Floating feet

[Beezer]

I just recently finished my OW check-out dives down in Moorea. I seemed to have fairly good control of my bouyancy during the dive and didn't have a problem swimming level, but at the end of the dive during my 15 ft. stop I had to hold on to the rope because my feet kept floating over my head! I wear booties and Dacor Tiger fins. Should I consider ankle weights? Or?

 

[Dryglove]

Well i can think of a couple of different things to try depending which route you wanna go.

Ankle weights is one solution but i try to avoid those things due to the fact they tend to fatigue your legs faster.

Im guessing you were using an aluminum on your dive.They tend to become a few pounds bouyant when they get low.It may be pulling your feet up when it gets low.

There are some places that sell tank weights that you can place on your tank.If you place them low on the tank make sure there on good with a secure buckle system.One that comes to mind is called the tank keel.It straps a 5lb weight near the bottom or wherever you need it for trim.Seasoft and some other places also sell tank weights.

One thing that worked nicely for me was the set of luxfer neutrally bouyant tanks.They weigh about 5lbs more than a standard 80 and most of the weight is in the bottom of the tank.Plus they dont tend to shift when low cause they dont want to float like a standard 80.

One last thing that comes to mind are a set of neutrally bouyant fins although i dont think they will help much if your feet are floating that bad.

Last but not least make sure you are neutrally bouyant in the water at 15 ft with around 500 psi in your tank.This may be the first thing you wanna check as it is the most important.If your positively bouyant with no air in your bc and at around 500psi in your tank your body is going to wanna rise even though your hanging on to the line.Check out these sites for more help with trim and bouyancy http://www.scubadiving.com/training/DLAP/july97.shtml
http://scubadiving.com/training/instruction/buoycalc/buoycalc.shtml

 

[devjr]

You didn't say whether you were wearing a suit, a belt, or what kind of BC. Try to avoid the leg weights. If no suit and an aluminum tank, try a weight belt with six pounds of lead. This should cause you to inject a small amount of air into the vest, and the counter balance should hold you upright.

 

[gadget]

The last post was right on the money and I'll just add a few things to check/ change which might help:

- Is the tank mounted correctly? if you lower it a bit you will change your trim slightly

- Many different types of trim weights can be used including BC mounted trim weights.

- Tank weights can also be used to affect trim. These can be as simple as a regular 2 lb dive weights and a plumbers clamp (try to avoid things which might catch line etc). Another option is a tank weight made out of sheet lead. Just cut a circle lead and remove your tank boot and drop it in then put your boot back on. There are also a few commercially made tank weights available.

- If you are buying tanks go for steel.

- If you haven't bought a BC yet see if you can demo one first. Each BCD has its own trim characteristics and will preform differently and you may ind one which works for you.

- If you do have to go with ankle weights start light and don't be afraid to experiment.

 

[sharpenu]

There are alot of things that can cause trim problems. Here are a few:

1 What kind of BC? For example: Rear inflation BC's are more prone to trim problems if you are not properly weighted.

2 How is the weight distributed? Move some of the weight from the front of your belt or weight pockets to the rear.

3 You may have too much weight. Too much weight can cause you to have a high SAC and cause trim problems, especially at the end of the dive when you are near the surface. ( You are more bouyant in the shallows)

If you carry enough weight that you are negative at the end of the dive with an empty BC, you are too heavy. Excess weight is the number one mistake new divers make. Excess weight causes all kinds of problems. There are all kinds of things you can do before diving too heavy.

Set your weight to be neutral at 15 feet with 500 or less PSI left in the tank. That is a good starting point. That should put you withing a pound or two of your ideal weight. (Remember if you set your weight for fresh water to allow for extra when diving salt water.)

 

[ScubyDoo]

I agree with everyones previous posts.

Padi teaches to do a weight check prior to dive where you float at eye level with an empty BCD while holding a normal breath. Thats the proper way, but with a full tank of air its not totally accurate.

The compressed air in your tank has weight (normally about 5 lbs). As the dive progresses that weight is altered as the tank slowly empties. By the time you reach your safety stop with 500 lbs pressure, you are around 4-5lbs lighter than your pre-dive. So, if you were neutrally buoyant at the beginning of the dive, your now positively buoyant at the end because your 5lbs lighter.

1. Do a weight check with a full tank so that you float at eye level with and empty BCD holding a normal breath. Once achieved, add another 5lbs of weight (either on your belt, weight integrated, or tank weights). This added weight allows for the 5lb loss which occurs as your tank empties.

2. At the end of your dive, do another weight check. The goal is float at eye level with empty BCD holding normal breath with 500 lbs pressure in your tank. If you sink past eye level, take off a couple of pounds. If you float above eye level, add a couple of pounds. If you need to adjust in smaller increments you can always look at carrying something that weighs 1lb or 1/2lb. in your BC pockets.

You start the dive negative so you can end it neutral....or slightly negative.

 

[sharpenu]

There is an even easier way to compute weight. A way which will result in almost perfect results. Without a wetsuit or any other gear, jump into the pool and see what amount of weight will make you neutral. Then, find out how much weight it takes to hold each of your wetsuits to the bottom. You then compute your salt water weight and the weight for your tanks when empty (you can get this off the tank manufacturer's website. For example, you weigh 200 lbs and in the pool it takes 2 lbs for you to be neutral. You make a chart like this:

Fresh water 2
Shorty suit 1
Full suit 3
AL80 4
AL63 3
steel 120 -1

To compute your weight for saltwater, you take your bodyweight (200) plus your freshwater weight (2) and multiply the result (202) times 1.025 (=207) and subtract your body weight to get your saltwater weight. Your weight in saltwater is 7.

Then you just add the numbers to determine your weight for each dive. Example: Using the above numbers, my required weight for a saltwater dive with an AL80 and a shorty wetsuit would be:

Saltwater 7
Shorty 1
AL80 4

Total: 12 lbs

I even made myself a laminated card to keep in my bag. Don't forget that any major changes in your body weight will require you to refigure this chart. Hope this helps.

 

[Beezer]

Thanks for all the great advice! I'll have to give some of them a try next time I dive and see if they help.

I have a Seaquest Diva LX weight integrated BC. I had 8 lbs of weight - 4lbs in each side pocket. I have a 3mm wetsuit and booties w/ my fins. I think the tank was aluminum but I'm not sure (how does one tell?).

Once I'm at depth I can get neutrally bouyant and then just control it with my breathing. Just seems that I have more problems once I get closer to the surface both on the descent and ascent.

I also had some problems descending and my instructor had to give me more weight during the dive so I could get down. Do you think I should try descending head first?

I'm sure alot it will get better and easier the more I dive.

 

[sharpenu]

All new divers dive heavy. There isn't any real cure except practice, practice, practice.The markings on the tank will tell you what the tank is made of. It should be in your book. Once you have 15 or 20 dives behind you, you will start to see a big difference.

 

[Paul168341]

I'd just like to add that the nearer to the surface you are, the more buoyant you actually are. There's less pressure acting on all of your airspaces, including the small ones that make up your neoprene wetsuit.