Can someone explain the difference between the DSS Torus and LCD wing? From what I can tell, the LCD has a zipper to access the bladder while the Torus does not, and the LCD wing can be removed from the backplate easier than the Torus. are there any other performance differences?
edit: stupid autocorrect, the title should be "DSS"
The center panel features on all DSS singles wings are exactly the same. We use the exact same steel rule die to punch the openings, and install the exact same custom molded grommets. Same shell materials, same bladder materials, same custom grommets, fittings and locator tabs. main construction difference is the top arc zipper in a LCD and no zipper in the Torus models.
There have been untold numbers of innocent electrons needlessly wasted extolling the "benefits" of donut wings.
Those with a basic knowledge of physics should be able to recognize the fallacy of these arguments.
In a nut shell:
Gas *always*, without exception fills the highest point in any BC. The laws of physics demands it.
For a horizontal diver the gas in *any* partially filled wing is two bubbles, one running down the each side of the cylinder in the "side pontoons" of the wing.
All wings, horseshoe or donut (or Toroidal) will have a "Top Arc" that connects the two side pontoons. This top arc is above the crown of the cylinder. The Top arc is free to wrap up until it hits the valve and first stage.
Donut wings will have "bottom arc" that connect the lower end of the two side pontoons. This lower arc passed under the bottom of the cylinder, i.e. between the diver's side of the tank and the diver's rear end. Wings longer than the cylinder are bad idea and greatly increase the risk of damage to the wing. As such nearly all wings will be shorter than the cylinder and the lower arc will be *under* the cylinder.
For a horizontally trimmed diver this lower arc is the absolutely *lowest* part of the wing. Unless the diver is ~ 75 degrees heads down, or the wing is fully inflated this lower arc will have no gas in it.
Remember to transfer gas via the lower arc one needs to make the lowest part of the wing higher than the gas in the side pontoons.
Often the claim is made that "full circle" or "Donut" wings allow the gas to circulate. They don't, it's myth. Gas simply does not abandon the laws of physics and travel down under the lower end of the cylinder and up to the other side. We have removed the bladders from donut wings, rf welded the lower arc shut, reassembled the wing and gave them to test divers. Not one could tell the difference.
What makes a wing easy to vent while in horizontal trim is the amount of tank wrap. The tank is the hotdog, and the wing is the bun. Wings with wide center panels, and or lots of capacity will have more tank wrap than a wing with a narrow center panel, and no more capacity than the application requires.
Keeping the level of the gas in the side pontoons as low as possible (less wrap) means the diver needs to "break trim" only slightly to transfer gas from one side to the other via the top arc. Remember the top arc is free to wrap up a bit, it's not trapped under the cylinder.
Any one diving a drysuit will need to slightly raise their shoulders to vent the dry suit during ascents. With a narrow center panel, minimum capacity wing,
horseshoe or donut will equalize from side to side more or less automatically when vent the dry suit. Even in a wetsuit the change in trim rrequired to transfer gas via the top arc with a well designed, narrow single wing is trivial.
Another common, but mythical claim made on the internet is that donut wings provide lift at the divers hips. Wings provide lift where there is gas in them, and the lower arc will be the last part of wing to fill.....
It's my belief after answering this question thousands of times over 13 years is the "Myth" of donut wings providing fresher breath, brighter teeth, and magic diving skills springs from the fact that the *only* wings made in the early days of BP&W's were very high lift, (70+ lbs) *doubles* horseshoe style wings with ~10" wide center panel. When fitted with a STA (single tank adapter) these wings were a genuine chore to dive due to massive tank wrap.
Some of the first dedicated single tank wings offered happened to be donut style. If one has had the experience of using a 70 lbs doubles horseshoe with a single tank, and a ~30 lbs dedicated single tank wing that happened to be a donut the donut was no doubt easier to use, but not because of the donut shape. The benefit was the greatly reduced tank wrap.
Of course like all things internet one Original myth gets repeated thousands of times until it becomes accepted fact.
Tobin
