Going deeper than your friends, no one that can help you?

[Hawaii Surfer]

Here is my situation: I love freediving, and am able to go more often, and deeper than anyone I go with (nobody else is as serious about freediving as I am in my circle of friends). I pretty much only go in the summers over here (Oahu).

I used to do it only for training for big wave surfing, but now I like the feeling of going deep. 60 feet is my record so far, but I felt I could go more pretty easily, but there is no saftey net.

Aside from the idea I read about of attaching a line to your body(diver retrieval sytem), how do you train, and go deep if there is no one there able to help you on your deepest dives?

Also when I went down that deep, when I would equalize, this strange noise was coming out of my chest, maybe sucking air out to equalize?

 

[island_sands]

What are you holding in that picture?

(sorry not to answer your question..)

 

[Aquagenic]

Looks like a rock to me, I think it's a surfer thing. (not that I would know, I can barely pass a sobriety test when sober, much less surf)

 

[jome]

Aside from the idea I read about of attaching a line to your body(diver retrieval sytem), how do you train, and go deep if there is no one there able to help you on your deepest dives?

Here's how I make most of my dives:
We have a buoy (needs to be big enough, for example a 30L plastic container is ok) and a rope goes down with a bottom weight (keeps the rope straight). You then attach your self to the rope with a lanyard (a 1m cord that has a carabine in the other end that slides on the rope and is quick to detach in case of emergency).

When I leave the surface, I'll let my buddy know what depth will I be going for and roughly how long should it take and he'll keep watch. As I reach the depth I wanted to and turn, I pull the rope once real good, signalling to the guys at the surface that I have turned. This is a signal for the safety diver to leave the surface in about 10 seconds and go wait for me at around 10m (or more if it's a really deep dive). If everything goes as planned, I meet him at around 10 meters and he escorts me to the surface, looking for signs of stress or samba. As I'm in the surface, he keeps looking at me for at least 30 sec (samba/blackout can happen up to 30 sec after you start breathing). The people at the surface can feel then carabine sliding against the rope, so they know if I'm moving up. If for some reason it seems that I'm not moving up or the dive is taking too long, they'll start lifting the rope up. Now that is why it's important not to have too much weight on the bottom plate in these types of dives (we use about 5kg). We have also agreed that more than 1 pull on the rope means trouble, so the same reaction. As they bring the rope up, the troubled diver should come with it.

If I'm going for a deep dive or trying a new personal best, they'll start bringing up the rope slowly about 10 sec after the turn in any case. By doing this they ensure that if there is trouble, the reaction time is shorter (especially if not on a boat, hauling a rope up can be slow...So train that).

This is a very basic system and it's good for medium depth dives (I would feel unsafe going deeper than 50m with this, even with a very experienced crew. With an inexperienced crew, much less). For deeper dives, you would like to have at least a counter ballast to help you bring up the rope in case of emergency.

A few things to remember:
-The buoy has to be big enough so that the diver can pull him self up on the rope in case of emergency (leg cramps etc). With a 5kg ballast it's possible to pull your self up even if you lanyard gets stuck and you have to bring the bottom plate too (if the depth is reasonable).

-The rope has to be even, with no knots along the way and the bottom plate/weight especially has to be "clean", so that the lanyard cannot get stuck in anything. Some use a tennis ball attached about 1m above the bottom plate to stop the lanyard. It can still happen just by wrapping itself around the rope, so be careful. The lanyard should be of such a material that it does not knot very easy. A popular choise is a cord that is covered with a plastic tube or heat shrinking tube. The carabine has to be round an big enough (too sharp corners can again get stuck on the rope).

-This system requires that your buddies are up to date on how you operate and paying attention. It would be best if they were fairly experienced too. You need to also practice the emergencies, not just agree on them. So have you buddy pull you up from 10m while you play limp. Have them haul up the rope while you hang from it. Go to a moderate depth and practice unraveling the lanyard. Practice pulling your self up from the rope etc...

Without a rope, even in good visibility, I would go only to very conservative depths...Especially if there isn't a diver who can follow me that deep.

Also when I went down that deep, when I would equalize, this strange noise was coming out of my chest, maybe sucking air out to equalize?

Could you describe this noise in a little more detail? Sounds strange...I do know people who make this kind of "ummph" sound when they equalize, that's because it's the only way they can control the epiglottis or something...Not dangerous. But that's just about the only sound I can think of coming from the chest...

 

[Hawaii Surfer]

What are you holding in that picture?

That's an alien space pod. Naw, a rock on the sandy part of shark's cove on Oahu, doing some big wave training. Here is a thread I started last year about it [ame="http://forums.deeperblue.net/showthread.php?t=38030"]Freediving training for big wave surfing[/ame]

I guess the sound in my chest I hear is a sort of ummph.. hard to describe.

Great advice regarding the safety line, but man that would be a pain to deal with when you have to swim out 150 yards to get to the ledge where is gets deep....


Off this topic, but about how long is normal time under for different dives? Like say for 60 feet, what like 45 seconds?

 

[kingohyes]

40-45 seconds seems pretty normal if you are just swimming down and up again.

 

[laminar]

Hey Jome and Hawaii Surfer,

5kg seems a little heavy to me. In Vancouver we usually use 2kg or so and even that will exhaust my arms after 30m of pulling and I'm in reasonable shape. In an emergency, I don't think that's the best solution, especially when the depths are deeper. Also,in your system do you lie your body on top of your float/buoy and use that buoyancy to help you pull the person up? This is what I do just to pull the line up at the end of the day. We don't practice this kind of retrieval system because I don't think it would work well enough to make a difference.

Given the limitations of safety for people like us who want to train for depth as safe as possible who don't have the ability to pay for and round up scuba divers (who have limited use at big depths), some kind of counter weight would be a good idea or an alternate system.

Another idea I had was to build a flywheel with a 1.5m circumference on top of a well-stabilized float with ballast to keep it from tipping over. There would be no more than 2.5 kg on the bottom of the line. While you may get some curve in the line from current, better that than being unable to drag your buddy up from depth fast enough! Attached to the flywheel would be a crankshaft and handle and the flywheel itself would be made of hollow molded fibreglass or some such strong but light material. With each crank of the wheel, you would raise the bottom plate by 1m. One person would start cranking at a 1m per second rate 5-10 seconds after the diver reaches the bottom (by pre-arranged time limit or by feeling the tug or both), so that if the diver blacks out near the surface or even at the bottom, there's no decision involved in when to start pulling him up and you don't waste any extra time.

In addition to the person at the wheel, there would be a regular spotter going down to 10-15m as usual.

I made a sketch of this system which I'll try to post soon. I have not built it yet. Too busy with other things.

The main problem I see with a counter weight is that once it is activated it is difficult to adjust the speed of retrieval and also usually you need considerable weight to make it work. With the right flywheel/crank ratios and physics you could have an 1.5m/s ascent rate on the retrieval or much more without too much physical effort. Also if the diver is always attached to the lanyard by the wrist then you greatly increase the speed of the recovery. I don't think this system would cost that much to make.

I'll post more details later.

Pete
Vancouver, BC

 

[jome]

Thanks for the reply Pete.

As I said, I would not consider my system safe for very deep dives and the safety of it greatly depends on the experience of the crew. But let's say Hawaii Surfer keeps going to 20m and his buddies can not dive that deep. At least they have some contact with him (of course this system would be pointless if all the divers can go to 20m+). Also what makes this system work is that 99.9% of the time no one has to touch the rope, everything goes fine and the diver comes up as planned. But you have to have some trust on your self, the other divers etc, so that no one is taking too big chances.

Pulling to rope up without a boat or any help from, say 30m, is no small feat. But it is possible to do relatively fast in an emergency, especially if there is more than 1 person at the surface. From a boat, it's no problem...

I agree that 5kg may be too much. I use plastic coated dumbell weights of 5kg, but they may actually be much less in water, since they are so buoyant.

The good thing about this system is that it's very simple, all you need is a buoy, a rope and a weight. A counterbalance system requires much more engineering skills and time to set up etc, it's just too much for recreational type of CW diving IMO.

I've seen a counter weight system where the counter ballast is actually equal or just very slightly more than the bottom weight. So the ballast does not pull the diver to the surface, but it makes the job easier. It seemed like a good solution (you can control the speed of the ascent easily).

Hawaii Surfer: Very rarely do I get to dive without swimming at least a 150m(yards), it's not that bad if you don't have too big a weight and you rig everything properly...

 

[laminar]

Hi Jome,

Thanks for the clarification. For 20m, your method does sound relatively simple and useful. Nice one.

To both of you: 150m swim is nothin'! :duh I used to have to drag a float, 100m of line, and 3 kg of weight at least 500m each way to get to deep enough water.... :rcard

I found that holding my breath for every 5-10 arm strokes or kicks would leave me not too winded and ready to dive.

Good thing we train by recreational freediving and other methods nowadays!

Pete

 

[megathumpzila]

Maybe a board with a line tied to the leash cup would be just right. Paddle the gun out, maybe with a friend or 2 too, and use that as a base. It's familiar and an excelent float. If I am sitting on a board I can haul rope up pretty quick. I can rest on the board and watch you at the same time, and drop off and hang as you come up. If your spotter leaves the board when you turn, he should meet you just before the halfway point and have a few seconds to wait. a 30 second breath hold will be pretty easy for anyone who surfs country regularly.

 

[donmoore]

Hawaii Surfer,
Simo and Pete have it right for deep freediving competition like training. But for what you want to do and what everyone did for years before there were lanyards and counter balance systems, is just to have someone meet you at 20 – 30’ and come up with you.

To understand this you need to look at the physics first. As you descend, even though you are burning O2 and the volume of the air in your lungs is compressing, your O2 particle pressure is also increasing which will push the available O2 in the lungs into the blood. Overall you should have the most O2 in your blood stream you will ever have during the dive, at the bottom. The chances of blacking out at the bottom from lack of O2 are almost non-existent if you just reach your bottom and start back up. Sure some worldclass competitive freedivers have been narced at 300’ but your hundreds of feet from that depth anyway.

On the ascent and toward the surface is where you have the largest chance of loss of coconsciousness and need spotting. Pressure change is the most dramatic here and the wonderful high O2 partial pressure you had at the bottom is now swinging the other way. O2 actually gets sucked out of the blood stream and back into the lungs as they expand. To compound this you have now held your breath the longest and have burned a lot of the O2 up.

Water clarity so the spotter can see the diver, current, and other conditions play a big factors. A straight rope is a great thing to dive on, because it gives a reference point for the diver and the spotter. It can help you learn what straight down should feel like. Many people don’t dive straight down until they have the opportunity to practice on a rope. Timing the dives so the spotter knows when to dive to meet at 20 – 30 feet is important. The spotter should come up with the diver looking into his face if possible. If there is a black out or loss of motor control the spotter should take hold of the dive and assist them to the surface and then keep their airways clear at the surface.

Spotting should continue at the surface for at least 30 seconds for a diver who made it to the surface on their own. It takes 10 –20 seconds from a divers first breath before the new O2 reaches the brain, so the lowest blood SaO2 is going to happen at the surface. Hence most blackouts happen at the surface and I believe most deaths happen because the diver is alone and weighted too heavy. They take a breath or two, blackout, exhale, and sink and drown.

A rope really isn’t practically for spearfishing. When we spot spearfishing we usually stay at the surface unless we see a problem that we could assist in or the diver signals on his ascent that something is wrong.

So I guess the whole point is, you don't have to have to be with someone who can dive as deep as you to dive safe.
don

 

[Hawaii Surfer]

Man, great advice, all of it, thank soo much! Especially the info about O2 levels and such. I really like the surfboard idea, it makes it faster to swim out to were it actually drops off 80-100 feet. (about 150 yards at Haleiwa.)

Mahalos!!!