Re: Wings and back plates

[Alex Towns <Alex.Towns@xxxxxxxxxxxxxxxxx>]

I'm in much the same boat as Kane - deliberating over which wing to go for 
and still cannot decide to go for bondage or not. There appear to be quite 
a few pros & cons against the OMS but little cons presented so far for the 
free wing. Which free wing is most favoured?


> 1) too much drag - they create more drag than un-bungeed wings

Considering flow dynamics in my head, I can appreciate that a free wing 
will shape itself around the tanks & cause less turbulence than it's 
bungeed cousin - but then how relevent is this saving of drag? As 
streamlined as we might try a diver with twins & stages is not particularly 
hydrodynamic - does the drag caused by a bungeed wing really make so much 
of a difference? 

Most diving of this sort, is down the shot, nose around the wreck (normally 
by pulling yourself around with your hands) then back up the shot! 
Admitted, for those scootering over great distance, then everything needs 
to be optimal if to prelong battery life etc - but I simply don't see how 
this (minimal?) reduction in drag is of great benifit to the wreckie, 
especially if you favour slowly moving around the wreck.

> 2) In the event of a puncture, the bungee will force ALL gas out of the
> wing

I'm not 100% convinced on this either way. I feel it's dependant on how the 
bungees have been adjusted. I tend to agree somewhat with the view of Phil, 
if a non-bungeed wing tears there are still problems - although maybe not 
as great as for a bungeed set. Has anyone actually tried or simulated it 
with both setups?

I can't say I'm too convinced on the effectivness of a membrane suit 
either for secondary buoyancy. When teaching CBL I always get them to use 
the BC & ignore the suit, otherwise the air farts out of the neck seal. 
Admittedly, you are compensating for boths divers in this senario and hence 
over weighted. On your tod it'd be more managable, but it'd still be a 
ropey ride. 

I don't like the idea of dual bladder for reasons stated, but feel if you 
needed to use your suit the diver must be aware of it's limitations & the 
need of correct buoyancy skills. U/w wouldn't be so bad, but using it to 
keep your head out of the water is another thing!

> 3) The lift provided by bungeed wings is not as supportive as un-bungeed.

Again I guess this depends on how the bungees are adjusted, but get your 
drift.
 
> The un-bungeed wing does not flap about.  Because it is free to move
> around, it can flow in the slipstream.  Also when inflated, the wing wraps
> around the tanks, thereby providing lift to the immediate source of weight.

This is what I majorly dislike about the free wing. I've been in many a 
situation where my tanks have scraped on either side when going through a 
bulkhead. With the wing semi inflated to support the diver, streamlining 
itself against the tanks - I see a great possibility of the wing finding 
itself caught between wreck & tank & subsequently tearing. 

The bungeed wing appears to nestle quite comfortably between the diver and 
tank & IMO even with the little bungees looping themselves around, is less 
likely to bring the wing into contact with wreckage. For the bungees to get 
snagged - I think the wing would have been torn first, simply due to the 
positioning of body, tanks, wing and bungees when secured. Likewise for a 
piece of wreckage to find itself in the postion to tear a bungeed wing, I 
fear a free flowing would suffer much the same fate.

Do any make suffer from inherent defects - I've heard reports about the 
elbow of the inflator hose for OMS coming off!

Finally - what sort of lift do most use?

Still unconvinced either way
Alex