? on back inflation

[FF-EMT Diver]

Hey, I dive with Cressi Bak Jak which is back inflation only, the only disadvantage i found (although I Knew this before buying) was that it tilts you forward, But it really does so well on horizontial leveling it is worth the incon. I'm sure I'll get more used to it with more use, My point is, to help myself out I moved most of my wieght to the back pockets leaving about 1-2lbs in each front pocket which are my emergency dump pockets, Although ( I may be wrong ) I dont see a lot of neccesity in dumping, I realize the importance don't get me wrong, But you can really come up FAST by inflating. Let me know if this is (good) (bad) or (niether), any comments/suggestions will be appreciated. Thanks in advance.

 

[cool_hardware52]

Hey, I dive with Cressi Bak Jak which is back inflation only, the only disadvantage i found (although I Knew this before buying) was that it tilts you forward,

If your BC is forcing you forward you are probably overweighted, and over inflating the BC. If you are properly weighted you only need a "puff" in your BC to be comfortable at the surface.

But you can really come up FAST by inflating.

Rapid ascents are a good way to get hurt, and should be avoided. Some time spent with an instructor working on Slooow ascents could be time well spent.

Tobin

 

[pasley]

Back Inflate BC or Backplate and wings if not worn with a crotch strap and/or over inflated will tend to do that. To help prevent/reduce the tendency of a back inflate to tip you over I recommend:
1. Use the crotch strap. If yours does not have one (DSS and all the better ones do) then add one. This will make you one with the unit and when you inflate it, instead of it ridding up on your back and then pushing you over face first into the water it will lift you up with the BC. The being tilted forward occurs when the top of the backpack is behind the head instead of the shoulders where it belongs.
2. MOST IMPORTANT of all, Do Not OVER INFLATE the backpack. Inflate the backpack JUST ENOUGH to establish POSITIVE buoyancy. All BC's are designed to float you with your chin out of the water, not your armpits and chest. Many divers over inflate their BC as if they were trying to get high enough out of the water so show off their bellybutton ring. If you do this the back inflate will remind you it is only suppose to float you with your chin out of the water by smacking your face into the water, particularly if you don't have a crotch strap.

If you do all of the above, you will eliminate the tendency to tilt you forward in the water.

 

[scott&sara]

I guess I am a little confused by your question... I thought the whole reason to dive a back inflate BC (or wing) is for proper trim aka diving horizontal.

If you want to be vertical then get a jacket style BC like most recreational divers and then dive like you walk!

Scott

 

[FF-EMT Diver]

Hey, Thanks guy's for the response, the biggest ? I was asking was about putting most of the weight in the back and not being able to dump it should an emergency arise, I was in NO way implying that a fast ascent is great, That is one thing my instruct. really drilled in, I was saying that should you OOA or whatever else may come up and you had to make an emergency ascent I see no big need to dump weight, Sorry for the misunderstanding, Also mine did not but I really like the idea of the crotch strap I'l prob. try that, Also I found pretty much my answer on Scubatoy.com under reasons to have back inflation, Which said to just put more weight in back, Thanks again.

 

[Walter]

I guess I am a little confused by your question... I thought the whole reason to dive a back inflate BC (or wing) is for proper trim aka diving horizontal.

If you want to be vertical then get a jacket style BC like most recreational divers and then dive like you walk!

Scott

Scott, I believe FF/Emt Diver is referring to when they are at the surface, not while they are actually diving. BTW, no BC forces divers to dive in a vertical position. You can easily dive in a prone position regardless of your BC choice.

FF/Emt Diver, simply lean back, bend your knees and don't over inflate your BC, you'll be comfortable in your rocking chair.

 

[pasley]

Hey, Thanks guy's for the response, the biggest ? I was asking was about putting most of the weight in the back and not being able to dump it should an emergency arise, ....

Weight dumping is normally done at the surface in an emergency. Primary purpose of dumping the weight is:
1. to get positive in an emergency. The emergency in an extremely odd and unlikely circumstance could be a failure of the BC (bladder burst/tears on something, or over pressure valve gets stuck open). It is not recommended to be underwater, negatively buoyant with no functioning BC and unable to swim the weight up (I am can swim my weight up, in fact when I ascend, I normally dump all air and fin up).
2. to reduce the amount of weight you are having to move around during that emergency.
3. to reduce the amount of weight the rescue personnel are going to have to lift out of the water in an emergency. But heck, they are going to dump your BC and all your gear before they lift you out of the water anyway.

So I don't think you want all of your weight as no-ditchable, it is ok to have some no-ditchable. I will eventually end up with weight plates on my backplate and have about 1/3 of my weight as ditchable. Distribute the weighs as trim and safety dictates.

Crotch strap, there is a reason why the manufacturer recommends it. You will be much happier once you use one. Recently there was a dive instructor who had purchased their first backplate/wing and it was face planting them into the water. They included photo of themselves which showed the problem, a bladder as full as it could be with the material stretched tight and riding high out of the water (the bladder not the diver) up behind her head. She was advised to A.) reduce the air in the bladder and B.) use the crotch strap provided by the manufacturer but which she had not installed. She continued to report problems, and also co-incidentally continued to dive without the crotch strap as she did not see a need for it. Eventually she added the crotch strap and by some mystery, the issue resolved itself. Go figure.

It is logical if you think about it. On the surface and vertical, you have an air bag on your back trying to float with nothing effectively restraining its upward movement on your back. The unrestrained airbag rises up behind your head, which in turn pushes you face down in the water. The crotch strap holds the airbag down on your body behind your shoulders where it belongs. This causes the air bladder to lift your entire body with it. Of course if it is fully inflated it will still try to rise out of the water but is more easily controlled by laying over on top of it as you float/swim on your back. But again, the air bladder should be mostly empty on the surface. One or Two lungs full of air is all that is required (try manually added the air using the oral inflater)to be positive (you were neutrally weighted when you stared the diver weren't you?). Your backpack should not be filled so it is tight on the surface. If you have to add lots of air on the surface to get positive, you may want to recheck you weighting.

 

[FF-EMT Diver]

Hey Pasley, point me in the right direction maybe I overlooked it but I have not seen any crotch straps, Where might I get one?

 

[Blackwood]

Without touching on my feelings about OOA situations and emergency ascents, I want to try to point out a flaw in your plan (if I am reading it right).

I was saying that should you OOA or whatever else may come up and you had to make an emergency ascent I see no big need to dump weight,.

and

I realize the importance don't get me wrong, But you can really come up FAST by inflating

So it seems that your solution to an OOA situation is to ascend, and that to ascend you need to inflate. What do you plan on inflating with?

 

[Sas]

So it seems that your solution to an OOA situation is to ascend, and that to ascend you need to inflate. What do you plan on inflating with?

Yea that is what I was wondering too...