Chris B(Offline)

I am interested to know how people handle the descent time when deciding their deco/ave depth.

Most of the time i simply start my BT when I leave the surface, up to 40mish this is no big deal but the longer the descent (something I'm not inclined to rush) I am potentially loosing more actual BT and slightly extending my deco too......if you follow me.

So, do people do it the simplistic way, nclude descent time in the BT, or decrease the ave depth for a slow descent or what...?

Cheers

Chris B

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MonkSeal(Offline)

Generaly, descent in not included in BT, ascendig to first deep stop is.

Clare Gledhill(Offline)

I don't include it as long as it is reasonable. Mark time and gas on the bottom.

However, if we had a problem on the descent which made it overly long I would make a judgement on taking some of it into account - and be aware of this when calculating average depth.

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Mark Chase(Offline)

Decent time is always included in my bottom time. It keeps reading the bottom timer simple and the addition of the 2-5mins provides a small buffer to pad out the deco. 70-100+m It might become an issue but not much of one unless there was a problem on decent forcing a long dwell at 6m or something like that.

I wish divers would see the same benifits in conservitave deco as they do in conservertive DIR diving systems. As far as i am aware there are very few risks in doing an extra 15mins deco.

ATB

Mark Chase

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Alastair(Offline)

Needless to say my approach is the same as Clares (as we dive together). I disregard the descent time provided it is a small amount of time.

Mark - I really do respect this. I was actually having a conversation today about deco and we were debating knowing what's appropriate. This is probably worth a different thread but the issue is you need to know how quick you can get out if you have a problem. You also need to know what's sensible which is usually what you do. The longer you are deco'ing though there is an added risk of surface conditions changing, greater exposure to high pp02's or if the boats had an issue how far you've drifted from them.

I don't think it's sensible to massively prolong the deco - there has to be a balance between what's needed and what is added conservatism. After all you have to get out sometime! The longer BT you tend to pull skews the deco somewhat so perhaps you need more conservatism. I often compare the profiles I run to Decoplanner and they do approximate 5/90 GF so they aren't exactly right out there on the bleeding edge.

Cheers
Al

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Clare Gledhill(Offline)

Hey Al - shouldn't you and I have better things to do?

Doing just enough is a tough one isn't it.

I like soft boiled eggs with my toast.
I hate undercooked eggs.
Hard boiled are no use for sticking my toast in.

Problem is that I can't see how I am getting on until it is too late.

So I have to base my decision on what Delia Smith tells me is a good strategy and what was successful last time. Gordon Ramsey has a different view - but what does he know?

Given that undercooked is much nastier than overcooked I will tend to skew my decision to avoid that outcome but the temerature of the water, the size of my eggs and pan I use may all have an impact.

Most of the time I manage to get somewhere close to what I need without ending up with hard boiled eggs though...

If only deco was this simple






OK - I'm stressed and talking bollox - I'm going now

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A-M(Offline)

OK - I'm stressed and talking bollox - I'm going now [/quote]

Absolutely not!!
It's about the first time I understand deco-on-the-fly!!
So please go on about those eggs and cooking times

Mark Chase(Offline)

Massively extended deco is a bad thing I suppose but is 10 or 15mins massive for a dive of say 120min run time?

In a country like the Phillipeens where you cen get in glass flat warm water in 30 degrees of sun and 120mins later be in hurricane conditions, I think there may be an issue. In the UK we generally have a pretty good idea what the conditions will be in the next two hours. Not always, but most of the time. In dodgy conditions we cut the dive short. Short bottom time short deco.

More than once i have cut back on deco to the minimum i thought i could get away with because of bad conditions or feeling ill. However this is the exception not the rule and i make the decision in the educated knowledge that a session in the pot is the lesser evil on the day.

Touch wood I have never been potted for a bend but I have spent a couple of afternoons sucking 02.


Maby it comes back to what Richard called "Primacy". I was always taught to round up or down on the side of safety. He is rounded up 02 rounded down, on tables depths were rounded up and so was bottom time. That was the way I was taught.

I went through a phase of spending hours trying to shave off some deco because, for example, the 40min bottom time at 70m was giving me a massive amount of time in the water. In the end I was finding that on the day, I was happy to pad it out a bit or that I had to stay in the water to clear my buddy anyway, so now I don't bother. I just got used to doing the deco.

I always carry in my head the 100/100GF bailout plan, but I do the 20/85GF deco unless there is a problem.

ATB


Mark Chase

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Leigh u(Offline)

Some dives we include it ..some dives we don't. Ascent to the first deep stop as well as the first gas switch are covered in your minimum gas calculations.
I also prefer hard boiled eggs with soldiiers.

graham_hk(Offline)

Mark - they are called typhoons in the pacific

Anyway you know if a typhoon is coming its the squals that are the problem - can reduce visibility to a few meters and whip the sea up into a fearsome state. Even so they are pretty rare and its still no reason to rush deco.

Graham