It only takes a little while of living on a yacht to develop a mental map of sounds. If you are on the right wavelength, a change in the usual symphony of noises can tell you when something is wrong. No matter how deep your sleep off watch, the slightest new sound or change of frequency will wake you, instantly.

The ear soon tunes into some sounds, such as the rumble of chain as the ground tackle moves over the bottom or swings to a wind shift and the chatter and gabble of water along the topsides as she begins to turn at anchor to the new tide. Some of these sounds can be quite peaceful. I love to hear the soft inevitability of water lapping at the hull as the tide turns on a calm night. I enjoy the fox’s doze that you can drift into while waiting for a yacht to fall in with the new stream.

Many little noises will tell you that something has changed: the autopilot drive working too hard; a water pump running with a different note. Being parsimonious about the use of freshwater, a habit from small boats that dies hard, I get twitchy when I hear a pump running with frantic bursts. On a recent sailing trip, the skipper remarked that I hadn’t been able concentrate on a conversation because another crewmember was taking a long shower. That made him laugh.

There are some maddening sounds on board that almost everyone hates: halyards slapping on the mast when you’re trying to sleep on board at a mooring or alongside or, infuriatingly, another yacht’s halyards clanging when yours are tightly frapped; pans clanking in the galley or, worse, bottles rolling somewhere unreachable in a locker as the yacht rolls at anchor. Almost as bad are those indeterminate little tapping sounds that can never be traced when you pad up on deck at night, half-clothed, but are immediately magnified again as soon as you are back in your bunk.

Some of the best off watch sleeps are to be had under motor, when the regular noise of the engine drowns out anything else and you can allow yourself to be lulled by some predictable miles in the right direction. Conversely, though, almost nothing will wake you faster or get you up on deck quicker than a sudden change of engine note or revs.

But some of the longest and most unpleasant nights I’ve spent on board have been while tied up alongside. I’ve spent insomniac nights in the cavernous, empty aft cabin of a new yacht as the counter slapped enthusiastically at the water all night. Even the sound of wind wailing through the rigging can be more restful.

Being attuned to changes in sounds is such a useful skill that many skippers sailing on long passages offshore forbid crew to listen to music on earphones while on watch. On one hand, music is a big help in staying awake while standing a single person watch because it makes the hours go by that bit faster. But it does mute awareness, and there is an argument that being alert to sounds as well as motion and wind is part of a crew’s watchkeeping responsibilities.

That said, you can’t think of visit of any length on board a crewed yacht without stashing away some good earplugs in your wash bag. These are among of the best value bits of nautical equipment you will ever buy. There are times when their magical ability to extinguish a cacophony of noise, especially the manmade ones, is absolutely priceless.