Watermaker Selection: What Actually Makes Sense on a Small Cruiser?

Choosing a watermaker isn’t just about litres per hour — it’s about freedom, power, and practicality. A desalination system can transform your cruising life, but the wrong one can drain your batteries, space, and patience. With major brands like Rainman and Spectra setting the benchmark, how does the LEDI Scout compare, and which system truly suits a small boat or off-grid adventurer?

How to Choose the Right System

Every watermaker decision revolves around four things:
crew size, water habits, energy budget, and installation space.
A couple on a 9 m monohull who use 40 L a day doesn’t need a 140 L/h AC unit built for superyachts. In fact, oversizing your system often means wasted energy, more maintenance, and unnecessary expense. Compact 12 V units, by contrast, can make enough water quietly while you charge your batteries or run a small solar array.

Comparing Power and Performance

Rainman Portable AC (100–140 L/h)
This Australian-made powerhouse is designed for large vessels with generators. It produces up to 140 litres per hour via a 1.25 kW AC motor — roughly 6 A at 230 V or 12 A at 115 V. It’s fast, but noisy, heavy, and thirsty for energy. At AU $8K+, it’s also a significant investment for smaller boats.

Spectra Catalina 340C (53 L/h)
Spectra’s DC-powered systems are known for quality and quiet operation. The Catalina makes around 53 L per hour and draws about 20 A at 12 V. With proprietary membranes and control electronics, they work beautifully when maintained but can be costly and complex to service at sea. Expect to pay roughly AU $20K+.

LEDI Scout (10–20 L/h)
The Scout produces 10–20 L of fresh water per hour while drawing only about 19 A at 12 V DC. It weighs around 18 kg and fits in a locker or under a bunk. Designed for seawater or slightly brackish sources, it includes a built-in UV steriliser for microbiological safety — something rare at this size and price. The Scout runs happily from batteries or solar, making it one of the few truly generator-free options for small cruisers.

Real Cost of Ownership

Buying the unit is only part of the story. Over three years, energy consumption, filters, membranes, and maintenance all add up.

• Rainman: High throughput but high operating costs. Requires a generator or large inverter, and replacement membranes are expensive. Great for heavy users but inefficient for light ones.

• Spectra: Excellent build quality, but proprietary parts mean higher service costs and longer lead times for spares.

• LEDI Scout: Designed around standard membranes and filters, meaning parts are globally available. The compact DC pump and low power draw cut energy costs dramatically. Its owner-serviceable design lets you maintain it with basic tools — no technician required. At a retail price well below AU $6,000, it delivers one of the lowest total costs per litre in the category.

Space, Simplicity, and Serviceability

Rainman’s systems are powerful but bulky — think of them as the “diesel truck” of watermakers. Spectra offers quieter performance but still involves fixed plumbing and control electronics that take up valuable locker space.

The Scout, by contrast, was built for boats in the 7–12 m range, where every cubic centimetre counts. Its modular frame, quick-connect hoses, and optional carry case make it both portable and installable. You can deploy it on deck, stow it between voyages, or fit it permanently under a seat. Its design emphasises ruggedness and field serviceability, so you can replace a filter offshore instead of waiting for a technician in port.

Who Should Choose Which?

• Rainman: Best for 12 m + yachts with generators, high daily water demand, and crew comfort expectations like daily showers and deck washdowns.

• Spectra: Ideal for mid-sized yachts (10–15 m) with robust 12/24 V power systems and a need for continuous high-quality output.

• LEDI Scout: The sweet spot for small cruisers, liveaboards, and overland travellers. Its modest draw (about 19 A) means it can run entirely on solar or batteries, and its 10–20 L/h output comfortably supports two to four people. It’s light enough for dinghy runs and sturdy enough for blue-water passages.

Why the Scout Makes Sense

For most small cruisers, the Scout strikes the best balance between cost, convenience, and capability. It’s roughly one-third the weight and half the cost of many competitors, yet it can make enough water daily to keep a couple or small family independent indefinitely. Because it uses standard reverse-osmosis components, it’s easier and cheaper to maintain — you won’t be locked into proprietary service kits.

Perhaps most importantly, it eliminates the generator from the equation. You can make fresh water silently, at anchor, powered only by sunlight and stored charge. That means less fuel, less noise, and more freedom to explore — exactly what small cruising boats are built for.

Conclusion

The best watermaker isn’t the one with the biggest numbers on paper; it’s the one that fits your life afloat.
Rainman delivers brute output for big vessels. Spectra brings high-tech polish to medium yachts. The LEDI Scout delivers something different — self-sufficiency for small boats. Compact, solar-friendly, and built for real-world use, it turns the idea of “small cruiser compromises” on its head.