Duck dive for descent?

[Manchz]

Newly certified diver here.

Can you duck dive from surface to descend with all your gear on your back?

I recently floated up to the surface during a recreational dive (my buoyancy control not established yet), (I am very accustomed to duck diving in non scuba environments) - but found I couldn't duck dive or even swim downwards from surface as the gear kept weighing me down in the opposite direction. Was the first time I tried it, as deflation on BCD wasn't working.

 

[dmaziuk]

Edit - this is not to descent. I descent as taught, feet first, exhale, deflate BCD.

This is for when I float up during the dive and when BCD is already deflated and exhaling won’t bring me down. Exploring an alternative, rather than being stuck on the surface. I couldn‘t duck dive cos’ the weight of the gear was pulling me behind my shoulders (towards my back) and duck dive requires a curl forward. If that paints a picture.

Add more weight. You can try rolling left and right to get the air bubble to the shoulder, but most likely you need more weight.

Ducking is like a swimming flip turn: if you're horizontal, it's just bending forward (down). If you are not horizontal, you might want to relocate some of your weight to trim pouches on the camband.

Ducking won't really help: I've done the safety stop upside-down and finning, and it's only fun once. The rest of the time you want to be able to float at 3-5 msw with 50 bars in your tank and no air in the BCD.

 

[scubadada]

@Zinman

Do a proper weight check. With your cylinder near reserve pressure (500 psi in an AL80), you should be neutral at your safety stop with no air in your BC. You should be able to do a nice, controlled, slow ascent to the surface. If this is not the case, adjust your weights. With a full cylinder, you should be a little over 5 lbs negative at the beginning of a dive due to the gas that you will consume during your dive. You should have no trouble descending and will need to put some gas in your BC as you approach your bottom depth to become neutral. Practice.

I find the butt dump the most reliable way to get all of the air out of my BC. Butt up and side with the dump up, it becomes second nature.

 

[NDonahue]

You can but that is establishing bad habits.

Work on proper weighting and descents.

I often find when I’m perfectly weighted but on my first dive of the day that I need to work to get down 3-5m before I am descending with no effort.

Kicking down is not a bad habit if the diver is neutral at the end of the dive.

 

[formernuke]

I often find when I’m perfectly weighted but on my first dive of the day that I need to work to get down 3-5m before I am descending with no effort.

Kicking down is not a bad habit if the diver is neutral at the end of the dive.

It is

 

[Outbound]

I often find when I’m perfectly weighted but on my first dive of the day that I need to work to get down 3-5m before I am descending with no effort.

Kicking down is not a bad habit if the diver is neutral at the end of the dive.

If you have to work/kick to get down to 3-5m at the start of a dive, how are you holding your safety stop at the end of the dive? I can see maybe having to push down for a few feet on the very first dive of a trip with a bone dry wetsuit. But 3-5m?

 

[boulderjohn]

This is for when I float up during the dive and when BCD is already deflated and exhaling won’t bring me down.

. I couldn‘t duck dive cos’ the weight of the gear was pulling me behind my shoulders (towards my back) and duck dive requires a curl forward. If that paints a picture.

It does paint a picture. It is a picture I saw often while working with new divers.

What I have frequently seen with new divers is that they are swimming (at best) at a 45° angle, kicking constantly to maintain their depth. They think they are neutrally buoyant, but if they were to stop kicking, they would sink. They also think they have all the air out of the BCD, but they don't. Their body position and their kicking eventually brings them shallower, which causes the air they don't think is in their BCD to expand. They start to ascend even more, so they go completely vertical (while still kicking) to try to dump air, which makes things worse.

In many cases, these people are already overweighted, which is why they have so much air in the BCD, which is expanding as they rise. If that is the case, adding more weight will make it worse.

 

[NDonahue]

If you have to work/kick to get down to 3-5m at the start of a dive, how are you holding your safety stop at the end of the dive? I can see maybe having to push down for a few feet on the very first dive of a trip with a bone dry wetsuit. But 3-5m?

Maybe 3-5 is too deep an estimate. My point stands that one can be perfectly weighted for the end of the dive and still need to kick down at the start.

 

[dmaziuk]

The highest mastery of duck-fu is when you kick down, pull the butt dump, let out exactly as much air as needed to be neutral at your planned depth, and no more.

 

[rx7diver]

Newly certified diver here.

Can you duck dive from surface to descend with all your gear on your back? ...

Yes, you can, absolutely! Keep in mind that there is a natural tendency to take a deep breath before submerging. Don't do that. Instead, exhale when you begin, and then breathe normally after you've descended a short distance--you know, after your wetsuit has compressed a bit.

rx7diver

 

[tursiops]

Maybe 3-5 is too deep an estimate. My point stands that one can be perfectly weighted for the end of the dive and still need to kick down at the start.

I guess I don't agree. At the beginning of the dive you have some kg (2-3+) of air you do not have at the end. No need to kick down.