Weighting question... slightly too heavy or light?

[Storker]

Get some 2 lb. and even 1 lb. weights and do a proper weight check. Sorry I can't do kgms.

For just a couple of them, kg = lbs/2, lbs = 2*kg. If a small handful or more: kg = lbs/2 -10%, lbs = 2*kg+10%. That's usually more than accurate enough, even if you're mixing metric and imperial weights on your belt.

So:
Imperial to metric: 1lb = 0.5kg, 2lbs = 1kg, 10lbs = 4.5kg, 20lbs = 9kg,
Metric to imperial: 1kg = 2lbs, 2kg = about 4.5lbs, 5kg = 11lbs, 10kg = 22lbs

 

[IBjones]

I prefer to start the dive a little over. Then when my tank is empty I'm just right. If I start the dive just right with my aluminum 80 then I'm fighting to stay at depth during the safety stop as the tank goes buoyant.

I guess if I had a steel tank it would be different.

 

[stuartv]

I prefer to start the dive a little over. Then when my tank is empty I'm just right. If I start the dive just right with my aluminum 80 then I'm fighting to stay at depth during the safety stop as the tank goes buoyant.

I guess if I had a steel tank it would be different.

An AL80 holds 6# of gas. If you start the dive 6# heavy, you will be perfectly neutral when it's empty. It's the same for a steel 80.

 

[Neilwood]

An AL80 holds 6# of gas. If you start the dive 6# heavy, you will be perfectly neutral when it's empty. It's the same for a steel 80.

Agreed - so long as the volume of gas used doesn't change, the weight change of 6# remains the same. The only difference is that the AL cylinder will require more weight at the start compared to the steel to give the diver the same buoyancy.

I would always opt to be heavy at the start and try to be near perfect buoyancy at the stop. Starting light means you finish way light.

 

[kelemvor]

Hi all,

On my recent liveaboard trip, I found myself struggling between 2 increments of weights:

Me: 5'9, 160lbs or so
Weight options on board: 1.5kg each
Conditions: saltwater, 5mm wetsuit

With 3 weights (4.5kgs) <TOO LIGHT>

With 4 weights (6kg), <TOO HEAVY>

Unfortunately the boat didn't have any smaller weights (0.5kg or 1kg) which could have helped.

Buy some smaller weights of your own for the next trip. Maybe just two 1kg weights. Although, I'd probably just use the 6kg if it were me. 6kg (13lbs) isn't all that excessive and should be well within the lift capabilities of any BCD.

 

[IBjones]

An AL80 holds 6# of gas. If you start the dive 6# heavy, you will be perfectly neutral when it's empty. It's the same for a steel 80.

An AL80 starts NEG and ends POS as it empties. An AA80 starts Neg and ends Neg as it empties. So there's a little more physics involved than just throwing on 6 # and calling it all even.

Lord knows I hear enough cackling from guys at the dive shop about how I should switch to steel and how their steel is so awesome and how they'll never ever go back to aluminum.

I'm just a poor disabled vet on a limited income so a $150 aluminum VS a $400 steel really wasn't any internal debate in my mind.

 

[scubadada]

From Dive Gear Express:

You need less total weight with a steel cylinder. I use 100s and use 4 pounds less with the steel cylinder than I do with aluminum. It varies by cylinder, based on the buoyancy when empty, or nearly so

 

[The Chairman]

It's amazing to me how competitive our non-competitive sport can be. 1.5 kg is nothing to worry about. Hell, even being 3 kg overweight really isn't that bad. Your lungs can easily accommodate a 3 kg swing.

 

[victorzamora]

It's amazing to me how competitive our non-competitive sport can be. 1.5 kg is nothing to worry about. Hell, even being 3 kg overweight really isn't that bad. Your lungs can easily accommodate a 3 kg swing.

I was going to say that I always dive overweighted recreationally. It was a habit I got into during DM training and certainly something I found useful.

I've used that extra weight to help hold down floaty divers (by catching them) and I used to be in the habit of diving with at least 2x2lb weights I could release quickly (like a suicide clip) that I'd clip off to divers that needed it.

 

[The Chairman]

I dive with enough weight to be comfortable, but I don't try to shave every ounce, either. Using the lowest amount of weight has become a competition much like having the lowest SAC or the smallest bladder on your BCD. Everybody wants to be a special snowflake. If you want to see how much weight you really need, try Dr Bob's weight titration:

At the beginning of the dive, on a normal breath with no air in your BC, no weight in your pockets, legs crossed (to prevent kicking) and arms crossed (to prevent sculling), have someone estimate how far the top of your head is above water. For every inch (25mm) add 2 punds (1 kg). Repeat until the top of your head is just awash (barely under water). When you exhale, you should begin to sink. Need to sink faster? Kick or pull on a down line. Using this method, you should comfortable at your safety stop.