How do I clean the water-tank air vents on a Hallberg-Rassy 55?

Clean the freshwater-tank vents by tracing each breather hose from the tank to its outlet, cleaning the outlet and any mesh, then flushing the hose with its tank end disconnected. First check for kinks, trapped water or a blocked screen, as cleaning will not fix a collapsed or sagging hose.

Trace each breather hose

Start at the top of each freshwater tank and identify the vent connection. The filler hose is substantially larger; the smaller breather hose lets air escape during filling and enter as water is drawn off. Trace it physically rather than relying on diameter alone.

On an HR 55, the outlet position, fittings and access can vary with hull number and later alterations, so use the boat's freshwater-system drawing if available. Do not assume a hose ending in the bilge is original, or that a nearby hull vent serves the drinking-water tank.

• Look for flattened hose behind joinery, tight bends and loose clips.
• Check low points where water can collect and obstruct airflow.
• Inspect the outlet for salt deposits, insect debris and clogged mesh, if fitted.
• Check for hose that has hardened or cracked, and internal dirt that warrants replacement.

Slow filling, water backing up at the deck filler, or a tank changing shape during pumping can indicate restricted breathing. Stop filling or pumping if the tank visibly distorts.

Disconnect the tank end

Lower the water level below the vent connection, switch off the freshwater pressure pump and stop any automatic filling or watermaker supply. Clean around the tank connection before removing the hose to keep loose dirt out.

Photograph the hose route and label connections before dismantling. Use a screwdriver or socket that fits the hose-clip screw, support the tank fitting and gently twist the hose free. If it has seized, do not lever against the tank spigot. Replace an old hose rather than risk breaking the connection.

Cover the exposed tank connection with a clean temporary cap. Remove the outlet's serviceable cover or screen if its design allows, but leave a sound, sealed hull fitting in place unless removal is necessary. Keep potable-water tools separate from tools used on diesel, toilets or bilges.

Never use compressed air against a connected tank. Even modest pressure can damage the tank or its fittings.

Clean the outlet and hose

1. Brush loose dirt from the outlet with a soft nylon brush. Wash removable parts in warm water with a little mild detergent, then rinse thoroughly.
2. Clean mesh gently from both sides. Replace torn or badly corroded mesh; do not enlarge the holes with wire or a drill.
3. With the tank end disconnected and directed into a bucket, rinse the hose with clean drinking water so debris leaves through the disconnected end.
4. If accessible, remove the hose completely for cleaning. Use a suitably sized flexible nylon tube brush only where it passes freely; do not force it around elbows.
5. For persistent slime, use a cleaner labelled for potable-water systems and compatible with the hose and fittings. Follow its dilution, contact time and rinsing instructions.