Watermakers for catamarans
Catamarans change the arithmetic in three ways at once: more roof for solar, more room for machinery, and usually more people aboard using more water. The first two make the problem easier and the third makes it bigger.
The power reality. Cats typically carry the largest solar arrays in cruising, which widens the range of systems that genuinely fit. Many also carry a generator, which widens it further.
What matters on catamarans
Size for the boat full, not the boat empty
A cat that sails as a couple and charters as six needs to cope with six. This is the vessel type where undersizing bites hardest.
Split the install across a hull
A modular system suits a cat well: pump in one engine bay, membranes along a bulkhead, filters somewhere reachable. You rarely need a single large space.
Two engine bays, two intake options
Choose the side that stays in the water on your usual anchoring attitude, and keep the intake well away from the heads discharge.
The solar advantage is real
With a large array the daily surplus can support a conventional DC system that would be marginal on a monohull. Run the numbers rather than assuming you need the premium unit.
Shortlist for catamarans
The 8 best matches of 35 that suit catamarans, ordered by balance of both. Run time and energy below are for 140 litres a day.
| System | Power | Output L/hr | Draw W | Wh per litre | Price |
|---|---|---|---|---|---|
| Zen 100 Schenker | 12/24/48V DC or AC | 100 | 400 | 4.0 | $9,600 |
| D100 DUO Dessalatorreported | 12/24V DC | 100 | 700 | 7.0 | on request |
| Newport 400C Spectra | 12/24/48V DC | 64 | 288 | 4.5 | $14,500 |
| Modular 48VDC 140L Rainman | 48V DC | 100–140 | 1,250 | 10.4 | $6,421 |
| 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 |
| Modular AC 140L Rainman | AC 240V | 100–154 | 1,250 | 9.8 | $5,460 |
| Frame AC 140L, auto Rainman | AC 240V | 100–154 | 1,250 | 9.8 | $11,168 |
Common questions
- What size watermaker for a catamaran?
- Cats usually carry more crew, so 100 to 200 litres a day is common. That points at 60 to 140 L/hr so the run stays inside two hours. Check the energy that costs against your array before choosing.
- Do catamarans need bigger watermakers than monohulls?
- Usually yes, but because of crew numbers rather than hull count. A cat sailed by a couple needs no more water than a monohull sailed by a couple.
- Where do you install a watermaker on a catamaran?
- Most often in an engine bay or a locker in one hull, with a modular system split so no single space has to take everything. Keep the prefilters somewhere you can reach without emptying a locker.
Guides that go deeper
Not quite your boat?
How the shortlist is built. 140 litres a day is 5 aboard at 28 litres each — a planning figure for this kind of boat, not a measurement of yours. The list is filtered to systems whose power source suits catamarans and ordered by balance of both. Every figure is the manufacturer’s rated output and draw; Wh per litre is one divided by the other. Methodology.