How to Choose a Watermaker for Your Yacht

The most common mistake when buying a watermaker is treating the catalogue figure — litres per hour — as your daily water supply. A 50 L/hour unit produces 50 litres in one hour of operation, not per day. If your crew needs 200 litres daily, that same unit must run for roughly four hours. Start with daily consumption, then work backwards to hourly capacity.

For a full model comparison by boat type and power supply, see our Which Watermaker Is Right for Your Boat? guide.

Quick Formula

Daily need ÷ Hourly output = Run time (hours)

Example: 200 L ÷ 50 L/hour = 4 hours/day

Calculating Daily Water Consumption

Use the table below as a starting point for a typical cruising crew. Adjust up or down based on your habits.

Item	Low	Medium	High	Unit
Drinking water	3	4	5	L / person / day
Cooking, beverages	5	8	12	L / person / day
Shower	15	30	50	L / person / day
Cleaning, laundry	5	10	20	L / person / day

Example Scenarios

4 crew — sailing yacht (15 m)

Medium use: ~35 L/person/day

Daily total: ~140 L

SCW-50 (50 L/hour) → ~3 hours/day sufficient

8 crew — motor yacht (22 m)

Medium-high use: ~45 L/person/day

Daily total: ~360 L

SCW-150 (150 L/hour) → ~2.5 hours/day sufficient

12 crew — gulet (24 m)

High use (guests + crew): ~50 L/person/day

Daily total: ~600 L

SCW-350 (350 L/hour) → ~2 hours/day sufficient

What Does Hourly Capacity Actually Mean?

The rating on a watermaker label — for example 100 L/hour on an SCW-100 — is the maximum fresh water output under nominal conditions (seawater ~25°C, salinity 3.5–4%). Actual production may vary by 5–15% depending on water temperature and filter condition.

Calculate how many hours per day the unit must run to meet your needs. As a rule of thumb, aim for 2–5 hours of daily operation — good for energy efficiency and membrane life.

If you need 6+ hours daily → consider the next model up
If 1 hour is enough → a smaller model may suffice
Planning long anchorages with no shore water → size tank capacity and watermaker output together

Model	L/hour	In 4 hours
SCW-30	30	120 L
SCW-50	50	200 L
SCW-100	100	400 L
SCW-150	150	600 L
SCW-350	350	1,400 L

Starting Point by Boat Length

Use this as a first filter — always confirm against your power system before ordering.

Length	Type	Typical Daily Need	Suggested Model
8–12 m	Small sailing yacht	80–150 L	SCW-30 or SCW-50
12–16 m	Mid sailing yacht / catamaran	150–250 L	SCW-50 or SCW-100
16–22 m	Motor yacht / large sailing yacht	250–400 L	SCW-100 or SCW-150
22–28 m	Gulet / large motor yacht	400–700 L	SCW-150 or SCW-350
28 m+	Superyacht / commercial	700 L+	SCW-350, SCW-500

Blue Cruise and Long-Range Sailing

If you are planning a blue cruise from Göcek, Marmaris or Bodrum — or crossing to the Greek islands — water independence matters more than on a marina-hopping itinerary. Gulets with 8–12 guests and crew often consume 400–600 litres daily when showers are included. Motor yachts wintering in Turkey and operating through the season benefit from a watermaker sized for peak guest load, not average day-use alone.

Seacraft provides on-site installation at marinas across the Turkish coast. We come to your berth — see our service locations for your area.

Frequently Asked Questions

No. 50 L/hour is the output in one hour of operation. For 200 litres daily you need roughly four hours of run time. Daily production = hourly capacity × hours running.

If your tank exceeds daily consumption and you take on marina water every night, a watermaker is optional. For extended anchoring, remote coves and high marina water costs — common on the Turkish coast — a watermaker gives real independence.

A larger unit runs for fewer hours but needs more power, space and budget. Moving to SCW-100 on a pure 12V battery system is often impractical. Talk to our team before oversizing — the right fit balances output, power and cost.

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