[Mark Chase]

Just reiterating Andrews point realy. Computers can and do fail and only a fool would plan the dive and not cut manual tables before hand. The fact that we often cut these tables on a home computer gets frogoten but what the hell.

I have never knowingly carried out a decompresion with out a minimum of bail out tables and a computer.

Deco on the fly is OK with pre set gas mix diving but it is not suitable for best mix diving.

The fact is that a computer is a useful tool. If working corectly it can and does do a far better job of monitering a dive than the diver can. It can help to releive the stress of a dive where math on the fly might add a few problems. A quick glance at the wrist and you know where you are. BUT you MUST be able to look at the data and say 'hang on thats rubbish'.

I recently looked at two dive profiles and immediatly thaught, they dont look right. On further alalisis I couldent even get the most adventurous modle to accepth the profile. Both divers who did the dive got bent. They got bent because they didnt fulley understand what they were doing and they had no computer to warn them of their error.

I think tables will be like the logeritham books  we used at school. In 20 years time when computer modles are more advanced and multi gas computers are the norm we will look back at tables and laugh. It is already the case in leasure  / holiday diving where single mix computer only diving is the norm. It is only the so called Tec diving that still has a pasion for tables and I beleive it is the newness and cost of the computers that is affecting this area.

That said a computer is a tool with no heart and a cold logical brain. It dosent know how fit you are it dosent know what level of hydration you have it dosent know you spent the boat trip out throwing up over the side and it WILL bend you unless you use your knoladge of decompresion and your brain to pad out the basic data to suite the dive and your state of health.

It is possable (see recent posts on profiles) to totaly screw up your tables and set down a plan that will bend you no matter how fit you are. The computer would be screaming a warning at you that you then have to choose to accept or ignore. So the computer adds a safety feature to table dives.
Theoreticly the tables should always be more conservitave than the computer as they are planned at a depth on a square profile. If the computer is giving you more deco than your tables you have to ask why?

I run my computers on 0 safety for this reasion and invariably the tables and the computer are prety close.

To dive on tables and have a computer as back up is fine. To dive on tables and have a computer that is capabale of maping that type of dive (multi gas computer) and not use its capabuilities is IMHO daft.

To rely totaly on a computer for a deco dive with no pre palnning is daft

To rely totaly on one computer only on a no deco dive is daft

To dive without understanding decompresion is daft


So in short there is nothing wrong with a knoladgable diver diving on a computer with adquate contingancy for redundancy.

Why any one should think there is baffeles me.

ATB

Mark Chase