DIR video of open water divers

[Soggy]

sheck33 once bubbled...



I am in a shellsuit as well and it is not a problem, what makes this a problem for many many divers is the fact that they have too much air in their drysuits to begin with.

Too much air is definately not a problem for me. I often find myself thinking, "gee...I'm not very comfy...oh yeah...my suit is empty." However, no matter how little air you have, it is a simple matter of physics that your feet need to be below your arm/shoulder/exhaust valve in order to release air. Even the smallest amount of air at depth will become a lot when inverted. I understand that you don't have this problem, but if you don't, your feet are below your arms and you are not in a "horizontal" position.

Another factor is undergarments. When wearing thick thinsulate underwear, the air will have a more difficult time moving to the exhaust valve.

Everyone dives differently. I accept that. I have reasons for the way I dive, as do DIR followers. I'm simply trying to say why I do it the way I do.

 

[jepuskar]

Any video that suggests a certain technique is wrong or unnecessary and shows the 'correct' method is a plug for that method..which is also know as an advertisement. I dont care if its broadcasted or hidden, it is implying that one method is better than another thus promoting its technique....it is advertising its method.

That was the whole purpose of the video....if it wasn't then there is no need to have the other divers on the line in the background. Why couldn't they of just showed the DIR divers by themselves?

Anyways, this is silly, do what you think is right and I'll do the same....sheesh.

 

[The Iceni]

sheck33 once bubbled...
I am in a shellsuit as well and it is not a problem, what makes this a problem for many many divers is the fact that they have too much air in their drysuits to begin with. I have never even had any tendency for an uncontrolled feet up ascent.
But again, if you have too much air in your suit it WILL be a problem. As a matter of fact the exhaust on the forearm is the better place rather then the shoulder. Too much air in the suit is very often also the reason people wear ankle weights, you dont need them, those weights 'fix' a problem that doesnt exist.

Hi Sheck33. This is Just the sort of advice I was given when I retstarted diving three year ago and used a membrane dry suit for the first time. To my mind this proves just how few divers really understand the problems associated with a (thick) pile undersuit necessary for comfort in cold waters.

My undersuit displaces nine litres of water. (I need nine more kilograms when wearing it under my membrane than if I do not.(my own experiment)). It therefore must contain nine litres of air even when I am partially "squeezed" at depth. On an ascent from 30 metres this nine litres of air expands to 36 litres so of course I have have too much air in it! (we were discussing ascents weren't we?).

This air will only vent if the dump is located above it.

I use an autodump fully open during the dive and ascent, so provided the vent is situated to the top of the "bag" it will vent automatically, maintaing the "squeezed" nine litre volume and thus constant bouyancy at all times;- even after I have injected air to reduce squeeze on the descent. After a considerable amount of trial and error I can now rotate in the horizontal position, or yaw in the vertical position, to assist dumping if necessary as this raises the dump. I see no reason to put it on my forearm (or to use a cuff dump) since this means I cannot use that arm without upsetting this finely tuned constant bouyancy control mechanism. In the erect vertical, hands down, attitude a cuff dump is well below the top of the "bag" in any case.

Apart from any other concerns I ascend face up so I can see where I am going.

As for ankle weights? Again "sisssies" only need them and as you say it is a problem that does not exist. I am afraid you are wrong again sheck33. The whole undersuit has a volume of nine litres and a good proportion of this is in the trousers. ie below the waist and below the weight belt. In the horizontal attitude there is at least 2 Kgs worth of bouyant air in the legs. Following the wellmeaning advice of experienced divers I was initailly pursuaded not to use ankle weights and found, even when squeezed, I was very, very uncomfortable with a head down attitude even when neutrally bouyant unless I corrected this by vigorous finning.

Tranferring 2 Kgs from my weight belt to my ankles corrected this.

I have found out the hard way by trail and error that there is a world of difference between bouyancy and attitude control when using a thick pile undersuit (necessary for diving in the North Sea in winter) and a wet suit, semi dry or crushed neoprene dry suit. It was like learning to ride a bicycle. I now maintain bouyancy control by means of the one item of equipment specifically designed for bouyancy control, my wing. (It starts with at least 6 litres of air which is gradually dumped as my 6 Kgs of breathing gas is used up during the dive.)

I for one fail to undertstand why some "experts" insist on using their suits for this purpose with cuff dumps as they are simply introducing a second, ever varying, source of bouyancy that is less easy to control.

All of which confirms what I said earlier. .

What is right for a Caribbean reef or wall dive may not be right for the a wreck in The North Sea or the Atlantic or Arctic Oceans, or for a quarry or a sump.

I say again. I am not for or aginst DIR, ridicule or for rigid rules misapplied but for safe diving techniques properly applied with a modicum of common sense.

We are all adults and must be allowed to make up our own minds. How I dive works for me. It may not suit everyone, or indeed any other single person.

There is no one rule that can ever apply in every single case.

 

[Uncle Pug]

..but don't assume that the only way to dive a shell suit in cold water with thick undergarments is vertical. You do yours your way... I'll do mine my way

I dive both a thin trilam shell and a crushed neo shell. I wear 300 gram polartec or a Weezel Extreme undergarment. One suit has a shoulder dump... the other suit has a forearem dump. One suit has Rockboots the other has insulated neo boots. Sometimes they are inflated with EAN32 and sometimes with Argon...

But...

I descend, dive and ascend horizontally.... and I can control it enough to slow the ascent to a millenial crawl.... without hanging onto a line or finning.

 

[The Iceni]

Sorry Uncle Pug, I don't really follow.

Are you saying there is only one way to do it or are you saying each diver should continually assess his own abilities and learn from his "mistakes" some of which may be prompted my well intentioned advice. For example one senior instructor told me that with my 300 bar twinset I did not need a weight belt at all!

From the variations in your kit configuration I gather one size does not fit all, and I suspect you adjust your style of diving according to the kit you use, even though as an extremely experienced and skilled diver you may not consciously realise you are doing it, which I think is the point I was trying to make.

Now tell me exactly what I am doing that is wrong or dangerous.

 

[sheck33]

AaronBBrown once bubbled...


Even the smallest amount of air at depth will become a lot when inverted. I understand that you don't have this problem, but if you don't, your feet are below your arms and you are not in a "horizontal" position.

Another factor is undergarments. When wearing thick thinsulate underwear, the air will have a more difficult time moving to the exhaust valve.

Everyone dives differently. I accept that. I have reasons for the way I dive, as do DIR followers. I'm simply trying to say why I do it the way I do.

Not true, my feet are above my vent and i am horizontal. If i am at depth, lets say we call deeper then 50 or 60 ft 'at depth' and i invert myself not much will happen, suppose i go from being almost horizontal say to totally inverted then my feet will rise a mere maybe 3 feet or so depending how tall i am, the pressure change and hence the volume change is not significant enough to cause any problem, again provided you dont have more air in your suit then needed to prevent the squeeze from becoming painful. Shallower this might be different as the relative pressure change increases, a reason by the way why the ascent from 20 ft to the surface should be very slow.

i doubt that undergarment is 'dense' enough to hinder airflow, to obstruct airflow the material needs to be much much tighter packed than just the fibers in undergarment, as a matter of fact fibers in undergarment are not tightly packed since there insulating property depends on trapping air, were it tightly packed very little air could be trapped to provide insulation.

discussing stuff like this is fun and interesting

 

[sheck33]

Dr Paul,

Of course i am not saying one shouldnt vent when ascending, of course 9 L at 30m will expand to 36 L at the surface.
But getting inverted at 30 m will not cause a problem because of the small relative pressure change.

You say you were uncomfortable in a head down position when neutral and this could only be corrected by vigorous finning Why would you have any need for 'vigorous' finning when you are neutral?? Where were you going finning vigorously? were you diving doubles? Not to ride you but i am just trying to get a picture of what you are doing and how your weight might be distributed. Are you weighed correctly?

I have a dump on my forearm and i can do anything without upsetting my bouyancy since i am horizontal since my dump is in this way usually the lowest point so i dont loose air when i dont want to.

i too maintain bouyancy control with the one item meant for this purpose which of course is my wing. I dont even really have to dump much if any air from my suit until i get shallower than 40 ft or so.

but we can disagree, that is perfectly fine

actually i persuaded my GF to get rid of her ankle weights and her bouyancy control and trim have improved significantly.

 

[Rick Murchison]

sheck33 once bubbled...
Why would you have any need for 'vigorous' finning when you are neutral??

One can be perfectly neutral, but if there is a significant distance between their center of lift (CL) and their center of gravity (CG), then trim becomes a big problem. This can really be a problem when diving big steel doubles with wings and a drysuit, where CL is often below the CG. If the CG is directly above the CL in the desired horizontal swimming position, no problem... like buoyancy itself, it is unstable but manageable - until... the diver gets out of position. Then the CG/CL misalignment will create a rotational moment that, left uncorrected, will rotate the diver into a position where the CG is directly below the CL... the diver "turns turtle" or goes "Tango Uniform."
A diver with this CG/CL problem who gets out of position will require "vigorous finning" to overcome the rotation and get back into a manageable position where CL is again aligned directly below CG. And for many divers with big steel doubles, they are presented with a Hobson's choice. They can only move their CG closer to their CL by adding weight at their belly, and must choose between overweighting or instability. I suspect this is what Dr. Thomas is experiencing.
Rick

 

[Uncle Pug]

Dr Paul Thomas once bubbled...
Sorry Uncle Pug, I don't really follow.


Now tell me exactly what I am doing that is wrong or dangerous.

Just feeding your own line back to you to see how you handled it.

Adding the extra about drysuits was to show you that you are not the only one who dives them... and since I have had many and presently have two... and dive them with different undergarments and different suit gases and with different configurations (singles and doubles) that the suit itself is not an impediment to horizontal positioning.

You are free to continue on in your verticality....
Horisontally yours,

 

[divernva]

... since I don't dive dry... yet.

As for being comfy and not having gas in your suit, that is probably the right feeling. Basically, adding gas should be dependent on feeling squeeze due to the depth.

As for trapped air in the legs, you can try some gators around your calves. This helps prevent gas from getting to your boots.