Difficulty with doubles

[down4fun]

I wasn't sure where to post this so if this is the wrong place, feel free to move it.

I am attempting to make the transition to technical diving and as part of that plan started taking a NAUI cavern course in doubles. This was my first introduction to doubles, as well as BP/W and long hose. So needless to say I had a lot going on. But here is my difficulty. I am horribly head down in the water. At first I was almost verticle, as in head down feet soaring towards the surface. Over the two days I became a little better in controling my trim, but no where near where I want to be. I really did not expect the switch to throw me off as much as it has. Did anyone else find the switch to BP/W with doubles difficult.

FYI I am not done with the course, my instructor is continuing to work with me until my skills have improved.

 

[Doc Intrepid]

There are a wide range of variables that can impact on trim. Some are inside your head, others have to do with your gear. What type of tanks you have can be critical. At the risk of assuming, it would appear that you might do well to start off with a set of steel 72s if you could find a set. They are smaller, lighter steel tanks and easy to work with.

Some tanks are longer and 6.9" or 7.25" in diameter. Others are shorter, but 8" in diameter. Steel or aluminum. Backplates can be steel or aluminum. Even some regulators are chunkier and heavier than others. The reason why all these things matter is that depending on where they sit against your body, relative to your own personal center of gravity, they each can impact the total effect: your ability to hover effortlessly with excellent bouyancy and trim.

In the water column your bouyancy and trim depend on how you 'balance' or trim out around your center of gravity in a state of perfect equilibrium. Your body is like a lever, and the fulcrum is at your center of gravity.

So...don't get discouraged. Part of the transition is slowly working these things out over a series of dives. The more diving you do, however, (under controlled conditions or 'confined water') the more quickly you will see things coming together: especially if you are working with an instructor or mentor. The mentor can see whats happening, and may have access to a wide range of tricks to make your transition easier.

It's initially difficult for everyone. But...once you get it dialed in, from there on out you'll find it gets much easier.

Hang in there,

Doc

 

[cool_hardware52]

I wasn't sure where to post this so if this is the wrong place, feel free to move it.

I am attempting to make the transition to technical diving and as part of that plan started taking a NAUI cavern course in doubles. This was my first introduction to doubles, as well as BP/W and long hose. So needless to say I had a lot going on. But here is my difficulty. I am horribly head down in the water. At first I was almost verticle, as in head down feet soaring towards the surface. Over the two days I became a little better in controling my trim, but no where near where I want to be. I really did not expect the switch to throw me off as much as it has. Did anyone else find the switch to BP/W with doubles difficult.

FYI I am not done with the course, my instructor is continuing to work with me until my skills have improved.

Sounds pretty typical. Head down is very common.

Your tanks need to positioned where you can reach the valves. They may now be higher than you need.

You can shift your center of mass towards your feet by:

Raising the tank bands on the tanks if possible,
Using a lower hole set in your BP ,if so equipped,
Raising your wing relative to the Back Plate, if your wing permits multiple locations,
Changing to a different set of tanks. Short tanks like LP 95's and HP 80's make the head down effect worse.
Extend your legs,
Use negative fins, like Jets.
Use a tail weight.

Pool time is the key, plan to spend some time playing with weighting and trim weighting.

Here's one example of a tailweight http://www.thedecostop.com/photopost/showphoto.php?photo=2200&cat=500&ppuser=4897

As mounted http://www.thedecostop.com/photopost/showphoto.php?photo=2207&size=big&ppuser=4897

First Doubles Dive can be an experience, don't worry it gets better fast.


Regards,


Tobin

 

[scubafool]

For me, the transition to a BP/W went rather smoothly, but I dove single tank for quite a while. With a single tank, I could get trimmed out by adjusting the tank up or down in the cam bands.

When I started out in doubles, it was a slightly different story.

One thing that I like about the DiveRite Classic wings is that you can place the wing at any of three different heights to help adjust trim. I believe that there are other wings that allow you to do this, but I am not certain.

Another thing that has helped me is changing only one thing about my gear at a time. For a while, even with my wing set as high as it can go, I was very slightly head heavy. I was ready to adjust the bands on my tanks upwards slightly to correct this, but when I added a canister light into the mix, I actually had to move the wing to it's middle position to correct a foot heavy problem. So if I had added the can light AND adjusted the tank bands at the same time, I would have been way out of wack.

The Intrepid Doc touched on a lot of other considerations that are important. Most important is don't get discouraged, this is a major change you are making, but it will be worth it.

Edit: I meant to include, but Tobin beat me to it, you can fine tune your trim slightly by the position of your legs and hands.

 

[Green_Manelishi]

Too many significant changes can lead to trouble regardless of configuration or the upcoming dives.

In addition to the other suggestions (and pardon if it was in one of them), switching to an AL plate can be a positive as well. Of course, the weight you "lose" will probably need to be added to a weight belt or something else but it lessens the amount of negative ballast that is positioned above your waist.

For singles I use very short, highly negative tanks (Faber HP80s) and I have to use an AL plate and DUI W&T in order to remain in trim. The advantage to the extreme negativity of the Fabers is the amount of weight on the belt is only about 15 pounds.

When I dive doubles (LP95s) I have to use the W&T even if I use the steel or AL plate; a "V" weight still has the weight too high on my body.

 

[Mark Vlahos]

I wasn't sure where to post this so if this is the wrong place, feel free to move it.

I am attempting to make the transition to technical diving and as part of that plan started taking a NAUI cavern course in doubles. This was my first introduction to doubles, as well as BP/W and long hose. So needless to say I had a lot going on. But here is my difficulty. I am horribly head down in the water. At first I was almost verticle, as in head down feet soaring towards the surface. Over the two days I became a little better in controling my trim, but no where near where I want to be. I really did not expect the switch to throw me off as much as it has. Did anyone else find the switch to BP/W with doubles difficult.

FYI I am not done with the course, my instructor is continuing to work with me until my skills have improved.

Doc's post is full of good info, as usual.

In my case I was extremely head down on my first double dive. Here are some of the changes I made...

From a steel backplate to a plastic plate (aluminum would provide the same solution).

Move the tanks as far down my back as possible while still being able to reach the valves. This was accomplished by positioning the bands as high as possible on the tanks and puting the bolts in the lowest possible set of holes on my plate. Of course still being able to reach those very important valves.

Move the wing as far up my back as possible.

Heavier fins, specifically Jet fins.

Arching my back.

I have since used double 95's again with far fewer problems, and keeping trim was far easier but if I completely stop moving I will still drift to a head down attitude, so the last solution was to switch to 130's and separate the 95's for use as singles.

I am 6 foot tall and weight 220 lbs so my situation will almost certainly be different than yours, at least with regards to my need to simply switch tanks.

For me switching to the light weight plate was the biggest single thing since I was only ever able to move the tanks and wing a little.

Keep with it, you will also notice a huge difference in side to side weight shifting. The need to keep those tanks centered over your back is very different when compared to a single tank, even a steel one. Have you been caught by surprise and turned turtle yet, facing up and not being able to easily assume a normal swimming position.

Have fun,

Mark Vlahos

 

[Bobby]

Things listed above are all good at dialing in your trim. One other thing is to pay attention to how you are using your lungs to affect buoyancy. Depending on the position I want in the water I will breath from my upper track to my lower track or use both. When setting a tie off low on the floor I want my head more down to reach it with out getting close to the silt and will use the lower section of my lungs to breath. When using an over head tie off then I will use my upper lungs to be more head up. It takes some practice but will make an impact on trim.

Bobby

 

[scubafool]

BobbyF, how do you change what part of your lungs you breath with? Sounds interesting.

 

[Bobby]

Breath deep in your belly while holding the top part of your chest in or the other way around or both. Takes a little practice but will fine tune buoyancy very tightly.

Bobby

 

[daniel f aleman]

Too many tasks.

Learning to dive with a BP/W AND learning to dive with doubles AND learning Cavern... all this should be done in progression. Also, you can take Cavern in a BC with a single AL80.

Learn the BP/W first, then Cavern, then doubles.