Streamlining my gear

[tyesai]

As a total newb diver I've found streamlining does help! But not with effort or efficiency of underwater propulsion. No, to me that is almost laughable, not because it isn't true, but because we are so task loaded that we wouldn't be able to sense it anyway. Most of us newb's blow through air like a Texas forest fire so less effort isn't a concern yet. What it does do is cut down on confusion/task loading. If I know that when I put my left hand down at 7 o'clock position I'm going to find my computer/air gauge, and I know when take my right hand and place it over my right breast my octo is going to be there. It cuts down on task loading and it makes it harder for things to get tangled or confused. I have a regular BCD and with the adjustability the shoulder/chest/stomach straps comes lots of extra dangly bits that can, at least for me, cause some momentary confusion.

 

[vladimir]

That's a wierd assumption, given the obvious consideration that professional swimmers put into their streamlining... where even the design of swimsuit materials utilises highly developed technologies to reduce water resistance.

It's odd to find a member here who is championing an ethos of mediocrity and apathy. Scoffing at the advice of other experienced divers doesn't make you appear more knowledgeable...

I think Mossman is showing appropriate skepticism for the amount of streamlining a diver can accomplish, rather than "championing mediocrity and apathy." Genuflecting to "experienced divers" without thought or question doesn't serve anybody, but I'd give quite a lot of weight to the opinion of an expert in hydrodynamics.

Personally, I suspect that the principal benefit to divers of streamlining is a more organized gear profile, easier to use and less prone to entanglement, rather than a noticeable reduction in drag coefficient. And your analogy to professional swimmers would be apt, perhaps, if dives were timed in hundredths of a second the way swim meets are, and if divers devoted all of their effort, gear, and technique to maximizing their speed.

Where streamlining pays the biggest dividends is during those nice, slow, relaxed dives.

No, reducing drag "pays the biggest dividends" at the highest speeds, since drag increases as the square of velocity.

 

[DevonDiver]

As I've said before in this thread... it isn't a case of speed. It's all about efficiency through reduced resistance... especially if a diver intends to 'kick-glide-kick'. Lots of water resistance will really make a difference when a diver is trying to glide for maximal efficiency. Water resistance can dictate speed, but it also dictates efficiency/energy requirement at a given speed.

Of course, you don't have to "genuflect" to experienced divers"... but the flip of the coin also says that demanding evidence from an expert in hydrodynamics is a pretty lazy and lame way to justify an otherwise indefensible arguement.

I've noticed significant differences to my air consumption - matched with significant increased efficiency to my kick-glide-kick technique - as I streamlined my kit. When I started diving many years ago, I was significantly fitter than I am now. I use common sense to dictate that streamlining, plus trim, buoyancy and weighting improvements have ALL contributed to reaching an optimum air consumption.

AND... I don't need to be an 'expert' in hydrodynamics to understand that increased surface area penetrating water leads to increased water resistance.

 

[Antagonist]

How do i close this thread because some of these responses are getting crazy. Thanks for all the information everyone.

 

[vladimir]

As I've said before in this thread... it isn't a case of speed. It's all about efficiency through reduced resistance... especially if a diver intends to 'kick-glide-kick'. Lots of water resistance will really make a difference when a diver is trying to glide for maximal efficiency. Water resistance can dictate speed, but it also dictates efficiency/energy requirement at a given speed.

I don't question that you can reduce drag by streamlining. But by how much? A minimal amount, in my opinion. And whatever that reduction in drag is, its effect will be increased by the square of the speed you are traveling--so it is about speed. If you are going slowly, the reduced drag will have a much smaller effect on the effort required than it would if you were moving faster. In the simplest analysis, the cross-sectional area being propelled will determine the drag, along with fluid density and speed, and ignoring a lot of other stuff. So how much does that tucked-in hose reduce the cross-sectional area you propel forward?

Of course, you don't have to "genuflect" to experienced divers"... but the flip of the coin also says that demanding evidence from an expert in hydrodynamics is a pretty lazy and lame way to justify an otherwise indefensible arguement.

Your argument is, essentially, that tucking in a hose will yield large, measurable, noticeable reductions in swimming effort. You offer anecdotal evidence and nothing else. And I'm "lazy" for wanting (I don't think I "demanded" anything) some scientific evidence? And my argument that the effect of your streamlining is probably minimal is "indefensible"? Is it the mountain of contrary evidence you have cited that makes it indefensible? The array of data quantifying your claim?

I've noticed significant differences to my air consumption - matched with significant increased efficiency to my kick-glide-kick technique - as I streamlined my kit. When I started diving many years ago, I was significantly fitter than I am now. I use common sense to dictate that streamlining, plus trim, buoyancy and weighting improvements have ALL contributed to reaching an optimum air consumption.

What sort of measurements and multivariate analysis did you use to separate the effect of changes in trim, buoyancy, weighting, and fitness from the effect of the streamlining?

AND... I don't need to be an 'expert' in hydrodynamics to understand that increased surface area penetrating water leads to increased water resistance.

We agree. But by how much, as a percentage of total drag?

 

[vladimir]

How do i close this thread because some of these responses are getting crazy. Thanks for all the information everyone.

It's okay to just stop reading the thread--or any other thread that gets too crazy for you. If you believe somebody has violated the terms of service, click on the triangular "report post" button.

 

[knowone]

What was it, that happens if you speed around with a woodie full ofundies again?

 

[Brendon]

How do i close this thread because some of these responses are getting crazy. Thanks for all the information everyone.

Whats the problem? This is how just about every thread goes. Its all a matter of opinion and theory... I have yet to see a thread where everyone agreed or not highjacked at some point.

 

[DevonDiver]

I don't question that you an reduce drag by streamlining. But by how much? A minimal amount, in my opinion.

Agreed. We're really talking about fine-tuning, in the assumption that all other larger factors have been addressed.

A single hose probably has no noticeable impact, but the effect is cumulative as more hoses and danglies add to the total equation.

As you say... that resistance is primarily dictated by speed. But... I also feel it has an impact on deacceleration... grinding those nice glides between kick strokes to a more abrupt halt. Thus, requiring more kick strokes per set distance. A few extra kick strokes, does equate to an impact on air consumption.

What sort of measurements and multivariate analysis did you use to separate the effect of improved trim, buoyancy, weighting, and fitness from the effect of the streamlining?

I didn't...and nor would I want to. It's an integrated approach. I know that many divers mention a 'plateau' effect with their air consumption improvements... and, at that time, it is the fine-tuning that allows further progress to be made.

If there are any mathematicians on the board... or if anyone has connections amongst the 'Mythbusters' TV team... then please feel free to add some science to the debate.

How do i close this thread because some of these responses are getting crazy. Thanks for all the information everyone.

You have to ask a Moderator to close a thread. It's unlikely that a thread will be closed for any reason other than a serious and/or continued breach of TOS. Threads aren't 'owned' by the original poster, if that makes sense. They are for everyone to enjoy.

If you feel that you've had enough information about how to streamline, then the option is to disengage from the ongoing debate. However, if you feel that some of the ongoing debates within the thread are 'off-topic' and preventing any progress with the primary role of the thread, then please just hit the 'Report!' button and let the Mod staff look at it

 

[vladimir]

If there are any mathematicians on the board...

I have a degree in mathematics...which is a long way from being a mathematician. What I do know, however, is that some top minds have devoted careers to understanding turbulence, for example. It does not lend itself to simple modeling and much of the practical analysis relies on experimentation, as in wind tunnel tests.