A Newbie Buying Gear!

[2airishuman]

False.

What AJ said.

Well, mine does, and that was the OP's experience, and it is the experience of many others. He is, by his own admission, new at this.

In the interest of moving the discussion forward, we could point out that the extent to which this occurs depends on the type and placement of other gear, how heavy steel tank(s) will counteract this to varying degrees depending on the tanks, how placing ballast on tank straps or using a heavy backplate, or a weight belt with weights placed behind the diver, will all mitigate this effect to varying degrees. We could point out that an oversized wing can increase the tendency to push the diver face forward.

But I'm not sure the OP is asking those questions.

I was just trying to point out, in a fashion appropriate to the "New divers" forum, the drawbacks of back-inflate BCs.

I dive a DSS backplate and wing myself. It's great. It will not float me armpit-high, vertical, above the surface, with an AL80, however, which a jacket BC will do.

 

[eelnoraa]

The knighthawk poshed me faced down too much, comparing it to another BCD I tried during discovery scuba.
I looked into diverite's BCD and they seem pretty cool. Like mentioned on the first page, they look pretty much like my parachute harness.

I can think of two reasons. 1) you are severely over weighted. 2)Knighthawk has a badly design, overly large integrated weight pockets. If you think about it, all your lift is at your back (back inflate). All you weight is in the integrated pockets, which is forward of you body. If you are set on Knighthawk, I will say split your weight. Put some in your cambands. Just put the ditchable amount of weight in the pockets. Or better yet, put on a weight belt, make sure weight are threaded so that they are on the side of your hip, not front.

Personally, I can never understand the need for such a large integrated weight pockets. I don't own knighthawk, but from the picture, it does NOT free up value space on the side of front at all.

 

[JohnnyC]

snip

So what you're saying is that a GUE cave diver with MULTIPLE exploration credits to his name (@PfcAJ ) and a cave diver/CCR diver (me) are incorrect in our assessments?

How experienced are you again to make such sweeping generalizations? I didn't realize you were a Subject Matter Expert. Maybe you could put in your signature how experienced you are, so we know to trust your advice over that which is given by guys like AJ and I.

(Here's a hint, if your bp/w is throwing you face forward on the surface, you're doing it wrong)

 

[Colliam7]

Salt water pool (I dont think its highly salted anyway, more like lightly salted pool lol) with no shirt. Id have to factor the buoyancy of the suit I got (used Pinnacle Merino 7mm from these forums) I guess to then add weight. . .

So, no exposure suit. In fact, no shirt. And, you were wearing a HP100 cylinder? And, they started you off with 20lbs? I think 'meteor' was probably an accurate, albeit understated, description. .

The knighthawk poshed me faced down too much, comparing it to another BCD I tried during discovery scuba.

I am not sure I would 'blame' the Knighthawk for that. It is a back inflate BCD. Yes, it has trim pockets, but if A LOT of weight was put in the integrated weight pockets (and, probably most / all of it was), that places the weight forward of your vertical midline (viewed from the side). You were overweighted. You added air to the BCD to compensate, and keep your head above the surface. The weight and the air seek to align themselves vertically (simple physics) which cause the air bubble in the BCD to push your face down a bit. You add moire air to offset that sensation, which only makes it worse. Back-inflation BCDs with integrated weight pockets get a bad rap, for 'pushing me face down'. It isn't the fault of the back-inflation design. Rather, the combination of excessive weight and the usual (poor) placement of the integrated weight pockets makes it almost inevitable. With proper weighting, and more importantly, proper distribution of the weight, it does not happen.

To amplify an earlier comment made by several posters - PLEASE don't rush into buying equipment quite yet. (BTW, if the experience you describe above was facilitated by the local dive shop that wants to sell you the Knighthawk, etc., you might want to think about at least visiting a second one - just for grins if no other reason.) I don't think you have enough exposure / background to make a good decision quite yet on some of the major equipment. Yes, I personally think you will ultimately be well-served by a stainless steel backplate. But, I wouldn't even encourage you to buy that, yet. Call Tobin at DSS, who can offer A LOT of insights on weighting and equipment configuration. Find a local instructor to get in the water with you, in the exposure suit you will most likely be using for your local diving, and try some different rigs. You will not regret delaying the purchase for a few weeks.

 

[Doby45]

Back-inflate BCs, if fully inflated at the surface, will push your head forward.

Lies, all lies. My Zeagle Express Tech has never pushed my face in the water, even fully inflated to the point the OPV is popping. It is not the device that is the problem, it is the wearer of said device if you are face planting with a back inflate.

 

[Neilwood]

Lies, all lies. My Zeagle Express Tech has never pushed my face in the water, even fully inflated to the point the OPV is popping. It is not the device that is the problem, it is the wearer of said device if you are face planting with a back inflate.

I think a lot of people are under wrong impression with regards to back inflate.

I think it is more to do with where the combination of the weight and where it is than the back inflate.

If there is excessive weight at the front, it will have a tendency to pull you forward irrespective of where the buoyancy is. As Colliam says above, if the weight is already dragging forward, the initial thought is add more air which simply compounds the issue. Splitting the weight into ditchable in the pockets and some on a belt/harness (with the weight properly located on it) would make a far more stable platform than simply load all the weight into the pockets.

 

[tbone1004]

ok relax gents.

yes a back inflate bc, and/or a bp/w will float you face down if you are overweighted and/or fully inflate a wing that is too large. Now, that is operator error, and is easily remedied by pulling your legs up as if you were sitting in a bar stool, and basically sitting on the crotch strap. If you don't have a crotch strap, the whole rig will tend to ride up on you, and that will of course try to push you face first in the water.

No, a properly set up, balanced rig, with a bp/w or back inflate bc, especially one with a crotch strap *it is the second most important strap on the harness aside from the waist strap at the surface* will push you face first into the water. Just isn't going to happen. Sidemount rigs will, but all the weight is on your chest, and all the lift is on your back, so no sh!t sherlock

Double 72's, 60lb Dive Rite rec wing, Transpac harness, no extra lead, 5mm wetsuit

Sidemount 120's, 7mm farmer john top, Dive Rite Nomad XT, no extra lead, sitting quite happily at the surface of P1. Note leg position. If I had dropped my feet straight down, I would have been flat on the surface....

four divers, on the surface, all in bp/w's, no one face planting on the surface, all sitting quite comfortably, albeit a bit chilled

Fighting to go vertical actually because it is more natural to stay in that slightly leaned back position with proper leg orientation than it is staying vertical

 

[george_austin]

Learn to dive without a BC - after you get certified with one. Forget that Knighthawk thing and get a used BP and 18# wing. Spend the money you save on a high quality wetsuit.
A smart, informed shopper can get fully equipped for 1/2 or less of what that shop quoted you. You don't NEED a computer - you'll be new and doing single tank dives. Know how to work your Navy Tables and get a depth gauge and a good watch.
Mask - 100.00
Fins - 100.00
Snorkel - 30.00
BP/W - 400.00
Reg - 250.00
Wetsuit- 350.00
Depth gauge -wrist mount

Thats for brand new stuff. - be patient and smart

Good luck - see you out there