It's from the Halcyon website. I have some pictures of myself underwater, but I don't look as good as that guy 
Drag !!! ?????
- Thread starter Butch103
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blodal once bubbled...
I was wondering if there is a picture or diagram of the perfectly streamlined diver. Thanks,
Bill
sure there is, just look at my profile
ROFL...good one, AQ...here is a pic of me that I daresay is pretty streamlined, albeit grainy
OP
You guys are tooooooooo much.........To all those that quoated the drag formulas and the relavent theory, personally that is not new to me ( I am an engineer by education). The question was more of a query to the the real relavance of reducing drag in the water. Streamling to reduce snags of course reduces drag inherently.
Has any diver actually done a comparison ( and I mean qualitatively) to see what the savings on air they had.
Randy.....you and Scooter are always swimming too fast, and the biggest problem with that is YOU ARE BOTH GETTING LOST QUICKER......Thats why I say I will lead the way and this way we don't have sucha long surface swim back to find the dammm boat......:boom:
Has any diver actually done a comparison ( and I mean qualitatively) to see what the savings on air they had.
Randy.....you and Scooter are always swimming too fast, and the biggest problem with that is YOU ARE BOTH GETTING LOST QUICKER......Thats why I say I will lead the way and this way we don't have sucha long surface swim back to find the dammm boat......:boom:
From a UHMS abstract article
"The effect of diver pitch angle was assessed by comparing the drag at positive pitch angles with drag at zero pitch. It was found that a head up pitch angle of 10deg increased drag by ~ 30%, whilst a 20deg pitch angle increased drag by ~ 130%"
I would guess that any equipment equal to the surface area mentioned above would have similiar effect on drag.
"The effect of diver pitch angle was assessed by comparing the drag at positive pitch angles with drag at zero pitch. It was found that a head up pitch angle of 10deg increased drag by ~ 30%, whilst a 20deg pitch angle increased drag by ~ 130%"
I would guess that any equipment equal to the surface area mentioned above would have similiar effect on drag.
The only quantitative analysis I know of is when the WKPP was trying out different configurations. Theyd configure a certain way, scooter for X minutes and see how far theyd go. Theyd try a different configuration and scooter again for X minutes and see how far theyd go. In Mexico they did some qualitative analysis by scootering in the halocline and observers above and below would analyze the slipstream and try and figure out how to reconfigure to get more gear in the slipstream.
The result of all of this is the DIR configuration you see today.
The only other attempt at analysis Ive ever heard of OMS laughable attempt to show that their convoluted BWOD wing exterior is more hydrodynamic than a smooth one. OMS threw a diver hooked up to a fish scale in some prop wash and revved the prop and measured how much weight showed up on the scale. I guess they assumed that vortices, uneven water movement and turbulent, cavitated water would not affect their test.
Note that they werent towing the diver. The boat was tied up and they really, really used prop wash to do their test!
Positive proof that OMS doesnt have a clear thinker in the house.
I mean, how much harder would it have been to put a boom out from the boat and tow the diver in clean water? Answer: Not hard, but they would not have been able to rig that test.
Yhea, this is so unbelievable that I just HAD to have made it up, right?
http://www.omsdive.com/faq-bc.html#faq-bc
Roak
Scooters are an ideal means of testing drag. But there is more involved than just gear configuration.
Shane and I are configured identically... the only thing different is our masks (and that does not make a significant difference.)
However Shane needs to have his scooter prop pitched two notches higher than mine for us to stay side by side. In other words when I am on 1 (lowest setting) he needs to be on 3.
It isn't the scooters... they are identical too... and we have traded scooters with the same results.
Body position & trim makes a big difference.
Shane and I are configured identically... the only thing different is our masks (and that does not make a significant difference.)
However Shane needs to have his scooter prop pitched two notches higher than mine for us to stay side by side. In other words when I am on 1 (lowest setting) he needs to be on 3.
It isn't the scooters... they are identical too... and we have traded scooters with the same results.
Body position & trim makes a big difference.
OP
Thanks for the info .........Is there any testing to say that the removal of the snorkel improves reduces your drag enough to make any significant improvement in the SAC rates or other measureable yard stick ??.....
I am really not trying to create any brain busting theories here. I really can't see how much difference leaving the snorkel in the bag or pocket really improves any measureable difference. I have ditched mine cause it is PITA pulling on the mask etc.
I am quite sure that incorporating the snorkel removal, no danglies, good trim and bouyancy all contribute to less drag and therefore longer BTs (?) and there fore I suppose that the same would apply to the snorkel.
My whole reason for asking this was from a response I read in another thread re diving with or without a snorkel. The response was to reduce the drag and it got me thinking ..."How much drag does it reduce??" This is not to ridule the posters answer. I believe they made a legit response. I do find that this alone cannot improve the diving and reduce the drag to any significant amount .
Anyway thanks to all those whom have responded.......:boom:
I am really not trying to create any brain busting theories here. I really can't see how much difference leaving the snorkel in the bag or pocket really improves any measureable difference. I have ditched mine cause it is PITA pulling on the mask etc.
I am quite sure that incorporating the snorkel removal, no danglies, good trim and bouyancy all contribute to less drag and therefore longer BTs (?) and there fore I suppose that the same would apply to the snorkel.
My whole reason for asking this was from a response I read in another thread re diving with or without a snorkel. The response was to reduce the drag and it got me thinking ..."How much drag does it reduce??" This is not to ridule the posters answer. I believe they made a legit response. I do find that this alone cannot improve the diving and reduce the drag to any significant amount .
Anyway thanks to all those whom have responded.......:boom:
I doubt there is any quantitative evidence to show that removing your snorkel improves SAC. However, when diving with a snorkel in a current, you can really feel that thing! Try it in a pool...I played underwater hockey a couple of times with guys that are pretty hardcore into it. They had these weird mouthpieces and trimmed down snorkels..I was in jetfins, a standard low volume black mask, and an old blue Dacor snorkel. When I was really hauling a$$ to get the puck, there was a steady, strong tug and vibration at the left side of my head due to the drag from the snorkel. It can even make your mask leak if you are fast enough (I am not...)..
Not that I know of, but to paraphrase an old car racing saying:
If you want to reduce drag by 20%, don't look for one place you can reduce it by 20%. Look for 20 places where you can reduce it by 1%.
Snorkel, light, jacket BC, dangling SPG, dangling octo, poor trim -- it all adds up.
Roak
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