ABSTRACTCollision avoidance aids used in conjunction with marine radar range from plotting sheets and special plotters to computer based “Automatic Radar Plotting Aids” (ARPA). One device, which has received very little attention is the hand‐held or pocket calculator. The potential of the calculator for use in radar tracking is explored. The use of calculators with differing capabilities are examined respecting their possible use for distance/velocity/time computations, vector arithmetic to determine relative and true motion and, with the more advanced programmable variety, solutions for closest point of approach (CPA) information as well as an aid in maneuvering to avoid targets whose CPA's are too close. An example of an algorithm for a programmable calculator is presented. The limitations of calculators as a collision avoidance aid are discussed. The conclusion is that the available hand‐held calculators will not replace ARPA's but could be useful as a backup to ARPA and as an aid on ships not equipped with ARPA when traffic density is not so great that the operator becomes ove