Perfect buoyancy

[Ukmc]

During my last dive I found out that with 6 lbs weight I feel perfect and can dive with no air in my BC. Finally, feels amazing as I no longer have to play with my BC at different depths. However, I felt a tad light at the very end of my dive (tank buoyancy). 8 lbs is what I had been diving with in the past and was a bit heavy on that. Should I try to find a 1/2 lb weight for each side? Sounds silly. Bring and extra flash light? I would appreciate your input.

 

[HKGuns]

@rsingler developed a spreadsheet here that will help you. I’ve found it to be quite accurate and it will help you adjust for the negative buoyancy of the AL80 at the end of your dive.

Optimal Buoyancy Computer

 

[rongoodman]

You're starting your dive about 5 lbs heavy if you're using a standard Al80. In addition, if you're diving with a wet suit, you will lose some buoyancy due to its compression at depth, quite a bit in the case of a 7+ mm suit. You have to compensate for that either with air in your BC or air in your lungs, otherwise you're just going to be light at the end of the dive. I'd rather be able to relax hanging out at my safety stop instead of being underweighted and having to fin down.

 

[herman]

I dive with no BC fairly often and almost never use air in one when I do so I have a lot of experience with this.
There is no way to be exactly neutral through the entire dive without dropping weight or adding air to a BC. Assuming an 80 tank, you will have 4 to5 lbs of swing from full to empty so it's impossible to be exactly neutral through the dive without changing something. That said, a couple of pounds is easy to deal with using breath control alone. I weight for dead on neutral with 1/2 tank pressure, which for an 80 makes me 2 over at the beginning of a dive and 2 under at the end, both easy amounts to deal with. If you want to add small amount of weight 8 oz fishing sinkers work well. Being slightly over at the beginning actually helps since there is always some trapped air in your kit that has to come out.
All of the above assumes no wetsuit that compresses, that changes things a lot. I use a sharks skin/lava core which do not add any bouyancy.

 

[Ukmc]

Herman, I like your suggestions. 30 dives in, I figured out that I dislike diving overweighted. I started out at 14 and now down to 6. With every 2 lbs shed, I feel more relaxed and my oxygen consumption improves. Diving with no air in the BC has made my dives more enjoyable so I don’t think I will go back to 5 lbs overweight. I dive Exowear (bare’s version of sharkskin) which is neutrally buoyant and relatively noncompressable and AL80’s. I understand what the calculator says but my breathing must be able to compensate for 2-3 lbs without being too uncomfortable. I will try the fishing sinkers on the next dive. I would love to hear more constructive comments.

 

[scrane]

As far as I can see, the only way you are perfectly weighted is if you can remain neutral at your safety stop with a near empty tank and an empty bladder. If you are positive at your SS you need more weight.

 

[CT-Rich]

You do realize you are only a bean burrito away from total chaos....

 

[johndiver999]

Herman, I like your suggestions. 30 dives in, I figured out that I dislike diving overweighted. I started out at 14 and now down to 6. With every 2 lbs shed, I feel more relaxed and my oxygen consumption improves. Diving with no air in the BC has made my dives more enjoyable so I don’t think I will go back to 5 lbs overweight. I dive Exowear (bare’s version of sharkskin) which is neutrally buoyant and relatively noncompressable and AL80’s. I understand what the calculator says but my breathing must be able to compensate for 2-3 lbs without being too uncomfortable. I will try the fishing sinkers on the next dive. I would love to hear more constructive comments.

As you continue to gain experience and refine your skills, you will be able to comfortably handle MORE lead. Wearing so little lead that you have to add little or no air to the BC does simplify the dive, but an experienced diver should be able to manage a modest volume in the BC with near zero bandwidth.

If you diving really shallow and varying depth during the dive, minimizing the size of the bubble in the BC makes things a lot easier. If you are over 60 or 80 feet deep for most of the dive, a slowly expanding (small) bubble in the BC is a non issue.

Instead of looking for a 1-lb weight, possibly think about adding or subtracting lead. For example, if you currently have two 3-lb weights and feel a little light, then replace the 3-lb weight with a 4-lb weight to dive with 7 total. If you currently are using 3 2-lb weights, just replace one with a 3-lb. There is often little reason to search for a 1-lb weight.

 

[ontdiver]

I started out at 14 and now down to 6. With every 2 lbs shed, I feel more relaxed and my oxygen consumption improves.

First and foremost, you are doing a great job and have been pro-active with your weight management. Your confidence is going to increase considerably over the next 30 dives...and you will also be better able to deal with the air in your BC. All of this takes time...

 

[wetb4igetinthewater]

As far as I can see, the only way you are perfectly weighted is if you can remain neutral at your safety stop with a near empty tank and an empty bladder. If you are positive at your SS you need more weight.

The only thing I'd like to add to this is for the weight to be distributed so you effortlessly maintain a horizontal position.