Weighting tips (too bouyant)

[Anthony A.]

Agreed. I always kick down at the surface when neutrally weighted. Fill your tank to 500psi and stay at 15' safety stop. Whatever weight you need to stay neutrally bouyant is what you should use. Thats neutral bouyancy. If you really must, add 2lbs more so its a bit easier to start sinking at the beginning of the dive.

 

[kmarks]

Why do you want to sink? You can kick down to where your wetsuit starts to compress and be able to continue the dive. The tricky part is if you have enough weight to hold a safety stop because your tank will be 6 lbs lighter.

Your wetsuit loses buoyancy the deeper you go, if your wetsuit has 30 lbs of lift at the surface at 33 ft is only has 15 lbs. Someone should have explained this to you during training. Also if you use weight belt, make sure it is tight as you descend, you don't want to lose it.

When funds permit, I would recommend taking a buoyancy course if you don't get the weighting worked out.

Agreed. I always kick down at the surface when neutrally weighted. Fill your tank to 500psi and stay at 15' safety stop. Whatever weight you need to stay neutrally bouyant is what you should use. Thats neutral bouyancy. If you really must, add 2lbs more so its a bit easier to start sinking at the beginning of the dive.

If you are neutrally buoyant at the surface (floating at about eye level) with an empty BC/wing, 500 psi in your tank, and holding a "normal" breath, you are properly weighted. With a full 80 cu ft tank, you should be about 6 lbs negative. Deflate your BC, exhale, and you should sink, no kicking required. That's how I get down.

 

[kmarks]

Refer to any chart to compare your height, weight and build to BMI and you will see that you are almost OFF the charts, well into the range of morbid obesity. I am not judging, not criticizing, I simply took your numbers and plugged them in and that's where you're at.

My suggestion is to lose weight. A LOT of weight.

I have a good friend who is an Olympic style power lifter. He is about half an inch shorter than me and outweighs me by 85 pounds. I'm very athletic, lift weights and workout regularly, and don't carry much fat, but my BMI is about 25. His is about 37, but his lean mass to fat ratio is near infinity and he is not at all unhealthy. BMI is not a good standard in isolation.

 

[rsingler]

@Takimbe , you've gotten a lot of good advice here.
But just in case it was buried in all the details, let me repeat one subtlety of a neutral buoyancy check that was nicely stated by @kmarks .
Rarely do people get a 500psi tank to do a formal buoyancy check. They do it with their full tank. So remember, when you do your buoyancy check with a full tank (half-full lungs/normal breath, float at eye level, EMPTY BCD): you are also carrying 4-6# of air weight that will NOT be there when you are trying to do your safety stop with your nearly empty tank.
So do your buoyancy check just off the boat/beach with your full tank, and add or hand off weight to a buddy until you're at eye level. Then ADD 4-6#, take the rest of the weight back to shore and go dive.

Air = 0.08 lb/cu ft.
3000 psi 79 cu ft tank
At 500 psi, there are 13 cu ft left.
So you are carrying 66 cu ft which you might conceivably use.
66 x 0.08 = 5 1/4 lb.
With that extra added to your bcd, you should have NO trouble descending. If you still can't...remember to exhale. Full lungs are another 6# of buoyancy.

Happy diving!

 

[2airishuman]

So I went for my first cold water dive with a custom 7mm wetsuit, and new gear purchased from a friend who had to quit diving, and I could not for the life of me sink, even with 30 lbs of lead. On my warm water dives, I needed only 15 lbs of lead with an AL80 and a nighthawk bc, with boardshorts and a rash guard.

I have made many dives in 7mm. The least lead I've used with an LP72 single and a steel backplate is 16 pounds. With an AL80 (+3) and a jacket BC (+6 for the absence of the steel backplate and +2 for padding) I would use at least 25 pounds. Wetsuits, when new, can be unusually buoyant, requiring even more lead.

In 7mm, when properly weighted and with an AL80 or LP72, it is not possible to sink at the beginning of the dive because the wetsuit is not compressed enough to allow it. It is necessary to do a "duck dive" as when freediving and then swim down. If it is important to sink, or even to maintain neutral buoyancy at very shallow depths, more lead is required.

When diving in 7mm, I use a steel backplate and steel cylinders. I have an HP95 that is 9 pounds negative when empty that is my preferred cylinder for this configuration, for singles, because it allows me to reduce the weight on my belt to a reasonable amount. I have a DSS backplate that has the steel ballast plates I can install, which also helps, but it's easier to just grab the HP95.

 

[broncobowsher]

My first thought is really make sure the BC is really empty. I have seen many times where there is an air bubble in what someone calls an empty BC. The latest big issue one was a large person and the BC rode up on them. The dump was no longer on the back of the shoulder but on the front of the shoulder while diving. The only way to get the air out was to roll over or stand straight up. Needed a crotch strap to keep the BC in the right place.

But some people just need a lot of lead. 7mm is very floaty as well. You have just about the worst need for lead there is (adding a drysuit would generally make it worse). You probably just need to add more weight. As long as the BC is getting empty, adding weight is the fix. Where else can you be hiding a hidden air bubble?

 

[Takimbe]

Refer to any chart to compare your height, weight and build to BMI and you will see that you are almost OFF the charts, well into the range of morbid obesity. I am not judging, not criticizing, I simply took your numbers and plugged them in and that's where you're at.

My suggestion is to lose weight. A LOT of weight.

What Kmarks said is more in line of my situation. I lift 5 days a week, do pool workouts 2 days a week, and can run 5 miles a pop without having my knees explode. I used to play D1 water polo as well, and my BMI is still around 34-35. I started my cut late, so only about 2 weeks into it. I should be around 245-250 by the end of summer.

I was able to get out for a quick dive before work yesterday and after trying these suggestions, was able to get down with 34 lbs:

1. Started off with a full tank, was already eye level at 30 lbs, had a friend hand me 2x 2 lbs, and had no trouble getting down or maintaining safety stop with 700 PSI left in tank

2. Soaking myself, putting on the wetsuit, and then soaking the wetsuit before entering the water. Seemed to help and I didnt feel like a guy in a fat suit in the water. Again, it being a new suit, I am sure itll take a few more dives to break it in and I can probably remove a little more weight. To keep variables the same I didnt wear a hood or gloves either time.