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Fixed or variable ? - How fast do you come up?

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Finless: You couldn't invent him...
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Fixed or variable ascent rate on a dive – that is the question.

I have raised this query before (a long time ago) and, although I forget most of the details, I do remember that I was convinced, at that time, that a fixed slow rate was best. However, on consideration, I am sliding back to the thought that up to 25 mtrs a faster rate might be better.

If it makes a difference, I personally am talking about a two mix dive (no helium) with accelerated deco, HOWEVER, I would like to hear what you none deco types do.

Pls add a “reply” with the depth at which you change rates and/or what ascent rate you try to maintain and, if you can be bothered, the reason why you think your way is best.

I am not at all well up on physics/chemistry so the intricacies of the detailed deco theory are lost on me – all I really need to know is which is best (if there is a definitive answer yet).  If not, I tend to rely on the experience of suitable divers e.g. Mr Pyle, whose stops I now include on every dive.
 

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10m/min, then slower for 6m to the surface.
At least, that's what it seems to work out as afterwards. I just come up nice and slow and it turns out to have been 10m/min just like that
 

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A short fat well off crap cave diver. Likes wrecks
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On a non deco dive it would be 10m/min to 6m then 1.5m/min to the surface.

On a deco dive to 50m it would be 10m/min from the bottom to first stop depth. 3m/min from first deep stop to first shallow stop (Without stopping) this cleares all the deep 1min stops. Then 10m m /min or less to each shallow stop and finaly from 6m 1.5m/min or less to the surface.

On a dive deeper than 50m I would repeet as above but would ascend faster to the first stop depth possably as fast as 20m/min on a very deep dive but more like 15m /min on say a 60-70m dive.

This is due to the low diferential presure at that depth and the rapid on gassing below 45m being detromental to the deco profile.

Hoiwever that all said I just do it by feel and I dont attempt to stick to any definat rate untill I hit the 6m stop. Like Dom said it just kind of works out that way when I look back at the figures.

ATB

Mark Chase
 

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Finless: You couldn't invent him...
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[b said:
Quote[/b] (Mark Chase @ Oct. 13 2003,13:49)]Hoiwever that all said I just do it by feel and I dont attempt to stick to any definat rate untill I hit the 6m stop. Like Dom said it just kind of works out that way when I look back at the figures.

ATB

Mark Chase
I have my dive computer set to 10 mtrs per min and don't like to get over 60% of the ascent rate showing on the display.

Thinking back, I do recollect that I believed I felt less tired after a dive when I changed to a slow fixed rate of ascent.

Bye the bye, I had an excellent dive on Sat - beautiful sunny day, flat calm sea - 5 to 6 mtrs viz (with a torch) at 35 mtrs. Even got 3 to 4 mtrs on the drift close in to shore. Bloody marvellous!!

On the drift I caught a dog fish by the tail and managed to get it into my goody bag after quite a struggle (it was only a little fish so I was going to let it go when I got back on the boat). It was beginning to irritate me because the bag was wriggling around all over the place. It gave me a bit of a shock when I looked down and saw this fish staring at me, eyeball to eyeball, from the top of my goody bag (which was clipped to a shoulder D ring). I believe I rcv'd a telepathic two fingers from it before it shot off.
 

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old time
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<font color='#0000FF'>Do i dare say it ....

Do required deco stops from computer details .

Then get the fu** out .


Andy
 

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Finless: You couldn't invent him...
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[b said:
Quote[/b] (Andy the Commie 2 @ Oct. 13 2003,18:23)]Do i dare say it ....

Do required deco stops from computer details .

Then get the fu** out .


Andy
I couldn't agree more, apart from maybe an extra few minutes at 3 mtrs. The question is how fast to travel between stops? Go like Superman or ....
 

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Never really paid it any mind to be honest. As long as the computor isn't screaming at me to slow down then I am happy, this method has seen me through alot of  very silly dives and hasn't failed me yet so I must be doing something right...famous last words, best go touch a bit of wood just to be safe  
 

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DUE CEO, Booking agent, Coffee maker & Dogsbody...
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Hi Finless

As i posted last time you asked this we as a club traditionally come up very slow, 5m min max i'd say. This is from 30 ish m range dives. Deeper i do much the same as Mark. We do have a very good safety record using this method.

This is not based on any science, its just something that works well for us.

I would use the Coke bottle analogy? If as in normal deco stops you release the top till it starts to bubble then do the top back down till it settles you are controlling the release as it starts to overflow.

If however you undo the top very, very slowly you can release it completly without haveing a rush of bubbles.

I would add that i am probably talking total sheite, but it works for us.

Dive Safe, assend slow


Paul
 

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[b said:
Quote[/b] (Finless @ Oct. 13 2003,14:35)]On the drift I caught a dog fish by the tail and managed to get it into my goody bag after quite a struggle (it was only a little fish so I was going to let it go when I got back on the boatI believe I rcv'd a telepathic two fingers from it before it shot off.
blimey Mark, what had the poor wee dogfish done to deserve being fishnapped into your goodie bag? Specially if you werent intending to keep it anyway? I dive to look at the fish, not denude the sea bed!
 

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Finless: You couldn't invent him...
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[b said:
Quote[/b] (Steve W @ Oct. 15 2003,10:46)]I try to come up as slowly as is practicable, my view is "what's the rush..."
There has to be an optimum rate (or set of rates) for the most efficient offgassing. Maybe it might even vary from dive to dive depending on your physical state.

If you come up too slow then you may still be ongassing - depending on your nitrogen saturation levels.
 

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Finless: You couldn't invent him...
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[b said:
Quote[/b] (my_evil_twin @ Oct. 16 2003,10:00)]blimey Mark, what had the poor wee dogfish done to deserve being fishnapped into your goodie bag? Specially if you werent intending to keep it anyway? I dive to look at the fish, not denude the sea bed!
Sorry - I think you have me confused with someone else. I am Bryan, however, I am the dogfish molester. A boy's got to have hobby.

The dogfish in question did not seem to mind - when it got out of the bag it dropped straight to the sea bed a mtr away and did not even bother to look to see if I followed it. I just wanted to have a look at it in proper light on the boat before returning it.

On a slightly different tack - can anyone tell me what dogfish eat (apart from annoying divers).
 

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Finless: You couldn't invent him...
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[b said:
Quote[/b] (Paul Oliver @ Oct. 15 2003,20:59)]Hi Finless

As i posted last time you asked this we as a club traditionally come up very slow,
Oh dear - I think I'll go and see a doctor abt my memory. I do now remember the bottle of coke analogy.
 

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Dogfish eat small shellfish and crustaceans, they have spiky plates in their mouth to grind them up. They'll eat almost anything they can fit in their mouths to be honest. And they're tough little buggers too. I like the way they tie themselves in a knot if you bother them while they're asleep. Their skin was used in the old days as the grip on sword hilts coz. it's rough and lasts for years - always fancied a dogfish skin diveknife hilt.
 

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[b said:
Quote[/b] (Steve W @ Oct. 15 2003,14:44)]I wouldn't be happy advocating all responsibility to the 'puta, just ask Peter K about 'putas !
Steve,
         I'll tell you one thing I have noticed with my, err, revised deco. procedures. I'm nowhere near as tired after a dive(or two) as I once was. I reckon that feeling of tiredness is micro-bubbles doing odd things to your brain. My usual profiles now are, and I've not been deeper than 30'ish yet, leave 30mtr bottom after 30mins, 3mins-20mtrs, [email protected], 6mins-9mtrs, [email protected], 2mins-5mtrs, hoover cylinder to 30barlast 30bar to surface

I've just made that up off the top of my head but it's the general idea according to how much gas I've got. I'd now rather hang about at 5 for as long as possible. If I have a gas problem at 5 then I can go onto pony or in worst case scenario I'll be able to bolt for the surface without any problems.

But, computers, if you follow one then you'll get bent eventually. You might not have any signs but you will be bent at some point. F**king machines. Too many people now are just throwing themselves in the water thinking "It's OK! My computer will figure it all out for me, I don't really need to understand this deco. stuff". How many times a week do you curse at your PC? Quite a few I suspect! Yet most folk are happy to strap a stupid little box onto their wrist and trust their own safety with it. A PC fu**ing up won't kill you, a f**ked up dive computer might.

All in my humble opinion of course.
Peter
 

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Finless

We are well aware that our slow assents will mean tht we are still on-gassing, but i have never had my computer add on deco time once i start one of these assents.

I check my dive time, max depth and and deco time at the bottom of the shot / start of the assent. While i am assending i chek this against my tables. this i feel (maybe incorrectly mixing 'puters and tables), gives me a back up to my 'puter. It also gives me another option to fall back on if i have an incident during the assent an have to change the plan.

We used to have a French girl in our club who also swore by a slow assent, and would always do a 3m stop as it made her feel a lot better after the dive.

Also being a Dr she was a useful club member to have on the boat, although in France it is aparently a tradition for the big male macho divers to carry the womens kit


Can't see that catching on over here


Dive Safe, Assend Slow

Paul
 
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