Celestial Navigation · Sextant Corrections — Dip
Your height of eye is 25 feet. Using dip ≈ 0.97 × √(height in feet), what is the dip correction (to the nearest 0.1')?
- A+4.9' (added)
- B−4.9' (subtracted)✓ Correct
- C−2.4'
- D−9.7'
Explanation
Dip = 0.97 × √25 = 0.97 × 5 = 4.85' ≈ 4.9'. Dip is always subtracted from the sextant altitude (it is negative) because height of eye places the visible horizon below the true horizontal.
Authority: Nautical Almanac, Dip table; Bowditch (Pub. No. 9)
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