Struggling to understand buoyancy and trim wearing my gear

[seaway2121]

Following, where were you carrying the 18b weights? I carry my 8lbs in attached in front pockets of BP/W harness.
For the tilting, it sounds like the air in wing is not distributing evenly, so what type of wing? You were in Florida, so it seems like the smaller warm water wings would distribute air quickly.
My experience:
I wear a 7mm wetsuit, 4lb steel Freedom BP, 32lb Hog wing, Steel 80’s on my 160lb 5’2” self and only need 8lbs weight, and I put the tank as low as it can go, harness webbing fits close with just the fist space under it.
i can position myself upright or head down as needed for photography, but while hovering i don’t tip.

All the weight was in the only two pockets on the harness, near the waist. They were pretty much maxed out. It was a donut wing, with smaller compartment on the top front and back I think. I could feel the air bubble if I tilt left or right, but didn't really feel it moving around front to back.

 

[MichaelMc]

- A weight belt with six to eight pounds of that lead might help by putting that much a bit further down.
- Negative fins would help, even simulating them at first with a one pound weight strapped to each of them.
- The HP80 is not helping as its negative buoyancy is a bit higher up due to being short.

 

[seaway2121]

I'm only asking this question because it's germane, but are you fat? I'm obese BMI-wise and I need 26 lbs. with a brand-new 8/7mm wetsuit, hood, and boots, with light fins, a steel 100 and traditional BCD. 18 lbs. seems like a lot for a non-obese person with your gear configuration. The plate (even neutral), and fins are going to take off at least that much. Simple physics says the more weight you're carrying, the more opportunities you have to get it in the wrong place.

As others have said, you need to get to a pool in your gear. Did you have a chance to do that before your Fundies course? No point in trying to make large adjustments when dealing with everything else. Start with way less weight that you think you need. I was taught to do a weight check at the start of a dive by taking a normal breath at the surface and holding it (the only time you're allowed). Correct weighting would hold you at the surface roughly at eye level.

Once you've got the amount set, start moving it around. If your head is dropping, move the weight as far back and as low as you can. It's easier to get completely relaxed when you're in the pool. Ideally you should be able to get horizontal and just float up and down. Take your time. Good luck!

I'm pretty thin. 140lbs. I tried weight testing just the shorty 7-mm, and that was about 14 lbs to be neutral I think.

But I really need to do the proper weight check myself as you said. Definitely should have done this before the course.

 

[AfterDark]

Thanks.

The instructor did this in the pool. He tried manipulating my body a lot. Each time I would feel completely relaxed and still nose dive when he let me go. He said I needed to keep my head up, shoulders relaxed, and legs straight with bend at the knees. I couldn't figure it out.

I think the tank was HP80, but it didn't seem any shorter. We also used AL80 on the first day, but had the same issue. I had 9lbs in each weight pocket of the harness near my waist, and I'm pretty sure the tank strap was right below the crown/shoulder of the tank.

In other words, I don't think I could put the weight any lower...

Perhaps this setup doesn't work well with double 7-mm suit and boots? The fins he rented me were neutral.

You also could try a tank weight placed towards the bottom of the tank. I found 2 ankle weights buckled together around the tank works well. I position my tank as low on the BP as I can, placing the weight of the tank closer to my feet. Note in the picture how the bottom of my tank is almost even with my knees.

 

[Bubblesong]

You also could try a tank weight placed towards the bottom of the tank. I found 2 ankle weights buckled together around the tank works well. I position my tank as low on the BP as I can, placing the weight of the tank closer to my feet. Note in the picture how the bottom of my tank is almost even with my knees.
View attachment 699972

Nice picture at Ft Wetherill!

 

[inquis]

Quite the puzzle! Is this a fast or slow rotation?

I would suggest trying the AL tank again, now that you know a little more about what's involved. That tank should have required about 4 more lbs than the steel (more weight on the waist), so perhaps that aspect was overlooked. The other cheap option to try is a weight belt instead of integrated weights, as it will typically ride lower.

Definitely adding another cam band to the lower end of the tank to hold weights will help. That's a long lever arm and you could easily shift 10-12 lbs to there which I'd guess would substantially over correct.

Negatively buoyant fins would help (XL Hollis F1 is -1.5 lb combined). Fins are not terribly negative, but the lever arm is also long. Try to borrow for a test so you're not out $$ if it doesn't work.

 

[seaway2121]

The heavy fins are another way to go although depending how much they weigh it may be too much. The ankle weights I use when I do use them can be any weight I require, one end is Velcro so I can add or subject just the right amount of shot for the correct weight. I put one of my dry suit boots in seawater and added weight until it sank slowly to the bottom.
That came to just over 1/2lb, that's how I came to use 1/2lb in the ankle weights.
I could do the same thing by sticking a couple of 8OZ fishing sinkers in my boots.

OP may have a buoyant fin boot combo in which case different fins would definitely change things.

These seem quite versatile! I think a heavier fin might do the trick too. Didn't realize proper weighting was so nuanced.

 

[Julius SCHMIDT]

Pushing water is heavy enough why wear yourself out more pushing heavy fins as well

 

[MichaelMc]

These seem quite versatile! I think a heavier fin might do the trick too. Didn't realize proper weighting was so nuanced.

It's really just the same physics as on a grade-school playground see-saw. Just some bits are more constrained in where they can go.

Pushing super heavy/negative fins is more work, but your feet being a bit negative means you can dynamically adjust your weight distribution by pulling them in a bit more or extending them out a bit more. So some negativity in the feet is helpful. (or positiveness, but that would make you not having a balanced weight distribution worse.)

 

[seaway2121]

I assume you have a nice heavy pair of fins?
I know that as a new ish diver, it takes some practice,, when I did my first drift dive I couldn't keep my feet down, felt like the water kept trying to flip me over,
I tried ankle weights, then got nice pair of heavy turtle fins, and got rid of ankle weights,
Now I can use any fin I want, though I prefer my turtle fins.
What changed? Experience, practice,

Maybe ankle weights for a few dives might help your form, and you'll notice you are feet heavy. And you can get rid of them, the weights.....
And really try to do a dive or two and practice no movements just trim out relax maybe a bit of kicking, but be aware of what subconsciously your legs are doing, I find new divers have a really hard time not moving their legs, and that effect can cause all kinds on bouyence movement,

Thanks, I want to try the better weight districution. I didn't realize the integrated pockets were not "1-size fits all situations" type of thing..