BP Wings vs BCD explanation

[SeaJay]

...That you'd bait for another million-post thread like last time... As I said before, I think you just like to hear yourself argue.

Feel free to dive any way you wish. I couldn't care less how you dive. Apparently you like quick disconnects and jacket-style BC's. I once felt the same way. I invite you to educate yourself through formal training as to why some gear works better than others. If you choose to ignore the invitation, then so be it.

The argument of the half-full bladder has already been addressed. I invite you to read it at http://www.scubaboard.com/showthread.php?s=&postid=387070&highlight=article#post387070 . No doubt you will find points to argue... But you will not find me participating. I simply don't wish to argue with you any longer.

In light of your recent argument that plastics can be tougher than metals (which I agreed with you on, depending on the materials and circumstances) I find it interesting that in the above example you fixed a piece of plastic with a piece of metal.

...But whatever. I'm sorry... I simply won't argue with you.

 

[-hh]

SeaJay once bubbled...
The argument of the half-full bladder has already been addressed.

And you admit that its vastly simplified.

My point is that if you actually try to model accurately, the reality is the "half full" bladder, not the full one. When you model its CB locations, you're not going to get the extreme worst case, which is what you've represented it in your oversimplified study.

You did taper the Jacket BC in your illustration to reflect that they are indeed narrow at the top and wide around the waist. The result of this is that when the diver is oriented horizontally, the CB shifts down to that wide section, and ends up quite close to his CG and weightbelt, minimizing your "bad moment arm" concerns.

No doubt you will find points to argue... But you will not find me participating. I simply don't wish to argue with you any longer.

I didn't invite you to this thread, nor cite your work.

But here's a simple piece of Engineering advice for you: if you're going to bother to build a model, you're going to have to defend it. Which means that you can't take the heat, don't publish.

In light of your recent argument that plastics can be tougher than metals (which I agreed with you on, depending on the materials and circumstances) I find it interesting that in the above example you fixed a piece of plastic with a piece of metal.

You missed the part that it was a camera instrumentation port. The choice was to either delay the test and trash our schedule, or do without that camera. We did without the camera.


-hh

 

[SeaJay]

-hh once bubbled...


And you admit that its vastly simplified.

Of course.

Let's see YOUR published article on the subject, -hh.

My point is that if you actually try to model accurately, the reality is the "half full" bladder, not the full one. When you model its CB locations, you're not going to get the extreme worst case, which is what you've represented it in your oversimplified study.

Calling it "oversimplified" I think is a bit harsh... But hey, you're entitled to your opinion.

I suggest, though, that you read the link I sent you before spouting off. What you're looking for has already been addressed.

You did taper the Jacket BC in your illustration to reflect that they are indeed narrow at the top and wide around the waist. The result of this is that when the diver is oriented horizontally, the CB shifts down to that wide section, and ends up quite close to his CG and weightbelt, minimizing your "bad moment arm" concerns.

Actually, it doesn't. His CG is quite a bit lower.

Sure, the shifting of the bubble gets his CB closer, but it's still quite a bit of distance. Furthermore, there's the issue of the diver needing to manage a moving CB. Imagine if he was having to manage a moving CG as well... Why would he want to do that to himself? Of course, this was already addressed, so I'm not going to bother reiterating.

I didn't invite you to this thread, nor cite your work.

...And nobody asked you for your opinion either. But hey, it's a free country, and you're welcome to spout all you like... As am I. I simply said that I'm not interested in arguing any longer.

But here's a simple piece of Engineering advice for you: if you're going to bother to build a model, you're going to have to defend it. Which means that you can't take the heat, don't publish.

Oh, okay... Is that the Philosophy of Publishing by -hh? Tell me, -hh, what sort of experience you have at publishing... Or being published?

The bottom line is... I don't mind the heat. But I still reserve the right to refuse to argue. This time, however, I'm not going to egg you on for 50 posts before refusing to go any further. It's obvious to everyone here that you're just some guy with a chip on his shoulder.

You missed the part that it was a camera instrumentation port. The choice was to either delay the test and trash our schedule, or do without that camera. We did without the camera.

What difference does it make WHAT sort of port it was? The point was that you fixed a piece of 5" "unbreakable" plastic with what... A 1/2" steel plate? Do you not see that as supporting my position from our last argument?

Whatever.

I rest my case. And that's the end of my posts to you on this subject.

 

[-hh]

SeaJay once bubbled...
Let's see YOUR published article on the subject, -hh.

Here's one 4 year old piece that's scuba, but its not about dive gear: http://tinyurl.com/nl0x If you want something specific and new to be researched, you'll have to commission it.

Tell me, -hh, what sort of experience you have at publishing... Or being published?

My open literature works are predominantly Symposia Papers that are easily found; try the NDIA. But most of my works are distribution-limited, so you'll have to file a Freedom of Infrmation Act (FOIA) request. I can give you one leg up: the existence of Technical Report ARFSD-TR-93043 (May 1994) is now public domain. I also have a very small work pending with Harvard, but I don't yet have any details on its publication date.

It's obvious to everyone here that you're just some guy with a chip on his shoulder.

Either that, or someone who's not at all afraid to tell someone flat out when they're blowing (ahem) smoke.

But since we're on this whole egotistical 'Credentials Game' bit, its your turn to return the favor: since this is about technical qualifications, college, major, and degree(s) awarded, please.


-hh

 

[paulwlee]

OK, I'm jumping in the fray.

I read Seajay's article some time ago and liked the way the arguments were presented. However, I do feel that some very important considerations were left out, leading to a somewhat unfair comparison. If you are reading this Seajay, maybe you can look at this, and if you agree with me, add some more information.

In Seajay's article, the major advantage of the BP/wing system is that all of the weight is on the back of the diver.
But a cold water diver who dives with a 7mm farmer/john or a drysuit, regularly needs around 30lbs of weight. Thus, moving 6lbs to the back, although beneficial, does not really make that light and day difference as suggested in the article.
Moreover, most current BC's have rear trim pockets that can add up to 10lbs, right at about the same location, with about the same effect.

 

[Wyno]

-hh once bubbled...

Meantime, the claims about any system being "more streamlined" are just that: claims. No one has cold, hard Engineering data that actually proves it. And without data, its just an unsubstantiated opinion...or Marketing Hype. If someone's going to make the claim, they had better be able to come up with the data. Besides, even if there was a 10% difference in drag, does it even matter if you're doing drift dives?

-hh

I just started to dive a BP/Wing and can feel that it is more streamlined. And if you look at a BP/Wing diver compared to a jacket style diver you can see that it is more streamlined.

 

[paulwlee]

I recently purchased a new BP/wing setup to replace my broken BC. I did so, because I liked that it gave me a clean front area, and I didn't need pockets any more. (New drysuit! ) I also was thinking about getting into technical diving over the next few years. I did a couple dozen dives with BP/wings, and so far I like it, but I don't see that much of a difference when in the water.

That said, I think many of the arguments in favor of BP/wings for recreational diving are blown way out of proportion. Good fit can be achieved with a BC, and trim is no different between BC and BP. I don't think the streamlining argument holds any truth in it unless one is scootering.
I also have to agree with -hh on the failure point issue. After reading the GUE DIR-F, Tech1, Cave1 manuals and reading things such as a transcript of GI's lecture, my impression is that when these people talk about those things, it's taken from situations where they are doing thousands of feet of cave penetrations, often at depths in excess of a couple hundred feet. If I were in that situation, I would also be excessively cautious about everything. However, when we are talking about the run-of-the-mill single tank recreational diving, it's really pointless. I'm not really a very experienced diver (252 dives so far, starting 1992) but what with my being in a college dive club (with lots of old and banged up equipment, mind you) and then helping in classes more recently, I think I've observed a few thousand dives being done. I've never seen a plastic QD break during that time. And QD's are much more convenient, compared to both weightbelt buckles or nothing.

Despite all that, if one believes that QD's should still be avoided, maybe that person should put in four-point harnesses in his/her carseat and wear helmets when driving.

 

[DeepTechScuba]

Backplates went out of style back in the early 1970s (seems ancient now) when ScubaPro invented their first jacket-style B/C.

Then wings came into style on non-inflating jackets for lifting heavier loads.

Now backplates are back in style, with wings on them.

In style, out of style, ho hum.

I truly hope SeaJay has given up that nassssty smoking habit of his. Other than that, I don't think it matters whether he or anyone else is diving in style or out of style, backplate or no.

 

[DeepTechScuba]

"MEMBER" ... ahhh that has a nice ringggg to it!

 

[paulwlee]

Wyno once bubbled...

I just started to dive a BP/Wing and can feel that it is more streamlined. And if you look at a BP/Wing diver compared to a jacket style diver you can see that it is more streamlined.

Consider that many people think split fins are useless because it feels so, until they look back and see their buddy desperately trying to catch up!

I'd be very interested in any real comparative studies on this streamlining issue. I for one, don't really feel any difference. But then again, maybe that's because I'm in a drysuit that has enough drag that it covers up any advantages the BP/w gives me.