The spreadsheet distance.xls implements the formula from Bowditch to calculate the distance by vertical angle between the waterline and the top of an object. Select "ft" or "m" in cells C1 and C2, and enter the corrected vertical angle in cell B3. The distance in nautical miles is displayed in cell B4.

Summary for spreadsheet distance.xls:

Input cells: B1, C1, B2, C2, B3

Output cells: B4