Buoyancy I’m confused

[Scraps]

I just started reading Steve Lewis' The Six Skills and Other Discussions: Creative Solutions for Technical Divers.

I'm sure long-time Scubaboard.com members have known how awesome this book is for a long time. Nevertheless, it's all new to me, and I read your question just a few hours after I read his explanation of how to figure out the particular needs for your gear.

So my advice is to buy his book. I'd say the buoyancy chapter alone is worth the money, but frankly, I thought the introduction was worth the price of the book, so everything else is free.

Now, if you'll excuse me, I must take my new wetsuit, some weights, and a mesh bag to the pool.

 

[DogDiver]

As a starting point for my students in cold fresh water wearing 7mm wetsuits is
10% of your body weight +4 pounds. That formula worked well in Ohio quarry’s using a single AL 80 and normal BCD.

 

[Tank601]

So I rechecked my buoyancy and it’s the same. I think it’s due to the suit and maybe some air getting trapped inside. Not much but some. This is the first time I’ve used an open cell. I’m not totally sold on it just yet. We will see. I checked myself without anything and it took 1-3 lbs to sink me. So that’s normal. So I actually have 9.2lb on rig and 12 on belt. So around 21 for fresh. Add 7 for salt and I’m at 28lbs. That’s with a mako 5mm freediving suit and 3mm boots

 

[Tank601]

The whole reason I bought the mako suit was for maneuverability and that it supposedly requires less lead. I’m not feeling it

 

[Tank601]

Dang just seen this. This hit the nail on the head!
DiveBuddy

 

[AfterDark]

Also used al 80 tank

That there is your problem. Cold water diving is best done with steel tanks. Did you have a full AL tank? Try it with a AL @ 500psi you'll probably need more weight. I've been diving the cold waters of New England for 50+ years. A few of those years I used a AL80 because it was at the time the latest and greatest. I had a total of 30lb on my belt, no steel back plates back them. I got rid of that tank and went back steel. With a 7MM farmer and 6lb B/P I use 12 lb on my belt with a 72 stl and 4lb with a 96 stl.

 

[Tank601]

That there is your problem. Cold water diving is best done with steel tanks. Did you have a full AL tank? Try it with a AL @ 500psi you'll probably need more weight. I've been diving the cold waters of New England for 50+ years. A few of those years I used a AL80 because it was at the time the latest and greatest. I had a total of 30lb on my belt, no steel back plates back them. I got rid of that tank and went back steel.

Yea I used a almost empty tank. Steel would prob shave off 5lbs. I agree.

 

[AfterDark]

Yea I used a almost empty tank. Steel would prob shave off 5lbs. I agree.

My 96's are 11lb negative full and 6lb negative empty, they do however weigh 48lb full. Those tanks will shave off a lot more than 5lb. Find yourself a list of tanks and their buoyancy full and empty you'll find what you need.

 

[Scraps]

Dang just seen this. This hit the nail on the head!
DiveBuddy

The DiveBuddy calculator may be good for identifying your initial ballpark, but I wouldn’t use it for anything beyond that.

For me it always suggests more weight than I need, sometimes a lot more.

I dove the other day for the first time with my new Deep6 7mm wetsuit and a steel 100. I used 20 pounds and was overweighted, which meant extra work when I had to retrieve a customer who tried to drift off after surfacing. The DiveBuddy calculator suggests a range of 22-27 pounds depending on diver experience/skill.

With thinner wetsuits, I find it even further off. For example, when I use a steel 120 with my 3mm wetsuit, I don’t add any weight at all. DiveBuddy would have me at 16 pounds.

There’s too much variation in gear and bodies and skill for an app to be able to solve the problem reliably.

 

[lexvil]

The dive buddy calculator is pretty close, always remember it takes what it takes, I would check again after 10 or 20 dives in the suit, you’ll probably shave a few more pounds off after break in.