WHEN SUMMER BECOMES THE ULTIMATE STRESS TEST FOR YACHT SYSTEMS
A familiar sight in Mediterranean marinas these days: crowds of tourists gather around modern yachts, watching thick streams of water continuously discharge from outlets along the hull.
Theories quickly follow: water ingress, engine cooling water, even shower wastewater…
The reality is much simpler.
Mediterranean hotspots are packed during the summer, and almost every modern yacht is running its air conditioning—often together with a watermaker—whether at anchor or in the marina.
The reason is obvious: yachts heat up incredibly fast under the blazing sun. Just like a parked car, interior temperatures of 60°C (140°F) or more are not uncommon. Modern yachts with large glass surfaces, teak or synthetic teak decks absorb even more heat, making efficient ventilation and air conditioning an essential comfort feature rather than a luxury.
One question we hear regularly is:
How large do the seawater intakes actually need to be?
An 18,000 BTU marine air conditioning unit requires approximately 5,000 litres (1,320 US gallons) of seawater per hour at full capacity to cool its condenser. Add a watermaker, and the demand increases even further. A system producing 100 litres (26 US gallons) of fresh water per hour typically requires around 1,000 litres (264 US gallons) of seawater per hour, with approximately 900 litres being discharged back into the sea—slightly warmer and with a higher salt concentration.
In the Mediterranean, where seawater temperatures often exceed 27°C (81°F) during summer, seacocks and through-hull fittings operate under particularly demanding conditions.
For this reason, we believe non-metallic composite seacocks are the best solution. We consistently install TruDesign products because they do not corrode and won’t leave rust stains around hull outlets. Through-hulls and discharge fittings should ideally not be made of metal. Even stainless steel can suffer from crevice corrosion under unfavourable conditions.
Here’s another interesting fact:
A 1-inch seacock installed at approximately 1 metre (3.3 ft) below the waterline can theoretically supply up to 8,000 litres (2,110 US gallons) of seawater per hour. Whether multiple consumers—such as several air conditioning units and a watermaker—can safely share the same intake, and how an intelligent flow controller can optimise the entire system, is something we’re always happy to discuss.
We exclusively supply and install @Blue-Airco air conditioning systems and Schenker Watermakers professionally installed on your yacht.
So next summer, you can stay cool on board while everyone enjoys a proper shower: