How do you assess your students weight and buoyancy?

[Bubbletrubble]

The sine qua non of proper weighting is performing a weight check. It can be conducted at the beginning of the dive with a full tank or at the end of the dive with a near empty tank...so long as you are compensating for the remaining gas in the tank. Try your best to work out any air pockets if you are doing the check at the beginning of the dive.

Others have already mentioned what to look out for in beginner divers who are having buoyancy control/weighting issues: kicking, funny breathing, non-horizontal trim, etc.

The fact that your daughter was floating up while clearing her mask doesn't necessarily mean that she was under-weighted. It just means that she was changing her breathing pattern while doing the mask-clearing skill. Loss of buoyancy control (up or down) during mask clearing is common, particularly in a novice...and particularly when diving in cold water (that cold water can cause a diver to gasp a little).

 

[TSandM]

Actually, and this one is REALLY nit-picking, it's not how much gas you intend to use, it's how much you are actually carrying. If you only intend to use half your tank and weighted accordingly, but due to a leak or an unexpected air-sharing, you'd end up using most o the tank, you'd be a little light, at least in theory.

I think most of us weight ourselves for something short of a completely empty tank. When I say, "The gas you intend to use," I mean the maximum amount of gas you are willing to use on a dive. Yes, I have ended up using more than my projected amount, and no, the last ten feet weren't comfortable, but they were manageable. Nowadays, if there's a question between two possible amounts of weight, I round up

 

[freewillie]

Thanks for all the advice so far.

A formal weight test for my daughter would have put her close to 10 lbs. If she floated eye level, then exhaled she would have started to descend. When we started our first descent she did get 2-3 ft under. That's when she sorta just stopped. We stayed there for short time then I decided to go back get few more lbs.

I guess I could have tried her 2 more lbs but I wanted to make sure she got under and didn't really want go back if she didn't. I never thought of giving her just 2 lbs and carrying and extra 2 with me just in case.

When we did get under she looked fine, at least to me. She wasnt going up or down in dramatice changes. She said she felt heavy because she had a tendency to sink. I think she needs few more dives to dial in her breathing.

Fortunately we have time to work on her skills. Family vacation coming up in August in Hawaii. Diving is definitely on the schedule and we have the green light from Mom to do lots of diving together!

 

[Bubbletrubble]

A formal weight test for my daughter would have put her close to 10 lbs. If she floated eye level, then exhaled she would have started to descend. When we started our first descent she did get 2-3 ft under. That's when she sorta just stopped. We stayed there for short time then I decided to go back get few more lbs.

If this weight test was performed with a full tank, then it's possible that she was underweighted by the weight of the gas in her tank (6 lbs. for AL80?).

When we did get under she looked fine, at least to me. She wasnt going up or down in dramatice changes. She said she felt heavy because she had a tendency to sink. I think she needs few more dives to dial in her breathing.

You mentioned that your daughter complained of feeling "heavy" during the dive. Maybe she just needs to add a little air to her BCD to get neutrally buoyant. She hasn't had much experience in the water yet. Perhaps some simple hovering practice is in order.

Fortunately we have time to work on her skills. Family vacation coming up in August in Hawaii. Diving is definitely on the schedule and we have the green light from Mom to do lots of diving together!

Have fun! Sounds like some great father-daughter bonding time...

 

[ed.hamilton1]

Have you considered doing the peak performance buoyancy speciality course? My favourite speciality to teach and makes a real difference to all you future dives improving dive comfort and eventually increasing the time you can dive (within table limits). I have known 250lb divers who can dive with a couple of pounds and 65lb divers who require 16lbs+. Its all about comfort and confidence in creating neutral buoyancy.

 

[MichiganScott]

Agreed - I like TSandM's description. I know that when I did my OW dives I was grossly overweighted, but the thing is, I couldn't sink with less weight. And while the instructor told me I was overweighted and should not need that much, he never explained why I wasn't "sinking" or how to overcome it. I think I probably would have been fine at the right weight if I had known about the breathing/not-kicking tips. (Also we never did a weight check, but I still know that I was overweighted because I have since done one.)

Yeah I can relate to this, but when I dod my OW, I was about 350 pounds with a custom 7 mill farmer john. All conventional wisdom kinda went out the window. That week end It took 52 pounds (yes with ankels crossed) to sink. That is when I first started doing inverted dives. Kind of do a snap bend, thrust and kick. I was alwasy first on the bottom, but learned quickly to put on the breaks, cause people get pissed when you kick up a silt storm.

 

[freewillie]

Thanks all. Yes, father daughter bonding time Bubble. It's the only time teenage girl wants to be with Dad. Before peak performance buoyancy will have her dive few more times. In August will try get in water early but I will take few extra lbs just in case. Just to confuse things will have her current wet suit but no hood or gloves.

 

[japan-diver]

If your daughter was already a few feet under the water she had enough weight- the weight belt is not supposed to be an anchor to pull you down. If she had just kicked a bit to down to squeeze the suit a bit she probably would have been fine. Its not a race to the bottom.