Weighting and Trim

[dave42]

I am a new diver, recently certified. Although I had what I would charatercize to be a good class, my one complaint is that we were overweighted in order to make sure we stuck to the bottom. So this past weekend I went diving with the simple goal of learning to dive with less weight. I went from 8 lbs (class) to 4 lbs (yesterday) using essentially the same gear.

So here is my question, while I was able to maintain nuetral buoyancy (hover in the water, not crash to the bottom or rise to the top), anytime I stopped swimming I ended up feet down (vertical) in the water. Is this a matter of technique (do I just need to work on keeping my hips up) or a matter of distributing the weight differently. I was wearing all the weight in an integrated pouch (2lbs each side). My BC is a Zeagle so it has two tank bands I could get tank pouches and put some weight in back on either the lower band or the higher one, but I wanted some advice before I did this.

 

[Jim Lapenta]

Short answer is could be both. Or that you have heavy legs, heavy fins, or a combination of all! If you were to come to me here is what we would do.

1. Check your weighting requirements with only your exposure suit, mask, fins, and snorkel.
2. Recheck with your BC on.
3. Work on helping you adjust your body position. ie horizontal with back slightly arched
4. Determine if you needed to move the tank up or down. Sometimes an inch either way is enough.
5. See where we needed to move weights to. Many times it is a matter of getting some weight higher up on the BC. Whether it be through pouches on the tank bands, a weight around the tank neck, or there are now small pouches you can put on the shoulder straps to get a pound or so in.
6. Take the tank down to 300-500 psi and recheck 2 - 5. Some tanks get butt heavy as they empty, more so than others.

First thing you need to ask is what is the largest air space you need to account for? Answer: your lungs. Getting weight over them when you are horizontal is very important. This is why BPW systems are said to help with trim. Technique has a great deal to do with it as well but it certainly does not hurt to have some lead or steel over your chest.

 

[TSandM]

HERE is a superb article on the topic, and HERE is another one.

Basically, body posture is the foundation. If you are dropping your knees, you will tend to rotate head up. If you have a nice, flat body with your head up, you can play with how much you bend your knees to see what it does to your stability -- if you're using heavy fins, for example, bending your knees more shortens the lever and helps prevent foot drop.

If you have good posture and can't control the rotation with your arm and leg position, then you need to move weight. But if you are only using 4 lbs, and you have it around your waist (which is not far from most people's center of gravity), I suspect you can control the problem with posture.

 

[DukeAMO]

Just for reference, I had the same problem with my feet pulling down. I ended up with 1/4 of my weight on the top of the tank (ankle weights), another 1/3 in the trim pockets on the tank band, and the rest at hip level. See if you can borrow some ankle weights, trim pockets, or clip-on weights just to try it. They're on the expensive side if you don't really need them, but they're great if they work. But since you only have 4lbs, this is probably less important for you.

You also have to get yourself accustomed to swimming horizontally. Take a buoyancy class or have someone watch you to see how close you are to horizontal. I found that the frog kick is easier to use in a horizontal position, because it forces you to pull your feet up.

Once you can hover horizontally without sculling, and swim horizontally, you'll save a lot of air and you'll find it much easier to control your buoyancy. So it's definitely worth fixing!

 

[DukeAMO]

Here's a link to a post showing just how much it can help to fix your weighting: http://www.scubaboard.com/forums/ne...k-performance-buoyancy-class.html#post6361554

 

[stormtrooper505]

I am a new diver, recently certified. Although I had what I would charatercize to be a good class, my one complaint is that we were overweighted in order to make sure we stuck to the bottom. So this past weekend I went diving with the simple goal of learning to dive with less weight. I went from 8 lbs (class) to 4 lbs (yesterday) using essentially the same gear.

8 lbs to 4 lbs? Holy crap. I too just certified for OW and I had on 24 lbs. This was my biggest complaint. We never took enough time to do a proper buoyancy check.

 

[TSandM]

It would be my guess that you two were using very different exposure protection. We typically put 20 to 30 pounds on our OW students, but they wear 14 mil of neoprene on their cores. That's very different from no wetsuit, or a 3 mil, where 4 lbs might be quite enough.

 

[Hawkwood]

....This was my biggest complaint. We never took enough time to do a proper buoyancy check.

That truly was unfortunate.

If you took the PADI OW course, you are supposed to learn how to do a proper weight check in your second confined water dive. Then, at the surface at the start of each of the four open water dives you are to "adjust weighting".

 

[kdsmithjr]

8 lbs to 4 lbs? Holy crap. I too just certified for OW and I had on 24 lbs. This was my biggest complaint. We never took enough time to do a proper buoyancy check.

24 lbs?! Yikes!.....oh....KY.....probably colder water than here in the Philippines. I wear a rash guard and 2 mil neoprene bottoms. 8 lbs is more than enough for me (btw, i'm 210 and 6 ft tall so i aint no twinkletoes)

 

[Hawkwood]

24 lbs?! Yikes!.....oh....KY.....probably colder water than here in the Philippines. I wear a rash guard and 2 mil neoprene bottoms. 8 lbs is more than enough for me (btw, i'm 210 and 6 ft tall so i aint no twinkletoes)

The weight needed is the weight needed. You simply can't sit back and go..."geeze, I only use X amount"... See TSandM's post.

24lbs? Where I teach and dive, that's going to be on the light end of the range. The challenge for students doing there first OW dives is simply getting used to the transition from the pool to OW. They might have been just fine in the pool with 4 or 6 lbs, but the transition to 24 to 30lbs of weight in OW is a challenge.

As long as everyone takes the time to do a proper weight check, the weight needed is the weight needed.

Oh, and kdsmithjr....this was not directed at you as such, you just had the perfect quote to use.

Bill