Jacket BC or Wing BC

[danvolker]

Ok Thanks. Not sure I would spend close to $600 for fins even if they are the "Lamborghini Gallardo" of the group but I will certainly look into the Cressi Gara's you have mentioned. I did see that Mares has something like a free diving fin but it appears to be about 6" shorter that a true freediving fin but is much longer than a std fin. Don't know if they are any good or not. Here is a link: Mares Avanti Quattro Power Full Foot Long Blade Fins, Black

These are not long enough to utilize the long moment of bending and longer propulsion component of the freedive fin with the correct shape in kicking style....kind of like a hybrid bike, they can sell well in a shop, but they are not the real solution, and don't really do anything really well...but can be kind of a "multi-tool".


Back to the BC and wing discussion HH has reincarnated.....
A couple things I will concede.... :

• For a large part of diving, most divers will be swimming at between .5 mph and 1 mph, or slower.
• At these speeds, drag is low, and differences between BC vs bp/Wing for effort moving are hard to feel. This does not relate to ability of each system to be easily trimmed to perfection, just to how either moves if the diver is horizontal as they should be for efficiency.

Increasing speeds above the slow / normal swim speeds, requires exponential increases in propulsion ability or in streamlining efficiency.....Competitive Cyclists have a very similar issue....Almost anyone that rides 10 to 15 miles per day, can get to the point of efficiency and power, that it is fairly easy to hold 17 to 18 mph, for a very long time.....However, once the pace needs to pick up, as in when riding with a bunch of fast riders, things change....Once you hit around 22 or 23 mph, just increasing one mph faster means almost doubling the horsepower put out by the cyclist, and for each additional, it doubles again....( this is not exact, but it is discussed in cycling, and is useful morefor the conceptual, and the ease in duplicating this for yourself)...A cyclist that can pedal to 26 mph and hold this himself for an hour, is in an entirely different level from the normal 18 mph max cyclist.

Now, take the cyclist that can max out at 22 mph...put him on a full aero time trial bike, and suddenly he can slide through the air much easier, often making as big a difference as 2 to 3 mph top average speed. This is huge!!! This is running away from your evil twin on the non-aero bike....Night and day, if you are a cyclist.

Same really in diving....get in a current you need to go upstream into, where 1 mph would have you going backwards, and where 2 to 3 mph is closer to the desired average speed...and the equivalent of the aero bike is needed. Part of this is the Halcyon type bp/wing with 30 lb wing...part would be the carbon fiber composite freedive fins to make this easy.

However, if the diver is slick enough, and perfectly trimmed, and can hug the bottom 2 inches off of it with non-silting frog kicks, the skin friction drag of the bottom may allow this diver to proceed upcurrent effectively with jet fins...

....the evil twin wearing a big bulky vest bc with console hanging, might try to copy this, but ends up constantly snagging the bottom with his console, and the bulky bc is catching the big flow of water, and acting like something of an underwater sail--not helping the poor guy....If this poor guy is also using Apollow bio fin split fins, he is flutter kicking like a mad man, leaving a cloud of silt behind him with the appearance of the smoke from a forest fire, and he is having no luck fighting this current

Similar to cycling....once you go above a critical threshold speed, any significant increase in speed for the scuba diver will require enormous increase in propulsion power or an enormous reduction in drag. I think the point in scuba diving is around 2mph .. kind of like hitting 22 mph on a bike.... Going from 2 mph as a diver, to 3 mph is like a cyclist going from 22 mph to 25 mph ( and this is huge!!!).

 

[DevonDiver]

In all those trips, I have never seen a single DM or Instructor wearing a BP/W. Not once. And I have made it a point to look since joining SB because of all the wild claims made on these threads.

1. Because it's a relatively new innovation - and still has regional bias in usage.

2. Because most Instructors spend 90% of their time in a swimming pool or shallow water signing "you - watch - me" before doing a snorkel-regulator exchange etc.

3. Because in areas where the kit isn't [yet] popularized, people on a DM or instructor salary aren't going to speculatively purchase and ship in new equipment from overseas - they'll make do with what they have.

4. Because many (I'm tempted to say most) recreational instructors don't have a clue about stuff outside of their immediate threshold of scuba knowledge - that being OW, AOW, Rescue and DM training.

If the BP/W was so superior in it's streamlining over a jacket BCD, why haven't these professionals caught on? I mean these guys/gals dive pretty much 6 days a week and several times a day. If you are diving for a living, wouldn't that person want to be in a BC that gives them optimal performance under the water? I just don't understand why all these professionals haven't seen the light. Maybe it's just that they have such a high level of diving skills that it doesn't matter what BCD they are using.

A rather desperate argument IMHO. Come to the Philippines, where many, if not most, serious divers are in BP&W.

Which has made me wonder the following. If a person wearing a jacket BCD has perfected their trim and buoyancy, are they the more skilled diver than the person wearing a BP/W since it is suppose to be easier to achieve perfection in a BP/W?

By your rationale, skilled motorists should only by crappy old cars. Correct?

It still seems to me that the superiority of the BP/W is more of a ScubaBoard phenomenon than anything else as I have never seen or heard this type of discussion outside of here.

Perhaps you just need to travel more.... or extend your circle of friends?

 

[BDSC]

1. Because it's a relatively new innovation

I thought they had been around for 10 years plus. Of course maybe that's "new" in the diving world. Don't know.

2. Because most Instructors spend 90% of their time in a swimming pool or shallow water signing "you - watch - me" before doing a snorkel-regulator exchange etc.

Not really sure what that has to do with anything.

3. Because in areas where the kit isn't [yet] popularized, people on a DM or instructor salary aren't going to speculatively purchase and ship in new equipment from overseas - they'll make do with what they have.

Any they do very well with what they have. Maybe one of those, "If it ain't broke don't fix it" situations.

4. Because many (I'm tempted to say most) recreational instructors don't have a clue about stuff outside of their immediate threshold of scuba knowledge - that being OW, AOW, Rescue and DM training.

Now you're really reaching.

A rather desperate argument IMHO. Come to the Philippines, where many, if not most, serious divers are in BP&W.

Nothing desperate about it because I'm not arguing. Just an observation of mine. By the way, what is a "serious" diver? Sounds like a desperate term to me.

By your rationale, skilled motorists should only by crappy old cars. Correct?

How did you come up with that? Wouldn't my example actually be saying the motorists who learned to drive crappy cars would be better motorist than the ones who learned to drive the newer cars?

Perhaps you just need to travel more.... or extend your circle of friends?

I absolutely do need to travel more for sure. One of these days I'm going to come to your side of the world and let you strap me in a BP/W for an entire week and see if I can be converted. I'm going to be really pissed if I find you are right!!!!!!

 

[danvolker]

Yes, although some "purists" will claim otherwise. Not to worry - - from a basic physics standpoint, a BC is simply a device that holds a bag of air, and there's only historically been three locations that this bag has been positioned:

a) In front of the diver (horsecollar)
b) Behind the diver (wing)
c) Surrounding the diver (jacket)

The difference between a BP/W and a "Rear Inflate" is effectively a pedantic hair-splitting exercise that tries to make a big deal out of the differences in the harness configuration that attaches that 'bag of air' to the diver, which are utterly insignificant for the general purpose (and especially novice) Rec diver.


FWIW, over the past four decades, I've used all three basic styles. I've literally just switched this spring from using a Wing back to a Jacket, and am satisified with the change.



-hh

I had almost forgotten what it was like to have HH around, to keep us on our toes

Glad you are back HH...

Now, as to the classic picture of HH wearing a harness with 3 bags of air attached, perhaps milk jugs with low presssure hoses and opv valves, we have HH performing perfection in trim and bouyancy, moving along on a low or no current dive, at speeds around .5 mph and slower....
He can do anything his evil twin could do at this speed, with the bp/wing system....this is skill.

However, since he was anchor diving in this still water destination, he has a problem when a storm comes up, and "no current" becomes 2 mph of current, and rising. Now his milk jugs are moving around, and catching in the stream of water flowing past him.

There are many tropical destinations, where HH would be happy with his milk jug BC 100 % of the time.
There are other detinations, where the milk jugs would be sea anchors, and where HH would suddenly develop a keen interest in a slicker bp/wing system. He would not need big statistical correlations for this... just his own keen observations..... Often good science is good observation.

HH, visit Palm Beach, and dive some of the "wilderness sites" with me. Do a few with the milk jug bc system, and a few with a bp/wing system I will let you borrow. Then you offer some of your "observations"

---------- Post added ----------

I absolutely do need to travel more for sure. One of these days I'm going to come to your side of the world and let you strap me in a BP/W for an entire week and see if I can be converted. I'm going to be really pissed if I find you are right!!!!!!

You only need to visit Palm Beach for this !!!! Just let me know

 

[BDSC]

You only need to visit Palm Beach for this !!!! Just let me know

Will do!

 

[Teamcasa]

In lieu of 'scientific data', I believe there is a vast amount of anecdotal evidence and direct personal experience from divers who have used both jacket and BP&W configurations.

The plural of anecdote is not data.

Until that time, please cease and desist from a counter-argument that has no evidential basis to disprove an acceptable claim.

How about some physics. A significant component of resistance in water is total frontal resistance. The more surface area that you present in the direction of the movement, the more resistance you create and the more force you need to overcome that resistance (drag = kv^20 In other words, water resistance varies with the square of velocity. (to go twice as fast requires 4 times the power, 3 times as fast requires 9 times the power)

Like it or not the single most significant factor in any divers ability to move through the water is not the gear configuration, it the diver's ability to generate the power to overcome the resistance of water, derived from their strength, fitness level, and skill - not their gear.

Speed is power first, everything else just helps out a little bit.


Side note: Anti-lock brakes were not introduced into F1 until the early 70's.

 

[DevonDiver]

Like it or not the single most significant factor in any divers ability to move through the water is not the gear configuration, it the diver's ability to generate the power to overcome the resistance of water, derived from their strength, fitness level, and skill - not their gear.

Then how does that explain my ability to effectively propel myself without fins, using bare-foot frog kick? Kick-and-glide isn't about power, or speed, but minimal drag resistance inhibiting whatever forward momentum you possess.

Speed is power first, everything else just helps out a little bit.

What about momentum? How water resistance nullifies momentum? I think that's more relevant to good diving technique than considerations of power or speed.

 

[Teamcasa]

Then how does that explain my ability to effectively propel myself without fins, using bare-foot frog kick? Kick-and-glide isn't about power, or speed, but minimal drag resistance inhibiting whatever forward momentum you possess.

Ok, your begging for a compliment, fine - you are one amazing diver. But thanks for making my point.

What about momentum? How water resistance nullifies momentum? I think that's more relevant to good diving technique than considerations of power or speed.

You can not have momentum without initial power.


Look at it this way, If Lance Armstrong was riding a poorly maintained, 60's era beach cruiser and I was riding the best racing bicycle money could buy in a ten mile race, Lance would still get to the finish line with enough time to shower, have lunch, give two speeches and hand out 10,000 plastic bracelets before walking a mile back to the finish line to watch my fat ass, huff and puff my way across, cussing that skinny, hard seat all the way.

 

[fisheater]

My non-scientific observation is that when I spent two weeks with Atlantis (Puerto Galera and Dumaguete) in The Philippines, almost all the DMs and much of the other staff who dove) were using BP/Ws. They were a hodge-podge of various manufacturers' offerings. I was the only BP/W-clad guest.

My hypothesis is that they were free ti dive whatever gear they could get their hands on, as Atlantis doesn't try to push dive gear, and they have a lot of high current and/or muck diving. This, BP/Ws make a lot of sense.


Sent from my iPhone using Tapatalk

 

[-hh]

I had almost forgotten what it was like to have HH around, to keep us on our toes

Glad you are back HH...

No worries Dan ... BTW, speaking of keeping you on your toes, do you still have your business relationship with Brownie and/or Halcyon? Afterall, clear disclosures of potential conflicts of interest are in the public interest of the readership.

Now, as to the classic picture of HH wearing a harness with 3 bags of air attached, perhaps milk jugs....

No need to imagine any picture, since a fellow SB'er posted the real thing of me on a dive earlier this month; here's a re-link:

Golly, all of those danglies are just horrible, particularly that big orange 6ft SMB with finger spool. And that trim position..tsk, tsk! And look at all of the bottom kicked up ... and why are the fins arranged that way? They're not in the correct orientation for a flutter kick! Egads, what a bad, bad, bad diver.

There are other detinations, where the milk jugs would be sea anchors, and where HH would suddenly develop a keen interest in a slicker bp/wing system.

You try to make it sound like you're the only person in the world who has ever dived in currents.

HH, visit Palm Beach, and dive some of the "wilderness sites" with me. Do a few with the milk jug bc system, and a few with a bp/wing system I will let you borrow. Then you offer some of your "observations"

Since I've already done a few hundred dives with a wing, are you really going to try the argument that I simply wasn't using the correct brand? So then tell me Dan, just which brand is the right one? Is it the Oxycheq stuff? Oh, wait, they're out in Washington State, so that can't be the right one...

Seriously, the only gear loan I'm really interested in is one where it is available to be dragged through the towing tank at Stevens Institute of Technology as part of an ungraduate engineering project (with written report) for the 2012-13 school year. Just let me know. I'm sure that Scott would be quite interested in putting his stuff up in a real head-to-head test against his old boss's products.

You only need to visit Palm Beach for this !!!! Just let me know

Don't you remember???? I've already been to Boynton Beach (a mere!!! 15!!!! miles south)!!!!

But I might be in the neighborhood again soon anyway to make a social call, as I need to visit a friend in the area. They're a personal priority and since we have other things booked, if we're able to do it soon, it is likely to become a quick Fri-Sun trip, which makes it hard to also squeeze in a dive.


-hh