Ascent Question

[formernuke]

A steel tank with 40 pounds of lead, wow. Unless you are a really, really, really really big person you are massively overweighted.

 

[divad]

A steel tank with 40 pounds of lead, wow. Unless you are a really, really, really really big person you are massively overweighted.

Probably the instructor's idea?

 

[boulderjohn]

I will not buck the consensus so far.

• Start the ascent while neutral and dump air a little at a time as needed during the ascent.
• It sounds like you are seriously overweighted.

 

[bushcat]

A steel tank with 40 pounds of lead, wow. Unless you are a really, really, really really big person you are massively overweighted.

Yip either 32 + 4 or 32 + 8 can't quite remember and trust me I will never attempt to ascend negatively buoyant again

 

[inquis]

I’ve had it hammered into me empty BCD fin to ascend

Lose this habit right now. You should be neutral, in control at whatever depth. If you want to ascend, just take a slightly larger breath and you'll start up, then air in the BC expands, allowing you to exhale but continuing the ascent. The BC expands more, accelerating ascent, so you vent the BC to slow the ascent. Control the rate with suitable venting.

I get you were doing a drill where you had to halt a descent, but when you're negatively buoyant, dumping the BC only makes it worse. If it simplifies things in your mind, yes get neutral first, halting the descent.

 

[boulderjohn]

Lose this habit right now. You should be neutral, in control at whatever depth. If you want to ascend, just take a slightly larger breath and you'll start up, then air in the BC expands, allowing you to exhale but continuing the ascent. The BC expands more, accelerating ascent, so you vent the BC to slow the ascent. Control the rate with suitable venting.

I get you were doing a drill where you had to halt a descent, but when you're negatively buoyant, dumping the BC only makes it worse. If it simplifies things in your mind, yes get neutral first, halting the descent.

I wrote about this on another thread. Some instructors actually do teach to empty the BCD before ascent. I had a DM in Belize emphasize that. It works fine with a properly weighted diver with a 3mm wetsuit, but it can be a very bad in a thicker wetsuit or a drysuit. If you are overweighted as well, it can be a disaster.

 

[inquis]

the drysuit also had no air in it

I haven't seen this touched upon yet, but this can be extremely dangerous, possibly deadly.

For single tank diving, the simplest approach may be to use the suit instead of the BC for buoyancy below the surface. After you become more familiar, the advantages to using both (minimal air in the suit and the Buoyancy Control Device/BCD for primary buoyancy control), may be worth the effort to develop those skills.

I don't want to derail your thread with debate about which of those approaches is better, but I think everyone would agree that "no air in the suit" is a bad thing.

 

[kaylee_ann]

The way I always did it was to put a little air in the BC to begin ascending (if inhaling wasn’t enough), then vent air as needed for a slow, controlled ascent.

 

[boulderjohn]

The way I always did it was to put a little air in the BC to begin ascending (if inhaling wasn’t enough), then vent air as needed for a slow, controlled ascent.

You should never need to add air to the BCD to begin an ascent.

Many instructors inadvertently teach students to do this, though. They do pool skill sessions on the knees, heavily weighted, with empty BCDs. Then they finish the dive and go to the surface. Yes, the students must add air to the BCD, but that should be wrong, wrong, wrong in real diving.

One of the first rules of instruction in any skill area is never have students do something in practice that they do not do in the game (or whatever).

 

[rongoodman]

The way I always did it was to put a little air in the BC to begin ascending (if inhaling wasn’t enough), then vent air as needed for a slow, controlled ascent.

I just go a little head down and do a back kick or two to start. It puts the expanding air right under the dump and positions me to kick back down if things start to get out of hand.