The selection of the storage depth for the deck decompression chamber (DDC) is
based on the approximate planned diver working depth. This can be achieved by
comparing the storage depth and planned diver working depth with the descent
and ascent limits of the Unlimited Duration Excursion Tables (Table 15-7 and
Table 15-8). When the diver’s working depth range is small, the DDC should be
compressed to approximately the middle of the range. This minimizes the amount
of gas used in pressurizing or depressurizing the personnel transfer capsule (PTC).
When the expected diver work range is large or multiple objectives at different
depths are to be accomplished, several different storage depths will be required.
The unlimited excursion procedures may be used at several progressively shallower
storage depths to accomplish the objective.