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?

 

[Alekseolsen]

If you have had no issues, you are not underweighted - period

All divers should do a weight check when they start out, removing as much weight as possible until one is unable to sink with empty lungs, wing, and crossed fins (since most new divers are unconsiosuly finning).

The PADI (and all others!) Recommendation is at best a starting point for such a test, and you've already prooved you have enough weight during your dives

 

[rongoodman]

You should be able to hold your position during your safety stop at the end of the dive with a nearly empty tank. If you can't, you're too light. If you have more than a little bit of air in your wing/BC you can then drop some more weight.

 

[gnat]

If you have had no issues, you are not underweighted - period

All divers should do a weight check when they start out, removing as much weight as possible until one is unable to sink with empty lungs, wing, and crossed fins (since most new divers are unconsiosuly finning).

The PADI (and all others!) Recommendation is at best a starting point for such a test, and you've already prooved you have enough weight during your dives

Thank you. I had no issues but I'll try your suggestion to remove all weight until I'm unable to sink just to fine tune my buoyancy.

You should be able to hold your position during your safety stop at the end of the dive with a nearly empty tank. If you can't, you're too light. If you have more than a little bit of air in your wing/BC you can then drop some weight.

I had no issues holding my safety stop at the end with my BCD empty. I just read about the horror stories here about students being overweighted and was just curious about the risks of underweighting. thanks for the response.

 

[halocline]

Thank you. I had no issues but I'll try your suggestion to remove all weight until I'm unable to sink just to fine tune my buoyancy.

I had no issues holding my safety stop at the end with my BCD empty. I just read about the horror stories here about students being overweighted and was just curious about the risks of underweighting. thanks for the response.

If you can hold a safety stop with a near empty tank, as rongoodman wrote, you’re fine. Your own body weight and the weight of your gear on land doesn’t really matter. The buoyancy of your wetsuit and gear (tank, mostly) in the water are primary factors.

 

[The Chairman]

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?

Almost all instructors overweight their students. I doubt you're any different. People who find that they are "suddenly" underweighted are usually undergoing some sort of panic episode.

 

[justinthedeeps]

Most divers are overweighted, including most PADI divers.

Even in the (old?) PADI guidelines, you are supposed to float with the water at eye level while *motionless* with full lungs and empty BC, and you have to breathe out to descend.

Then they say "add five pounds back, if you like," but this is usually optional, as your tank will never be fully empty (and you won't be staying under anyway if it is), and the suit will be a bit more compressed on the safety stop etc.

Most divers are overweighted, such that they (we) would not still be at the surface with an empty BC. The BC is not supposed to be half full all of the time. It is a hazard if the BC fails, and it's inefficient because of added volume and drag underwater. You want *all* of that bouyancy available in an emergency etc.

There are exceptions for people carry extra cylinders or atypical extra gear etc

But most divers can't stop kicking on the surface, or don't remember to breathe out to descend, and many don't know how fully empty a BC or do this real weight check either

 

[coldwaterglutton]

If you can hold a safety stop with a near empty tank, as rongoodman wrote, you’re fine. Your own body weight and the weight of your gear on land doesn’t really matter. The buoyancy of your wetsuit and gear (tank, mostly) in the water are primary factors.

Very correct, and I want to add a few words on what halocline is getting at -- it's something that will trip up new divers.

There is a need to account for the change in your tank's buoyancy during the dive. As air is consumed, the tank becomes more buoyant. On an aluminum tank, that difference can be as much as 4-5 pounds of buoyancy. That's why your optimum weighting is best measured at the end of the dive at the safety stop.

 

[hilljo88]

You ask if there are risks to being underweighted. The risk is that at the end of your dive, with less air in your tank, you might have difficulty holding your position for your safety stop. Many instructors will consider 1KG extra weight for a new diver to be a reasonable precaution. As you get more dives in and get better at controlling buoyancy you can fine tune your weight to its optimum based on your gear configuration.

 

[therookie]

Another risk (at least for me) to being underweighted is that it can result in ascending too quickly from the safety stop. At least, that was my experience the one time that I wasn't carrying enough weight. Combine that with having too much air in your BCD during the stop as mentioned above (something I still have to work at as a new diver; it takes a bit of practice to get that right at the end of a dive) and you run the risk of making it difficult to not ascend quickly in those last 5 metres of the dive - which is a really bad place to be ascending quickly...

However, making an assumption about your height and using the Optimal Buoyancy Calculator that you can find here on ScubaBoard 5kg seems like a reasonable amount to be carrying. The Calculator is an excellent starting point, but the real test is as stated above - can you hold your position with your tank at reserve pressure at safety stop depth without finning / moving?