Water for a yacht trip and picnic: how much and how to keep it cold

In short: for a day at sea, plan on 3 to 4 litres per person, twice the usual amount, because sun, wind and salt water dry you out faster. Still water in 0.5 L PET and personal flasks are handier and safer on deck, while glass is for serving at the table. Ice in a cool box keeps water cold for roughly 6 to 8 hours.

How much water for a day at sea?

Plan on 3 to 4 L per adult for a day out, twice the usual amount. Sun, wind and salt water dry you out more than you notice, and thirst arrives late. For a group of eight that is 25 to 30 L: for example, one 18.9 L bottle plus around twenty 0.5 L bottles. Children need less by volume, but should be offered water more often. Take another litre or so on top for the crew and for rinsing the salt off your face after snorkelling.

• Baseline: 3 L per adult for a day out, more with snorkelling and alcohol
• Children need less by volume but more often
• A litre or so extra for the crew and for rinsing off the salt
• Better to come back with a spare bottle than to finish someone else's

Packaging for deck and beach

On deck, still water in 0.5 L PET wins, Icelandic Glacial or 6ty Degrees: it does not break, it is easy to hand round and it fits any cool box. The bulk of the volume can come as an 18.9 L bottle with a pump, poured into personal flasks. Save Narzan and Essentuki No. 4 in 0.45 L glass for lunch at the table in the saloon, because a shard on a wet deck next to bare feet is dangerous. Mark the bottles with a pen, otherwise half of them will be opened and abandoned by lunchtime. And check the caps: a half-empty open bottle does not survive long in a swell.

• 0.5 L PET: unbreakable, easy to hand round, fits any cool box
• Glass of 0.45 to 0.5 L is for lunch at the table and for photos, not near bare feet
• Mark the bottles with a pen so nobody opens a second one
• The cap must close properly: a half-empty open bottle does not last in a swell

Keeping it cold

Freeze some of the bottles the night before: in the box they work as ice, and by evening you drink them. Pack the rest in layers and put the ice on top, since cold travels downwards. Open the box as rarely as you can, because every time you lose a noticeable amount of cold. With ice and infrequent opening, the water stays cold for around 6 to 8 hours, which covers a day trip. Keep the deck supply in the shade, as plastic heats up in the sun within minutes.

• Freeze some bottles the night before: they work as ice and then get drunk
• Cool box with ice: pack the bottles in layers, ice on top
• Open the box as rarely as possible, because cold escapes each time
• Do not leave water in the sun on deck, as plastic heats up within minutes

Mineral water after a day in the sun

A day at sea takes away more than litres through sweat: sodium, potassium and magnesium go with it. A glass or two of mineral water at lunch goes down better than sweet drinks, and Narzan's label gives 200 to 600 mg of calcium and 50 to 180 mg of magnesium per litre. Alcohol in the sun dries you out more than usual, so drink water between glasses. This is general information and manufacturers' data, not medical advice.

• Sweat takes away more than water: sodium, potassium and magnesium go too
• Mineral water of moderate mineralisation goes down better at lunch than sweet drinks
• Alcohol in the sun dries you out more, so drink water between glasses
• This is general information based on manufacturers' data, not medical advice

Sources

• GOST R 54316-2020: composition of Narzan water (table A.1)