Is this a Dangerous Dive Profile?

[Jarrett]

This is a dive I did in a scuba park last weekend. It pretty much consisted of playing around a sunken airplane. I am interested to hear your thoughts on it.

www.elliscountyequine.org/images/dive3.xls

Thanks in advance.

 

[ScubaTexan]

Since it looks like a seismograph during an earthquake, I'm guessing yes...

j/k

 

[mattroz]

only 25 feetmax depth with shots up to 15 feet, you should try to avoid that... the other problem is it looks like you made a pretty rapid ascent. you could have used negative numbers for your graph then it would be a normal profile..

 

[Midnight Star]

I'm not an expert by far, but here's what i'm thinking:

The biggest potential danger was the "yo-yo" effect of your depth. This could be caused by a bouyancy problem thats causing to you to consistantly "fin down" (under weighted at that depth), or over inflate then purge your BC (over weighted). Once I dove with just 8 pounds in full wetsuit and gear. I could go neutral at 30', but within the 15' range I would go up without, finning down. Now with the potential danger... Most of your depth, if i'm reading that correctly was within a 10' margin, between a safety stop ceiling (around 15') and about 25'. This is above the 33' floor (above that and deco isnt likely on a single tank dive, below that, deco is possible). So as far as dangerous for that dive, I dont see it ... but potentially dangerous in a deeper, slow ascent required time due to nitrogen absorbtion dive, yes. Do you know what caused the "yo-yo" effect? Was it bouyancy, or were your swimming over a reef? The floor of the dive site can also vary.

-----

Mike.

 

[spectrum]

You pretty much explored in a 10 foor window. It looks ratty due to the shallow overall depth but if that was the contour of the site I don't see an issue at that shallow depth. This assumes that this represents where you intended to go and it was not an out of control diver. Looking at a bunch of my shore dive profiles that explore coastal ledges yours is nothing alarming.

If you went to 80 feet and went up and down by a comparable proportion of 35 feet throughout the dive then it would be another matter.

How did you feel afterwards? If you crashed and burned then you stressed yourself. If you felt fine then you probably were well behaved.

The "check mark" profile is all fine and good but on shallow dives it's often not practical.

The time scale is too compressed to be sure about your final ascent but the last 8 feet look fast, a visible slope would have been better after :58 underwater. You effectively had a safety stop before the last brief deep excursion to 23 feet. Avoiding that last 8 foot drop would have been nice. Your NDL would have remained off the scale at these depths so I see it more as a comfort thing.

I have to wonder if an "undeserved hit" might arrise from this. Was it the 1 and only dive that day?

Pete

 

[Jarrett]

Thanks for the feedback so far. Here are some more details:

This was a second dive of the day after a 2 hour surface interval and I felt fine after the dive. No problems at all. I was not out of control, my buoyancy was on. That is the contour of the dive, from the top to the bottom of the plane was about 7 feet. My computer did not give me any violations for this profile, neither did the computers of the other 3 people that were diving with me.

I'm just interested to see if people consider this a dangerous profile.

 

[spectrum]

If dive 1 was a deep dive this might have the potential to aggravate your offgassing despite the 2 hours SI. It might be compared to skin-diving after diving. repetetive compression and expansion of dissolved gasses by 1/3 ATA.

What would be a deep dive of significant duration to elevate this risk is beyond me.

Pete

 

[1_T_Submariner]

Hi Jarret....In my opinion no this isn't. You might want to try changing the sample rate of your computer. It looks like your computer is sampling every 30 seconds. this makes your profile look more choppy than it really is.

 

[Tassie_Rohan]

Not dangerous at this depth....

You didn't pass 8 metres (25 ft) so your tissues wetn't getting too loaded with nitrogen. Ditto you din't go shallower than 5 meters (15 ft).

However - if you went deeper at the start, got a decent amount of nitrogen into your tissue, then accended and started your seismogram profile it could be a different matter.

It may of also been risky if you were bouncing closer to the surface, say from 25 ft up to near surface (say 6 ft).

Cheers,
Rohan.

 

[DandyDon]

It's more challenging to stay at the same depth in shalow dives than at depth. I add 2# of weight for the shallow dives for better conrol.

I don't have the program to look at the graph, but it sounds like u do need to change sample rate and work at leveling out both.