Dumb questions

[del_mo]

I'm currently studying for my AOW through PADI. The LDS I'll be using in not in my area, so asking them questions isn't so easy.

Two questions: One - Avoid "saw tooth" diving profiles. How much change in depth constitutes "saw tooth"? If I were to rise just to get over an obstruction, or get on the other side of a coral head, have I broken the rule?

Two - To help with disorientation, the book says you can hug yourself. Hug yourself? What does hugging yourself do?

Sorry to anyone bored by this thread.

 

[scubatoys]

I'm currently studying for my AOW through PADI. The LDS I'll be using in not in my area, so asking them questions isn't so easy.

Two questions: One - Avoid "saw tooth" diving profiles. How much change in depth constitutes "saw tooth"? If I were to rise just to get over an obstruction, or get on the other side of a coral head, have I broken the rule?

Two - To help with disorientation, the book says you can hug yourself. Hug yourself? What does hugging yourself do?

Sorry to anyone bored by this thread.

If you have to go over something... so be it... don't sweat it. They are taking about doing up and down over and over... and probably in the 15 + foot range... going up to clear over something and sink back down on the other side is no big deal.

The hug yourself thing... Yea... kinda stupid. Suppose the idea is based on if disorientated, you might be thrashing arms about, and hugging your self, at least you would not be thrashing, and your are making a contact with something - instead of open water, so hopefully you will calm down and pull the world together.

I'd suggest bringing a Dallas Cowboy Cheerleader to hug instead... but maybe that's just me...

 

[del_mo]

If you have to go over something... so be it... don't sweat it. They are taking about doing up and down over and over... and probably in the 15 + foot range... going up to clear over something and sink back down on the other side is no big deal.

The hug yourself thing... Yea... kinda stupid. Suppose the idea is based on if disorientated, you might be thrashing arms about, and hugging your self, at least you would not be thrashing, and your are making a contact with something - instead of open water, so hopefully you will calm down and pull the world together.

I'd suggest bringing a Dallas Cowboy Cheerleader to hug instead... but maybe that's just me...

I'd suggest bringing a Dallas Cowboy Cheerleader to hug instead... but maybe that's just me...

I'll suggest that to my wife.

 

[BigJetDriver]

Two - To help with disorientation, the book says you can hug yourself. Hug yourself? What does hugging yourself do?

Since PADI headquarters is out on the "Left Coast", this is probably one of those "touchy-feely" things that seem to spring up every so often from the depths of the PC collective mind of the People's Republic out there. It is probably intended to keep your hands off the cheerleader you were mentioning!

 

[miketsp]

Although most agencies tell us to avoid saw-tooth profiles, latest research says different:

'Yo-yo' dives have previously been considered high risk, yet research shows that the incidence of DCI that results from these dives is lower than that of a single, relatively long, no decompression dive."

From:
http://www.divernet.com/news/stories/hse070604.shtml

I am on holiday at the moment diving every day and every day I see local DMs doing multiple rapid ascents and descents when looking for wrecks. Yesterday, for example we were looking for a wreck at 33m in difficult conditions and the DM made 3 consecutive descents to try to find it without success, each time hitting 40m+ before we aborted and went to another site.

 

[Divemastr]

My 2 cents on the saw tooth question.. If you are feeling like you need to equalize often without intending to change depth, you are in a saw tooth profile. I tend to stay slightly above the intended max planned depth and descend when I am wanting a closer look at something as long as it is not below the planned max. As long as YOU are in control of the depth changing and it is desired, you should be OK. If you find you are changeing depth without wanting to or being forced to by an unwanted current, etc, then keep working on your bouyancy control. Again, my 2 cents...

 

[Doc Intrepid]

Two questions: One - Avoid "saw tooth" diving profiles. How much change in depth constitutes "saw tooth"? If I were to rise just to get over an obstruction, or get on the other side of a coral head, have I broken the rule?

Two - To help with disorientation, the book says you can hug yourself. Hug yourself? What does hugging yourself do?

I am on holiday at the moment diving every day and every day I see local DMs doing multiple rapid ascents and descents when looking for wrecks. Yesterday, for example we were looking for a wreck at 33m in difficult conditions and the DM made 3 consecutive descents to try to find it without success, each time hitting 40m+ before we aborted and went to another site.

Mike is correct regarding the DM's behavior. But there are a few things to ponder. First, on a lengthy dive - in contrast to a quick bounce dive to locate a wreck - you may be down for 45 minutes or so, on-gassing throughout the duration. The "sawtooth profile" advice refers to avoiding repeated variances in depth (ascents) of 15-20' or greater that may result in seed bubble formation - hence the connection to DCI.

Second, there are physiological differences between DM's who dive daily, are reasonably young, in great shape, and are familiar with the sites and conditions (relaxed and comfortable underwater) and vacationing divers who don't dive as frequently, aren't in the same physical condition, and are stressed and nowhere near as comfortable in the water. DCI isn't completely understood, in terms of causation or why one diver gets a hit while their buddy does not. But it might be prudent to plan your dives and dive your plan to take into consideration the physiological differences between those DM's and yourself.

The 'hug yourself' bit is basically BS. Disorientation is certainly possible and can be a very disturbing sensation underwater. But if you experience disorientation severe enough to cause extreme anxiety underwater, the correct response is not to go fetal and hug yourself. Instead, you communicate your distress to your buddy and thumb the dive.

Best of luck with your future classes and diving,

Doc

 

[knotical]

Although most agencies tell us to avoid saw-tooth profiles, latest research says different:
'Yo-yo' dives have previously been considered high risk, yet research shows that the incidence of DCI that results from these dives is lower than that of a single, relatively long, no decompression dive."
From:
http://www.divernet.com/news/stories/hse070604.shtml

Thanks for the link to the interesting article. It compares pushing no decompression limits with breaking that dive up into two or more dives that they call yo-yo, but sound like just dives of shorter duration. ( "dividing the total bottom time into several shorter dives alternating with a surface interval" ). This isn't the same as what I understand a sawtooth to be - several partial ascents and descents during one dive.