Rainman Desalination

Sizing A Watermaker For A Cruising Boat

Output should be chosen from the crew's real daily water use rather than from boat length alone. Drinking and cooking may require relatively little water, while regular showers, washing machines, deck rinsing and liveaboard use can multiply consumption. A higher-output unit can shorten run time but may demand more AC or DC power. A low-energy DC system can suit a solar-heavy yacht but may need to run for many hours to fill the tanks. Owners should compare litres per hour, watts consumed, daily energy required and the capacity of the boat's battery, alternator, solar, inverter or generator system.

Installation space is equally important. Modular systems allow the membranes, filters and pumps to be separated around a machinery space, while framed systems can be easier to install and service when enough room exists. The intake should be located where it is unlikely to draw air or contaminated harbour water. The brine discharge needs a reliable route overboard. Filters, pressure gauges, flushing valves and membrane housings should remain reachable for routine maintenance rather than being buried behind permanent joinery.

Maintenance And Long-Term Use

Watermakers reward regular use and correct shutdown procedures. Seawater left stagnant inside a membrane system can create biological fouling, so freshwater flushing is important when the unit will sit unused. Longer lay-ups may require preservation or pickling using the manufacturer's specified process. Prefilters need routine replacement and should be checked more often in silty, plankton-rich or polluted water. Product-water quality should be monitored before water is diverted into the main tank, particularly after servicing or a long period of storage.

Owners planning remote cruising should ask which spares are sensible to carry. Typical items may include sediment filters, pump service parts, O-rings, belts or impellers, hoses and preservation chemicals, but the correct kit depends on the specific system. Membranes often last a long time when operated and maintained correctly, so replacing them simply because of age is not always necessary. Diagnosis should consider feed flow, pressure, temperature and water quality before assuming the membrane has failed.

Bathurst Harbour

Bathurst Harbour (Port Davey system), in south‑west Tasmania, is a vast, almost land‑locked estuarine harbour inside the Southwest National Park and World Heritage Area. It offers a remote, sheltered anchoring environment protected from the Roaring Forties, but demands careful planning, an awareness of marine‑reserve rules, and a willingness to operate in shallow, tannin‑stained waters. Best suited to experienced coastal cruisers and small expedition yachts prepared for self‑sufficiency, Bathurst Harbour is more a place to linger and explore on foot and by tender than a port of call for busy,