I did buy a new watch with the hunting timer(CASIO)and after setting log + lat,GMT, its very close to the O'neil hunting table(within 1/2 hour).it goes off a little earlier then the table shows by about half hour,gives me time to settel in.Its probley the GMT time I have set -5 GMT maybe it should be -5.5 but then I wouldnt have a 1/2 hour safe zone.....A well 37.00 dollors spent,besides I needed a new watch .