If the crew were having problems with the TANS, the first port of call would be SELECT DOPPLER
Would it? On a system with GPS available and knowing that the system is trying to "average" the GPS position and the Doppler position in a situation where Doppler will always be more of a guess because of surface motion of the water? Did the SuperTANS not have the ability to select GPS only? It would seem to me to be a logical option.