Zeagle Zena - Buoyancy issue

[Tri]

Hi,

Bought the Zeagle Zena for women. Lovely BCD. Have tried diving with it for a few times but always faced problem when first entering the water. Very hard to initiate the descend. But once inside, everything is okay.

The problem appeared again about 8m from the surface where it's hard to control the ascend even though the BCD was being deflated. It's just going up too fast :depressed:

My weight is 57kg and I am using 8kg of weight lead. Is this because of the back-inflated design? Have used jacket-type BCD and I don't have such problems.

Any help and pointers are appreciated.

 

[Jim Lapenta]

Jacket or back inflate really does not matter. What method did you use to determine your weighting requirements for this BC? What type of exposure suit are you using? Fresh water or salt? Steel tank or aluminum? We need this info to give a better answer, or really any answer. We have two Zena's for pool use. The last student I had in one with a 3 mil suit, al80, and she was approx your size required 12lbs. Too much weight can cause you to have problems on ascent. The extra air you need to offset the weight will expand too rapidly and give problems controlling the ascent. Your Instructor should have showed you how to determine your correct weighting and advised you to do a check every time you change set ups.

Improper technique coupled with incorrect weighting will also give you difficulties on descents. Are you fully venting the BC to descend and are you descending vertically or horizontally? That can also make a difference. Provide a bit more info as noted and we can give you a much better answer. Thanks.

 

[Tri]

Thanks for responding. Here's the info: Wet suite 3mil, sea water (warm 29C), aluminium tank. Always upright vertical descend from the boat. Weight has been adjusted by divemaster around 5-6kg by checking it underwater.

I am pretty sure I vented out on the descend (holding the hose above) under the watch of the DM. And emptying my lung on entry. It always takes about 2-3 minutes struggling before I can go under.

When returning to surface (around 8m away), the lift became very fast even though I deflated the BCD but always late to stop the fast ascend. Dive depth is usually around 20 meter.

Thanks.

 

[DiveMaven]

I'm not sure how much this will help, but when I deflate my Zena, I always tilt my left shoulder up a bit higher than my right to make sure I don't get any trapped air in the top part of the wing. You also might try flooding your wetsuit since you may have a bit of trapped air that is adding buoyancy at the start of your dive. And a last suggestion would be to cross your ankles to prevent inadvertent finning that may be preventing you from sinking while you're exhaling fully.

You also might want to completely empty your wing prior to starting your ascent, then get those last bubbles out at about 25' below the surface.

I'm a bit stumped at your difficulties since I weigh about 72kg and only need 4.5kg of lead in a 3mm full suit with an AL80 in warm salt water. Heck, I only use 6kg with a 5mm merino lined full suit. I always do horizontal ascents and decents, and have weights in all 4 pockets....not sure if that makes a difference or not.

 

[Tri]

Thanks DiveMaven. Will do so for my next dive.

I usually inflate first, waiting for my buddy then vertical descent together. Never try horizontal before. Is horizontal descent = negative entry?

again tq.:blinking:

 

[TSandM]

No, horizontal descent and negative entry are not the same. A negative entry is where you get all the air out of your BC before you jump off the boat, and let the momentum of your jump carry you completely underwater immediately. (You had better have done a good gear check before doing this!)

I do not understand the DM being able to check your weights while underwater -- unless he had you take some off, to see if you could still stay submerged, and this would only be valid if it were done in water at or shallower than your safety stop depth.

The combination of inability to descend AND inability to maintain a shallow stop can really only be one of two things: A very novice diver, or underweighting. (Air trapping in the BC is a remote third possibility.)

 

[Tri]

Thanks TsandM for the info. Huh, still need a lot to learn. :sos:
have to find my 'correct' weight first then.

before we dive, the DM will do check dive. so everybody on shallow water (6m) doing the procedures then check on our weight and buoyancy control. DM carried extra weight in case not enough weight.

i will note all of your replies and apply them on my next dive which is in may. hope i can get it right.

 

[knowone]

The sooner you start to utilise your shoulder dump

the sooner will bring happiness to you will be

Hose lifting and button pushing is slow

and attempts to hinder physics

 

[Tri]

Thanks everyone for your inputs. Will practice them in my next dive.

 

[AnnSul]

The sooner you start to utilise your shoulder dump

the sooner will bring happiness to you will be

Hose lifting and button pushing is slow

and attempts to hinder physics

Love your poetry, I do.
I see Yoda speaking as a Shaolin priest.
Just sayin'.