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ScubaScotty561
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Thanks for the info everyone
deploying smb?
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Hey, Scotty - that breath thing, and why you cannot really get an answer --
You have a 6' SMB -- what is the diameter? 3" 6" 9"????? If it is tall and skinny, the number of breaths are different than if it is tall and fat.
As noted above two things are important - the lift of the SMB (volume, not just length) and how you intend to use it.
A small (short and skinny) SMB with 3 to 5 pounds of lift shot from any depth is pretty easy as you can launch it on one breath with no significant bouyancy change and for consistency sake you'll fill it as much as possible with that breath.
A 6 ft tall SMB with 50 pounds of lift is a different matter and to have it be full on the surface you need to launch it from a fairly deep depth and adjust your buoyancy so that you don't change depth when launching it.
Doing the math it's got 25 pounds of lift at 33 ft, 17 pounds at 66 ft, 12.5 pounds at 99 ft, 10 pounds at 132 ft and 8 pounds at 165'. So if you come off a wreck at 200' and shoot a bag at around 170 ft to do drifting deco, you need about 8 pounds of gas / 1 ft of gas in the SMB to have it arrive full at the surface.
That is not a lot of lift but it's enough for you to adjust your buoyancy to maintain your depth during the launch, so you'll inhale, dump 1-2 pounds from the wing, then exhale (4-5 pounds) while inflating the SMB, then release the bag when you just start to rise, and restore neutral buoyancy by inhaling and adding the gas back into your wing as you release the SMB. (alternatively you can leave the wing alone and fin downward slightly, but that makes it more difficult to remain clear of the line and SMB during the launch.)
The good news(at that depth) is that if you screw up and get caugt in the SMB or line at launch, it does not have much more lift in the first 30-40 ft so you can fix the problem and stay neutral while doing it just by exhaling - after that you are probably looking at having to release the reel or spool if it snarls.
As suggested above, once the bag is on the surface you need to keep some weight on it so you'll dump a bit of extra gas to stay 3-4 pounds negative with a large SMB, but obviously you'd practically sink a short skinny one with that much weight.
If you listen closely, you can hear the wailing of the purists who insist you should remain neutral during your ascent and deco and on deco let the reel or spool hang and just "ok" the line a few inches above the spool or reel. Those divers are easy to identify as their large SMB is laying flat on the surface. Unfortunately in any sea state at all they are harder to see and track as the SMB is hidden in the trough of the waves most of the time so those divers are hard to find if they drift away from other teams.
Since it's not about looking cool in the water and demonstrating a skill that should be a given at that point, I recommend you stay 3-4 pounds negative during deco.
That also means that you need to be weighted so you are still 3-4 pounds negative at your deco stop/safety stop for a technical diver, their reserve gas will provide that negative buoyancy. With a small/short/skinny SMB for recreational diving 1-2 pounds negative is plenty so in both cases there is no need to overweight your self significantly.
A small (short and skinny) SMB with 3 to 5 pounds of lift shot from any depth is pretty easy as you can launch it on one breath with no significant bouyancy change and for consistency sake you'll fill it as much as possible with that breath.
A 6 ft tall SMB with 50 pounds of lift is a different matter and to have it be full on the surface you need to launch it from a fairly deep depth and adjust your buoyancy so that you don't change depth when launching it.
Doing the math it's got 25 pounds of lift at 33 ft, 17 pounds at 66 ft, 12.5 pounds at 99 ft, 10 pounds at 132 ft and 8 pounds at 165'. So if you come off a wreck at 200' and shoot a bag at around 170 ft to do drifting deco, you need about 8 pounds of gas / 1 ft of gas in the SMB to have it arrive full at the surface.
That is not a lot of lift but it's enough for you to adjust your buoyancy to maintain your depth during the launch, so you'll inhale, dump 1-2 pounds from the wing, then exhale (4-5 pounds) while inflating the SMB, then release the bag when you just start to rise, and restore neutral buoyancy by inhaling and adding the gas back into your wing as you release the SMB. (alternatively you can leave the wing alone and fin downward slightly, but that makes it more difficult to remain clear of the line and SMB during the launch.)
The good news(at that depth) is that if you screw up and get caugt in the SMB or line at launch, it does not have much more lift in the first 30-40 ft so you can fix the problem and stay neutral while doing it just by exhaling - after that you are probably looking at having to release the reel or spool if it snarls.
As suggested above, once the bag is on the surface you need to keep some weight on it so you'll dump a bit of extra gas to stay 3-4 pounds negative with a large SMB, but obviously you'd practically sink a short skinny one with that much weight.
If you listen closely, you can hear the wailing of the purists who insist you should remain neutral during your ascent and deco and on deco let the reel or spool hang and just "ok" the line a few inches above the spool or reel. Those divers are easy to identify as their large SMB is laying flat on the surface. Unfortunately in any sea state at all they are harder to see and track as the SMB is hidden in the trough of the waves most of the time so those divers are hard to find if they drift away from other teams.
Since it's not about looking cool in the water and demonstrating a skill that should be a given at that point, I recommend you stay 3-4 pounds negative during deco.
That also means that you need to be weighted so you are still 3-4 pounds negative at your deco stop/safety stop for a technical diver, their reserve gas will provide that negative buoyancy. With a small/short/skinny SMB for recreational diving 1-2 pounds negative is plenty so in both cases there is no need to overweight your self significantly.
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