Jacket BC or Wing BC

[-hh]

BTW, It's Physics and as I've said before, the plural of anecdotal is not data.

There have been opportunities presented on a Silver Platter to go measure data ... and one would particularly expect that if a manufacturer really did have a better product that they would welcome the opportunity to crush his competitors with hard data.

But no, it doesn't happen. It has been observed that such opportunities have fallen through so many times that it can hardly be considered a mere coincidence anymore...although scientifically, any purposeful intent to deceive hasn't been proven.

In layman's terms, the remaining manure is simply too deep to believe the claim that the stable is clean.

Dan, if drag and propulsion efficiency are the key factors in what BC to choose, then why do they frog kick* (in a non silt dive), arms crossed across the chest, and knees bent up as opposed to straight legs and arms either out front of down their sides? Why carry all that extra gear in their drysuit pockets? Why take a can light? All of that stuff has real value but it adds more to the drag.

And hey, let's throw in the "long hose" as another source of drag too. Afterall, if drag streamlining is the most important factor in one's dive gear setup, then the long hose must come under fire.

My view, drag is just one very, very minor factor in choosing to use a BP/W. The two major factors are one, the ability to use double tanks and second, it has a crotch strap. Everything else falls into the small benefit category.

Which is really where observation as how it contributes to the scientific process takes us on our journey to identify significant contributing variables to quantize. The human plays the biggest part, through their control over the variables of trim, weighting, fin choice, fin stroke mechanics, "cotton arrangement", their personal fitness levels, dive planning (intelligence over braun), etc ... and for the diver as a consumer*, it should be noted that these contributing variables are mostly "Free" in that they don't come from a $500 widget from a manufacturer's catalog, but simply are personal skills development.

* - especially for the Novice diver seeking good advice, since this thread was originally in SB's "New Diver" section

Plus, most divers that have a BP/W simply don't need another BC in order to dive, even nice warm water reefs.

The biggest hazard of diving in warmwater with a larger-lift BC isn't in the water, but at the airport, in the form of an airline overweight baggage fee. And a BP/W user with a weighted STA isn't going to be treated any differently by the airline.

The issue here is that a small number of people push the BP/W as the end-all-be-all of diving gear. While I agree that it's indeed a very good system, one that I use as well, but for a significant majority of divers, it's just not needed and not all that important in order to safely enjoy a dive.

Well said. Unfortunately, the more that the BP/W is promoted as the "best solution for everything", the more that it will develop a reputation as being snake oil that isn't good for anything.


-hh

 

[danvolker]

I found a great learning toy for HH, to assist him in getting to functional math, as opposed to just assuming his calculations include all the needed variables( which obviously they don't)

This is a calculator for how much power it takes to get a bike to go a certain speed. Bike Calculator
Some of the cool things about it, are that you can see that many elite cyclists are hitting 800 watts for a 30 second to a minute long effort ( based on speeds attained every weekend I have hit 1000 myself in the past when I raced, but nowdays, I am not training hard enough to get much over 750 or 800 watts... More importantly....there is a drop down for seeing the speed difference with a rider being on the tops(hoods) of the handle bars (read this as floppy BC), on the drops( decent BC with streamlining) and on aero bars( bp/wing maximally slick with perfect trim etc).....you can see the effect of streamlining on speed, at a given power rating....AND. without the streamlining, you can see the massive power needed to hit those faster speeds.


A normal diver would get on a bike, and 13 mph will seem like the top cruising speed. This is 80 watts of output....and realize there are plenty of divers who can not do even this. A fit diver can do 300 watts and hold this themself for 2 or 3 hours, just as easily--this is riding at 22 mph--a nice cruising pace for 1 or 2 riders. If this rider increases power output to hit 25 mph, he is riding at an output of 400 watts...which some could sustain for 10 minutes to 20 minutes, but pretty much any cyclist that wants to ride this fast without drafting, will want to switch to aero bars....in which case the 400 watts would yield 29 mph, a speed sustainable for most racers for less than 15 minutes, though world champion riders can hold this for an hour. 300 watts on the aeros allows 26 mph, a speed many category 3 riders can hold for an entire hour. This is a little over three times the power output of the normal human or diver. The world champion will get 4 times this. We are dealing with aerobic power here....one minute efforts ( anaerobic power) will allow up to 1000 or 1200 watts efforts, and this can be 10 times the power output of many divers. This is emergency speed efforts for a diver...you see another diver out of air and must get to them FAST...you see an emergency you need to respond to fast....you are in a current and must get upcurrent to an anchor line, etc. These are examples of what you use anaerobic respiration for in diving. This is the only time a diver needs maximum streamlining AND maximum power of like 400 to 800 watts. Also know this kind of power can only be used by a diver in less than 100 feet, due to CO2 buildup...., and really, the big power use better be more like 30 feet or less, if it lasts more than a few seconds, or there will be headache galore

It's all science HH Enjoy.


*** In an effort to be fair to HH, the physics of the cycling power and speed issues have been dealt with by a relatively MASSIVE effort of many of the top minds in this area, for decades....in diving, the similar issues have drawn only a handful of entrants to the party, and HH has actually done a great job, given the small amount of work he had to build on from others before him. There is little driving the science world to go through the diving issues we are arguing, compared to what goes on in cycling. For now, I think most of us will agree there are some strong similarities between diving and cycling for power and streamlining. We need to use these. Also, I will stipulate, that the most streamlined vests, are quite close to bp/wings in streamlining, and especially so if the diver is very close to the bottom where skin friction drag reduces the resistance on the diver's chest and stomach area ( which the vest wearer will benefit from even more than the Bp/wing wearer--kind of evening them out more in a strong current)

 

[-hh]

This is traditionally an F4 Phantom joke, but there's apparently no easily found cute graphic, so this will have to do:





In the meantime, piles of bicycling data ... doesn't result in any drag data for different BC's.

Not even for:





-hh

 

[-hh]

The facts have still not changed:

Despite Joe Isuzu hyperbola, there's no objective data to substantiate BC "superior drag/streamlining" claims, either by BC style or by BC brand.

The derogatory terms, name-calling, innuendo, condescending remarks ... are all examples of the ad hominem logical fallacy of attempting to obfuscate that truth by trying to attack the person instead.


Disclosure:

I have not and do not have any affiliation with any dive gear manufacturer that could result in any real or perceived conflicts of interest.

I have nothing to sell. I have no reason to lie.



-hh

 

[chrpai]

I just laugh at this point. Back in 2003 ( yes I was here ) I would get flamed for for diving a stab jacket. Fast forward to 2012 and I've started diving a BP/W and now I would get flamed for falling for the hype.

Meh... whatever. I'm just glad to be diving again. And for the record, price being about the same for what I paid for my initial seaquest jacket and what I paid for the BP/W and all things considered, I feel like I'm in a better rig now. But if I'm ever at a dive site without my gear, I'll throw a jacket on. I'm fine with that...

 

[boulderjohn]

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A ScubaBoard Staff Message...

OK, OK. I am going to close this mess temporarily and clean out all the personal insults and references to it. When it reopens, let's try to keep this on the topic of differences between BP/Ws and Jackets.

EDIT: OK, Pool's open again!

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[chrpai]

Awww, I hoped it would stay closed longer.

 

[BoltSnap]

It isn't fun anymore :crying2: