Wing Sizing Questions

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Bubbletrubble

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Tobin,

I purchased a DSS LCD rig from you a few years ago. It performed so well that my girlfriend "stole" it from me, and I ended up with a second hand BP/W. She's happy, so I'm happy, I guess. :) At some point in the future I'll be purchasing another DSS rig. If you have a few minutes, I was wondering if you could answer a few questions regarding wing sizing for me.
  1. My drysuit + undergarment have about 24 lbs. of positive buoyancy. I use a total of 12-14 lbs. of lead. My tank is a HP100 steel that is 10.5 lbs. negatively buoyant when full. My stainless steel backplate is -6 lbs., my STA is -3 lbs., and reg is -2 lbs. My wing has 30 lbs. of lift. At the beginning of the dive, I have 12 lbs. of lead + 11 lbs. of other ballast (SS BP, STA, reg) + 10.5 lbs. contributed by the tank. I distribute my lead weight by wearing an 8 lb. weight belt and putting 4 lbs. in trim weight pockets on the tank cambands. In your opinion, is my wing undersized?
  2. I've read several of your other posts regarding wing sizing. It makes sense to me that a wing needs to be able to do the greater of: (a) being able to provide enough lift to keep the diver's rig afloat (without him in it) or (b) being able to provide enough lift to compensate for maximal loss of the positive buoyancy afforded by exposure protection (drysuit or wetsuit). However, I recently came across this post you made in the Deco Stop Forum which appears to use a different formula. Can you explain the apparent discrepancy? Perhaps I am misinterpreting what you wrote.
  3. Would you suggest that I use your 8 lb. plates with your recommended DSS configuration? I was considering foregoing the 3 lb. STA and 4 lbs. in trim weights in favor of your weight plates.

Thanks in advance...
 
Tobin,

I purchased a DSS LCD rig from you a few years ago. It performed so well that my girlfriend "stole" it from me, and I ended up with a second hand BP/W. She's happy, so I'm happy, I guess. :) At some point in the future I'll be purchasing another DSS rig. If you have a few minutes, I was wondering if you could answer a few questions regarding wing sizing for me.
  1. My drysuit + undergarment have about 24 lbs. of positive buoyancy. I use a total of 12-14 lbs. of lead. My tank is a HP100 steel that is 10.5 lbs. negatively buoyant when full. My stainless steel backplate is -6 lbs., my STA is -3 lbs., and reg is -2 lbs. My wing has 30 lbs. of lift. At the beginning of the dive, I have 12 lbs. of lead + 11 lbs. of other ballast (SS BP, STA, reg) + 10.5 lbs. contributed by the tank. I distribute my lead weight by wearing an 8 lb. weight belt and putting 4 lbs. in trim weight pockets on the tank cambands. In your opinion, is my wing undersized?
  2. I've read several of your other posts regarding wing sizing. It makes sense to me that a wing needs to be able to do the greater of: (a) being able to provide enough lift to keep the diver's rig afloat (without him in it) or (b) being able to provide enough lift to compensate for maximal loss of the positive buoyancy afforded by exposure protection (drysuit or wetsuit). However, I recently came across this post you made in the Deco Stop Forum which appears to use a different formula. Can you explain the apparent discrepancy? Perhaps I am misinterpreting what you wrote.
  3. Would you suggest that I use your 8 lb. plates with your recommended DSS configuration? I was considering foregoing the 3 lb. STA and 4 lbs. in trim weights in favor of your weight plates.

Thanks in advance...

BT, the post you linked to on TDS regards wing sizing for doubles. The math is the same, the assumptions are little different.

If have tested your suit and know it to be +24 lbs you could use a Torus 26 wing, although a LCD 30 maybe a better choice. The LCD 30 will allow for more undies in the future.

A medium SS plate, harness, reg and full cylinder will be about - 18 lbs. If you use the bolt on weights (8.1 lbs per pair) your rig will be about -26 with a full cylinder, and it will provide about 18 lbs of ballast with an empty cylinder. That leaves ~6 lbs in belt.

Assuming you are taller than 5'3" and under 6' a medium plate is appropriate

Recap:

Medium SS Plate
LCD 30 wing
Hogarthian Harness
(cambands and wedge blocks are included)

Optional 8.1 Lbs (per pair) bolt on weights.

Let me know if you have other questions.

Tobin
 
https://www.shearwater.com/products/perdix-ai/

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