Weighting for very shallow dives

[drinksfromtap]

Do any of you out there vary the amount of weight you carry based on the depth of your dive? Since getting certified, I've done most of my dives off the beach in Lauderdale by the Sea at depths of around 12-15 feet. On these dives, I use 19 lbs of lead, no air in my BC, and have to manage my breathing carefully to avoid popping up when the tank is near 500 psi. However, I noticed that when I went on a deeper dive (around 60 feet), I felt like I could have easily dropped a couple pounds and still not have had an issue completing a safety stop at 20 feet. I'm interested in hearing what your experiences have been. Thanks!

 

[SC_Hoaty]

I keep a chart of the amount of lead I use, with variables of fresh vs. salt water, wetsuit thickness, and tank (size and AL vs. Steel). Depth is not something I factor in.

When doing that safety stop after the deeper dive, was there air in your BC?

 

[macado]

This is pretty normal. Are you wearing a wetsuit? At 10-15ft your wetsuit really hasn't compressed that much. As you go deeper the wetsuit will compress more and lose its buoyancy.

Also, depending on what tank you're using (for example, an AL80) you may need to add a 2-4lbs to counteract the positive buoyancy of the tank. When an AL80 is completely empty it is around +4.4lbs buoyant.

You want to be able to hold a safety stop at 15fsw-20fsw with an empty tank so in some cases it may make sense to add a few extra lbs of lead to your kit. Note: I'm not advocating intentionally over-weighting yourself but merely compensating for the change in buoyancy of your tank

 

[drinksfromtap]

Thanks. If I remember correctly, I had vented it fully before I hit the safety stop.

 

[SailNaked]

+1 wetsuit compression, but no I do not vary the weight by depth.

 

[tdtaylor]

On some of my more shallow beach dives of 12-20 feet in a drysuit, I definitely add more lead, as do most I dive with in these situations. It has minimal impact on my air consumption, for I typically have no issues staying 90+ minutes, at which time my throat is so dry it is time to end the dive. Adding 3 or 4 pounds just makes it a more comfortable dive, and it also lets me keep a little more air in my drysuit so I can stay warm during these long dives.

It is similar to adding a few additional pounds during the first OW day of OW training where we spend the day on a 12-15 foot platform.

Terry

 

[TMHeimer]

I don't vary it according to depth (this is really the first I've heard of this). Diving 20-30 feet I'm usually ready to surface well before gas or NDL limits so I've never thought of it.

 

[spectrum]

Do any of you out there vary the amount of weight you carry based on the depth of your dive? Since getting certified, I've done most of my dives off the beach in Lauderdale by the Sea at depths of around 12-15 feet. On these dives, I use 19 lbs of lead, no air in my BC, and have to manage my breathing carefully to avoid popping up when the tank is near 500 psi. However, I noticed that when I went on a deeper dive (around 60 feet), I felt like I could have easily dropped a couple pounds and still not have had an issue completing a safety stop at 20 feet. I'm interested in hearing what your experiences have been. Thanks!

On those shallow dives you are using the bare minimum of weight. A little surge and you'll be in trouble. At the beginning of the dive do you have to keep your lungs kind of full to be neutral? If not you could add a little weight so you are breathing in your most normal manner 1/2 way through your air. What you are doing is scuba diving buoyancy control in it's purest form. With that skill you are well on your way.

Now to answer your observation...... You describe 2 identical dives except deeper on the one where it easier to stay down at the end. You probably realize that your neoprene compresses and loses buoyancy as you go down. What you may not realize is that recovery is not 100% immediate. When you get back to safety stop depth your suit is still a little denser that it is on the shallower dives. Hence after a deep dive you can stay down easier.

Also, you speak of 12-15 feet as shallow dives and a 20 foot safety stop those 5-8 feet will also make a significant % difference to your neoprene.

Your choice of cylinder material has nothing to do with it. That buoyancy property is factored into your baseline weighting. If you use a larger cylinder then the potentially greater amount of air consumed will increase the buoyancy swing.

On the deeper dives you were probably feeling heavy while down there ( if you are not adding air to your BC) and that is normal if any neoprene is involved. As you get more and more neoprene and/or larger cylinders it becomes imperative that you use you BC to offset the swings. This is not a sin.

Finally your first question.... Divers practicing this "vintage style" will select they weights for the dive so they can be comfortably in a neutral range during the bottom time.. By definition this may mean needing to use a stone or rope to ascend slowly though with limited neoprene it can be done on lung volume with skill and spot on weighting. Again the less neoprene the better. The 72 CF cylinder is the one of choice for these folks and that means they are only dealing with about 5 pounds of swing from deleted air on a dive.

Finally 2 links.....
The same question with answers from when I asked some 9 years ago.

Weighting 101

Pete

 

[clownfishsydney]

On a couple of shore dives where the end is very shallow for quite a distance, I often add a pound or two to make it easier. Nothing wrong in doing this nor is it unusual in my experience.

 

[aprivetera]

I remember something like this when I used to do very shallow reef dives and surveying. Managing your buoyancy at the shallower parts with surge can be trickier. Especially at first.

Once you go down deeper you will actually want to start adding air to your BCD to stop yourself from sinking too much. Just watch out because as you go up that air will expand and you will get progressively more buoyant.

I would recommend to focus on your breathing, to make sure you can make the minor adjustments right. Once you can start to observe the effect your breathing has on your buoyancy you can start adding and subtracting weight to get it just right. The trick is to not overdo it and rely only on your weight or breathing, but rather a combination of proper weighting and breathing techniques.