Watermakers for boats under 33 feet.
Under about ten metres the constraint is rarely water — it is where the machine lives and what the bank can spare. A boat this size usually has one modest battery bank, no generator, and nowhere obvious to put a framed system, which rules out most of the market before efficiency is even considered.
The electrical reality at under 33 ft. Typically a single 12 V house bank, no generator. One bank, no genset, and usually a small array. Everything has to run off 12 volts and fit inside what the fridge leaves behind.
What matters at under 33 ft
Space decides more than specification
On a boat this size the honest question is where the pump, the membrane housing and the prefilters go, and whether you can still reach them. A portable unit that lives in a cockpit locker between uses often wins on that alone.
Two people need surprisingly little
At a frugal 15 litres a head, a couple gets through 30 litres a day. That is under an hour on almost anything in the table, which means you are buying efficiency and simplicity rather than output.
Watch the current, not just the watts
A 12 V system pulling 40 amps is a serious load on a small bank. Check the amp draw against your cable, your breaker and what the alternator puts back on a short motor.
Tankage may be the better buy
On a small boat another 60 litres of tank is cheap, silent and needs no power. Exhaust that before spending five figures on a system you then have to find room for.
Shortlist for under 33 ft boats
The 10 best matches of 12 that suit a boat this size, ordered by fits and stows. Run time and energy are for 30 litres a day.
| System | Power | Output L/hr | Draw W | Wh per litre | Price |
|---|---|---|---|---|---|
| Scout SW20 LEDIreported | 12V DC | 20 | 200 | 10.0 | on request |
| Portable 24VDC 55L Rainman | 24V DC | 45–61 | 600 | 11.3 | $4,898 |
| Portable 12VDC 34L Rainman | 12V DC | 26–37 | 400 | 12.7 | $4,898 |
| Zen 30 Schenker | 12/24V DC | 30 | 110 | 3.7 | $6,300 |
| Ventura 150 Deluxe Spectra | 12/24V DC | 24 | 108 | 4.5 | $6,000 |
| Ventura 150 Connect Spectra | 12/24V DC | 24 | 108 | 4.5 | $7,400 |
| 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 |
| Modular 24VDC 55L Rainman | 24V DC | 45–61 | 600 | 11.3 | $5,053 |
Common questions
- Can you fit a watermaker on a boat under 33 feet?
- Yes, and portable units in particular are designed for exactly this — nothing to install, and they stow when not in use. The limit is usually locker space and battery capacity rather than the watermaker itself.
- What size watermaker for a 30 foot yacht?
- Work from crew, not length. Two people at a frugal 15 litres each need 30 litres a day, which even the smallest systems in our table make in about an hour. Buy the efficiency, not the output.
Not your size?
Before you shortlist
Length is a proxy, not a measurement. 30 litres a day is 2 aboard at 15 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 fits and stows. Watt-hours per litre is rated draw divided by rated output. Methodology.