Tips for new divers on bouyancy

[elan]

Aluminum tanks suck!!! If you weigh yourself properly at the beginning of the dive then by the end of the dive you're too light. If you weigh yourself properly at the end of the dive then you're overweighted at the beginning and during the dive.

If possible, rent or buy a steel tank and get your weights dialed in per the previous posts.

Out of curiosity, how is it going to change the situation ? No matter what tank you have it will lose it's weight as the air is breathed out thus the mass of the tank is reduced proportionally to the amount of air lost. You lose approx 1lb for each 13cuf as far as I remember no matter what kind of tank you have. Yes steels have shifted to the negative side buoyancy, this only means the diver requires less ballast to add to the weight belt.

 

[LeadTurn_SD]

@psychocabbage: Blackwood and H2Andy are correct. If you're using the procedure in your post (with empty BCD), I recommend adding enough lead to offset the weight of the gas in your full tank. For an AL80, that would be about 6 lbs.
For the sake of the novice divers, I hope that you meant to say that you did the weight check with an empty tank...then swapped the empty tank for a full tank and went diving.

Actually: Psychocabbage is describing (approximately) the method of weighting that Tobin of Deep Sea Supply often recommends: Weighting for neutral at the surface with a full tank.

This does result in carrying less ballast than weighting for neutral at the surface with a near empty tank as is currently taught by most agencies.

Tobin's theory, as I understand it , is that for a typical single tank dive using a wetsuit, and finishing with around 300-500 lbs, you will be able to hold a safety stop at the end of the dive because there is enough wetsuit compression at 10-15 feet to offset the weight of the gas used during the dive, plus neoprene does not fully regain it's starting bouyancy until many hours after being compressed.

It is in fact the way we used to weight ourselves in pre-BC days.

Newer divers might have a problem with this weighting method. It is harder to descend. You do need to concentrate more at a safety stop, or hold the stop closer to 20 feet rather than closer to 10 feet.

I still use a modified version of this method to weight myself, but do add a couple pounds.

Best wishes.

 

[MauiScubaSteve]

If for any reason I have to breath my tank down to near empty and require buoyancy control in shallow water, possibly with a boat passing overhead, I prefer to be what most of you all would consider slightly over-weighted. I still manage to have decent buoyancy control and trim at depth with all that extra air in my BC.

 

[H2Andy]

I am very sensitive to weight. I only take up to 4 lbs with an AL tank, usually 2 if I don't wear my full farmer john.

(i dive a steel plate)

with a 3 mil shorty I can descend with 0 lbs but I get real squirrely upwards at the end so I wear 2 lbs weight

with doubles this is not an issue for me even in a drysuit as the tanks are enough weight throughout the dive

 

[mikemath]

PADI offers a Peak Performance Buoyancy course that is mostly designed for newly certified divers. I took it with about 40 dives under my belt and still learned a lot, including discvoering a significant overweighting problem. You can read about my experiences with the class here. I agree with all the advice given so far on this thread, but if you'd like to spend a pool session and a couple dives just buttoning up your buoyancy control and weighting, I'd recommend the class.

 

[Beachdiva]

As one who just completed AOW, I made a HUGE improvement on maintaining neutral buyonancy and making proper adjustments after taking PADI Peak Performance Buoyancy. I recommend that class as well as it helps control the yo-yo effect.

Once I could maintain buoyancy even between 10-15ft, my instructor could make more accurate weight adjustments. Example, one time I thought I was overweighted cos I was sinking, so my instructor told me to add a quick shot of air in my BCD. I took a deep breath at the same time and began rising rather quickly like a getaway balloon! Well I learned later that though I needed to drop 2 lbs, the way I kicked and breathed made a much bigger difference in the end.

You can test proper fitting as others have mentioned, but you still need to learn to control breathing patterns. You can give someone a great pair of Air Jordans, but they still need to learn how to shoot properly.

 

[a22shady]

I can Say Diving with a steel Tank will make alot of difference Due to Most Steel Tanks Being Negativly Buoyant when Empty. I recently Used one during a dive not to mention i was able to shed 6lbs from my weight Due to the tank but at the end of the Absolutly perfect. Also for the aluminum 80 i just added an extra 4lbs in trim weights to counter act the Positive buoyancy of aluminum tank and that also worked but i am still switching to Steel..

 

[elan]

I can Say Diving with a steel Tank will make alot of difference Due to Most Steel Tanks Being Negativly Buoyant when Empty. I recently Used one during a dive not to mention i was able to shed 6lbs from my weight Due to the tank but at the end of the Absolutly perfect. Also for the aluminum 80 i just added an extra 4lbs in trim weights to counter act the Positive buoyancy of aluminum tank and that also worked but i am still switching to Steel..

The fact of the AL being positive does not make much difference. You can have the same effect as you get with steel just spreading you weight properly between your belt and pockets or just using a steel plate. IMHO aluminum tanks are being bashed for nothing.
If you were not absolutely perfect with an AL it simply means your weight is not distributed as it should be. You consume the same amount of air no matter what tank you use so at the end of the dive it becomes as much lighter as any other one. Weight distribution over the length and the width of the tank what makes them different. Each tank is good for it's task. Here I hear almost everyone saying AL80 is bad. Though I dive steels I do it only due to the fact I need less lead to carry with me as I have to put much with my drysuit and due to the fact the HP can be pumped up more so I get more air in a tank of almost the same weight. When I put an AL80 on I just add 6lb and distribute them accordingly .

 

[Vash]

My bouyancy is pretty good and i have little problems with maintaining the same depth, but i have some trim problems when try to hoover vertically and sometimes hoovering horizontally. I keep going backwards (or sometimes sideways) when i try it. I will play with my weights tommorow to see if there is anything i can do, but tips or insights are very welcome. another question is if makes a big difference to dive with 2 or 4 weigths on a weightbelt? I use 10 lb btw

 

[LeadTurn_SD]

My bouyancy is pretty good and i have little problems with maintaining the same depth, but i have some trim problems when try to hoover vertically and sometimes hoovering horizontally. I keep going backwards (or sometimes sideways) when i try it. I will play with my weights tommorow to see if there is anything i can do, but tips or insights are very welcome. another question is if makes a big difference to dive with 2 or 4 weigths on a weightbelt? I use 10 lb btw

When you say you are "going backwards or sideways" when hovering, do you mean rolling to one side or having your fins sink, or do you mean moving through the water in that direction?

If you are not finning, at a complete stop, and actually in a true "hover", you wont move forward or back or sideways. You are stationary. You can have tendancy to roll, or for your head or feet to sink.

The best answer is to have an instructor or experienced mentor watch you in the water to see what is going on, but here is some basic info:

Weight distribution can effect your trim in the water. It should not matter whether you use 2 or 4 weights on a belt, just make sure they are distributed evenly. Most find it a bit easier to maintain a horizontal position if the weights are moved slightly forward of the hips.

Some weight can be placed higher up by attaching it to the tank camstrap using a weight pocket(s). XS Scuba makes pockets for this purpose that work well. Moving some of the weight up onto the tank will help if your feet tend to sink when you try to hover in a horizontal position (try 2 or 4lbs on the camstrap). If your feet tend to float, you can try moving the tank lower in the BC (if possible).

Good luck & Best wishes.