Free Calculator: Planning Your Water for Long Passages

There’s a moment every long-distance cruiser faces—the day you leave the coast behind and watch land sink beneath the horizon. The sea feels infinite, but your supplies are not. Among all the resources you manage on passage, water is the one that matters most. It dictates comfort, safety, and even morale. Underestimate it, and every sip becomes a calculation. Overestimate it, and you’ll spend half your voyage lugging weight you’ll never use.

Getting water right is both an art and a science—and a compact watermaker can make the difference between anxiety and freedom.

1. Know your consumption

Before plotting miles or meals, learn your water rhythm. Most cruising couples use between 30 and 50 litres per day for drinking, cooking, and basic hygiene when living modestly. Add more if you have kids, pets, or enjoy the simple joy of a long rinse under the transom shower. The best way to know your true use is to measure it: fill your tanks, live aboard for a week, and see where it goes.

Once you know your daily draw, you can plan properly.

2. Tank capacity and safety margin

Multiply your daily use by the number of days between reliable refill opportunities. Then add at least a 20 % buffer for comfort and contingencies. Let’s say you use 40 litres per day and plan a 15-day passage between ports—that’s 600 litres plus 120 litres for safety. Seven hundred-plus kilos of water. That’s a huge share of your displacement, eating into speed and storage.

Many sailors realise too late that carrying all your water isn’t the same as having enough water.

3. The watermaker equation

A compact reverse-osmosis unit changes everything. A small system like the Scout 20 produces 20 litres per hour. Run it for three hours, and you’ve replenished 60 litres—enough for a day and a half for two people. The Scout 10 takes longer but runs on the same thrifty diet of power, drawing only about 200–250 watts (around 9 amps on 12 volts). That’s well within the output of a modest solar array or battery bank, meaning you can make fresh water in silence while you sail.

Instead of searching for marinas or carting jerry cans in the dinghy, you turn sunlight and seawater into independence.

4. Routine, not rescue

Think of your watermaker as part of your daily routine, not an emergency lifeboat. Running it regularly keeps membranes flushed, filters clean, and systems predictable. A few litres made each day beats panic production when you’re already low.

That said, prudence matters. Always keep a few days of stored water as backup in case of breakdown, dirty feed water, or rough seas that make operation impractical.

5. Freedom in every drop

A reliable watermaker changes your entire cruising psychology. You stop rationing tea water. You stop worrying whether the next anchorage has a tap. Showers become normal again, not guilty pleasures. You start to plan passages by wind and weather, not by where you’ll top up your tanks.

It’s a subtle but profound shift: independence isn’t just about range—it’s about comfort and confidence.

A Scout on board means your voyage is measured not in litres carried, but in horizons crossed.

Why cruisers choose Scout

Compact, quiet, and efficient, the Scout 10 and Scout 20 are purpose-built for sailors and off-grid adventurers who value self-reliance. Designed in New Zealand, they run directly off 12 V DC or solar power and produce 10–20 litres of fresh water per hour—enough to turn seawater into comfort wherever you roam.

• Lightweight (~25 kg) and portable

• Low-power draw for solar setups

• Easy self-installation and maintenance

• Built for blue-water reliability

→ Learn more about the Scout range
→ Get your introductory pricing until 31 Oct 2025