Okay to pull yourself down?

[Web Monkey]

You will never be heavier or less buoyant than you are at the beginning of the dive.

This means that as your dive continues and you use air, you will become progressivly more buoyant, and at some point will be unable to maintain neutral buoyancy and your depth.

What makes this worse is that as you ascend, your wetsuit and to some extent your body will become more buoyant, and you will be unable to control your ascent rate, find yourself on the surface very quickly, and be unable to descend again or do a stop.

In short, being underweighted is really bad.

You did the right thing by aborting the dive.

Terry

PS. A guess by the DM as to how much weight you should use is completely irrelevant when compared to your actual experience using any particular amount of weight. If you felt overweighted, it was your call to remove a pound or two. If you felt OK, you should keep it.

Hi, I need some advice on weighting and descending properly.

I went diving recently with a group of friends who had just finished their training. I haven't dived in over a year, and haven't done a cold water dive in over four years. The dive was to be to about 80 feet.

The DM asked everyone how much weight we were carrying and told me I was way over weighted so, ignoring the little voice in the back of my head, I took some weight out. Too much I think.

We got into the water and grouped at the surface by the anchor line to start our descent but I couldn't go down! The others used the chain to pull themselves down, but I tried everything I'd been taught: breathing easy, crossing my ankles so I wouldn't accidently fin, etc. but still just hovered.

My buddy came back to see what was up and suggested that I pull myself down by the chain also. I know that if I got down to a certain depth I'd be able to descend, but I didn't want to do this because I thought, If I'm underweighted, how will that affect me at depth?

I wasn't comfortable with that so, I aborted the dive. Was this the right thing to do or would I have been ok to use the chain to descend?

Thanks.

 

[markfm]

A little jittery, slightly hard to get down, might be fine, but if I had to pull myself it would be a concern. On an AL80, you lose 5 pounds of air going from 3000 to 500 psi -- if you start positively buoyant, being an additional 5 pounds buoyant at the end is not going to make a safety stop reasonable.
(That's why one way of doing a buoyancy check is to get neutral at the surface with a full tank, then add 5 pounds -- the 5 pounds compensates for the air weight expended as you suck a tank down during a dive. But "neutral" in this case means you are vertical, mask right at the water/air edge, and if you fully exhale you start to sink -- if you're pulling yourself down you aren't neutral, never mind neutral + the necessary 5 lb.)
Good job calling it in such a case!

 

[The Dive Bum]

You did the right thing. An equipment problem is an equipment problem. You do not dive with equipment problems. 80 feet is way too far to shoot to the surface from being underweighted.

 

[timle]

I'm curious why you couldn't just add some more weight? Or is that what you did - got some more weight and then went down? Is this still considered an abort? I would consider it weight fine tuning.

 

[ClevelandDiver]

If you couldn't get down with a full tank, then you wouldn't be able to do a safety stop with an empty (lighter) tank. Sounds like you did the right thing.

Myself, I might have worked at it to get down and then grabbed a rock or something, but I'm not sure that's the "right thing"

The safety rock is an important part of my vintage diving set up! Diving without a BC in a 1/4" suit almost requires one. I weight for depth and have to kick hard to get down. At the end of my dive, I grab a safety rock to hold my 15 foot stop. Fortunately there is an abundance of rocks when diving in a quarry.

 

[Kevfin]

You did the right thing.

Not sure about the DM though. I hope we're not talking that you had 20 lbs extra weight, but if his only issue was your weight and you have dove like that before, unless he is specifically going to work with you on buoyancy, he should have left it alone.

Don't know what other equipment you have, however, like most people are saying, it probably would have made your safety stop difficult.

Sorry you had this bad experience. As you can see, if you read a lot on this board, there are a lot of DMs that aren't qualified to lead in a wading pool.

 

[mark99]

I'm not sure what all the people who are advocating "abort the dive" intend for you to do on the next dive. If you really had a "buddy", then the two of you could have worked on checking out your buoyancy and getting you correctly weighted for THAT dive. I agree with the others, you should not pull yourself down the anchor line unless you are sure you are correctly weighted. Most times on the first dive, I have difficulty descending- I believe it to be because the wetsuit is not saturated and there is some air trapped in the wetsuit and BC. Knowing that, and that I have been properly weighted at the end of other dives with the exact same equipment, I would use the anchor line, or fin down, to get submerged on the first dive. A smarter approach for you would have been to do the traditional buoyancy check (as described by Markfm above) , perhaps adding an extra 7 pounds rather than 5, and then do another check at the safety stop at the end of the dive.

 

[N2Baja]

Thanks, everyone, for the responses. I'm glad I listened to my inner voice. Regarding adding more weight, I'd told my dive buddy to go ahead and he joined another twosome. So if I'd added the weight I'd left on the boat, it would have meant descending alone to meet up with them. Not being familiar with the dive sight, and considering the depth and limited visibility, I wouldn't have felt comfortable trying to catch up with them.

Thanks again! My next dive will be better!

 

[spectrum]

Where do I start?

Well first you did the right thing in aborting the dive. Just jumping into the water you were almost as negatively buoyant as you will be. This means that as you breathe down your 80 CF tank you will drop about another 5 pounds. On an 80 foot dive this won't cause a problem at depth. However should you need to ascend away from the anchor line or loose your grip you were sure to loose control. When in doubt get out.

I say you were almost your heaviest at the start of the dive because gear will trap air to varrying extents. I find that if I get right down to a fixed depth I need to slowly add air for about 5 minutes as padding saturates and bits of air escape from my suit. In this time the weight of air is hardly depleted. For this reason it's OK to do a slight duck dive to get the descent started but needing to pull yourself down the chain is a red flag. This initial stowaway buoyancy is why you should do your final weight checks at the end of the dive. Adding 5 pounds to a pre-dive weight check will tend to overweight you, but it is a good safe starting point. Remember the point of the weight check is to have just heavy enough to end the dive under control in a free ascent with your tank down to about 500 PSI.

You should have had a better handle on your own weight requirements. Having been out of the water that long with less than 15 total dives a boat dive to 80 feet was the wrong place to be that day. Regardless of having a divemaster and some anxious newly certified friends. Regarding them going to 80 feet freshly certified there was a whole thread on that a week or 2 ago.

It is true that you may have been breathing heavy, that relaxing would have let you get down normally but in the absence of a proper weight check the end result is all speculation. Taking a stone from the bottom is a time honored technique but not one to engage in without forethought and understanding the risks of diving and finding no stone or loosing it at the wrong time.

You did the right thing. Now get a handle on your weight configuration then dive safe and dive often, the two are intertwined.

Pete

Hi, I need some advice on weighting and descending properly.

I went diving recently with a group of friends who had just finished their training. I haven't dived in over a year, and haven't done a cold water dive in over four years. The dive was to be to about 80 feet.

The DM asked everyone how much weight we were carrying and told me I was way over weighted so, ignoring the little voice in the back of my head, I took some weight out. Too much I think.

We got into the water and grouped at the surface by the anchor line to start our descent but I couldn't go down! The others used the chain to pull themselves down, but I tried everything I'd been taught: breathing easy, crossing my ankles so I wouldn't accidently fin, etc. but still just hovered.

My buddy came back to see what was up and suggested that I pull myself down by the chain also. I know that if I got down to a certain depth I'd be able to descend, but I didn't want to do this because I thought, If I'm underweighted, how will that affect me at depth?

I wasn't comfortable with that so, I aborted the dive. Was this the right thing to do or would I have been ok to use the chain to descend?

Thanks.

 

[The Kraken]

NO ! ! ! ! !

the K