5. OSTC Custom Functions

The OSTC dive computer supports several configuration options (aka Custom Functions) that allows to customize decompression or interface details. The full list is here.

The OSTC Planner supports most of them (remember, we share the decompression code). Hence you can test and configure before you go wet.

CF11: Bühlmann saturation factor [%].

Security margin used only when diving in ZHL-16 mode (ie. no gradient factors). This is the saturation speed (gas loading factor) of the tissues.
Defaults to 110%.

CF12: Bühlmann desaturation factor [%].

Security margin used only when diving in ZHL-16 mode (ie. no gradient factors). This is the desaturation speed (gas off-loading factor) of the tissues.
Defaults to 90%.

CF18: ppO2 max [bar].

Maximum allowed oxygen partial pressure. Used only for MOD (max operating depth) calculation.
Defaults to 1.60 bar.

CF32: GF Low [%].

Security margin used only when diving in ZHL-16-GF mode (ie. with gradient factors). This is the maximum allowed gradient factor when reaching the first (deepest) stop.
Defaults to 30%.

CF33: GF high [%].

Security margin used only when diving in ZHL-16-GF mode (ie. with gradient factors). This is the maximum allowed gradient factor when reaching surface.
Defaults to 90%.

CF39: Adjust fixed setpoint.

Used only in CCR (closed circuit rebreather) mode. When the target ppO2 is too low (because the diluant is to rich), adapt decompression computations to the real value.
Defauts to false.

CF54 : shallow stop first.

Show stops in reverse order (ie. shallowest first), as most decompression table do.
Defaults to false.

CF55 : gas switch stops [min].

Adds a minimum delay for switching gas. This stop is inserted in the runtime (and TTS), and because it make you stays at the switching depth, the tissue loading is affected, and the remaining of the deco planning is changed.
Defaults to 0 min (disabled).

CAVEATS: don’t be surprised to get stops at the configured switch depth as soon as you dive deeper than those limit, and exceed the NDL (no deco limit) time…

CF56 & CF57: estimating gas consumption.

Gas consumption  parameters. CF56 is used during bottom time, and ascent up to the first stop. CF57 is used from (and including) the first stop up to the surface.
Defaults to 20.0 L/min.

CF58: Future TTS [min].

Enables the Future TTS feature. The OSTC dynamically recompute an alternate runtime, telling you the TTS (time to surface) if you stay extra time at the current depth. Very handy in two situations: to allow you some extra time at the bottom of a square dive when you make you planning with a max TTS strategy ; or during ascent to know if you are shallow enough so that wandering around the current depth won’t increase your stops.
Defaults to 0 min (disabled).

CF59: Cave Bailout [L].

For CCR cave divers, when forced to return to the cave entrance by the same dive profile. The computer makes an estimation of the return gas consumption (same profile to go back to entrance, plus all the deco stops), compare to the configured bailout volume, and warm (turn red) when the value exceed the configured limit.
Defaults to 0 L (disabled).