Initial Course
1st Initial Course :
Sen Ri = cos ln x sec l
Rumb line in the parallel of latitud of Ice Gate
2nd. Initial Course:
Sen Ri = cos ln x sec l´
Distance calculations
Cos D1= sen l x cosec ln
Cos D2 = senl x cosec ln
If cos D is + get < 90º
If cos D is - get > 90º