average personal buoyancy?

[easysqueezy]

I sink with a full 3mm wetsuit and no weight. I have been called dense but I think that is not what they meant. My tanks are 1.8# negative empty and I have no problem at 15-20ft holding still for a safety stop. Is this normal? should I be checked for a steel plate in my head I did not know about? aliens? also I have no weight to dump in an emergency but would assume since I have none to begin with it would not be a problem to swim to the surface even with a failed BC. I have an AL bp/w but not swimming with any real heavy gear like a tec light. oh well.

 

[ScubaSarus]

Wont alum BP be about -5 bouyancy or more.

A 3 mill maybe +3 to 5 bouyancy

You may have good muscle tone, and what water were you in salt, fresh, brackish ?

You are off to a good start though and picked good equipment.

 

[LeadTurn_SD]

I sink with a full 3mm wetsuit and no weight. I have been called dense but I think that is not what they meant. My tanks are 1.8# negative empty and I have no problem at 15-20ft holding still for a safety stop. Is this normal? should I be checked for a steel plate in my head I did not know about? aliens? also I have no weight to dump in an emergency but would assume since I have none to begin with it would not be a problem to swim to the surface even with a failed BC. I have an AL bp/w but not swimming with any real heavy gear like a tec light. oh well.

Your aluminum BP is probably about -2 lb., regulator -2 lb, I'm guessing you are using a single tank (and you did not say what size, HP or LP steel, etc.) is -7 to -10 lb. when full.

Add those up and you get -11 to -14 lbs. or so, which is partially countered by the buoyancy of your 3mm fullsuit, so at the surface you may be around -6 lb. at the start of the dive, and close to neutral at the end of the dive.

At depth your wetsuit will lose most, but never all, of it's buoyancy. So the most you should have to swim up is maybe - 12 lbs??

All this is gross estimation, and what is left out is your "personal buoyancy" which can be + or - depending on body composition, and does not change with depth. The best way of course is to actually test this by trying to swim up from 60' or so with an empty wing to make sure you can do it.... but from the info you posted it should be no problem.

Whether it is a good idea to have ditchable weight? Sure, but in some cases (thin wetsuits, lean diver) there may not be any to ditch.

Best wishes.

 

[don Francisco]

Personal density varies tremendously among individuals. Breaking it down; bone sinks, fat floats and muscle is just shy of neutral, so a person's body composition will determine his bouyancy.

Women tend to float, and athletic men, especially runners and cyclists are dense and tend to sink. Body type also affects trim, since the distribution of fat, bone and muscle also varies.

I wouldn't worry about being dense --- with age, poor diet, and sedentary lifestyle, you'll eventually float like styrofoam.

 

[Clanggedin]

I only use 4lbs of added weight in a 7mm suit w/hood and gloves. I do use a Steel 80 and a SS BP though. This is all in Fresh Water. I believe I am around 10lbs in salt

 

[redacted]

Most folks in reasonably good physical condition can float in FW with their lungs fairly full and lay on the bottom of a FW pool by exhausting a part of the air in their lung. Floating in SW is much easier. Many probably find it difficult or impossible to sink in SW just by exhaling without added weight. Then you need to start adjusting for scuba gear.

 

[SkipperJohn]

I have a less than average fat content (about half what is considered normal) and good muscle tone. I work out regularly. yet I float like a cork. I have oversized lungs (I make xray technicians crazy and they end up using 2 films on my lungs) which is why I float. So there are so many other factors besides fat, muscle and "denseness" (which I posess in great quantity myself)

 

[RonFrank]

Buoyancy is what it is! Your tanks are negative when empty, your reg is going to be negative, your BP is going to be negative. That is likely enough to offset the positive effects of the wetsuit, the bladder, and your body. No ones body is negative, bodies always end up on the surface unless they are weighted.

You don't say if this is fresh or salt. Salt water is more buoyant vs. fresh, approx 6lbs. more buoyancy in salt. I dive with 8lbs in salt, and dive a couple of lbs over weighted. I would imagine that in fresh, I could also skip the weight IF I could dive a 3mm, AND used steel tanks. Heck, I can almost skip the weight in salt if I dove steel, but I generally dive alum. My BP/W is around 12lbs negative, and I would be over weighted diving that setup in salt even with an AL80. I dive a Zeagle Stiletto in salt with a Alum tank, and don't need much weight.

 

[mikeyjoe]

I have been called dense but I think that is not what they meant.

Are you sure of this.....

No you are not unusual. Since I lost 20 lbs, I am now neg in a pool - finding that out in my Dive Master class. The 15 minute tread really sucks when you have to paddle like crazy just to stay afloat while you watch the rest of the class (+ bouyant) float effortlessly on their back......

Still need a crap load of lead for my drysuit