d2001d2001
Registered
Hi folks, I need 20kg to get down in sea water in a dry suit. I weight 75kg. Any advice to reduce my weight? Should I look at getting new undersuit? I'm using a neoprene suit and have dived about 6 times in sea water.
How to reduce weight 20KG
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I'm willing to bet technique and comfort in the water plays a part here. The two major obstacles for newer divers are:
1 - fully exhaling (and holding your breath/continue to exhale with empty lungs)
2 - not moving the legs
Regarding the first point, there's a lot of buoyancy in the air in your lungs, and buoyancy changes take a few seconds to come into effect, so you need to be comfortable exhaling fully and letting yourself sink a bit before inhaling again. This is magnified by the neoprene drysuit which needs to compress a bit underwater to lose a little bit of extra buoyancy.
Regarding the second point, any movement with your legs while they are below you will create upward momentum and cancel out any negative buoyancy. The legs need to be completely still until you are are fully submerged and at that point ideally in a horizontal position so movement won't propel you upward, unless you want to continue sinking vertically with still legs a bit further.
These two things are hard to achieve if you're nervous and uncomfortable in the water, so try to relax and exhale, letting yourself sink down. There will be gas when you need to inhale as long as you have done your predive checks correctly.
Also, make sure the dump valve on your drysuit is fully open so no air is trapped in the drysuit, that will give a lot of extra buoyancy.
1 - fully exhaling (and holding your breath/continue to exhale with empty lungs)
2 - not moving the legs
Regarding the first point, there's a lot of buoyancy in the air in your lungs, and buoyancy changes take a few seconds to come into effect, so you need to be comfortable exhaling fully and letting yourself sink a bit before inhaling again. This is magnified by the neoprene drysuit which needs to compress a bit underwater to lose a little bit of extra buoyancy.
Regarding the second point, any movement with your legs while they are below you will create upward momentum and cancel out any negative buoyancy. The legs need to be completely still until you are are fully submerged and at that point ideally in a horizontal position so movement won't propel you upward, unless you want to continue sinking vertically with still legs a bit further.
These two things are hard to achieve if you're nervous and uncomfortable in the water, so try to relax and exhale, letting yourself sink down. There will be gas when you need to inhale as long as you have done your predive checks correctly.
Also, make sure the dump valve on your drysuit is fully open so no air is trapped in the drysuit, that will give a lot of extra buoyancy.
lermontov
Contributor
how much weight did you use before, given all the other parameters are the same
You may be running excessive air in the suit. Try opening the suit vent all the way and frequently roll a bit right to let it vent. You'll need to use your BCD for any additional buoyancy needed. (If a wide open suit vent feels much too constricting after trying it that way, then run it a few clicks tighter.)
I've no idea if this applies to you, but if you're trimmed to be fairly diagonal, then you'll need more weight to be able to counter the upward component of your kicking. Being more horizontal may allow you to drop some weight.
As always, check how much air is in your BCD at the safety stop with the tank near reserve pressure. If it's not pretty empty, then drop a little lead for the next dive. Depending on your current underlayers, you may be able to get lower-buoyancy materials for the same warmth. These typically come at a premium price, unfortunately. At the end of the day, though, the temps will dictate the layers, which will dictate the ballast requirements.
I've no idea if this applies to you, but if you're trimmed to be fairly diagonal, then you'll need more weight to be able to counter the upward component of your kicking. Being more horizontal may allow you to drop some weight.
As always, check how much air is in your BCD at the safety stop with the tank near reserve pressure. If it's not pretty empty, then drop a little lead for the next dive. Depending on your current underlayers, you may be able to get lower-buoyancy materials for the same warmth. These typically come at a premium price, unfortunately. At the end of the day, though, the temps will dictate the layers, which will dictate the ballast requirements.
runsongas
Contributor
switch aluminum to steel tank, switch padded jacket to bpw with steel plate
KenE
Contributor
I concur with Steinbil and Inquis, in addition please do not worry about your weight amount. Work on your buoyancy and trim, then trim weight. You will be able to trim weight for the first year or two of diving. As you get more comfortable in the water your trim and buoyancy will improve and the need for weight will also decrease. Don't rush to reduce weight, it is counter productive. Enjoy diving, improve skills and after each safety stop evaluate the amount of gas left in your BC. If there is gas left then you are still carrying too much weight. Reduce each time, sooner or later you will find that there is no gas left in BC at your safety stop and then you might be a bit underweighted if your tank has any gas above 500psi (ie nearly empty).
Usually people are taught "Exhale, empty bcd, decend" without being told that order is important!
1. INHALE - Hold your breath (Yes, you are on the surface, completely safe)
2. Empty drysuit while holding your breath
3. Empty BCD while holding your breath (You will still be floating... )
4. Cross your legs (You might be inadvertantly be swimming to keep balance...)
5. Exhale while leaning a little bit forward
The result of this will be that you are 3m+ below and horizontal before you feel the urge to breathe, and hence, you will be able to stay under when you inhale instead of popping to the surface again.
This gave me the calm that I needed to start my dive properly. No stress. No fuzz. Properly weighted!
ORDER is relevant!
1. INHALE - Hold your breath (Yes, you are on the surface, completely safe)
2. Empty drysuit while holding your breath
3. Empty BCD while holding your breath (You will still be floating... )
4. Cross your legs (You might be inadvertantly be swimming to keep balance...)
5. Exhale while leaning a little bit forward
The result of this will be that you are 3m+ below and horizontal before you feel the urge to breathe, and hence, you will be able to stay under when you inhale instead of popping to the surface again.
This gave me the calm that I needed to start my dive properly. No stress. No fuzz. Properly weighted!
ORDER is relevant!
Squat squeeze with a finger in a seal to expel as much air out of your suit as possible after donning on land.
Dump valve fully open when entering water so the water pressure will further squeeze out remaining air in suit. Then set the valve to the setting you want.
Do what Imla said above.
Dump valve fully open when entering water so the water pressure will further squeeze out remaining air in suit. Then set the valve to the setting you want.
Do what Imla said above.
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