Watermakers for boats 40 to 46 feet.
Between roughly twelve and fourteen metres the boat stops constraining the choice. There is space for a framed system, bank enough for 24 volts, often a genset option, and enough tankage to buffer a cloudy week. That makes this the band where the decision is purely about how you use the boat.
The electrical reality at 40–46 ft. Typically 12 or 24 V, sometimes with a genset. Wide open. If a genset runs daily, buy output per dollar. If you are on solar, the energy-recovery premium buys you something real.
What matters at 40–46 ft
Size for the boat full, not the boat empty
A 44-footer sailed two-up uses half what it does with guests aboard. Size for how you actually cruise most of the year, and use tankage rather than pump capacity to cover the busy weeks.
This is where 24 volts starts paying
The same power at 24 volts halves the current, which means smaller cable and an easier run. It does not make the watermaker more efficient — watt-hours per litre is identical — but it makes the install tidier.
Genset or no genset changes everything
With one, a conventional high-output system fills the tank inside an evening run and the efficiency premium buys little. Without one, the same system is an engine-hours problem every day.
Servicing access is still the trap
There is enough space at this size to hide the unit somewhere beautiful and unreachable. Insist on seeing where the prefilter and membrane housing will sit before work starts.
Shortlist for 40–46 ft boats
The 10 best matches of 35 that suit a boat this size, ordered by balance of both. Run time and energy are for 100 litres a day.
| System | Power | Output L/hr | Draw W | Wh per litre | Price |
|---|---|---|---|---|---|
| Newport 400C Spectra | 12/24/48V DC | 64 | 288 | 4.5 | $14,500 |
| Zen 100 Schenker | 12/24/48V DC or AC | 100 | 400 | 4.0 | $9,600 |
| Zen 50 Schenker | 12/24V DC | 50 | 240 | 4.8 | $7,800 |
| D60 Freedom Dessalatorreported | 12/24V DC | 60 | 550 | 9.2 | on request |
| D60 DUO Dessalatorreported | 12/24V DC | 60 | 550 | 9.2 | on request |
| D100 DUO Dessalatorreported | 12/24V DC | 100 | 700 | 7.0 | on request |
| Portable 24VDC 55L Rainman | 24V DC | 45–61 | 600 | 11.3 | $4,898 |
| Modular 24VDC 55L Rainman | 24V DC | 45–61 | 600 | 11.3 | $5,053 |
| Portable AC 140L Rainman | AC 240V | 100–154 | 1,250 | 9.8 | $5,329 |
| Portable 48VDC 140L Rainman | 48V DC | 100–154 | 1,250 | 9.8 | $6,240 |
Common questions
- What size watermaker for a 44 foot yacht?
- Four aboard at 25 litres each is 100 litres a day. Anything from about 50 litres an hour covers that in a two-hour run. Above that you are buying speed, which matters if your power comes in a window and not much otherwise.
- Should a 42 foot boat have a 12 V or 24 V watermaker?
- Whichever matches the house bank. Voltage does not change watt-hours per litre at all — it changes the current, and therefore the cable and breaker. Putting a 24 V system on a 12 V boat means a converter and a new failure point.
Not your size?
Before you shortlist
Length is a proxy, not a measurement. 100 litres a day is 4 aboard at 25 litres each — a planning figure for boats of this size, not a claim about yours. Two people cruising frugally on a 45-footer use less than a family of four on a 38. The shortlist is filtered to systems whose power source and output suit a boat this size and ordered by balance of both. Watt-hours per litre is rated draw divided by rated output. Methodology.