Under weighted New Diver

[gnat]

Hello Scuba board. I have a question regarding whether I'm being underweighted for dives. During my OW dives in the ocean I used 4Kg in weights. According to PADI, this is less than the recommended weighting for someone of my size and gear config (71kg male, 3mm full wetsuit, jacket bcd, 80l tank), which is around 5% of my body weight + 2 kg, which is 5.5kg. I did fun dives with 5kg since I weigh 80kg now.

I had no issues with weighting during training and fun dives dives since but I wonder if there are risks to being underweighted and if I should increase it?

 

[TMHeimer]

Do the weight check. Also, don't let anyone tell you you are overweighted if the weight check says you are not. People vary a lot due to body make-up. One diver may need like 40 pounds and another of similar weight/size and equipment like 30 pounds. Some say that you will be able to drop a few pounds once you are experienced and have really good buoyancy, breathing, finning, etc. I could never understand that-- would not the weight check say the same thing whether you have 4 dives or a thousand?

 

[inquis]

would not the weight check say the same thing whether you have 4 dives or a thousand?

Not necessarily, and a couple possibilities come to mind. The most likely is that newer divers often breath from the top (or middle) of their breathing range, and the greater residual volume needs more lead in order to be neutral. A related effect is breathing more rapidly and not taking the time for a nice exhalation. Later on, they breath more normally with less residual volume, so less lead is required.

Another possibility is they may unconsciously fin a bit; if they're not in horizontal trim (very common), they will need more lead in order to "not ascend". The distinction that "not changing depth" may not be the same thing as "neutrally buoyant" is missed. I know it sounds crazy, but I've had someone swear to me they were "holding still" when they were definitely not. For illustration, I had them first get neutral/still (in their opinion) and then had them cross their ankles. They immediately descended. As such a diver improves their trim or quiets their feet (or hands to a lesser degree), they need less lead.

 

[PatW]

Hello Scuba board. I have a question regarding whether I'm being underweighted for dives. During my OW dives in the ocean I used 4Kg in weights. According to PADI, this is less than the recommended weighting for someone of my size and gear config (71kg male, 3mm full wetsuit, jacket bcd, 80l tank), which is around 5% of my body weight + 2 kg, which is 5.5kg. I did fun dives with 5kg since I weigh 80kg now.

I had no issues with weighting during training and fun dives dives since but I wonder if there are risks to being underweighted and if I should increase it?

Yeah, if you can hold your safety stop with a nearly empty tank and all the air out of your BCD, you are fine.

Being slightly underweighted is not too bad. You can invert and gently kick down to hold the safety stop. Or you can just hang onto the mooring line.

 

[TMHeimer]

Not necessarily, and a couple possibilities come to mind. The most likely is that newer divers often breath from the top (or middle) of their breathing range, and the greater residual volume needs more lead in order to be neutral. A related effect is breathing more rapidly and not taking the time for a nice exhalation. Later on, they breath more normally with less residual volume, so less lead is required.

Another possibility is they may unconsciously fin a bit; if they're not in horizontal trim (very common), they will need more lead in order to "not ascend". The distinction that "not changing depth" may not be the same thing as "neutrally buoyant" is missed. I know it sounds crazy, but I've had someone swear to me they were "holding still" when they were definitely not. For illustration, I had them first get neutral/still (in their opinion) and then had them cross their ankles. They immediately descended. As such a diver improves their trim or quiets their feet (or hands to a lesser degree), they need less lead.

Yeah, I see what you're saying and have had these aspects mentioned to me before. But I do question how many of these "defects" are present when a new diver does a weight check. Such as-- are they actually breathing differently (from the top of their breathing range) than they normally breathe when not diving?
Maybe, but it seems a stretch. As well, they're probably not finning at all during the weight check--probably in shallow water just too deep to stand in. When I started out, I don't recall needing more weight than after 20-100 dives, but that was 20 years ago, so maybe?