How is GTR calculated for multi-tank dives or decompression dives?
The GTR calculations on the Perdix AI are only for single-tank diving that does not require decompression stops.
GTR is a tool for no-stop (i.e. no decompression) diving. We do not recommend GTR as a tool for decompression diving. Decompressing diving involves significant pre-planning of gas reserves and typically requires multiple tanks and gas mixtures. The complexities due to managing multiple tanks and differing styles of gas management would make setup of GTR too complex for reliable use. We tried this during development, and experienced testers frequently made setup mistakes that resulted in incorrect GTR. Shearwater feels that GTR is a great tool for single-tank, no-stop diving, but unfortunately does not work well for more complex diving.