Logging tanks, nitrox and trimix

Cylinders, mixes and pressures are real fields on a dive, not something to bury in your notes.

Your gas is logged per cylinder, with the mix and both pressures as proper fields. Start on the Gas card, on the second step of the dive log: Divemates → Log a Dive → Your dive, by the numbers → Gas. Editing a dive later walks the same steps.

One tank, the quick way

With a single cylinder the Gas card is everything you need on a boat: choose the Type, then set Start and End. Pressures read in whatever unit you've set for yourself, and holding the plus or minus runs through them quickly.

End won't go above Start, since nobody surfaces with more gas than they went in with.

Nitrox and trimix

Pick Nitrox and an Oxygen row appears, so you record the percentage you analyzed instead of the word. Pick Trimix and you get a Helium row too.

Those figures stay on the dive and it gets labeled from them, so a dive on 32% reads as nitrox and anything with helium in it reads as trimix. On a dive with several cylinders, each row shows its own mix (Deco · EAN50, Twinset · 21/35).

Tank size and material

These sit one level in, not on the Gas card. Tap Manage Cylinders in the Gas card's header and every cylinder has a Role, a Mix, a Tank size and a Material of its own.

Tank size opens a list of common cylinders you can search by name or nickname. Pick one and its volume, working pressure and material fill themselves in. Tanks named the way you measure are suggested first, and volumes are listed in liters either way.

Choose a twinset from the list and the role switches to Twinset with the pair's total volume, which is how manifolded twins should be logged: one row, not two.

Tank size plus both pressures is what an air consumption figure needs, so it's worth a trip into the sheet even on a one-tank dive. See "Why is there no air consumption?" for the rest of that.

Note: the tank list is fetched, so it's the one part of logging gas that wants a signal. Everything else works offline.

Adding more cylinders

In Manage Cylinders, tap Add Cylinder. Up to ten fit on one dive, each with a Role: Back, Twinset, Sidemount Left or Right, Stage, Deco, Oxygen, Diluent, Bailout.

A role is a position in the rig rather than a gas, and it decides what counts toward air consumption. Your bottom gas counts, meaning back, twinset, sidemount and stage, while deco, bailout and oxygen bottles sit it out.

Add a Diluent cylinder and the whole dive reads as a rebreather dive, which carries no air consumption figure at all. One more worth getting right: Oxygen means the rebreather loop supply, so an open-circuit pure oxygen deco bottle is Deco.

Back on the Gas card, every cylinder gets its own Start and End, so you can set the day's pressures without opening the sheet again.

Your rig carries over

A new log opens with the cylinders from your last dive that had any: roles, mixes, tank specs, all of it. There's no gear locker to maintain, and changing kit is just editing the rows.

Pressures are the one thing that never carries over. Last dive's numbers are last dive's, so you type today's.

Freedives

Set Dive Type to Freedive and the Gas card steps aside entirely, cylinders and all. A breath-hold dive has no breathing gas to log, and Divemates won't pretend otherwise.