Need to practise making safe ascents & descents

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Yes, I've learned that if I start to fumble for inflator I'm usually in trouble. A quick pull on my inflator hose is a very good technique.

Let me tell a little story that you might find both amusing and instructive.

I was teaching a small OW class in Key Largo, and we were on our first OW dive. I had not had these students in the pool, so I was just getting to know them. We were diving in warm, shallow water, and I had them pretty well weighted. One of them was diving in very poor trim, with his head up and his feet below him, He kept rising up enough to have his BCD inflate enough to get him headed toward the surface.

On one such occasion, the rest of the class and I saw him about 10 feet above us, fumbling for his inflator hose so he could get back down to us. As so often happens, he found his snorkel instead. He held the bottom of the snorkel high over his head, pushed the bottom, and then sank down gently to join us. The rest of the class watched in amazement, their eyes wide as they looked at each other and to me in wonder.

When we talked about it later, I asked them why it was that he had been able to sink by pushing on the bottom of the snorkel. They eventually figured out that when he finally found the snorkel and thought he had the inflator, he had let out a great sigh of relief as he pushed the button. It was that great sigh of relief that had brought him down to us.
 
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I haven't tried butt valve dumping, will see how that goes.

It takes a bit of practice, but it's worth learning how to do.

In that horizontal position, roll [just U]a bit[/U] to the side, so the butt valve is at the high point, and then pull the valve release up, toward the surface. This valve is designed to dump air faster than the inflator valve can supply air (for obvious safety reasons, in case of stuck inflator). The shoulder dump valve not only requires you to be in a feet down position, which makes stopping any runaway ascent very diifcult, but that shoulder valve can not vent air anywhere near as quickly as the butt dump valve is designed to do.

The first few times you try this dump technique, you will dump too much air, too quickly. Practice just short automatic "burps" more frequently, instead of the big dumps when you suddenly notice things moving too quickly.
 
Let me tell a little story that you might find both amusing and instructive.

I was teaching a small OW class in Key Largo, and we were on our first OW dive. I had not had these students in the pool, so I was just getting to know them. We were diving in warm, shallow water, and I had them pretty well weighted. One of them was diving in very poor trim, with his head up and his feet below him, He kept rising up enough to have his BCD inflate enough to get him headed toward the surface.

On one such occasion, the rest of the class and I saw him about 10 feet above us, fumbling for his inflator hose so he could get back down to us. As so often happens, he found his snorkel instead. He held the bottom of the snorkel high over his head, pushed the bottom, and then sank down gently to join us. The rest of the class watched in amazement, their eyes wide as they looked at each other and to me in wonder.

When we talked about it later, I asked them why it was that he had been able to sink by pushing on the bottom of the snorkel. They eventually figured out that he finally found the snorkel and thought he had the inflator, he had let out a great sigh of relief as he pushed the button. It was that great sigh of relief that had brought him down to us.

Good story. I have a hunch I will be telling it myself one of these days! Thanks, great lesson!!!
 
I'm curious about this statement. I understand the exertion part of it but how would being horizontal help with off-gassing?

The off gassing issue is hydrostatic lung loading.....if vertical, tHere is a larger pressure differential in the lungs...when horizontal, the blood flow throughout your lungs will be better, this allowing your lungs to be more efficient at "filtering out" bubbles....this was one of the WKPP techniques which allowed shorter deco times after big saturation dives in deep cave, and deep ocean.

The suggestion here, is that if you have any bubbling taking place, the horizontal deco stop/safety stop will be more effective in preventing DCS than a vertical position for the stop.

Regards,
DanV
 
I'm diving with 24 lb lead, with steel 100 cf tank. Wearing a 7mm core warmer over 7mm one piece plus 7mm booties, gloves & hood. Descending with a deep exhale and empty wing works well, but have to work at getting down with a 1/2 full tank.

I'm not surprised that you're having difficulties with buoyancy. This is a ton of neoprene and a ton of weight too. The more neoprene and more weight you have the smaller your neutral buoyancy target is.

By this i mean if you get moving in either a positive or neutral direction you seem to go much faster that direction. What temperatures are you diving in that you're wearing 14mm on your torso, and 7mm everywhere else?

By comparison when i dive a 7mm jumpsuit, 5mm hood,gloves, and boots. I'm pretty comfortable in this at temperatures down to 49 or so. I wear 16 lbs of lead and wear and aluminum tank. I think you also mentioned that you're in a BP/W set up? Is it a steel back plate? I'd find a twenty foot section of quarry or try to dial in your weight a bit. A lot of the guys i know diving steel tanks and back plates wear zero lead.
 
In that horizontal position, roll [just U]a bit[/U] to the side, so the butt valve is at the high point, and then pull the valve release up, toward the surface. This valve is designed to dump air faster than the inflator valve can supply air (for obvious safety reasons, in case of stuck inflator).

We use this technique all the time. We call it the "rump dump".

In addition to being effective, it looks like a stream of bubbles are coming out of your bum... which is very fun in a "sophomoric" kind of way.

He's right though... you can dump way too much air if you just yank hard on your rump dump, you want to go easy on it.
 
I'm diving with 24 lb lead, with steel 100 cf tank. Wearing a 7mm core warmer over 7mm one piece plus 7mm booties, gloves & hood. Descending with a deep exhale and empty wing works well, but have to work at getting down with a 1/2 full tank.

I think it would be a good idea to fill out your profile a little. That would include telling us where you dive, etc. Right now the only thing I got from your profile is that you are a vacation diver. I don't know a lot of divers who take their vacations in places that require this sort of thermal protection. Where are you doing this diving? What are the water temperatures?

Although you have a lot of lead, it might not be a very high amount considering all that neoprene. It depends upon your personal factors--size and body composition.

However, when you sink that much neoprene, it does a whole lot of contracting as you descend and a whole lot of expanding as you ascend. Those changes happen the most in the top 20 feet of water. One of the most important characteristics of diving with that much neoprene is that you have no choice at depth--you will be overweighted. You need a certain amount of weight in the upper 20 feet, but you do not need anything like that much when you are deeper and the suit(s) compress.

If you are going to dive in water that cold frequently, I would seriously consider getting a dry suit. It will take you a while to get used to diving in one, but once you have that down, you will be happy with the benefits, once of the most important of which is that it won't have those wild buoyancy swings. Yes, you will have to master two different air bubbles, but once you have that, the fact that you have the same buoyancy at any depth makes things much easier.
 
Buoyancy control is also easier if you think of a snowflake. They do not fall straight down. They simply float down. I have my OW students working on horizontal snowflake descents and ascents the first night on scuba. After we have done proper weight checks and played with the inflator and breath control in a horizontal position. The weighting is critical. Too light and the struggle to get down. Too much and the amount of air needed to stay neutral can expand too fast and result in the uncontrolled ascent. On checkouts we spend a great deal of time in the 12-18 ft range working on staying in control and "ahead" of the buoyancy swings as Bob already noted. The shallower profiles also result in them having anywhere from 45-60 minute dives or more on their checkouts with lots of time to work on skills while swimming and just hanging out. My last OW class logged 3hrs 19 minutes for 4 checkouts.

I do skills while we swim, not stationary. This also helps with buoyancy as I stress maintaining a steady breathing rate when doing them. I noticed as a DM that many times when someone was about to do say a mask clear or reg recovery they would take in this huge breath and as a result end up floating towards the surface. It occured to me then to make sure that when we do these skills in my classes that they concentrate on not doing this. Just keep breathing and do the skill. No need for a big inhale. Doing this while swimming actually distracts them from the big breath tendency and they don't change position in the water column as result.

To the OP try to maintain a steady breathing rate and volume no matter what you are doing and short tiny bursts on the inflator when inflating or dumping and use that butt dump if you have one. If you actually feel yourself ascending without trying to you are going too fast. I like to actually swim up in circles while staying horizontal until that last 10 feet or so when it's time to look up for boats, docks, other divers, etc. If clear it;s back to laying flat out. If not then you should actually need to kick a bit to ascend. Not hard just a little while venting til you hit the surface. Then inflate.
 
I'm not surprised that you're having difficulties with buoyancy. This is a ton of neoprene and a ton of weight too. The more neoprene and more weight you have the smaller your neutral buoyancy target is.

By this i mean if you get moving in either a positive or neutral direction you seem to go much faster that direction. What temperatures are you diving in that you're wearing 14mm on your torso, and 7mm everywhere else?

By comparison when i dive a 7mm jumpsuit, 5mm hood,gloves, and boots. I'm pretty comfortable in this at temperatures down to 49 or so. I wear 16 lbs of lead and wear and aluminum tank. I think you also mentioned that you're in a BP/W set up? Is it a steel back plate? I'd find a twenty foot section of quarry or try to dial in your weight a bit. A lot of the guys i know diving steel tanks and back plates wear zero lead.

I know I can shave off perhaps 4 lbs, but my instructor doesn't want me to, just yet. I'll have trouble submerging with a 1/2 full tank.

I'm using a DiveRite Transpac, which took a lot of work figuring out the proper weight distribution to achieve proper diving position (ie. I was constantly turned turtle)

I dive in Northern Ontario, lots of cold water up here. :)
 
Satwar, where in Northern Ontario? I'm in Thunder Bay, perhaps I can help you sort things out
 
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