Sidemount BC

[Razorista]

Even your beloved Razor uses bungee which can influence wing volume. That's what happens when you bungee around the torso. But the bungee does not limit the max buoyancy when you need it. The bungee would get tight around the stomach if the wing was fully inflated, but the wing would inflate. Correct?. The OPV wouldn't burp until max wing capacity was reached.

In case of the Razor it works a little different in my opinion.
The bungee presses the wing against body and weight system edges.
Those restrict wing inflation but the bungee is neither thick nor very tight.
But the bungee in this case could also be webbing, or a steel chain, the bungee-flexibility effect is next to nothing on the BAT-wing.
Some make the mistake of thinking they have to strap it tightly to their body, that will make the overpressure valve react long before the wing reaches max capacity.
In my early experiments I could loose about 5 kilograms of buoyancy that way, today I loose none at all.

...This, however, still preserves sufficient flexibility in the bungee to permit full inflation of the wing (as supplied, the bungees are very loose).

I had mentioned that I personally do not think it restricts the wing very much.
The bungee will however increase the pressure you need from the inflator to inflate it to maximum, slow it's expansion - that is the idea in using it in the first place.

I then demonstrate how the wing capacity can be reduced by tightening the bungee much further, so that the bungee reaches it's maximum stretch before full wing inflation is achieved. Reducing wing capacity is the goal, and you have to more than double the stretch/pre-tension on the bungee, (relative to how it was rigged 'out of the box') to make that capacity reduction.

That sounds reasonable.
So what's your problem with what I am saying.
Most people will neither have you nor Edd to modifiy their Hollis.

 

[tbone1004]

they don't need him to modify it now, that's essentially what the SMS75 is

regarding the razor, you absolutely need to have it pretty tight if you're using the wing for much buoyancy compensation because it starts to lift off of your back. The bungee force experienced is directly proportional to the amount of air in the wing, and the bungee has to be some sort of tension on it. Not a fan of this type of retention. You dive in cold water, you have a more balanced rig than we do diving in warm water requiring less wing lift

 

[Razorista]

they don't need him to modify it now, that's essentially what the SMS75 is

regarding the razor, you absolutely need to have it pretty tight if you're using the wing for much buoyancy compensation because it starts to lift off of your back. The bungee force experienced is directly proportional to the amount of air in the wing, and the bungee has to be some sort of tension on it. Not a fan of this type of retention. You dive in cold water, you have a more balanced rig than we do diving in warm water requiring less wing lift

The bungee is not holding the wing, the screw at the shoulder plate is.

The default bungee is a 4-5mm, that does not have much power to hold anything.

 

[tbone1004]

precisely why the razor turns into a beach ball when it is fully inflated. Attempting to prevent that results in the bungee feeling like a noose

 

[Razorista]

precisely why the razor turns into a beach ball when it is fully inflated. Attempting to prevent that results in the bungee feeling like a noose

Nobody seriously using it would want to prevent that.
The 'beachballs' purpose is surface swimming.
You never need that much lift submerged without having made a serious mistake in the planing stage.

The half inflated wing is streamlined and because it is only partially inflated easily deformable, allowing you to pass restrictions without deflating the wing completely.

 

[tbone1004]

you don't know what you don't know.
the beachball is a result of Steve being adamant about having a dual bladder and not wanting to spend the time and money designing a properly baffled wing
Without having made a serious mistake in the planning stage? Really? A buoyancy compensator compensates for buoyancy changes. 40lbs of air is 500cf. Roughly equivalent to a pair of lp121's/19l's cave filled, with a pair of AL80/11l stages and a deco bottle. Explain to me how that was an error in the planning stage? I still have to carry all of those bottles in with me...

 

[Razorista]

you don't know what you don't know.

What do you presume to know that I don't know about?

the beachball is a result of Steve being adamant about having a dual bladder and not wanting to spend the time and money designing a properly baffled wing

From HPs explanation they both would like more streamlining but think baffles do not work the way they are intended to and are also an expensive thing to sell if the manufacturer makes indiscoverable errors and after a year the wings start falling appart.
He likes to be mysterious about it but tells me his solution for a Razor 3 BAT-wing would/will be a different concept.

Without having made a serious mistake in the planning stage? Really? A buoyancy compensator compensates for buoyancy changes. 40lbs of air is 500cf. Roughly equivalent to a pair of lp121's/19l's cave filled, with a pair of AL80/11l stages and a deco bottle. Explain to me how that was an error in the planning stage? I still have to carry all of those bottles in with me...

Very very very few divers carry that much gas - ever.
But that's the point I am trying to make!
Even a loadout for several hours of cavediving, deep wreck penetration, the proverbial '100m dive', will not reach the wings maximum capacity.
In the planning stage you should be able to calculate the amount of buoyancy needed at a certain point to keep the beachball in check and it will work like a charm.

Streamlining, however you only need with a 2 tank loadout.
With 4 tanks attached the resonably inflated wings will not even be noticeable much in pictures compared to the bulk of metal at your sides.

With two tanks you rarely need more than a few teacups of air-volume in the wing.
And when reaching a restriction you can deflate the wing (even when fully inflated) a little and will have no problem squeezing trough anything you could without the wing attached.

 

[tbone1004]

a few teacups? Those 121's on their own hold 26lbs of air, over half the capacity of the wing. Your reference to the beachball vs the metal negates your issues with rigs like the Nomad, SMS75/100 etc since they are no less streamlined than the razor when it is full

Take technical dive training, you will then understand what we are talking about, until then you don't know what you don't know

 

[Razorista]

It's is preferable to use optimized tanks anyway.
Now, your 26lbs of air are half the wings capacity. Have you ever seen a Razor BAT-Wing half inflated? You wouldn't since it is hard to notice (I'm joking)

When reaching a restiction you should have used some of that air, that leaves you with a less than half filled wing with even your extreme example.
There are reasons why some prefer 80 aluminum stages and smaller main tanks: easy planing easy transport, only real disadvantage: more regulators.

 

[tbone1004]

thanks for proving my point. total amount of gas is total amount of gas. 330cf of gas requires the same amount of lift from a wing whether it is with a pair of 121's that are cave filled, or 5 al80's