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Barnacles are tough. They attach with a natural cement, grow quickly in warm water and are very hard to remove once they have formed a layer. Marine growth and barnacle removal in Nagoya often starts with a phone call that begins: the cooling temperature is rising and we do not know why.
On the open Hull, barnacles raise friction and fuel use. In sea chests and gratings, they reduce the flow of cooling water. In intake pipes and strainers, they can fall off, block the flow or damage equipment. Mussels and tubeworms behave in much the same way. The worst areas are those with slow water movement and sheltered corners.
Sea chests are boxes on the Hull side or bottom that bring sea water to the ship's pumps. The gratings that cover them are easily blocked. A Diver can clean the grating by hand and, where the design allows, look into the chest with a camera. If the chest is badly fouled, it may need cleaning from the inside during dry-docking, but a surface cleaning from outside often restores flow enough to keep the ship working. The engine room should isolate the intake before the Diver approaches.
On the Hull, we use scrapers, stiff brushes or rotating tools, depending on the coating. Barnacles that have grown through the paint can leave the plate rough and exposed even after cleaning. We film the result so the owner can judge the condition of the paint, and we point out any area that needs recoating at the next dry-docking.
Barnacles on the propeller and rudder reduce efficiency and may hide damage. They are removed carefully with tools that do not mark the metal. The Diver checks the surface afterwards and mentions any pitting or erosion that the growth had covered.
In warm water, new barnacle larvae can settle within weeks. Return rate depends on the coating, the trading pattern and the water. Ships that move often foul more slowly. A ship that sits at anchor or at berth for long stretches should be checked more often.
Tell us where the problem shows up: temperature, flow or speed. We focus on the likely area. A partial job on the sea chests and the propeller often takes 2 to 4 hours, and a full Hull takes longer. The report includes video, photographs and a note on what was found.
Several signs show that a sea chest or intake is partly blocked. Cooling water temperatures rise, pump suction pressure falls, strainers fill with shell fragments, or alarms occur in the cooling system. If any of these has appeared, tell us. A Diver can often clean the grating and check the chest opening within a couple of hours, which may be enough to bring the ship safely to the next planned dock. We always report what we could and could not reach.
Never allow a Diver near an intake that is running. The engine room must stop the pump or close the valve and confirm it before we enter the water.
Q1. How quickly can barnacles settle on a Hull?
In warm water, larvae can settle within weeks, and a noticeable layer can form within a few months, depending on the coating and the ship’s activity.
Q2. Which ship systems are affected by barnacles?
Sea chests, gratings, strainers and cooling water intakes, as well as the propeller and the open Hull, which loses efficiency.
Q3. How long does cleaning the sea chests and propeller take?
A partial job on these areas often takes 2 to 4 hours of dive time.
Q4. Must the intake be isolated before the Diver approaches?
Yes. The engine room must isolate the sea water intake and confirm it before the Diver works near a sea chest or grating.
