Two safety stops?

[oldschoolto]

To this day, my largest concern on a recreational dive, is the top ten feet.....where I get quiet( so to speak), listen for props and doppler shift if I hear any, and then decide if it is smart to surface....if there is a lot of boat traffic, my 6 feet to surface will be at rocket speed but with wing empty of air, and I will be spinning 360 as I go, and spin-scanning the horizon 360 when I ht the surface...if a boat "was coming", I would be on my way back down at max speed. Since 72, I have had one boat go right over me--one near accident, this by a moron private boater that was supposed to be picking me up--and was running without looking ahead of himself....He was going about 12 mph.... I was so shocked he did not see me and was going to run over me, I actually waited longer than I should have...and actually "pushed off" with my feet/fins on the bottom of his bow..and was rocketing down at emergency speed to 12 feet or so in an instant...that was as close a call as I would ever want to have....Moral of that story is use professional Charter boat captains and boats, not some yahoo that dives and has a boat

When it's time to surface ... I do Rock, Paper, Scissors with my dive buddy.... Loser goes up to check...

Jim...

 

[danvolker]

And trusting a dive flag is almost as ridiculous as trusting that there will be no drunk drivers on the road with you on New Years Eve..... You need to EXPECT morons in private boats to run over your flag....and for the Marine Patrol or Sheriffs to not really care.

---------- Post added March 31st, 2013 at 02:07 PM ----------

Which is to say that the current thinking on a really slow last ten feet, may not be in your best interest if you can hear any boats around your area....
Those with hoods on, often could not hear a nearby explosion, so their awareness of boat or no-boat, will not exist untill they can visually scan the at the surface....they are coming up WITH NO IDEA of what they just stuck their head into!!!!

The unfortunate thing about good dive sites, is that private boaters intent on fishing, will often be cruising right over the tops of our favorite reefs or wrecks. Even in an area where there is little traffic, and you don't see a boat in any direction when you jump in to begin the dive....even in this area, everything could change in the next 30 to 60 minutes when you are coming back up!!!

 

[dumpsterDiver]

To this day, my largest concern on a recreational dive, is the top ten feet.....where I get quiet( so to speak), listen for props and doppler shift if I hear any, and then decide if it is smart to surface....if there is a lot of boat traffic, my 6 feet to surface will be at rocket speed but with wing empty of air, and I will be spinning 360 as I go, and spin-scanning the horizon 360 when I ht the surface...if a boat "was coming", I would be on my way back down at max speed. Since 72, I have had one boat go right over me--one near accident, this by a moron private boater that was supposed to be picking me up--and was running without looking ahead of himself....He was going about 12 mph.... I was so shocked he did not see me and was going to run over me, I actually waited longer than I should have...and actually "pushed off" with my feet/fins on the bottom of his bow..and was rocketing down at emergency speed to 12 feet or so in an instant...that was as close a call as I would ever want to have....Moral of that story is use professional Charter boat captains and boats, not some yahoo that dives and has a boat

A few years ago, we had a local guy get both of his lower legs removed after an ER Doctor who ran his boat over him (at a high speed) as he tried to re-descend after surfacing from a scuba dive. Terrible, he barely survived from the blood loss. A make my kid stay down alone, while I check the surface.. then he is allowed to surface.... around 1:20 shows the typical protocol. [video=youtube_share;Pza6K8c7EaQ]http://youtu.be/Pza6K8c7EaQ[/video] Another reason to have a little extra lead (and a pony bottle).

 

[jIM STEELE]

I do notice that Im tired less when we do stops every 10 ft starting from the half of the depth and then doing slow (4-5) minute ascend from 20ft.

A stop half way helps ajust your boyancy (good in cold water) and slowes your assent rate for outgasing

 

[NAM001]

In my Naui class 1972, there was lots on being able to do free ascent, how to ditch and don, and many skills to present day DM level performance...but zero on a stop....you ascended at the speed of the small bubbles. That was it.

I remember that in my class

---------- Post added March 31st, 2013 at 04:26 PM ----------

My instructor taught us i think to survive the skills dive's, Where we did it there were motor powered boats. He taught us to not count on the flag as a safety device because of lookie lu's. Hence stop look and listen prior to the final surface, Not having any exposure to anything else i guess i thought that was just standard course material. Heck i was only 15. He talked about a lot of realities adn falacies. such as

Dive flag will not keep you bfrom being run over. Cant get to a deco situation on a single 72 tank. Only one lake in the state allowed spear fishing. The J valve is not necessary your friend. The top 10 ft is where most divers die. (Refering to PPO2 and passing out)

Sounds like the instructor repurposed the kids street crossing mantra, my hat is off to him for a nice peice of work.

I looked in my books from '63 and '80 and didn't find that evolution. Actually, they only said look around, listen and put your arm up if you couldn't see the surface so you would know something was there before you cracked your head. I guess they figured the instructor could provide any helpfull techniques.





If you had two tanks or a set of doubles, all bets were off.



Bob
-------------------------------------------
There is no problem that can't be solved with a liberal application of sex, tequila, money, duct tape, or high explosives, not necessarily in that order.

---------- Post added March 31st, 2013 at 04:34 PM ----------

I was taught very much on those oncepts. check for safe to go up, dont dally, and get the flag as close to you as you can cause boaters are focused on the flag and not that surrounding area.

And trusting a dive flag is almost as ridiculous as trusting that there will be no drunk drivers on the road with you on New Years Eve..... You need to EXPECT morons in private boats to run over your flag....and for the Marine Patrol or Sheriffs to not really care.

---------- Post added March 31st, 2013 at 02:07 PM ----------

Which is to say that the current thinking on a really slow last ten feet, may not be in your best interest if you can hear any boats around your area....
Those with hoods on, often could not hear a nearby explosion, so their awareness of boat or no-boat, will not exist untill they can visually scan the at the surface....they are coming up WITH NO IDEA of what they just stuck their head into!!!!

The unfortunate thing about good dive sites, is that private boaters intent on fishing, will often be cruising right over the tops of our favorite reefs or wrecks. Even in an area where there is little traffic, and you don't see a boat in any direction when you jump in to begin the dive....even in this area, everything could change in the next 30 to 60 minutes when you are coming back up!!!

---------- Post added March 31st, 2013 at 04:41 PM ----------

Dan,,,, it sounds like we do things very much alike. I have to keep reminding my self of these skills after doing many dives in no boating areas. Thanks for bringing this up.

To this day, my largest concern on a recreational dive, is the top ten feet.....where I get quiet( so to speak), listen for props and doppler shift if I hear any, and then decide if it is smart to surface....if there is a lot of boat traffic, my 6 feet to surface will be at rocket speed but with wing empty of air, and I will be spinning 360 as I go, and spin-scanning the horizon 360 when I ht the surface...if a boat "was coming", I would be on my way back down at max speed. Since 72, I have had one boat go right over me--one near accident, this by a moron private boater that was supposed to be picking me up--and was running without looking ahead of himself....He was going about 12 mph.... I was so shocked he did not see me and was going to run over me, I actually waited longer than I should have...and actually "pushed off" with my feet/fins on the bottom of his bow..and was rocketing down at emergency speed to 12 feet or so in an instant...that was as close a call as I would ever want to have....Moral of that story is use professional Charter boat captains and boats, not some yahoo that dives and has a boat

 

[Matt_O'Brien]

On deeper dives and days when you are doing a few dives - it's a good idea, yes! If you can incorporate it into your dive it's less of a chore and more of an enjoyable element. The longer you take to ascend the more nitrogen will work it's way out naturally and less chance of any form of DCS. It also keeps your computer happy!
All for it, not really sure why you're asking the question - it should be obvious :blinking:
p.s. If you are an air pig - seek advice from a professional on advanced breathing techniques, you'll only benefit from the outcome!
I'm not saying my way is the right way - it's my way and I find it works..
Breath in slowly slowly, fill your lungs slowly (doesn't have to be all the way).
Exhale approximately three - four times slower than you inhaled (yes you can do it quite easily!) and empty the lungs (doesn't have to be all the way)
Don't smoke before a dive - better don't be a smoker (i'm an ex-smoker!)
Get fitter?
Don't fin around like a lunatic - very slow mellow controlled motions
Perfect your buoyancy - and don't touch your inflator hose once neutral (unless changing significant depth)
Use as little weight as required (base this on a cylinder at 50 bar)
Don't move your arms
Keep that hear rate down
Best of luck brother! It does come with practice.

 

[eponym]

On deeper dives and days when you are doing a few dives - it's a good idea, yes! If you can incorporate it into your dive it's less of a chore and more of an enjoyable element. The longer you take to ascend the more nitrogen will work its way out naturally and less chance of any form of DCS. It also keeps your computer happy!
All for it, not really sure why you're asking the question - it should be obvious.

Actually, it's possible to ascend from a deep dive at a slow enough rate to allow some compartments to continue to absorb gas and to eventually put the model in deco. You could face mandatory stops to allow those compartments to offgas.

This is a factor in deep dives and a reason as mentioned above that one makes the first leg of an ascent more quickly than the shallower legs.

 

[Bob DBF]

Actually, it's possible to ascend from a deep dive at a slow enough rate to allow some compartments to continue to absorb gas and to eventually put the model in deco. You could face mandatory stops to allow those compartments to offgas.

This is a factor in deep dives and a reason as mentioned above that one makes the first leg of an ascent more quickly than the shallower legs.

Even with a good ascent rate I came off the bottom @ 130' NDL and was in deco from about 105' to 55' on the way up. It was bit of a surprise, but I had plenty of gas and did a nice long safety stop since I don't like surfacing so close to deco. This is one reason I'm not keen on deep stops, had I stopped at 65' for 2 or 3 minutes it would have negatively affected my reserve by an unknown amount.


Bob
----------------------------
I may be old, but I'm not dead yet.

 

[nimoh]

Even with a good ascent rate I came off the bottom @ 130' NDL and was in deco from about 105' to 55' on the way up. It was bit of a surprise, but I had plenty of gas and did a nice long safety stop since I don't like surfacing so close to deco. This is one reason I'm not keen on deep stops, had I stopped at 65' for 2 or 3 minutes it would have negatively affected my reserve by an unknown amount.


Bob
----------------------------
I may be old, but I'm not dead yet.

I'm no expert on decompression theory, but it is my understanding that if your 130' dive was a square profile, then 65' should be above the ceiling, and you would be offgasing thus reducing your deco obligation.

However, if your average depth was less than 130', then the ceiling might be above 65' which is what your computer was probably telling you.

I'll temper this post with the fact that I am about half way through reading deco for divers, and I probably don't know the big picture, just trying to figure things out

 

[MXGratefulDiver]

I'm no expert on decompression theory, but it is my understanding that if your 130' dive was a square profile, then 65' should be above the ceiling, and you would be offgasing thus reducing your deco obligation.

However, if your average depth was less than 130', then the ceiling might be above 65' which is what your computer was probably telling you.

I'll temper this post with the fact that I am about half way through reading deco for divers, and I probably don't know the big picture, just trying to figure things out

... also keep in mind that what your body is doing and what your computer is telling you may be two very different things. A few years back I was routinely diving with two different computers (Suunto Vytec and Oceanic Versa Pro) which use completely different algorithms. On a dive like you just described, the Oceanic would be showing offgassing at the halfway depth while the Suunto would continue ongassing until I reached about 40 fsw.

So the question at that point becomes, who do you "listen" to?

... Bob (Grateful Diver)