James Turner’s tips for using a sextant on board
Using a sextant on a yacht is different from practicing on land, as James Turner explains
If you haven’t used a sextant on board your yacht before, you’ll need to find the best place to take sights from. If your standing rigging includes foreand-aft lowers, it’s generally best to go up there where you can wrap your arms around the rigging & keep your upper body really steady. If the rig is swept and there isn’t a pair of wires to wrap your arms around, the next best place is probably leaning back against the mast, with your feet well spread.
Sometimes the sun will be behind the headsail, so you’ll get a better sight by changing course for a few minutes so you can take the sight from the optimum position, rather than balancing precariously in a less secure place.
Also consider altering your course to head off the wind, which is generally a smoother ride. Get used to swinging your upper body to keep your shoulders lined up with the horizon, moving your legs as the boat rolls and pitches. Practice using your sextant and taking sights as often as possible. In due course you won’t need to take three sights, as you’ll know when you’ve taken a good one.
Finally, if you’re taking a single sun sight, go below with the angle still set on the sextant, and work it out before you move the arm to stow the instrument. From time to time your sight won’t make sense when you’ve plotted it, and the first thing to check is whether you wrote down the correct angle in the first place. If you’ve stowed the sextant you’ll have lost the data, so you’ll have to go and take another sight. According to Sod’s law of the ocean, the sun, by this time, will have gone behind a cloud, and the rock-strewn reef will be approaching!
‘Practice using your sextant and taking sights as often as possible’