Writing to SD card using GPS produce distorted sentences

Using Arduino Storage
8

LaurenceR:
The compiler only recognises it is a string if I use a Capital S?

After some googling, I found there is a possible max of 82 characters (80 visible characters plus terminators).

char NMEA1[83];
char NMEA2[83];

82 plus the terminating NULL ( '\0' )

Unfortunately for you the Adafruit library uses the capital S String objects, but they probably didn't anticipate all the other stuff you have thrown in.