Weight ~ just curious...

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LariatAdvance

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Messages
62
Reaction score
23
Location
Newport, NC
# of dives
200 - 499
I went online to some site, I forgot now, where you can calculate how much weight you'll need to get neutral buoyancy. I just got a new BC and was curious how much weight I would need to adjust.

I found it curious that the sire requires you to enter your "skill level" (novice thru pro).

So when I calculate using myself as "novice" I get the following estimate:
In Salt water, weighing 200 lbs, with a 3mm one-piece wet suit and Steel 80:
You will need an estimated 14 lbs of weight (+/- 1 lbs).


But when I recalculate claiming to be a pro, I get the following estimate:
In Salt water, weighing 200 lbs, with a 3mm one-piece wet suit and Steel 80:
You will need an estimated 12 lbs of weight (+/- 1 lbs).


Who woulda ever thunk that the law of physics dictates that your buoyancy changes the smarter you get.
 
It is not uncommon for someone to be able to ditch a bit more weight the more they get comfortable with the concept of scuba and get into their rhythm. Has nothing to do with physics and has more to do with they were a bit overweighed to begin with.
 
It is very much about relaxation, knowing how to get all the air out of your BCD and wetsuit, and being comfortable breathing off the bottom of your lungs.
 
I'm 5'8", wear a size XL 3mm wetsuit diving single/double (sidemount) AL80s.. and over 8000 dives. I use 4lbs of lead. With experience comes more complete relaxation and very effective breathing control.

I think most of the weight drop is due to breathing. Stress causes a deeper and/or more rapid breathing; lungs on average at a higher tidal volume of inflation. Liters in the lungs equates to kgs on the belt. You might not feel 'stressed' on your dives as a novice... but chalk up another 1000 dives and you'll realize that you were far from 'sublimely relaxed' at that stage.
 
14lbs with a 3mm wetsuit and a STEEL 80 seems like a lot of weight no matter what level of experience you have...
 
Another significant issue is that not all wetsuits are alike. I've noticed buoyancy differences between one brand and another. And... of course, the size of the wetsuit is critical... as this dictates the amount of neoprene to be sunk. It'd be preferable if all these 'weighting guidelines' just listed in wetsuit sizes rather than bodyweight....

The age of a wetsuit (or, at least, the amount of use/abuse it's received....) is also very important. Wetsuits tend to lose volume over their lifespan, especially with deeper diving. With repeated use, they don't 'spring' back to full thickness on ascent. My old 3mm suit was more like a 1mm skin suit after a few hundred technical dives...
 
14lbs with a 3mm wetsuit and a STEEL 80 seems like a lot of weight no matter what level of experience you have...
Good point! I'd missed that it was a steel 80.
 
I missed the steel too. I use 12lb with my 5mm in fresh with an aluminum 80.
 
It is not uncommon for someone to be able to ditch a bit more weight the more they get comfortable with the concept of scuba and get into their rhythm. Has nothing to do with physics and has more to do with they were a bit overweighed to begin with.

I get their point, but I was being more facetious than anything else in my post.
I think the DiveBuddy calculator is wrong. The BUOYANCY is exactly the same in both examples. 200 lbs guy, steel tank, same BC, saltwater, 3mil suit. The skill level of the operator has absolutely no bearing on buoyancy (true buoyancy). The operator is an outside factor affecting the PERFORMANCE, it's not affecting the buoyancy. The gear and the person has exactly the same buoyancy in both examples. I think they should present what the "raw data" is, say 12 pounds, then notate that there may be some variance depending on your skill level.

Let me give you an example. I work with some professionals at Fort Bragg. These guys fire on average 30,000 rounds per guy per year in training. We've actually had some guys get carpel tunnel from firing so much in the reactive range. Now suppose I send one of my guys thru the reactive range with a H&K .40 USP and he fires a 400. Then I go find me a guy off the street whose hardly fired a gun before and I send him thru the reactive range in identical conditions, same firing table, with the same H&K .40 USP my guy used, using the same ammo. He scores a 75.
Then I could say the pistol was better when my guy went thru the range? No, the pistol was identical. It was the shooter's training and experience that affected the higher score.

You could also use NASCAR as an example. If I got into Richard Petty's Plymouth and did 200 laps around the track, I'm pretty sure his performance would out do mine. But it wouldn't be because the car was better when he used it.

I still say the buoyancy is exactly the same with a newbie diver VS a pro diver. It's physics. It's predictable and uniform across the board if all physical factors are equal. The factor that is changing the weight is the performance of the operator.
 
https://www.shearwater.com/products/perdix-ai/

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