oceanic computers - what's up with the deco algo?

[paulwlee]

The more conservative makes simply penalize you of safe dive time, IMO - a very unneeded loss.

Suunto's are not simply just conservative. What it does is take factors that are not taken into account by a dissolved-gas-only model and uses those to tune the conservatism so as to cover more bases. This is very different from just backing off numbers from the same table.

An example of this is if you have a short surface interval, a dissolved-gas-only model will only calculate the theoretical off-gas rate and compute your time based on how much residual nitrogen you have, whereas in reality there is likely some bubbling that is slowing down the gas exchange, and can serve as a seed for bubble growth when you do a second dive. When you enter the water again before the bubbles clear, you are at increased risk, and the Suunto algorithm modifies the parameters to try and account for this increased risk, where a dissolved-gas-model doesn't. Same for some types of ascent rate violations and other factors.

The DCS rate is very low, and we are talking about fractions of a percent, so the increase in safety is not readily apparent. But it is well founded in current thinking of decompression theory.

 

[Fordan]

All Oceanic and Aeris computers use the same algorithm.

You also have the option of bumping up the "conservative" setting if you feel the times are too liberal for you.

That is one benefit of the more liberal computers: you can still crank up the conservatism settings if you like, both by turning on a conservative mode (which on the Oceanic/Aeris make the computer think you're doing an altitude dive 2000 feet above where you actually are) and by lowering the point along the Tissue Loading Bar Graph where the alarms start happening. Typically, you can't take a more conservative computer and make it more liberal.

 

[DandyDon]

Typically, you can't take a more conservative computer and make it more liberal.

:lol2: I've seen divers who wishes they could.