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

Yachting Monthly - - USING A SEXTANT -

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’

Prac­tice us­ing your sex­tant on a calm day at first and find a lo­ca­tion on board that suits you best

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