I use a dry suit and would never think about not wearing a BC. Granted the only time I use my BC is at the surface, once under water I use my dry suit to eliminate squeeze and control my buoyancy. To each their own, but IMO it think diving w/o a BC is an accident waiting to happen.
Lift for Drysuit diving
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sheck33
Contributor
A drysuit is exposure protection. It keeps you DRY, your undergarment keeps you WARM. The BCD, as it's name suggests is a device for bouyancy control.
The suit should not be used for bouyancy control. The BCD should be used for that purpose. All this nonsense about the so much feared feet first ascent with a drysuit is a non-issue when you use the suit the way it was intended to be used.
Why do a lot of people use ankle weights?? Because they use their suit for bouyancy control and have far too much air in their suits, Ankle weights solve a problem that doesnt really exist.
As far as how much weight one needs. That depends on what type suit you have, your undergarment and the rest of the gear.
You need to weigh yourself in such a way that you are neutral with empty BCD, empty suit and near empty tank at about 20 feet. How much lift does your BCD need? Again that depends on a few factors. It depends on how much weight you are carrying and also on WHERE you put it. If you take your set of on the surface for whatever reason you have to make sure your scuba unit floats when you are not in it.
If you do not use the suit for bouyancy control then a flooded suit is a nuisance, its cold, nothing more. Since you dont use the suit for bouyancy control you are not going to be much more negative when your suit floods right? You are weighed so you are neutral in about 20 feet, since there is only as much air in the suit as is needed to prevent painful squeeze you are going to be just as neutral at 100 ft, a flooded suit is not going to make much difference and there is no need to ditch a weightbelt.
As a matter of fact, i dive doubles in a drysuit and i dont even have any ditchable weight.
sheck33
Contributor
A drysuit is exposure protection. It keeps you DRY, your undergarment keeps you WARM. The BCD, as it's name suggests is a device for bouyancy control.
The suit should not be used for bouyancy control. The BCD should be used for that purpose. All this nonsense about the so much feared feet first ascent with a drysuit is a non-issue when you use the suit the way it was intended to be used.
Why do a lot of people use ankle weights?? Because they use their suit for bouyancy control and have far too much air in their suits, Ankle weights solve a problem that doesnt really exist.
As far as how much weight one needs. That depends on what type suit you have, your undergarment and the rest of the gear.
You need to weigh yourself in such a way that you are neutral with empty BCD, empty suit and near empty tank at about 20 feet. How much lift does your BCD need? Again that depends on a few factors. It depends on how much weight you are carrying and also on WHERE you put it. If you take your set of on the surface for whatever reason you have to make sure your scuba unit floats when you are not in it.
If you do not use the suit for bouyancy control then a flooded suit is a nuisance, its cold, nothing more. Since you dont use the suit for bouyancy control you are not going to be much more negative when your suit floods right? You are weighed so you are neutral in about 20 feet, since there is only as much air in the suit as is needed to prevent painful squeeze you are going to be just as neutral at 100 ft, a flooded suit is not going to make much difference and there is no need to ditch a weightbelt.
As a matter of fact, i dive doubles in a drysuit and i dont even have any ditchable weight.
"A drysuit is exposure protection. It keeps you DRY, your undergarment keeps you WARM. The BCD, as it's name suggests is a device for bouyancy control".
Ya Think?
Like I said, to each their own. I don't dive overweighted, so as I drop in depth the small amount of air I use in my dry suit to control the squeeze also corrects my buoyancy. I'd rather let my suit vent itself upon ascent rather than try to vent my bc and my dry suit at the same time. Works for me.
Ya Think?
Like I said, to each their own. I don't dive overweighted, so as I drop in depth the small amount of air I use in my dry suit to control the squeeze also corrects my buoyancy. I'd rather let my suit vent itself upon ascent rather than try to vent my bc and my dry suit at the same time. Works for me.
SeaJay
Contributor
Alright... So you dive dry and without a BCD... Let me ask you this...
Let's say that you're diving twins one day... You know that with your drysuit and with twins (whatever size they are) on a backplate only, you need 15 lbs to be perfectly neutral at the end of the dive. So you wear your drysuit, a backplate, twin tanks, and a weight belt with 15 lbs on it. This seems to set you up nicely for trim, too.
So you get into the water at the beginning of the dive... And you decend to 100 fsw onto a wreck that you were looking forward to. Obviously, this is the point in which you are the heaviest during this dive, because your tanks are full. Thus, you need to counteract the heavy tanks to remain neutral. How much, exactly, would that be? Well... It depends on the size of the tanks, but even if they're wimpy AL80's, you'd still be 12 lbs heavy, and thus would have to put 12 pounds in your BC to be neutral. Of course, you don't HAVE a BC, so you put 12 pounds of lift in your drysuit.
So there you are, nice and horizontal, with 12 pounds of air in your drysuit... What happens when you go and look down into a porthole or open hatch in the wreck? Every bit of air that you have in that suit rushes to your feet! Thus, you are hanging there in the water column, with all of the air in your dry suit around your ankles... And unable to vent it, too, so that you can right yourself...
Why dive with a BCD even when you have a drysuit? Well... Because it works best for trim...
Drysuits are a nice emergency source of lift... But you don't want to use it as a BC... It won't do much for your trim...
Imagine the above scenario with tanks larger than AL80's...
Let's say that you're diving twins one day... You know that with your drysuit and with twins (whatever size they are) on a backplate only, you need 15 lbs to be perfectly neutral at the end of the dive. So you wear your drysuit, a backplate, twin tanks, and a weight belt with 15 lbs on it. This seems to set you up nicely for trim, too.
So you get into the water at the beginning of the dive... And you decend to 100 fsw onto a wreck that you were looking forward to. Obviously, this is the point in which you are the heaviest during this dive, because your tanks are full. Thus, you need to counteract the heavy tanks to remain neutral. How much, exactly, would that be? Well... It depends on the size of the tanks, but even if they're wimpy AL80's, you'd still be 12 lbs heavy, and thus would have to put 12 pounds in your BC to be neutral. Of course, you don't HAVE a BC, so you put 12 pounds of lift in your drysuit.
So there you are, nice and horizontal, with 12 pounds of air in your drysuit... What happens when you go and look down into a porthole or open hatch in the wreck? Every bit of air that you have in that suit rushes to your feet! Thus, you are hanging there in the water column, with all of the air in your dry suit around your ankles... And unable to vent it, too, so that you can right yourself...
Why dive with a BCD even when you have a drysuit? Well... Because it works best for trim...
Drysuits are a nice emergency source of lift... But you don't want to use it as a BC... It won't do much for your trim...
Imagine the above scenario with tanks larger than AL80's...
detroit diver
Contributor
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Just to add to what SeaJay has said, in a drysuit,even if you don't have the air filling up your legs and feet, you have a totally unstable situation witha bunch of air shifting around as it wishes. The more air you add, the more unstable it becomes.
If you move that air mass into a smaller unit like a wing (or BC), it highly reduces the instability of the air mass because it is contained in a much smaller area.
If you move that air mass into a smaller unit like a wing (or BC), it highly reduces the instability of the air mass because it is contained in a much smaller area.
sheck33
Contributor
sorry guys, i gooved up and my message was posted twice :wacko:
ScoobieDooo
Guest
Being new to drysuit diving, I'd have to say the common sense that SeaJay and sheck33 endorse sounds pretty intelligent to me.
Why risk being inverted?
Why carry ankle weights?
Just use the BCD as always and fill the suit with JUST enough air to avoid being squeezed.
Sure makes a lot of sense to me!
Why risk being inverted?
Why carry ankle weights?
Just use the BCD as always and fill the suit with JUST enough air to avoid being squeezed.
Sure makes a lot of sense to me!
usil
Guest
If you are diving with a heavy weight rig with radical changes in bouyancy from full to empty tanks then cool use the bcd, but if its just a single and your weighting is correct, its nice and simple.. Just try it.
Thanks for all the replies.
I don't think I am about to take up drysuit diving without a BCD, but all the posts have helped me figure out that I shouldn't need that much more lift for Drysuit diving, except to compensate for the lead I'm carrying.
BTW I assumed when Leadweight mentioned dumping weight belt, he was referring to being at the surface with a flooded drysuit, I doubt he was suggesting dumping the weight at 30M due to a flooded suit.
I don't think I am about to take up drysuit diving without a BCD, but all the posts have helped me figure out that I shouldn't need that much more lift for Drysuit diving, except to compensate for the lead I'm carrying.
BTW I assumed when Leadweight mentioned dumping weight belt, he was referring to being at the surface with a flooded drysuit, I doubt he was suggesting dumping the weight at 30M due to a flooded suit.
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