Sailing at Night: Guarding Your Night Vision

Once the sun sets, your biggest asset is your eyes — and they're surprisingly fragile. It takes your eyes about 20–30 minutes to fully adapt to darkness, but only a single glance at a bright white light to ruin it. This is why night sailors are obsessive about preserving night vision: instrument screens dimmed to minimum, cabin lights switched to red light (which the eye's dark-adapted rods barely register), and no phone screens or spotlights on deck unless absolutely necessary.

Good watchkeeping is the backbone of a safe night passage. Recall from earlier cards how a skipper thinks ahead — at night that means a proper watch rota so nobody is exhausted (typical watches run 2–4 hours), clipping on with a harness in the cockpit, and a disciplined lookout. Scan the horizon slowly and use your peripheral vision: the rods that see best in darkness sit off-centre, so a faint light often appears when you look slightly beside it rather than straight at it.

At night you navigate largely by lights, not shapes. A vessel's red (port) and green (starboard) sidelights plus white lights tell you its heading and roughly its type; a steady bearing on another light means a collision risk. In reduced visibility — fog, heavy rain, snow — you may lose lights entirely, so the rules change: slow to a safe speed, sound fog signals, post an extra lookout, and lean on radar and AIS while trusting your compass over your instincts.