Misconceptions and Fallacies

[plot]

Does it really matter? What do you think will happen to the water when you add air to the BC? it should be expelled when the bc reaches its limit.

What if the water isn't over the dumpvalve?

 

[DivingCRNA]

BP/W's are better than regular BC's - it's really the buoyancy and skill of the wearer that counts!

Oh, No! You didn't!

BTW-This is not a fallacy. My BP/W is much better FOR ME than any regular BC I ever wore because I built and fit it to me, instead of making me fit a mass produced BC that the dive shop owner said was "the best" (and highest priced, btw).

It will also always be there for me-3 ml wetsuit-check. Drysuit-check. In swim trunks-check. Single 80 on vacation-check. Doubles-check. Scooter (need a ring)-check. I just cannot say this about every "regular" BC.

Sorry.

 

[DivingCRNA]

Fallacy: Dry suits

It should be called a drier suit. Drier than a wetsuit.

Yes, I dive "dry"

 

[DivingCRNA]

Myth: Back inflate BCs (and BP/Ws) "push your face in the water".

It is possible to end up with your face in the water on the surface, if you have all your weight on a belt on your front and/or you overinflate your BC on the surface and/or you do not simply lean back and relax on the surface.

In any of the possible scenarios above, nothing "pushes your face in the water". The BC bladder floats, and your weight, or the weight of your weights PULL your face in the water by GRAVITY.

There-I never want to hear that myth again

 

[MikeFerrara]

Now who is in 'the laboratory'?

I think we're crossing our wires here. The conversation began when one person said being overweighted does not increase consumption. That's certainly not true, and it was pointed out by a few people that there is a correllation. Everybody agrees that there are cases where the effect is very little, but it seems not everybody is agreeing that there are plenty of cases where the effect is noticeable.

Can I ask the following...

- the slight increase in air needed in your BC
- the increased drag through the water (even more so on the surface)
- the added exertion of packing around and swimming the extra weight
- the cumulative effects of all this on multiple dives

All of that amounts to nothing?

What exactly are you arguing? That sometimes all that amounts to very little? Scroll back several dozen posts and you'll see that was settled long ago.

Craig

I think the point is that many divers, including instructors and agencies, blame what is really the result of poor trim on being over weighted.

The fact is that you are always overweighted at least by the weight of the breathing gas you carry. If you carry lots of breathing gas you can be pretty heavy.

Aditionally, when diving in a wet suit you have suit compression and the loss of buoyancy that goes with it so you are additionally overweight at depth by the amount of that buoyancy loss.

Both those sources of buoyancy loss require you to put air into your bc...that's what the bc is for. Being overweighted (needing air in a bc to be neutral) is just a fact of life when diving all but the warmest waters with the smallest tanks. Moving easily and with control through the water is more a matter of where the weight is placed and technique.

 

[wettek]

Can't let that one sneak by. It's HUNDREDS of times denser....

Whoops! Embarassing brain dump there. It's about 800 times denser. Sorreeeeeeey.

 

[RJP]

Myth: Buying a rebreather will save you money.

Myth: Breathing helium makes you colder.

Yes, but breathing a rebreather can bring you to room temperature

 

[RJP]

Misconception: Self-donning

 

[Walter]

Myth: Wikipedia is a valid resource.

 

[NJMike]

I like this one.

Sharks are attracted to human blood.

Rock on, rockjock3! Thanks for this one...so will the real truth please stand up?

Isn't it true that human blood in water will attract sharks from miles away????

Potential future bleeders in the water need to know!