can be and let you get out of it, if you are diving doubles. You can get away with a sloppy harness with a single tank, but once you get all that mass on your back, any slack in the harness lets the tanks move around with respect to your body, and it's very unpleasant. I did several dives where I felt like the tanks were swimming around and all I was doing was trying to position myself underneath them -- yuck! Make sure the wing nuts are tightened down a LOT, too. If there's slack there, again, you get tank shifting. Once you get everything tight and stable, you'll actually find that doubles are LOVELY to dive. They're very stable as a platform above you, and their inertia makes buoyancy control much easier than a single tank. But you have to get everything adjusted properly for it to feel that way.

Finally, the trim stuff. I started out in a set of 72s, because they were small and relatively light. I can't balance them out, even now. They're too short and sit too high on my shoulders, and I'm just enough head-heavy that I can't stay in horizontal trim and not move. So I end up diving 30 degrees head-up to try to balance them. And if you look around you at new doubles divers, you'll see a LOT of people out of trim for this reason.

I now dive a set of Worthington 85s, and from the first time I went in the water with them, they felt SO much better. But I can't really imagine diving them without any weight at all -- I dive with 16 pounds on a weight belt, and that trims me out perfectly. On the other hand, I've dived a set of Al80's with an 8 pound V-weight and no other weight, and they trimmed out beautifully (this was in fresh water). If you can't trim out the steel tanks, you might want to try a set of aluminums, to allow you to put some weight on where you need it to balance. Oh, and that reminds me of something else -- Are you using a SS backplate? I had to go to an aluminum plate to let me move four pounds down my body.

Anyway, you're not unique in finding it a challenge to achieve the same level of comfort and competence in doubles that you have in a single tank. But I'll tell you, if I could get somebody ELSE to schlep them to and from the water, I'd never dive a single tank again. I love my doubles.

TS&M, thank you so very much for your input. My harness is as tight as I can get with being able to get in & out (they left some noticeable, but not painful bruises on my shoulders). I'm not sure of the manufacturer of the tanks (I looked but either couldn't find or recognize the manufacturer's markings), only that they are LP 85's with a 7.25" diameter. My back plate is aluminum. I thought about getting a stainles steel, but really didn't want any more weight on me than I needed. Before the first dive I did as best of a weight check as I could, since the tanks were full. When I emptied the wings, with a full breath of air (& reg still in mouth), I immediately began to sink over my head (of course I immediately inflated my wings to get back above the surface). I basically dive a trilam drysuit with 200gram undergarment & some thick under armor underneath that to keep comfortable. With that drysuit & an AL80 tank in fresh water, it took 30#'s to sink me. When I was diving my LP85's as singles (using my BP/W & a single tank adapter), I was able to drop to 18#'s, but still felt a bit overweighted at times, yet neutral when the tank, as a single was near empty. I have since had several people also tell me that it's like learning to dive all over again. That's the absolute truth, no better way to explain it. I plan on conducting more dives in these tanks in the shallow waters of the quarry (15- 20') & make sure I'm fully comfortable about my ability to handle them when they become cantankerous. My technical instructor who was at the quarry (to dive with some very advanced divers) said the set up looked like it was in about the right position on me, but that some minor adjustments may need to be made. I would say that these "minor adjustments" may make a world of difference when trying to handle that much weight. Where, in general, the tanks are easier to balance, if it gets tilted just a little bit, it's all I can do to get myself back on an even keel. Anyway, I do appreciate everyone's input.

 

[nereas]

I am asking this mostly to other ladies who have dove, or are diving double tanks about your first attempts at it. I'd just like to compare notes & get some ideas. Today I dove my doubled LP85's. I have been diving the tanks as singles for the last couple of months & was getting quite comfortable with them. At the urging of my technical instructor I had them doubled up for my Adv. Nitrox class. The first dive was terrible. We descended to a deep boat in the quarry (I reached near the bottom at 89'). I wore no extra weight & managed to still sink like a rock. ...

I think you are probably over-weighted.

[Caveat: I am not a lady.]

I dive with a stainless steel backplate together with an additional 26 lbs with a single steel tank, but with the same backplate together with an additional 14 lbs with my double steel tanks, in really cold water.

You spoke of diving "with no additional weight" however I am inferring that you therefore were using the same weight belt.

Being grossly overweighted would account for your various issues on your dive.

Ergo, I believe you need to re-determine your weight belt for your doubles, before you proceed further.

And I am guessing that for cold water diving, your weight belt for your steel doubles is going to be about half that for your single steel tank diving.

Its pretty common for new tech divers to wear the same weight belt as for single tank diving on their first twin-tank dive(s). However I am surprised that your tech instructor did not help you to re-determine your neutral buoyancy with the doubles. It's like starting over, and you need to Do This Right before you ever go into deco.