The spreadsheet alt_move.xls calculates the effective observed altitude associated with a line of position that is advanced or retarded by dead reckoning. In this technique of compensating for the vessel motion the assumed position is unchanged and only the final adjusted LOP needs to be plotted. Enter the original observed altitude and azimuth from spreadsheet intercept.xls in cells A2 and B2. Enter ground speed and course made good in cells C2 and D2. The time interval in cell E2 is positive to advance the LOP and negative to retard the LOP. The (signed) distance traveled in nautical miles is displayed in cell F2. Reenter the adjusted observed altitude from row 6 in cell E2 of intercept.xls to obtain the new intercept.

Summary for spreadsheet alt_move.xls:

Input cells: A2, B2, C2, D2, E2

Output cells: A6, B6, C6

Intermediate cell: F2