Wing size for 5mm wetsuit aluminum 80
- Thread starter gbtech
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cool_hardware52
Contributor
What do we both know?
Divers are routinely overweighted
Divers often have no idea how to determine proper weighting, with all sorts of bad rules of thumb being used "10% of your body weight" etc.
New divers expect to push a button and descend regardless of poor technique, still kicking, didn't exhale etc.
Most BCs sold offer 2-3 times the lift required, that allows new divers, most of the time, to carry far more ballast than they need.
Excess ballast *is* a factor in some deaths.
Under weighting is not.
Given the above it seems obvious to me that stressing proper weighting and erring on the side of slightly too little vs too much is the wiser course for the typical new, recreational, single tank, no mandatory deco diver.
Cold water divers that follow my weighting recommendations will never be negative at the surface, and after consuming even a bit of their gas will be positive. That simple fact alone mitigates most of the problems a panicked diver at the surface must deal with.
The industry has IMO created an outsized DCS buggyman, and largely failed to teach basic weighting. I'm far from alone in this opinion.
Tobin
when i weighted my plate and harness i got 4.5lbs. For the reg, octo and spg i got 4lb. Plus 2lb for a full al 80 = 10.5lb. I should require 2lb ballast to compensate for the wetsuit. Does this make sence or am i missing something?
halocline
Contributor
The weight of your gear on land is not the same as it's negative buoyancy.
cool_hardware52
Contributor
Humm, two points. An al 80 is -2 when it is full, it's + 4 when it's empty and about +3 at 500 psi (saltwater)
My definition of minimum ballast is "I can hold a shallow stop with an empty tank"
That means you need your total ballast to equal the buoyancy of your suit at 15 ft when you tank is empty.
You tested your suit. It's +12 at the surface. It's reasonable to expect it will be about +8-9 at 15 ft.
Let's say 9. That means with an empty tank you 9 lbs of things that don't float.
An aluminum plate and harness should be about -2, if you have stainless steel cambuckles it might be ~4 lbs negative.
Your reg is likely closer to -2, not -4. I usually only consider the first stage as the hoses and 2nd stage are not solid metal.
An empty 80 is + 4. +4 less your plate (-4) less your reg ~-2 leaves you with about -2 ~-3 lbs with just your rig.
The 6 lbs you have in a belt is how you are getting to -8~9 as rrequired to keep your suit under water at 15 ft.
Tobin
dumpsterDiver
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I feel otherwise. The error should be made toward over-weighting a diver. Why? Easier descents, the ability to stop an ascent at 5 ft, should a live boat appear above their head and probably most importantly: SMB deployment.
If an SMB is deployed, then it needs to be pulled downward to remain vertical at the surface. This requires that the diver have some excess ballast at the safety stop. Not a lot, but maybe 4-5 lbs. People have enough trouble deploying an SMB without having to struggle to swim down and fighting the tendency to float up and get tangled in their now slack smb tether line.
I agree that new divers are often grossly overweighted, but this does not mean that it is better to weight them so they can not arrest an ascent from 12 feet, should they decide to do so.
If you want to talk about common and dangerous weighting practices.. then my vote would be putting recreational divers in the water with zero ditchable ballast. How many times do we read SB members tell others that they should never ditch weight while underwater..so.. why even have ditchable lead..You know the line.. put all your weight in a steel plate on your back.
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what do you need 4-5lbs to keep a SMB vertical for? That's nuts... Small DSMB for marking the surface, big ass one for saying come find me, I'm lost. No need to deploy a 2m tall marker when you're underwater.... If you're in a high traffic area you should be towing a dive flag anyway so you're only shooting a DSMB to alert someone on the boat of something.
Overweight divers mean larger bubbles in the BC which translates to more difficult time maintaining neutral buoyancy at depth changes, especially at safety stops. The best solution is to get them to where there is next to no air in the BC for that stop so you can control your buoyancy with your lungs.
Overweight divers mean larger bubbles in the BC which translates to more difficult time maintaining neutral buoyancy at depth changes, especially at safety stops. The best solution is to get them to where there is next to no air in the BC for that stop so you can control your buoyancy with your lungs.
dumpsterDiver
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Where I frequently dive, towing a float is not practical/possible (current is too strong and it is too deep). We often deploy a large smb from depth, if it is rough, you want to have a larger float on the surface and you want it to stand up (as much as possible).
My preferred SMB is one from DAN, it has like 30 lbs of lift and is 5-6 feet long?
Your conclusion about what a diver "needs" might be different if you dove in different conditions.
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isn't it illegal in Florida to dive without a dive flag? Even with current, if you get some of the torpedo style ones the drag isn't that bad. The nicer DSMB's even though small, will still show up on radar screens.
Also, read up on Boyles law if you're shooting that thing from depth. Rumour has it you don't have to put 30lbs of gas in there for it to fully inflate at the surface, the 30lbs is only if it is fully submerged, which it obviously isn't otherwise it isn't doing a very good job of marking anything. Shoot it from 40ft where you only need 10 ish lbs of air in there which is just more than a full breath for most people, it will be full at the surface, and you don't have to pull on it....
Also, read up on Boyles law if you're shooting that thing from depth. Rumour has it you don't have to put 30lbs of gas in there for it to fully inflate at the surface, the 30lbs is only if it is fully submerged, which it obviously isn't otherwise it isn't doing a very good job of marking anything. Shoot it from 40ft where you only need 10 ish lbs of air in there which is just more than a full breath for most people, it will be full at the surface, and you don't have to pull on it....
packrat12
Contributor
In South Florida, we often will deploy a DSMB from a wreck at depth and deco on it. I have drifted over a mile (probably 2) while in deco. Big DSMBs help the captain find you when there can be many of them up on during the deco, spread over a good distance. As for radar - I have yet to see a dive operator in South Florida with one.
As for the 4lbs, Carter lift bags are recognized as some of the best DSMBs on the market. This is a quote from their page for their PF models, which I have CBPF-35 and a CBSS-25..
"A four pound weight will make the personal float stand up vertically in the water."
I know I will not trade mine for any other. Rugged and dependable.
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