Does A BP/Wing really push you face down at the surface?

[Blue Sparkle]

Just speaking for myself, I have not noticed this effect (although I, too, asked about it before purchasing my BC because it sounded ominous).

I have a SS backplate with a 17# or 18# wing (have two wings), and I've used an AL63, an AL80 and an LP95 with this setup. Exposure suits have ranged from none, to 3mm full, to 5mm full. I wear weight in two places: 1) On a belt and placed right to either side of the plate (so by my kidneys). 2) Strapped to the bottom of the tank with the aluminum tanks only (otherwise I'm head heavy/butt light).

The only caveat to this is that I'm comfortable in the water, so I'm not *worried* about being pushed forward. But, I also have not noticed it.

My usual buddy wears a Zeagle Stilleto back inflate vest BC. I have not seen him being pushed forward and he has not mentioned it as a problem either. He wears weight in the front/lower pouches and also some trim weight on the top tank band. Basically same tanks and exposure protection as me, but sub an AL100 for the AL63.

I don't have a problem hanging around "upright" on the surface (including some ocean type waves although not huge - maybe 3-4') for as long as I want to; however, if I want to just kick back and relax for a longer time on the surface for some reason, I sometimes lean back and just relax like I were on an air mattress.

I don't know if either the bp/w or the back inflate vest BC would float one with one's head out of the water if unconscious.

Blue Sparkle

 

[AbyssalPlains]

For my opinion on Wrap-around vs. BP/W BC, see my signature.

As to your question, a fully inflated BP/W does have a tendency to push you forward. That said, if your wing is fully inflated to keep you floating, you're seriously overweighted. One of the reasons I love my BP/W so much is that when I made the switch from my jacket-style BC, I was able to shave off ten pounds of weight right there.

From my experience, no BC will keep the head of an unconscious diver out of the water. BCs aren't live vests. It's a commonly heard argument, but not a valid one in my mind. A diver who reaches the surface unconscious has more serious problems than what kind of BC device he or she is wearing. With attentive buddies, you should never be in a situation where you drown because your BC didn't keep your head out of the water.

 

[Crush]

Many divers have way to much weight on their belt because they never take the time to determine the proper weight they need. With to much weight on the front side of their waist and then inflate the bladder you could end up feeling like it's pushing you face downward.

I dive in cold water (33 to 40 F) and about 26# is a perfect weight for me. This is not over-weighted, this is properly-weighted for my gear and local conditions. Place the 26# too far forward and you get a situation which might results in your being pulled forward. I doubt that poor weight placement would have a noticeable effect if you were only wearing 6# of lead.

 

[Firefyter]

it does not need to be overinflated to push someone forward. That seems to be a common myth but not true.

Blanket statements like this indicate either a lack of understanding of basic physics, or limited experiences, if not both.

You said it, not me. You have already admitted that you do not dive a BP/W, you dive a back inflate. That covers the limited experience. Your understanding of physics has yet to be proven as well. For it to push you, it has to have more air than necessary to stay afloat. Those of us that do dive BP's will agree with Peter, in that it depends.

 

[RJP]

You said it, not me. You have already admitted that you do not dive a BP/W, you dive a back inflate. That covers the limited experience. Your understanding of physics has yet to be proven as well. For it to push you, it has to have more air than necessary to stay afloat. Those of us that do dive BP's will agree with Peter, in that it depends.

With ~400 BP/W dives I've never been pushed face forward into the water. Of the half-a-hundred divers I know who dive BP/W, none of them seem to be pushed face forward into the water. Hell, in all of the too-numerous-to-count DSD's I've conducted with students using BP/W none of those folks were pushed face-forward into the water.

Can it happen? I suppose so - as easy as it is to avoid, there still seems to be plenty of people who manage to get themselves into such a situation.

Must it happen? Obviously not.

 

[Firefyter]

RJP - Not sure why you quoted me above. I'm in total agreement with you, I was just pointing out the pot calling the kettle black....

 

[fire_diver]

Absolutely wrong!

Show me one, ONE person, with a properly inflated BC of any type pushed face forward in the water. A properly inflated BC is just enough to keep you head clear of the water. Anything more than that is over inflated.

Blanket statements like this indicate either a lack of understanding of basic physics, or limited experiences, if not both.

You argue without presentation of any proof, facts, or even anecdotes. Your arguement is completely without merit.

 

[Doubler]

Many divers that switch from a Jacket to a BP/W have a tendency to over inflate the BP/W and not have the crotch strap tight enough. This combination will in fact push you face forward. By tightening the crotch strap you remove a leverage point and don't over inflate.

 

[Damselfish]

You said it, not me. You have already admitted that you do not dive a BP/W, you dive a back inflate. That covers the limited experience. Your understanding of physics has yet to be proven as well. For it to push you, it has to have more air than necessary to stay afloat. Those of us that do dive BP's will agree with Peter, in that it depends.

I think I was the first on this thread to say "it depends" then described a situation where it was more likely to be an issue. You're one who seems to think there's only one answer.

The physics are not especially different between a BP/W and a BI. (And if I did use a BP/W, it would be aluminum or plastic not SS and I wouldn't expect it to behave much differently. And note that with a nearly empty AL80 - bouyant - I don't need air in the bladder to have a force back there working against what I want.

As far as physics, I have an engineering degree so I'm pretty well set there, thanks.

I'm out now, feel free to have tha last word.

 

[RJP]

RJP - Not sure why you quoted me above...

Because I was agreeing...

:cool2: