Determining RNT With Table 3 (NAUI)

NAUI Table 3 can also be used to find the Residual Nitrogen Time (RNT) at the beginning of the dive. The RNT is added to the Actual Dive Time (ADT) of the repetitive dive to determine the Total Nitrogen Time (TNT).

To determine the RNT:

  1. Find the current Letter Group from Table 2 in the column on the right (e.g., suppose that the diver is in Letter Group F).

  2. Follow the row across to the column corresponding to the depth of the next planned dive; as before, round up to the next greater value if the actual depth is not listed on the table (e.g., if the planned dive is to 46 ft. [14 m], use the column corresponding to 50 ft. [15 m]).

  3. The RNT is the upper (black) number found in the box at the intersection of the Letter Group row and depth column (e.g., a 46 ft. [14 m] planned dive for a diver in Letter Group F would yield an RNT of 47 min.).

The student should be able to verify that a diver in Letter Group G who wishes to dive to 37 ft. (11 m) has an RNT of 73 min.