DINOFISH the dive

[AfterDark]

Not as hard as you might have guessed. I've done deep, long OC dives on pretty hypoxic mixes (60%+ He) mid December 2010 in Sharm El Sheikh, South Sinai, Red Sea, Egypt in a short and a T-shirt. My buddy (on CCR) was in his dry suit

Edit: water temp was 25 C (77 F).

In post 5 ajduplessis posted the water should below 18C for the fish. No possible way I could spent 4 hours in that water w/o protection. How about you? Do you know if the H affected your voice? These guys were talking on comms and sounding like they were on air. How hard is that for you?

 

[Red Sea Shadow]

The documentary didn't state the temp?

I've tried 17C in the sea a couple of times before but not for extended periods. Tried 14C in the pool in an old 3mm (1/8 inch) wetsuit.

He never affected my voice actually. That's after diving, as I didn't use comms before. I don't feel it's a colder gas to breathe either.

Edit: diving without protection is not my everyday practice, yet I find it quite feasible. Usually the only problem is the wind chill on the boat / on shore. In this situation a wet suit is even a bigger problem

 

[AfterDark]

The documentary didn't state the temp?

I've tried 17C in the sea a couple of times before but not for extended periods. Tried 14C in the pool in an old 3mm (1/8 inch) wetsuit.

He never affected my voice actually. That's after diving, as I didn't use comms before. I don't feel it's a colder gas to breathe either.

Edit: diving without protection is not my everyday practice, yet I find it quite feasible. Usually the only problem is the wind chill on the boat / on shore. In this situation a wet suit is even a bigger problem

No it didn't just that the fish lives in cold deep water. I've never dove in 77F water. I'm a US east coast diver. On a good summer the surface gets to maybe 70F the bottom is usually around 65F. After an hour in that water with a 7mm farmer john wet suit I'm ready to exit!

 

[ajduplessis]

The temp I cited is on the bottom, thus only 15min is spend there. The water on surface can be 24-30 depending on time of here.

---------- Post added October 13th, 2013 at 04:08 PM ----------

Helium will affect your voice while breathing. Go off that mix and things turn back to normal within 10 seconds or so.

 

[AfterDark]

The temp I cited is on the bottom, thus only 15min is spend there. The water on surface can be 24-30 depending on time of here.

---------- Post added October 13th, 2013 at 04:08 PM ----------

Helium will affect your voice while breathing. Go off that mix and things turn back to normal within 10 seconds or so.

OK but at what depth does the thermocline start?

Red Sea Shadow: They don't teach that lighter than air gases affect your voice in tri mix classes? Guess there's no time for that.

 

[Red Sea Shadow]

Red Sea Shadow: They don't teach that lighter than air gases affect your voice in tri mix classes? Guess there's no time for that.

They do teach that your voice might change while breathing He, and there's plenty of time over here. I'm just sharing my personal experience.

BTW, it's not about gas density. It's about speed of sound in the gas, which is independent to its density as far as I'm aware.

---------- Post added October 13th, 2013 at 06:16 PM ----------

The temp I cited is on the bottom, thus only 15min is spend there. The water on surface can be 24-30 depending on time of here.

This is actually better for decompression; cool BT and warm stops.

 

[AfterDark]

They do teach that your voice might change while breathing He, and there's plenty of time over here. I'm just sharing my personal experience.

BTW, it's not about gas density. It's about speed of sound in the gas, which is independent to its density as far as I'm aware.

---------- Post added October 13th, 2013 at 06:16 PM ----------



This is actually better for decompression; cool BT and warm stops.

Less density, more speed. One cu ft of air weights more than the same amount of He. Lighter makes it less dense, thus whatever travels thru it travels faster. The effect of He on the voice starts in the voice box.

 

[Red Sea Shadow]

Less density, more speed. One cu ft of air weights more than the same amount of He. Lighter makes it less dense, thus whatever travels thru it travels faster. The effect of He on the voice starts in the voice box.

The speed of sound in an ideal gas is independent of frequency, but does vary slightly with frequency in a real gas. It is proportional to the square root of the absolute temperature, but is independent of pressure or density for a given ideal gas. Sound speed in air varies slightly with pressure only because air is not quite an ideal gas. In addition, for different gases, the speed of sound is inversely proportional to the mean molecular weight of the gas, and is affected to a lesser extent by the number of ways in which the molecules of the gas can store heat from compression, since sound in gases is a compression wave. Although (in the case of gases only) the speed of sound is expressed in terms of a ratio of both density and pressure, these quantities cancel in ideal gases at any given temperature, composition, and heat capacity. This leads to a velocity formula for ideal gases which includes only the latter independent variables.

Excerpted from Wikipedia.

 

[ajduplessis]

This is going to sound strange but there is no real/hard Thermoclines. The temp gradually increase as you come to the surface. I looked at my last dive there earlier this year and the temp increased around 1 degree celcius every 1ATA coming up with the last temp increase around 30m/100ft (thermocline???).

You gents seem keen on the topic. Some more reading here http://eprints.ru.ac.za/550/1/ribbink2.pdf and Mr Timms site here Gallery

 

[vancouverdiver]

I saw a re-broadcast of the video. After viewing I can't help ask a number of questions. It doesn't look like the OC diver has enough gas for a 380 ft dive, nor deco cylinders? It doesn't look like the CCR divers have sufficient bailout? The OC diver has an OOA emergency, and is fumbling with spare gas inaccessible behind his doubles. He has to take the doubles off to access it. During the process, he wraps himself up with his upline, cuts it, and then the line seems to re-appear attached to the reel? During all this the videographer is steadily filming and not providing assistance? Doing a 4 hour tec dive without exposure wear, getting cool if not hypothermic, is not a good idea on a long tec dive? Flutter kicking stirring up silt and touching bottom? The annoying voice overs add to the credibility question. Now, I don't have the experience to do a 380 ft. dive nor do I know the people involved who are reportedly an "elite team", but this video seems really strange. How does an elite diver not monitor their gas and run out of gas? After doing 3.5 hours of deco, that looks like an aggressive exit of the water on to the boat. Anyone with 400 ft experience find this video odd?